CYCLING PERFORMANCE TIPS

THE TORSO - BACK AND ABDOMINAL MUSCLES

Back muscles are not adequate in themselves to supply the needed torso rigidity. Evolution has left us with musculature designed for quadripedal animals, and the muscles which could support a hanging, horizontal spine don뭪 stabilize a vertical one subjected to all the impacts and forces that upright posture dictates.

However, we have abdominal musculature which can aid in torso support. These are the muscles which contract the body to enable a running animal to bring its legs forward. The quads straighten the leg. The hamstrings bend it at the knee. The abdominal and groin muscles pull the leg over the top of the pedal stroke. But they do something else, too. They provide stiffness to the torso to support and reflect the force of the legs, whether pushing away against the ground in running, or pushing against the pedals in riding a bicycle. This is where we get stability on the bike.

If your only strength work is on your abdominals, this alone will vastly improve your riding. Strong abdominals are also the key to preserving a healthy back, and are the foundation of strength for a strong rider. Riding with undeveloped abdominals is something like riding a bike with a cracked frame. All the energy gets dissipated in flexion, and doesn't get you down the road.

Squats are also a good exercise to strengthen the torso, if done right. The weight and torso should rise together as the legs straighten, with the abdominals tight, helping the back muscles to hold the torso rigid. If you can't lift with this style, you are lifting too heavy a weight.

Strong Durable Bike Wheels

Table of Contents What makes a strong wheel? Ingredients Hubs Rims Spokes Nipples Tools for the DIY approach Building a wheel Lacing Tensioning and truing Stress relieving Further reading If you want someone else to do it for you

Everyone wants strong wheels that stay true and don't buckle. On top of that, they want them light and cheap. Well, the good news is that you actually can go a long ways towards getting this ideal wheel. This article aims to cover the basics of what you need to know to approach this, whether you want to make your own wheels, or whether you want to select parts for a wheel that someone else will build for you.

Almost everything I know about wheelbuilding comes from reading Jobst Brandt's book The Bicycle Wheel. If you want to be an expert in wheelbuilding, buy it and read it. This article has only a small amount of info that isn't contained in the book. My main purposes are to provide info on parts of wheels for people who want others to build their wheels, and to inspire people who are thinking of building their own wheels. Click here for a review of The Bicycle Wheel.

The strength of a wheel comes mostly from the spokes, and secondly from the rim. To have a strong, durable wheel, the quality of the wheelbuilding is far more important than the quality of the parts.

Most people seem to think that wheels fail in impacts because spokes break. In fact this isn't true. Most of the time when you have a buckled wheel, you'll find that despite the now potato-chip shape of your wheel, the spokes are all intact.

Wheels collapse when one of more of your spokes loses tension as a result of an impact. Obviously, the spokes that lose tension are the ones right at the point of impact. Then there's nothing supporting the rim, and it twists. The tighter your spokes are to begin with, the further they have to go before they lose tension. Thus a high-tension wheel is one that will resist impacts well.

And yes, spokes do break, but it's not usually as the result of an impact, typically they just break as you're rolling along. Spokes break as a result of fatigue. If your wheel is loose, then every time the wheel goes around, it flexes a tiny bit, and eventually it breaks. In fact spoke breakages are the most telling sign of wheels that don't have high enough tension. If your spokes are tight, the spoke doesn't move as the wheel turns, so they can last much longer. Thus a high-tension wheel is one that will last a long time with few spoke breakages.

The rim does contribute to the strength of the wheel, which is why rims for downhill mountain biking or expedition style touring are quite wide. However, they do this at the expense of quite a bit of weight. While you don't want a rim that's too wimpy for your intended use, the best way to increase the strength of your wheel is to increase the spoke count and make sure the spokes are about as tight as they can be.

Another thing that affects the strength of the wheel is the amount of dishing. This is mainly a problem with the rear wheel, although it is an issue with front wheels with disc brakes as well. On a normal front wheel, you have flanges equidistant from the center of the hub, and spokes go from these flanges to the rim. The spokes coming from each flange go at the same angle to the rim. On the other hand, consider a rear wheel. The right side of the hub has to have room for lots of sprockets, so the right side flange is much closer to the center than the left side flange. Thus if the rim is aligned with the center of the hub as it should be, the left side spokes will be more slanted than the right side spokes (in some cases the right hand spokes are nearly vertical). Thus, in order to keep the rim in the center, the right hand spokes will have to be much tighter than the left hand spokes. When the wheelbuilder is tensioning the wheel, the right side spoke will reach their maximum tightness long before the left spokes will. It is the weakness of the less-tight left hand spokes that makes a highly dished wheel (one where the angle difference between the left and right spokes is great) less strong and less durable than a wheel with less dish.

In order to offset the growing numbers of cogs used in the rear wheel, the total width of hubs has been expanding. Fixed gear track hubs have an over-locknut (basically, the width of the space between the dropouts on the bike) width of 110mm. The old 5 and 6-speed screw-on hubs have a width of 126mm. Now hubs are usually 130mm wide for road use, 135mm wide for off-road or touring use, and 140mm to 160mm wide for tandems. The idea with the wider hubs is to put more distance between the right flange and the center of the hub, so that there still will be a decent slant to the right hand spokes. You can then move the left hand flange in a bit to try to make the angle more equal.

At the center of it all is your hub. Almost all hubs have aluminum shells and flanges (the bits of the hub with spoke holes). First, it's lighter than steel. Second, the flanges deform a bit to support the spokes better. (This is why if you build a wheel using an old hub, you should look closely at the hub and lace it up the same way as it was used before.)

For the purposes of building a wheel, what you want are flanges that are going to support the spokes properly and aren't going to rip apart. To achieve this, the main thing to look for is a hub that's built via forging rather than being CNC machined. CNC machining allows the manufacturer to make all sorts of fancy shapes, but the result isn't as strong as an equivalent forged part.

In my opinion, there isn't much point in buying anything other than Shimano of Campagnolo hubs. They are good quality forged hubs and are good value for money. The only exception is if you want disc brakes. Shimano have gotten into the game only recently, and their offerings aren't as good as others yet. In particular they're quite a bit heavier than most other hubs. But given their track record, in a few years they'll have top-notch disc hubs.

Rims should be made of aluminum. Steel may last longer, since the sidewalls don't wear out under braking as with aluminum rims, but they are an absolute nightmare when it's wet. If you've got steel rims in the rain you're more likely to stop yourself by putting your foot down than by using the brakes. The only way to make steel rims work in the wet is to use leather brake blocks, which wear out very quickly. In addition, steel rims are heavier than aluminum ones. Wheels with alu rims also survive impacts better: they are less stiff than steel rims, so they bend a little bit under an impact, spreading the load to more spokes. This helps to prevent spokes from losing tension and collapsing the wheel.

Rims can vary in cross-section from a simple squared-U shape, to a multi-cavity box. In general, the bigger the cross-section, the more walls, and the thicker the walls are, the stronger the rim is. For most purposes, a narrowish (say 19 to 23mm width) single cavity (a simple box) rim will do fine. If you want something stronger you can get wider rims (for off-road and touring use) or deeper rims (for fast road use). The deep-section rims have the additional advantage of being a fair bit more aerodynamic than one with a more square profile.

Most better rims have steel eyelets lining the holes for the spokes. These distribute the stress of the spokes to a slightly larger section of the inner wall of the rim, making the rim less likely to crack. Some box-section rims have "double eyelets" which form a little cylinder in the cavity between the walls of the rim. This can help distribute stress from the spoke to the other wall of the cavity (the one nearer the tire) and also helps to prevent your nipples from going wandering in the cavity while you're lacing up the wheel. Unfortunately, many rims are made with only single eyelets.

Rims are extruded as straight bits, then coiled up into circles, and then the ends of the hoops are joined together. The old way to put rims together was to simply line them up accurately, put a small insert in the cavity, and press the two ends of the rim together. The newer way to do this is to weld the ends together, and then machine the sidewalls so they are even. The benefits of the old system were simplicity. Sometimes there would be a slight misalignment at the join, and this would result in the join catching at your brakes. However, the braking quickly wore this smooth. The benefit of the new system is that it's nicer right out of the box: there is no unevenness at the join. In addition the little ridges left by the machining initially improves your braking performance, but this wears off quickly, leaving smooth aluminum. The drawback is that it's a more expensive process which leaves the walls thinner. Of course you can argue that the walls are designed thicker to start out with, so machining leaves them with the right wall thickness. But then this is a waste of materials, and you're likely to end up with a varying wall thickness.

What the pinned or welded-and-machined argument boils down to is the initial impression. Once your brakes have worn down the unevenness of the join or the little machined ridges, both rims perform the same, except that the walls of the machined rims may be thinner or even an uneven thickness. Welded-and-machined rims cost quite a bit more than the old pinned rims. Given a choice, I would buy pinned rims exclusively, but they are getting hard to find. I do sometimes manage to pick them up at bike rallies, and when I find them there they're generally dirt cheap.

Some rims meant to go into rear wheels have spoke holes that are offset to one side. The idea is that you build up the wheel with the spoke holes offset towards the non-drive (left) side of the rear wheel. This decreases the angle of the left spokes while increasing the angle of the right spokes. With more equal angles, they are more equal in tension as well, allowing the left hand spokes to be tighter when the wheel is tensioned up. This theoretically makes the wheel stronger, but there doesn't seem to be any proof that it works in practice. As for me, I'm convinced by the theory and tend to by asymmetric rear rims, unless I'm buying vintage pinned rims, which definitely don't come in asymmetric versions.

Rims can have several finishes put on them. Some finishes are strictly decorative, giving a nice color to the rim. Hard anodizing (Mavic calls this CD) is touted by rim manufacturers as something that makes the rim stronger or longer-lasting. However, it is best avoided. If the anodizing is on the sidewall of the rim, then it will make the sidewall last slightly longer: first the black stuff wears off the brake surface, and then the aluminum underneath starts to wear. So theoretically your sidewalls could last a bit longer. However, this coating wears off quickly, so this is of minimal benefit. Furthermore, the anodizing decreases braking power considerably. You'll be eager for that black stuff to wear off your rim as then your brakes will start to work again... In fact some rims are machined after anodizing so the rim starts off with a clean braking surface.

You might then think that once the sidewalls have been scraped clean by your brakes (or the machining) that you'll then have some protection from the bits of it still clinging to the spoke bed. However, this not only does no good, but can lead to premature failure of your rim. The anodized layer is hard and brittle. Rims do flex slightly as they go around, and the anodizing can crack. These cracks can then propagate into your rim, and then the spokes can rip out of their holes. I'm not sure how seriously to take this danger of cracking. After all, I've had some hard anodized Mavic MA40 rims for years and have had no problems with cracking, so it may do no harm to your wheels. But it certainly won't do any good either. If you really want black rims, go for a cosmetic anodizing instead.

A ceramic coating on your rims is a more useful thing. This coating takes ages to wear off, and in fact doesn't come off at all unless you nick it with a rock. Once it starts to come off it will gradually flake off, but even if you ride in a very rocky area you can still get greatly increased rim life. In addition, braking in the wet is improved. There are some downsides though. First, the cost. The ceramic coating can just about double the price. If you generally retire wheels due to trashing the rims rather than wearing them through, ceramic rims will not be cost-effective. Second, the coating insulates the rim. Usually when you brake, the heat of braking goes into the rim where it is then dissipated. The ceramic layer prevents this, so all the heat stays in your brake blocks, and they can melt. You need to buy special brake pads for use with ceramic rims to prevent this. Third, although braking in the wet is better with ceramic rims, even with ceramic-specific pads it isn't quite as good in the dry as bare alu rims.

Spokes are mostly made from steel. On very expensive wheels, you can get titanium, carbon fiber, or aluminum spokes, but steel is the standard choice for several reasons. First, steel is cheap. Second, it is strong and has good fatigue resistance. Third, it's easy to cut smooth, strong threads in it for the nipples.

So the main things you need to ask yourself is: what shape (profile), how many spokes, and what thickness? First, shape. Almost all spokes are round in cross section. If you want the wheels for time trialling or triathlon, where you'll be going very fast and aerodynamics are important, you can get ones that are a bit flattened in profile. However, if you get them too flattened, you won't fit them through the hole in the hub. You can get special hubs for this if you're desperate for very areo wheels.

Second, number. Low spoke count wheels are trendy nowadays. But let's face it: spokes really don't weigh all that much, and they are really what gives the wheel its strength. So you really gain very little by using few spokes. Consider, for example, Rolf wheels. They have very few spokes, but the rims have to be heavier in order to provide structure for the wheel in the large gap between spokes.

Still, if you're very light and ride only on the road you'll be putting less stress on your wheels than if you're heavy or ride off-road, so you can get away with fewer spokes. As a general guide: for road riding, 32 spokes make a good durable wheel, while if you're large, ride off-road, or go touring, 36 spokes is better. If you're light and want a light wheel, 28 spokes will do. 28 spokes is also fine for a racing wheel, where you're willing to trade off some strength for speed (reduced spoke count makes for reduced areo drag) and lightness. For off-road riding, the greater strength of MTB rims (their smaller diameter and wider profile) means that most people can get away with 32 spokes. Heavy people or people who want to carry a significant load off-road, dirt jumpers, or downhillers would be better off 36 spokes. Tandems generally need more than 36 spokes: 40 or 48 is the norm.

Third, thickness. Here, you not only have a choice of how thick you want the ends of the spoke to be, but also a choice of having spokes that are narrower in the middle. The spokes that are thinner in the middle are called double butted. Double butted spokes are definitely the way to go. They are slightly lighter than straight gauge spokes, but their main advantage is that they make a stronger wheel. The thinner middle section allows them to stretch a bit when the wheel is hit, spreading the load to neighboring spokes to help distribute the impact. This helps to prevents the elbow near the spokes head from flexing (which leads to fatigue and spoke breakage), and also takes the stress away from the rim wall near the nipples.

One of the most common myths about wheels is that double-butted spokes will make your wheels weaker. Where people get this idea from, I have no idea. Spokes almost never break in the middle, only at the ends (usually near the spoke head), so common sense should tell anyone that a wheel built from double-butted spokes will be at least as strong as one built from straight gauge spokes. In fact because of their greater elasticity, double-butted spokes result in a stronger wheel.

In general, the thicker the spoke is near the head, the stronger it will be. However since spokes mainly fail from fatigue (see above, under What makes a strong wheel?) if the wheel is built well, this does not make a big difference. So don't go thinking that to have strong wheels, you need to have super-thick spokes. In fact you'd be better off by having more thinner spokes to distribute the load better.

I tend to use 14/15/14 gauge (2mm/1.8mm/2mm) DT stainless steel spokes in all my wheels, mainly because that's what the local bike shop stocks. I wouldn't hesitate to use 15/16/15 gauge (1.8mm/1.6mm/1.8mm) spokes if they were as easy to come by. You can also get spokes that are drastically thinner in the middle than they are at the edges, such as DT's Revolution spokes, which are 14/17/14 or 15/17/15 gauge. I wouldn't use these because it's hard to prevent spoke windup (twisting of spokes) with these spokes as they have so little torsional rigidity. However, if you're getting the wheels built by someone else, use them by all means as long as you don't mind the extra cost.

With nipples there's much less choice. You get nickel-plated brass ones, or aluminum ones. The brass ones are stronger, and the brass helps to lubricate the threads a little. (However, this alone is usually not sufficient, so it's best to put some grease or oil on the threads of your spokes before putting on the nipples to make sure they don't bind when the tension is getting high.) The alu are lighter, but in most people's opinion there is not enough of a weight savings to make up for their shortcomings. Serious wheelbuilders use brass nipples.

First and foremost you need a spoke wrench. The best one you can get without paying a fortune is the Spokey. It's a cheerful plastic disc with nipple-gripping bit on one side. The advantages of the Spokey are that the textured disc is easy to hold and gives you lots of leverage, it grips the nipple well, and it's inexpensive. Just make sure you get the right size for the nipples you use.

While it's possible to build a wheel without a wheel truing stand (using your brake blocks to tell you when the wheel is out of true) the task is made immensely easier with the use of a proper stand. You need to look for several things. First, it's useful if the feelers for the left and right sides of the rim can be moved independently, so you can choose which bumps to take care of first. Second, you need a gauge that goes up against the edges of the rim so you can check radial trueness.

I've used two truing stands. I wasn't pleased at all the the TACX Scorpio. The feelers didn't move independently. One knob moved them both in or out, and you had very little fine control over this movement. In addition it had nothing to help you with radial trueness. The Minoura Workman Pro I now own is much better. The feelers are simple screws, so you can move them independently and have fine control over how close they are to the rim, and there's a little movable plate for radial trueness. My only complaint is that the plastic bit that holds the feelers and the plate has cracked. I haven't been abusing it, so this suggests that it isn't very durable. It still hasn't broken though. Regular Performance catalog shoppers should note that the Minoura Workman Pro is exactly the same as the Performance Spin Doctor Truing Stand.

Finally, you need a dishing tool to make sure that the rim is centered between in the middle of the hub. These are pretty basic and all are similar. I have one by Minoura, but I'm sure any would do.

Making a wheel from the constituent parts has basically two phases. First, you put everything together. This is called lacing. I've done this enough times that it's pretty automatic, but there's no point in me typing it all out, as others have described it so well already. See Part II of Jobst Brandt's book The Bicycle Wheel, which has excellent illustrations. Or see Sheldon Brown's wheelbuilding pages. I'll only mention here that you should thoroughly grease the spoke threads before you start. That makes them easy to turn in the nipples and allows you to get the needed tension.

Once you've laced the wheel up, screw all spokes in until the threads of the spokes just disappear into the nipple. Then shove the thing on your wheel truing stand and get tightening.

Basically, the idea is to bring up the tension of the wheel while maintaining lateral trueness (lack of side to side wiggles), radial trueness (even distance of rim to hub) and dishing (equal distance from rim to locknut on both sides of wheel). For the first, you have the feelers feeling the sides of your rim to tell you when they're out of true. For the second, any decent truing stand will have a bar that you put next to the rim, and where it scrapes, that part is further from the hub. For dishing, you have your dishing tool, which is basically an arch with feet on the ends of the arch (you put that on the rim) and a feeler hanging down from the top of the arch. You adjust the feeler so that it just hits the locknut on one side of the wheel, and hopefully it just hits the locknut on the other side.

If the thing is out of true laterally, what I do is try to bring up the tension at the same time as I'm truing, by finding a place where the rim is out of true, and finding a looser spoke opposite the bulgy side (find looser spoke by plucking), and tightening that until it's roughly the same tension as the spokes near it. If there isn't a looser spoke, I tighten up two or three of the spokes a bit (half turn maybe) to bring up the tension.

If the thing is out of true radially, I tighten a few spokes near the bulge about a half turn, and ones next to those about a 1/4 turn, tightening spokes on both sides of the wheel. (Again my goal is to increase tension as I'm doing my truing).

If the thing is dished wrong, set up the feeler on the dishing tool so that it hits the locknut on one side, but has a gap between feeler and locknut on the other side. (Only do the dishing bit when the rim is laterally true; if you have side-to-side bulges you get different results depending on where you put the dishing tool on the rim.) Say we're looking at the wheel so that the gap side is on the right. Now, your goal is to bring the rim further to the left to try to close up that gap. What you need to do is tighten the spokes on the left (non-gap) side. Don't tighten too much at once here. Maybe 1/2 (or even 1/4, if the gap isn't too big) turn per spoke on the left hand side. This will bring the rim slightly closer to the left, giving a small gap on the left side, and making the gap on the right side smaller. Hopefully the gaps are now the same size, and when you realign your feeler, you'll get it just touching the locknut on both sides.

Your goal is to get a wheel that's true in all three senses, and tensioned enough. "Enough" is hard to gauge when you're starting out, but a rough rule of thumb is that the nipples should be quite hard to turn when you're finished. If you've managed to get all three aspects true but the wheel isn't to a high enough tension, then tighten all spokes about 1/2 turn, and retrue. Repeat until done.

When you're tightening (or even loosening spokes), turn the spoke a bit past the amount you're trying to tighten (or loosen) then back off. So if you want to tighten by 1/2 turn, then tighten by 3/4 turn, then loosen 1/4 turn. This helps prevent spoke windup (twisting of spokes). Unfortunately, despite your best efforts, you can end up with windup. This is the method I use to let the spokes unwind. Put a magazine on the floor and pull the quick release skewer out of the hub. Put on end of the hub on the magazine, and put your hands on two opposite places on the rim, then lean your weight on your hands. This releases the tension on the lower spokes just beneath your hands and lets them unwind if they've got wound up, making a pinging sound. Go around the rim this way, then turn over and repeat. You'll then have to put the wheel back on the truing stand to make sure this hasn't made the wheel go out of whack. If you've gotten spoke windup and you don't do this, you'll hear the pinging noises when you go to ride your bike with your new wheel.

Once you've got your wheel all tight and true, you want to stress relieve it. This relieves minute stresses that may have built up in the spokes. Again, see The Bicycle Wheel or Sheldon Brown's wheelbuilding pages for info on how to do this.

Other wheel-related stuff here

• Wheelbuilding tips
• Finding inner peace through wheelbuilding
• This wheel is made of memories
• Review of Jobst Brandt's book The Bicycle Wheel

Wheel-related stuff elsewhere

• Wheelbuilding the BikIndex Way
• Wheelbuilding by Sheldon Brown
• Spoke Length Calculator

I can recommend Roger Musson of Wheelpro. Unfortunately he only does MTB wheels.

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Vehicular cycling

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This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (May 2008)

Vehicular cycling (VC) is the practice of driving bicycles on roads in a manner that is visible, predictable, and in accordance with the principles for driving a vehicle in traffic. The phrase was coined by John Forester in the early 1970s to differentiate the assertive traffic cycling style and practices that he learned in the United Kingdom from the deferential cycling style and practices that he found to be typical in the United States.

Under the international Vienna Convention on Road Traffic (1968), a bicycle (or "cycle", as referenced by the convention) is defined to be a vehicle and a cyclist is considered to be a driver. In a minority of jurisdictions (the states of Arizona, California, Iowa, Illinois, Indiana, Minnesota, New York, and Texas in the United States^[1]) a bicycle is legally defined as a "device" rather than as a vehicle, but in all cases operators of bicycles share a basic set of rights and responsibilities with operators of motor vehicles. Bicyclists, who do not pose an extraordinary danger to others, are not burdened with certain additional responsibilities placed on drivers of motor vehicles — for example, only motor-vehicle operators are required to have a driver's license and, in some localities, carry liability insurance.

Sometimes vehicular cycling is referred to as integrated cycling (i.e. integrated with other vehicular traffic, as opposed to cycling on segregated cycling facilities ), integrated traffic cycling, cooperative cycling, or bicycle driving.

Contents [hide] 1 Principle 2 Origins of vehicular cycling 3 Practices, techniques and skills 3.1 Lane control 3.2 Lane sharing 3.3 Speed and destination positioning 3.4 Looking back 3.5 Negotiation 3.6 Attitude 4 Alternatives to vehicular cycling 4.1 Pedestrian cycling 4.2 Segregated cycling 5 Education 6 Advocacy 7 See also 8 Further reading 9 References 10 External links

[edit] Principle

John Forester, a cycling transportation engineer,^[2], has written that the principle of vehicular cycling is: "Cyclists fare best when they act and are treated as drivers of vehicles".^[3] This is coherent with the dictionary definition of bicycle: "a vehicle with ... pedals by which it is propelled ...".

[edit] Origins of vehicular cycling

The origins of riding in accordance with vehicular rules of the road go back to the 19th century when bicycles were invented and began sharing the roads with other vehicles, such as wagons and buggies.

Forester's book, Effective Cycling, is generally considered the primary modern reference work about vehicular cycling. John Franklin also describes VC practices in his book, Cyclecraft^[4], which is part of Bikeability, the UK's national standard for cycle training. A "nuts and bolts" reference to VC is John S. Allen's booklet Bicycling Street Smarts.^[5]

[edit] Practices, techniques and skills

This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (April 2008)

A vehicular cyclist is a cyclist who generally travels within the roadway in accordance with the basic vehicular rules of the road that are shared by all drivers, and the most effective cycling practices. Primarily, this means:

• Traveling on the same side of the road as other traffic traveling in the same direction.
• Staying outside of the door zone; when passing a motor vehicle that is parked parallel to the road, no closer than the width of the door.
• Respecting traffic controls, such as yield (give way) signs, stop signs and traffic lights.
• Between intersections and other junctions, choosing the appropriate lane or lateral position according to those rules of the road that are shared by all drivers.
• While preparing to turn or turning, choosing the appropriate lane or lateral position according to destination positioning.
• Ignoring designated bicycle lane stripes when choosing where to travel on the street (this does not mean to avoid riding in bicycle lanes; it means deciding whether to ride in the space demarcated as a bike lane just as one would if the stripe were not there).
• Changing lanes or lateral (left/right) position in response to, and in anticipation of, factors such as changing traffic conditions.
• Using the full lane unless overtaking traffic is likely to be delayed and the marked traffic lane is wide enough to share.
• When making a turn toward the nearside of a road when multiple traffic lanes are marked, merging into the traffic in each lane while using negotiation with other drivers as required.
• Generally feeling and acting like a vehicle driver, albeit the driver of a narrow and relatively low-powered vehicle.

Some non-vehicular cycling actions commonly taken by bicyclists include

• Riding on the opposite side of the road compared to other traffic traveling in the same direction.
• Riding in the door zone.
• Riding along sidewalks or crosswalks.
• Running red lights.
• Blatantly running most stop signs. There are exceptions to this in some places. In Idaho, human-powered vehicles are allowed to treat stop signs as yield signs^[6].
• Going straight across an intersection while positioned laterally for a turn or while in a turn-only lane.
• Darting inward across the roadway from the outer edge of the road, instead of merging across one marked lane at a time.
• Moving laterally without looking back and yielding to overtaking traffic that has the right of way.
• Splitting marked lanes instead of taking a more predictable position within a lane.
• While a traffic light is red, moving to the front of the traffic queue instead of taking one's place in line according to the first come, first served principle (even if doing so is outside the rules of the road).
• Passing slow or stopped traffic on the offside too fast and/or without recognizing the extra danger from passing a driver on the offside. ^[7]
• Not merging out of a curbside bicycle lane when approaching a junction or intersection where the cyclist intends to go straight or turn to the offside, which would violate the destination positioning rule.
• Traveling along the edge of a marked traffic lane when the lane is too narrow for sharing side-by-side with wide vehicles. Riding the edge can mislead overtaking drivers into thinking that the cyclist is giving approval for same-lane passing.
• Traveling where there is a minimum speed limit, for instance on freeways, where non-motorized traffic is often forbidden.

[edit] Lane control

A cyclist is controlling a lane (also known as "taking control of the lane", "taking the lane" or "claiming the lane") when traveling near the center of a marked travel lane. Controlling the lane normally precludes passing within the same lane by drivers of wide motor vehicles, while being positioned near a lane edge usually encourages such passing—even when it is hazardous to bicyclists.

Vehicular cyclists commonly control lanes under the following circumstances:

• when approaching a junction at which approaching or waiting traffic may turn or cross directly in front of the cyclist ^[8]

• when traveling at the normal speed of traffic at that time and place (often including whenever the cyclist is the only traffic moving in that direction at that time and place)
• when there is a gap in faster same direction traffic (to improve vantage and maneuvering space with respect to noticing and avoiding hazards up ahead, and to increase conspicuousness to traffic approaching from the rear as well as to traffic with potential crossing conflicts up ahead)
• when the marked lane is too narrow to safely share with overtaking traffic
• when approaching a place where the lane narrows (such as a construction zone) so as not to be "squeezed out" when that happens
• when merging across a roadway in preparation for a turn across the opposing lanes
• when overtaking and passing another vehicle, bicyclist moving more slowly
• when avoiding hazards
• when approaching an intersection or junction at which the cyclist's destination is straight ahead
• when approaching or traveling in a roundabout or traffic circle

John Franklin advocates operating bicycles in accordance with the basic rules of the road for vehicle operation. Using the terms "primary riding position" — meaning in the center of the traffic lane — and "secondary riding position" — meaning about 1 meter (3.2 feet) to the side of moving traffic, but not closer than .5 meters (1.6 feet) from the edge of the road — Franklin advocates the primary riding position as the normal position and the secondary riding position only when it is safe, reasonable and necessary to allow faster traffic to pass. ^[9]

Vehicular cycling, including controlling lanes when appropriate, is supported by traffic laws in most countries (California's Vehicle Code section 21202 is an example of this).

[edit] Lane sharing

All forms of lane sharing are aspects of vehicular cycling. While sharing lanes by normal width vehicles is rare, this is because lanes are rarely wide enough for two normal width vehicles to travel side-by-side. But, like motorcyclists, due to their relatively narrow width, bicyclists can often share lanes comfortably and safely. Even drivers of automobiles occasionally share lanes, such as when one is slowing and merging to the outside in order to make a turn from a very wide outside lane, while through traffic passes within the same lane to the inside.

As long as it is safe and not explicitly prohibited, lane sharing does not contradict the vehicular rules of the road. Due to the relatively narrow and slow nature of bicycles, the opportunities for lane sharing are generally more frequent for bicyclists than for other drivers. The practice of whitelining while being passed by faster traffic in both adjacent lanes is demonstrated in the Effective Cycling video/dvd. Lane splitting is often used by cyclists, including vehicular cyclists, to filter forward past slow or stopped motor traffic. Sharing wide outside lanes, when safe and reasonable, in order to facilitate being overtaken by faster traffic, is also a common vehicular cycling practice.

Vehicular cyclists know that often implicit in lane sharing is yielding of the remainder/unused portion of the lane. For example, when riding in a lane sharing position, a cyclist must yield to overtaking traffic using the other part of the lane, or obtain right-of-way to move over through negotiation, before moving laterally into that space.

[edit] Speed and destination positioning

Vehicular cyclists and other drivers who travel in accordance with the vehicular rules of the road use "speed positioning" between intersections. The basic principle is "slower traffic keeps to the outside (nearside in British English); faster traffic to the inside (offside in British English)". When lanes are marked, slower drivers generally operate in the outermost travel lane (in a country operating right-hand traffic rules, the outside lane is the right lane). When lanes are not marked, slower drivers generally operate as far to the outside of the traveled way as is reasonably efficient and safe.

Because of the bicycle's narrow width, a cyclist can "share" a marked lane (i.e., be passed by overtaking drivers within the lane lines) more often than the driver of a wider vehicle can. A bicyclist who decides to share a lane should ride about a meter (3.2 feet) to the outside of overtaking traffic and about the same distance from roadside hazards (such as the door zone). For this reason, bike lanes which are within a meter of a parking lane should be considered a hazard.

As drivers approach a junction of ways, the principle of "destination positioning" comes into play, and they should position themselves laterally according to their destination (left, straight or right):

• Where lanes are marked, slower drivers approaching a junction should choose the outermost lane that serves (i.e., corresponds to) their destination. For example, if the outermost lane is a turn-only lane, drivers in that lane who do not intend to turn outward should merge inward into the adjacent lane.

• When lanes are not marked, drivers approaching a junction will travel along the inside of their side of the road if turning toward the inside, along the outer side if turning to the outside, and in between if going straight.

The best rules of the road allow any slower driver (including a cyclist) to establish the center of the outermost marked lane (between the left and right tracks of wider vehicles) as their default or primary position. When traffic is

• overtaking and will likely be significantly delayed while waiting to pass outside that travel lane, and
• the lane can be efficiently and safely shared with that traffic

then the polite driver moves over in the secondary position, nearer to the outer edge of that lane. In general, vehicles (whether pedal or motor) are more visible and predictable when traveling along in the primary position. Bicycles in the secondary position are less likely to be noticed.

[edit] Looking back

The skill of looking back over one's shoulder is essential whenever a cyclist needs to

1. check that moving laterally or turning will not violate the right-of-way of someone who is overtaking
2. broadcast the cyclist's desire (to move laterally or turn) to other road users so that they can better predict the cyclist's path
3. see if someone who's overtaking is about to make a mistake and violate their right-of-way

Looking back is usually visible enough that it can suffice as a signal that the cyclist wishes to move or turn in the direction of the look. A sustained look back increases the odds that the signal will be noticed. Compared to hand signaling, looking back has the advantage of allowing the cyclist to keep both hands on the handlebars. Some jurisdictions, however, mandate that bicyclists use hand signals before moving laterally or turning.

Looking back can be challenging to perform: it requires traveling in a straight line while looking behind for up to a few seconds. The natural tendency is to not continue in a straight line, but to turn the bike in the same direction as the look. The tendency to turn can be countered with practice; learning to relax the elbow in the direction of the look is key. The more often looking back is done, the more comfortable and effortless it will become.

Special mirrors are available for mounting on a cyclist's helmet, eyeglass, or handlebar. Such mirrors enable the cyclist - with practice - to check for overtaking traffic with less effort. Another advantage is that the check can be accomplished more quickly, reducing the amount of time the cyclist isn't watching where they're going. Although such mirrors are small in size, the mounting is so close to the eye that the field of view can approach that of an automotive rear-view mirror (although that poses more of a challenge for eyeglass wearers). However, the field of view is usually still limited enough that looking back remains an essential skill for vehicular cycling.

Even with its limitations, mirrors are regarded as an important or even critical piece of safety equipment by some cyclists. Others value mirrors more as a means to avoid the shock of being surprised by high-speed traffic passing from behind.

[edit] Negotiation

The concept of negotiation is an important part of traversing across one or more lanes of traffic. The basic idea is to negotiate for the right-of-way in the adjacent lane, move into that lane, and then repeat the process for any additional lanes. This is an important vehicular cycling skill, because it allows the cyclist to merge in with the flow of other traffic instead of cutting across at a right-angle (as a pedestrian would).

The first step in traversing across a lane is looking back for traffic that may be overtaking in that lane. When there is overtaking traffic which will arrive too soon for the cyclist to merge out into the lane (i.e., there is an insufficient gap), the cyclist needs to either wait until traffic has passed and a sufficient gap becomes available, or request that someone in that traffic explicitly yield the right-of-way by slowing down to let the cyclist in. Simply looking back is often all that is required to signal the cyclist's intent, but sometimes a hand signal is helpful in getting a driver in overtaking traffic to yield right-of-way by slowing down to the cyclist's speed in order to allow the cyclist to move in front of the driver. Once right-of-way has been acquired in the adjacent lane, the second step is for the cyclist to move into that lane.

If there is another lane to traverse, the cyclist repeats the steps until there are no more lanes to traverse. The key to the process is that the cyclist merges into traffic lanes as per the rules of the road, one lane at a time, either when there is a natural gap to move into, or after someone slows down explicitly to allow the cyclist to move over.

The higher the relative speed of the overtaking vehicles, the more time and space a willing motorist needs to notice the cyclist's request and to safely slow down enough to allow the cyclist in. An assertive arm signal coupled with a timely look back is usually sufficient to accomplish this, even in very dense and fast traffic. When the relative speed is large and the gaps are too small for merging, the cyclist who is unwilling to use negotiation either has to wait for traffic conditions to improve or find another route.

[edit] Attitude

Vehicular cycling advocates such as John Forester contend that if a cyclist does not act like a vehicle driver, they are unlikely to be treated like one by other road users, stating "There is much more to the vehicular-cycling principle than only obeying the traffic laws for drivers. The vehicular-style cyclist not only acts outwardly like a driver, he knows inwardly that he is one. Instead of feeling like a trespasser on roads owned by cars he feels like just another driver with a slightly different vehicle, one who is participating and cooperating in the organized mutual effort to get to desired destinations with the least trouble". (Forester, Bicycle Transportation Engineering, 1994, p. 3).

[edit] Alternatives to vehicular cycling

[edit] Pedestrian cycling

An alternative to vehicular cycling is pedestrian bicycling, or bicycling according to the pedestrian rules of the road. Pedestrian bicycling often means riding on sidewalks, pedestrian crossings, and other pedestrian facilities. In those jurisdictions where such behavior is illegal, the cyclist may be held liable for any personal injuries or property damage that results. There are peculiar hazards associated with this activity, including (but not limited to)

• Opening passenger-side doors.
• Pedestrians, dogs, children playing, etc.
• Potential conflicts with other vehicles at all intersections, including driveways and alleys, as well as major intersections.
• Entering crosswalks, where drivers turning into your path are often looking the other way.

Many cyclists use a combination of vehicular cycling and pedestrian bicycling. Some cyclists will resort to pedestrian cycling to avoid busy roundabouts, using pedestrian crossings (if provided)--in Britain cyclists are often encouraged to do so by signs and shared-use footways (for pedestrians and cyclists).

This approach has the drawback that extra care must be taken when transitioning from one mode to the other, since transitioning often leads to actions not expected by others. In particular, during a transition, a cyclist must yield the right-of-way to both pedestrians and vehicle drivers. Car-bike collision statistics indicate that those who operate bicycles (and other pedal vehicles) in contradiction with the vehicular rules of the road are particularly vulnerable.

Examples of pedestrian bicycling:

• going straight across an intersection from the outside edge of the road (next to the curb)
• making inside turns only when it's clear (don't bother negotiating) by darting straight across the road during a gap
• resorting to pedestrian-style turns when no gaps are to be had
• avoiding streets with narrow outside lanes whenever possible (and, thus, where there is no room to be "out of the way")

[edit] Segregated cycling

Main article: Segregated cycle facilities

Another alternative to vehicular cycling, "segregated cycling", is available in areas with segregated cycle facilities that support cycling without sharing roads with vehicular traffic. Cities that are providing such facilities are reporting a high degree of usage, for example Montréal and Ottawa (Canada) and many European cities. Research indicates that cyclists are willing to pay a higher price in longer travel time for designated facilities such as an on-street bike lane.^[10][11]

[edit] Education

In addition to reading about vehicular cycling in textbooks, a cyclist can participate in training courses offered by organizations such as the League of American Bicyclists and the Canadian Cycling Association.^[12]

Another source for education regarding the basics of vehicular cycling is John S. Allen's pamphlet, Bicycling Street Smarts.^[5]

[edit] Advocacy

Vehicular cycling experts—such as John Forester, John Franklin and John S. Allen—advocate for the operation of pedal powered vehicles (including bicycles) in traffic according to the principles of vehicle operation (i.e., driving). Some VC advocates feel that, in addition to the safety and efficiency benefits, cyclists should operate vehicularly to increase societal acceptance and to directly challenge the government's sanctioning of priority for motorists.

Opponents often object to vehicular cycling as overlooking the needs and interests of the majority who feel that, since motorists effectively already have areas of priority (travel lanes and freeways), cyclists deserve their own priority areas (such as cycle lanes and tracks).

[edit] See also

• Effective Cycling
• Bike lane debate
• Utility cycling
• Cycling hand signals
• Segregated cycle facilities

[edit] Further reading

• Effective Cycling by John Forester (First edition, 1976; Sixth edition, The MIT Press, 1993) ISBN 0-262-56070-4
• Cyclecraft by John Franklin (First edition, Unwin Books, 1988; Fourth edition, The Stationery Office, 2007) ISBN 978-0-11-703740-3

[edit] References

1. ^ Sturges, Al (1997). "The Bicycle as Vehicle". League of Illinois Bicyclists. http://www.massbike.org/bikelaw/vehicle.htm. Retrieved 2006-04-19. 
2. ^ Jack Taylor. "A Brief Biography of John Forester". http://probicycle.com/jf/jfbio.html. Retrieved 2007-03-25. 
3. ^ Forester, John (1977). "Effective Cycling Instructor's Manual" (PDF). John Forester. http://www.johnforester.com/BTEO/ECIM6.pdf. Retrieved 2007-03-25. 
4. ^ Franklin, John (05 2004) [1997]. Cyclecraft. Stationery Office Books. ISBN 0-11-702051-6. http://www.cyclecraft.co.uk/book.html. Retrieved 2006-09-19. 
5. ^ ^{a b} Street Smarts, John S. Allen
6. ^ [http://www3.state.id.us/cgi-bin/newidst?sctid=490070020.K Idaho Statutes, Title 49, Motor vehicles, Chapter 7, Pedestrians and bicycles ]
7. ^ "Hill advises never passing large trucks or buses on the right, as they generally have multiple blind spots, limited maneuverability and a tendency to run over curbs. Tanner, Michael (June 4, 2009), "Safe streets:Workshops help cyclists trim risk", San Francisco Chronicle: F-32, http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/06/04/NSJ517S534.DTL, retrieved June 9, 2009 
8. ^ "when approaching an intersection where a dashed dividing line appears, riders should move to the left so that motorists can move in behind and make right turns unobstructed" Tanner, Michael (June 4, 2009), "Safe streets:Workshops help cyclists trim risk", San Francisco Chronicle: F-32, http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/06/04/NSJ517S534.DTL, retrieved June 9, 2009 
9. ^ Here you will be well within the zone of maximum surveillance of both following drivers and those who might cross your path, and you will have the best two-way visibility of side roads and other features along the road. Franklin, John (1997). Cyclecraft. TSO. pp. 58–59. ISBN 0117020516. 
10. ^ NCHRP Report 552 "Guidelines for Analysis of Investments in Bicycle Facilities, Transportation Research Board of the National Academies, Washington D.C., 2006, pages D-1 to D-9
11. ^ "Influences on Bicycle Use, by J.D. Hunt and JE Abraham, Transportation, Vol 34 (2007), issue 4 (July), pages 453-470)
12. ^ "CCA bicycle education and safety". CAN-BIKE PROGRAM. Canadian Cycling Association. http://www.canadian-cycling.com/English/programs/canbike/canintro.htm. Retrieved 2006-04-24. 

[edit] External links

• Segregation: are we moving away from cycling safety?, John Franklin
• Video of LAB traffic cycling instructors demonstrating lane control lane control.

Cycling aerodynamics

Bicycles and Aerodynamics

by Rainer Pivit

published in Radfahren 2/1990, pp. 40 - 44

Translated by Damon Rinard from the original German language article at:
http://www.lustaufzukunft.de/pivit/aero/aerodynamik.html .

(Numbers in parentheses refer to the pertinent bibliography)

Other articles by Rainer Pivit published in "Radfahren" magazine:

• Drag Forces in Formulas

• Measuring Aerodynamic Drag

The aerodynamic gains in bicycle racing are of great significance. While aerodynamic technology was first shown on the track in the '84 Los Angeles olympics, aerodynamic improvements in road racing had a piercing effect in the last stage of the '89 Tour de France. LeMond adhered uniquely to better aerodynamics than Fignon. Can the everyday rider also benefit from better aerodynamics?

The idea that at higher speeds the aerodynamic drag of the bicycle consumes nearly all the rider's effort is very old. As early as 1895 disk wheels were offered for bicycles to reduce aerodynamic drag. There were even wheels with 4 aerodynamically shaped spokes for the front wheel (23). This type of wheel has now become generally accepted with extreme Triathlon bicycles - made today from composite materials instead of sheet metal as they were before the turn of the century.

Restrictive Regulations

Also the idea to achieve a more favorable frontal area and thus a smaller aerodynamic drag by assuming a different seating position had already emerged before the turn of the century. Mochet's recumbent set several new hour world records. Starting from 1913 records were broken with aerodynamically faired racing cycles (5, 6). However, the governing body of bicycle racing, the Union Cycliste International (UCI), did not view these as regular records and tried to prevent any possible technical advantages to individual racers by changing the regulations. Racing should serve as a comparison of athetes, not a comparison of technology. Because of that the most important incentive to aerodynamic improvements to the bicycle was omitted going forward.

The revival of the topic of bicycle aerodynamics is due to a professor who had no more desire to explain to his students over and over again why water boils and why the perpetual motion machine is not a good idea. In 1973 Chester R. Kyle planned a project to improve the bicycle. The first measurements were made because of a bet about whether tubular tires or clincher tires were better. It turned out that for the cyclist the actual physical enemy is air resistance.

This led to quick improvements to the conventional bicycle (frame and wheel side covers made from thin sheets) and an aerodynamic shell for a normal racing cycle, which reduced air resistance by 80%.

In 1975 Kyle and Jack Lambie organized the first race for streamlined "human powered vehicles" (HPVs). Out of the the 14 participants 4 went faster than any bicycle before - if one allows riding in the lee of the wind. One year later the International Human Powered Vehicle Association (IHPVA) was formed, in order to organize independently of the limiting regulations of the UCI races, and to support the technical development of HPVs (16).

Kyle's Olympic Project

Starting in 1982 Kyle and others developed the technical configuration for the US Olympic Cycling Team for the '84 olympics in Los Angeles. Some aerodynamic components already existed beforehand, e.g. the aero helmets of the Czechoslovakian team. But now for the first time the complete system of the bicycle and rider was aerodynamically optimized. UCI regulations specify a conventional seating position and also forbid any aerodynamic accessories. Not forbidden, however, is the aerodynamic arrangement of functionally necessary components.

This means for example that covering a spoked wheel with plastic sheet is forbidden, since this has no basic function - it serves only aerodynamics. It is different however, if the wheel has so few spokes that it is not sufficiently stable in itself for racing applications and sufficient stiffness can be achieved only by the additional basic function of the disk (made from composite material). Later rules were added that continue to limit this principle somewhat; for instance the main frame must consist of 3 tubes which are not allowed to be arbitrarily broad. Wheels must have (at present still) at least 16 spokes or a full disk.

The bicycles developed by Kyle for the US olympic project, known as "Funny Bikes", were very successful at the olympics. The redesign was so broad that only a very few components remained unchanged, for example the tires. By the '88 olympics in Seol, however, teams from the other countries had nearly caught up, so the US cycling team members could no longer benefit so much from the technical advantages of their Funny Bikes.

Triathletes Improve Handlebars and Wheels

Some of the ideas that developed within the framework of the US olympic program were later offered commercially, so today normal bicycle racers can also benefit from better aerodynamics. The new ideas were adopted particularly intensely in Triathlon. Since technical regulations are not as rigid here as in conventional bicycle racing, there were some technical improvements in this area which improved the chances of victory.

The most remarkable innovation was the triathlon handle bar (Scott aero bar), which leads to a more favorable aerodynamic position and reduces fatigue on long distances. Another recent development are wheels made from composite materials with 3 to 5 broad, aerodynamically shaped spokes (trispokes). In a cross wind, bicycles with such front wheels are easier to control compared to a full disk front wheel.

Thus three trends in bicycle aerodynamics can be summarized: first of all the racing bikes according to the restrictive regulations of the UCI, secondly the triathlon machines with large tolerance of technical advantages, but with conventional rider position and without aerodynamic fairings, and thirdly the HPVs without any technical limitation.

Developments Usually Oriented Toward Racing

For the everyday rider the HPV trend is surely most interesting - why should the street rider follow road traffic laws and also the regulations of sport federations? The everyday rider would like to travel as comfortably and quickly as possible from point A to B, so to him technical advantages are very welcome. A comparison of the athletic performance of the everyday rider in traffic with a given technical regulation makes no real sense now. Therefore it is to be much regretted that the industry (and also the press) still orients itself to a large extent toward future developments in racing.

If one does not consider the regulations which limit the application of technology, efficient structures are possible. The speed record for bicycles over a distance of 200 m with flying start is a good 105 km/h (May 1986 at 2400 m altitude). The world hour record is at present 73 km/h (September 1989). Both records are held by the vehicle "Gold Rush", built by Gardner Martin, with Fred Markham ("Fast Freddy") as rider. Gold Rush has very good aerodynamics: an effective frontal area of 0.046 m² is indicated - a twelfth of a conventional racing bicycle; the vehicle weighs only 14.5 kg (19). Vehicles such as the Gold Rush are not suited to everyday life. Besides, other vehicles quite suited to everyday life have lower drag than racing machines which meet the regulations of the sport federations.

Aero Shopping List for the Normal Racing Cycle Rider

How can the normal racing cycle rider improve his aerodynamics? The aerodynamic drag of a conventional racing cycle without the rider is a third of the bicycle and rider together (12). Thus it is already clear that it is unreasonable to ride an aerodynamically optimized racing cycle with aerodynamically unfavorable clothes (e.g. normal everyday life clothing).

The aero shopping list, ranked by Kyle (13), shows possibilities of reducing aerodynamic drag. The costs are rough estimates; the proportional reduction of aero drag are relative to a conventional racing cycle and a rider with the usual racing clothing (racing shorts, jersey, cotton socks, gloves with knit backs) and without a helmet; the time gained is relative to a 40 km time trial at approximately 37 km/h - elapsed time 1 h 5 min. At higher speeds the time gained becomes smaller because of the shorter riding time.

An economical re-evaluation of the aerodynamics of a bike and rider with two aero spoke wheels, aero brakes, aero bottle, ANSI approved aero helmet, one-piece skinsuit, aero shoe covers, gloves with Lycra backs, silicone filling the gap between tires and rims, shaved legs and pump under the top tube costs about 1100 DM. In a 40-km time trial the rider equipped in such a way is 3 min 6 seconds faster than his conventionally equipped colleague with the same power, because his aero drag is less by around 21%. The speed of the aero cyclist is 4.8% higher than his conventional colleague (the last Tour de France was won with a lead of only 0.0025%).

Anyone who wants to invest somewhat more cash in his chances of victory (900 DM) and installs an aero crank set, an aerodynamically acceptable Schaltung, an aero bar and clipless pedals, can undercut his conventional colleague's aero drag value by around 23% and thus gain a lead of 3 min 30 seconds with the same performance.

Clothing and Helmet

In (15) Kyle points out that compared to the usual combination (long sleeved wool road jersey, Lycra racing shorts) aero drag can be reduced by 7.5% with a one-piece long sleeved skin suit made from Lycra; the same suit in rubberized coating gives an advantage of 8.4%. Aero helmets, as they are used for racing, which do not however meet the ANSI safety requirements, reduce the aero drag by approximately 2% compared to a bald head or a rubber cap over the hair. The Bell Stratos, an ANSI approved helmet, increases the aero drag by approximately 1.3 % over a bald head. Short hair worsens it around 4.6%, long hair around 8.6%. The leather hairnet helmets which can often still be found with racers - although completely insufficient according to ANSI - increases the aero drag by 6.3%. The wide-spread ANSI approved helmet Bell V1 Pro gains around 9.8% compared to a bald head. So far no measurements have been published concerning the influence of beards.

Disk Wheels are Front Runners

New wheels offer the largest aerodynamic advantage with the bicycle. Disk wheels are the front runners. Problemetic, however, are the high price and the severe impairment of the steering that comes from using a disk wheel in a cross-wind. Besides, an aero steel spoked wheel's air resistance clearly can be lowered already. If possible, few spokes in radial arrangement should be used.

Bladed spokes have 85% of the air resistance of normal round spokes (13). Narrow 18 mm tires likewise reduce air resistance. The rear wheel runs in an area where the air flow is already influenced by other components. Thus the effect of aerodynamically better material at the rear wheel is not as pronounced as at the front wheel. The use of a disk in the rear wheel is not worthwhile with a limited budget; a rear wheel with aero rim and bladed spokes also does the trick.

A particular example, which comes from measurements made by LeHanneur (10), is a bicycle with conventional wheels that has an effective frontal area c_wA of 0.05 m². Roval racing wheels, however, (developed in 1977: deep rim, bladed spokes with hidden nipples, 24 spokes for each wheel) have a value of approximately c_wA = 0.03 m².

From measurements by Kyle (17), a good, spinning disk wheel (AeroSport flat disk 26"; Kyle is involved in the company AeroSport) has an aero drag 35% of an appropriate conventional 27" wheel (normal rim, 36 round spokes). However he determined another disk had a value of 54% of the conventional wheel. There are thus noteworthy differences between the individual disks. In addition, a 24" wheel with aero rim and 18 aero spokes had only 40% of the aero drag of the conventional wheel.

Comparative measurements between normal wheels, the combination with disk in the back and spoke wheel in front, as well as disk both in front and in back were executed by the editors of "Bike Tech" on a time trial bike (with a measuring procedure whose accuracy is not yet known) (22). Replacing a conventional rear wheel with a Campagnolo Ghibili disk resulted in a reduction of aero drag by around 2.8%; replacing the 26" front wheel with an identical disk reduced the aero drag by 7.1% compared to the conventional configuration.

Aerodynamic Frames

Finally we come to the frame. Investigations by Kyle (12) show aero drag is reduced by around 5% for a manned track bike with aero frame, like the ones developed for the 84 Olympics, compared to a conventional track bike. It is particularly interesting that with a light side wind at about 10� the track bike with aero frame cuts aero drag around 12%, and with a 20� side wind has around 11% better drag than the conventional track bike.

In (17) Kyle presents investigations of commercial frames. Compared with a Gios steel road frame, an aluminum Cannondale frame with rider brought a reduction in aero drag of around 1.6%; a Trek aluminum frame was appropriately even with the Gios, a Kestrel 4000 composite frame brought a reduction of 4.7% and a very complex aero bike by Gleb - this time with 32 aero spokes instead of the 36 round spokes with the other bicycles - obtained an advantage of 7%. The track machines for the 4000 m individual pursuit riders of the US team in the 84 olympics showed an aero drag reduction of about 16% compared to the Gios road bike.

Tour de France in the Wind Tunnel

In wind tunnel studies Steve Hed (18) tried a reproduction of Fignon and LeMond on the last stage of the '89 Tour de France. LeMond rode with a plunging handlebar (bull horn bars) with Scott clip on aero bar, whereby he could assume the same very favorable aerodynamic position as with a normal Scott handle bar. Additionally he wore a Giro aero helmet.

Fignon however rode without a helmet - with a pony tail - and only with the plunging handle bar. Hed's measurements show a 22% advantage in aero drag for LeMond compared to Fignon. If Fignon had ridden with his team's aero helmet, then the difference would still have amounted to 17%. The difference between Fignon and LeMond was not really quite so large however, since Fignon used a front disk wheel, and LeMond only used one with 32 spokes. Hed did not use the different wheels in the wind tunnel. In each case measurements show clear advantages for the Scott aero bar, particularly with a position where the elbows are brought close together.

Now, after all the racing cyclist stuff, where is the bicycle as a means of transport? Aerodynamics are nowadays primarily a topic for the racing cyclist. Here each aerodynamic advantage - no matter how small - must be bought for the victory, so long as the additional weight is not counted as excessive. In addition, with the everyday rider different criteria must be consulted for evaluation. For example the racer pays attention to certain clothing conventions. Racing shorts are even fashionable, but the one-piece Lycra skin suit of the racer is (still?) not.

HPV Development Could Use the Everyday Rider

Sheilds raise aero drag by approximately 5% (11), but nevertheless I would not like to omit it. Am I to ride on vacation with a stripped down bike because the panniers and water bottle would increase the aero drag by approximately 12% or 2%? No, no, that won't do. The aero developments of racing bring almost nothing for the everyday rider.

Nevertheless, there is a certain hope that perhaps wheels made from plastic with a few aerodynamic spokes can be established within the normal bicycle arena on a long-term basis. Apart from the better aerodynamics - comparable with disk wheels - this would have the positive side effect that the problem of broken (steel) spokes would disappear with wheels that are almost always badly built. Factory built wheels are technologically on the lowest level, and often they do not get a grasp on their production quality, were replaced by other operations with high tech plastic technology.

In relation to the extensive investigations into the racing cycle there are relatively few measurements of ordinary bicycles. In (8) the influence of (weather-related) clothing was determined. A rider with summer sport clothing (running shorts and sleeveless t-shirt - fresh from the gym) served as reference on a Dutch style upright bike.

In contrast to this, aero drag increases by 19% for a long-sleeved shirt and long pants. Adding a closed wind jacket it was 24% more than with sport clothing. For winter a German Federal Armed Forces Parka and gloves measured 40% higher aero drag. With a rain cape and rain trousers the cyclist became a parachute: 69% worse aero drag than the summer sport clothes. Hopefully it does not rain very often!

Nevertheless the fact that aerodynamics and rain protection can get along together shows some developments with HPVs. The every day rider can benefit from the efforts in HPV development (hopefully) on a long-term basis; however, to a large extent racing cycle development is irrelevant for the everyday rider.

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Contact:

Rainer Pivit
Marktstrasse 29 a
D-33602 Bielefeld
Germany
Tel.: 0521 / 201 80 81
Fax: 0521 / 201 80 66
pivit@gmx.de

How much time does extra weight cost on Alpe d’Huez?