BUYER'S GUIDE: SELECT THE PROPER FRAME FOR YOU - http://www2.bsn.com/cycling/articles/framesize.html

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BUYER'S GUIDE: SELECT THE PROPER FRAME FOR YOU

by Eric A. Koide
Reproduced from: Cycling Science Winter '95

If you're looking to buy a high performance racing bicycle, take your time, research all your options, and come to an informed decision. Don't run out and buy the latest high tech innovation just because it looks or sounds great. Make your final selection carefully. Most important, make sure your new bicycle matches your riding position, your body's comfort zone, and the types of training and racing you do. Your new bicycle should help you to ride more comfortably and efficiently than before so that you can train and race longer, harder, and faster. The following will help guide you in your search to find a racing bicycle that will give you maximal results.

FIVE STEPS TO SELECTING A NEW RACING BICYCLE

1. RESET YOUR POSITION ON YOUR OLD BIKE. FIND YOUR COMFORT ZONE.
Before you select your new bicycle you should take stock of your old bike and determine what you liked and did not like about it and what changes you require in your new bike. Most important, you should analyze and reset your riding position and establish the parameters of your "comfort zone." The comfort zone is the position in which you ride the most comfortably, efficiently, and pain-free. Knowing the frame angles and measures you require to put you in this position will dictate which frames are best suited to you.

As a matter of course you should spend several weeks each year, preferably during the off-season or preseason, analyzing and resetting your ride position. Your objective is to find the position where you feel the most relaxed and biomechanically stable. This is accomplished by adjusting your saddle height and setback, stem height and length, handlebar width and drop, and crankarm length. Triathletes will also want to check and readjust their aerobar length and angle and armrest position.

While making these adjustments try to find the position that is the most comfortable and efficient. Don't be concerned about your most powerful or most aero position at this time. A comfortable and efficient position will allow you to train longer and harder whereas a powerful or aero position may be difficult and fatiguing to maintain throughout a full season of training and may lead to chronic aches and pains that reduce your productive training time.

Resetting your bike position is a continuing process that takes several weeks or months to accomplish. Make minor adjustments, ride on it for a week or two, then perhaps make more adjustments. Make position corrections to alleviate any aches or pains your body has acquired and make sure your new position does not cause any new aches or pains. Additionally, try out your reset position in a variety of workouts: long rides, intervals, hills, sprints, cornering on a crit course. Continue to make incremental adjustments until you find the most comfortable, efficient, and pain-free position possible.

After you've completely reset your position take a look at what you've found. Where is your seat position? Back in a relaxed position, in a neutral position, or pushed forward in an aggressive position? Have you raised or lowered your saddle? Perhaps you need to look for a smaller or larger size bike? How about your handlebar extension and drop? Does your reset position require your new bike to have a longer or shorter top tube? Perhaps you have ended up with a position similar to where you started?

2. SET GEOMETRY PARAMETERS FOR NEW BIKE.
From your position reset you can begin to determine the proper seat angle, top tube length, and frame size combination you need in your new bike.

Figure 1
Seat Tube Angle Rider Position Recommended Uses
shallow (<73.0) relaxed roadrace, century, ultra
normal (73.0 - 74.0) neutral roadrace, criterium
steep (74.0 - 75.0) aggressive criterium, time trial, triathlon
extra steep (>75.0) aggressive-aero time trial, triathlon

Refer to Figure 1 and compare your reset seat angle to the recommended seat angle for the type of riding and racing you do. Road racers who do lots of century distance rides in their training tend to prefer relaxed seat angles whereas criterium racers usually prefer a more aggressive seat angle to accommodate their need for power and sprinting. Triathletes tend to prefer an even more aggressive seat angle to attain a more aero position.

Don't be surprised if your reset position does not correlate with the position recommended for your racing interest. It is common for riders to be most comfortable with a more relaxed seat angle even if they prefer to race in a more aggressive position. Knowing your most comfortable seat angle and the recommended seat angle will give you a range of possible seat angles to look for in your new frame.

Your optimum position for comfortable training may be slightly different than your most powerful position for racing and you may make small adjustments between these positions throughout the season. When shopping for a seat angle take this into account and buy a bicycle that is midway between your most comfortable and most powerful or aero positions. During early season endurance training, when you are doing lots of spinning and distance, you may set your seat in a setback comfortable position. Then, as the season progresses toward important races, you may gradually shift your seat into your race-aggressive position.

Crit riders and triathletes tend to sacrifice comfort to attain a more powerful or aero position during races, but may find it fatiguing to maintain this position during year-round endurance training. Remember that this is a tradeoff and that what races well may be difficult to train with over the long term. If you have chronic or nagging aches and pains or any doubts, opt for a comfortable position. You'll be able to ride longer and harder in the long run, remain free of injury and burnout, enjoy the sport more, and probably achieve greater overall success in the process.

3. DECIDE ON MATERIALS.
Once you have determined the geometry parameters for your new bike, you are ready to decide on the materials. Nowadays high performance racing bicycles constructed of steel and aluminum as well as more sophisticated materials such as carbon fiber and titanium are all widely available. Moreover, the aerospace-derived titanium and carbon fiber are not as astronomically priced as they once were. Additionally, a few companies are experimenting with so-called "exotic" materials which have the potential for quality performance at incredibly low weights. Consult Figure 2 to help you determine which material's properties best fit your riding and racing requirements.

Figure 2
Material Advantages Disadvantages
Steel most versatile metal, most tunable performance characteristics, strong, inexpensive, crash damage can often be repaired inexpensively heaviest weight
Titanium most durable, most damage resistant, strong, resilient, lightweight, extremely comfortable ride characteristics expensive
Carbon Fiber lightest, stiffest, most moldable material, strong, shock and vibration absorbent cracking and damage from crashes is generally irreparable
Aluminium lightweight, inexpensive prone to denting when crashed and weakening due to metal fatigue
Exotics lightweight, strong most expensive

Steel is the most versatile material and can be drawn, machined, shaped, and alloyed with other metals to accommodate a wide variety of strength and performance requirements. The result is an impressive array of strong, comfortable, excellent handling, and inexpensive frames built of steel alloys. The one drawback to steel is that it is much heavier than newer materials.

Titanium is perhaps the best all around material for racing bicycles. It is extremely strong, lightweight, and durable, far outperforming steel in dhese respects. Additionally, it has the unique property of flexion without deformation. This results in a remarkably smooth and comfortable ride as the titanium frame responds to bumps, vibration, and torque application, but remains incredibly strong providing superior power transfer. Titanium is also the most durable of all frame materials and is extremely resistant to denting and metal fatigue. Additionally, titanium is a very unreactive substance and will not rust or corrode. Titanium's primary disadvantage is that it remains quite expensive.

Carbon Fiber is the lightest of all frame materials. Since it can be layered and reinforced, it produces some of the stiffest and strongest frames available. Additionally, it can be molded and sculpted into aerodynamic forms without sacrificing strength, making it a top choice of triathletes. Carbon fiber's one disadvantage is that in the event of cracking or damage the frame is not repairable and must be replaced. Also, a poor quality carbon fiber frame may be brittle and lack the shock absorption of top quality carbon fiber frames.

Aluminum is a popular material because it is extremely lightweight, produces strong tubing and framesets, and yet is remarkably inexpensive. Aluminum's major disadvantage is that it lacks the durability or damage and fatigue resistance of either steel or titanium.

Exotics are the latest wave of new materials. Some of the more notable examples are: ceramic composites, aluminum metal matrices, boron-aluminum compounds, and beryllium-aluminum compounds. Chemically these materials are significantly different from one another but they all have a high strength to weight ratio. Whether due to rarity or complicated production technology, exotics tend to be extremely expensive.

4. CONSIDER SPECIAL PERFORMANCE DESIGNS.
After determining your geometry parameters and materials choices, consider any other special requirements such as aerodynamics, aero positioning, light weight, 650C wheels, or special designs.

5. SELECT PROPER FRAME SIZE.
When you have finally chosen the best bicycle for you, or at least narrowed your choices to a few models, you can select the specific frame size that fits you best.

Measure your inseam. In your socks and on a solid floor, stand against a wall with your feet shoulder-width apart and place a thick hard cover book under your crotch so that it contacts your pelvic bone like a bicycle seat. Mark the height of the book against the wall. Measure from this mark to the floor to get your inseam length. Multiply this measure by 0.64 and 0.65. This will give you two frame sizes to consider. Look at the frame geometry chart accompanying each bicycle listing. Between the two sizes, select the size that gives you the best fit according to the seat angle and top tube length you need. If neither size gives you the proper seat tube angle or top tube length you desire you should consider a different bicycle.

If both sizes give you the proper measurements, you should select the smaller size frame. Although a frame that is too small can cause some problems, a frame that is too large is worse. With a slightly small frame you can lengthen or raise the stem and seatpost to get the proper fit. With a frame that is too big, it just remains too big no matter what adjustments you make. If the top tube is too long, your front center and steering will remain too long and you will always be overreaching.

Whatever high performance racing frame you select, make sure it matches your training and racing requirements and gives you access to both your comfort zone and your power/aero position. Consider all your options carefully and make an informed decision. Then, get out there. Go ride.

Eric Koide Aerospeed Review Davis, CA

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