ELECTRONIC BIKE FITTING PROCESS

By Roger Young, former Olympic Cycling Team Coach

Years ago, bike fitting was an art done by expert coaches with years of experience. Coaches would visually critique and adjust the positions by sight. Then along came the mechanical kit that allowed bike shops to measure riders. Expert riders had also defined equations and procedures for taking measurements to fit riders to bikes.

The problem with the kits and experts' books is there is no interaction and it is presumed that nobody has special conditions. The truth is everyone has special conditions, and there is always need for position tuning and fitting even when standard equat ions and procedures for taking measurements to fit riders to bikes.

Using a CompuTrainer, anyone can fit any rider expertly to his or her bike safely and accurately through electronic means. The process puts people on their own bikes riding under conditions similar to the level and type of riding they want to be adjusted to. The way it works is to compare heart-rate to watts of power output at various riding positions, adjusting to the lowest power "cost" for the specific riding speed and terrain chosen. Here are some of the advantages:
  1. The process uses the person's own bike and equipment.
  2. The adjustments to posture and position are done under real riding conditions.
  3. Different positions may be defined for specific riding terrain and levels of riding.
  4. It's easy to perform the fitting.
  5. It's fun because of the rider interaction (riders see their riding become more effective throughout the fitting process).
  6. The procedure is repeatable.
  7. A person's performance is improved by 5-15% compared to standard fitting.

The theory behind the process is this: By using physiological responses to determine where the bike needs to be adjusted, a correct position is achieved. This assures that the bike complements the anatomy of the rider. It also means that a rider's bike may be finely adjusted to optimize performance under various conditions like climbing, time-trials, or sprinting. Since performance itself determines the best position, optimum performance is guaranteed.

ELECTRONIC BICYCLE POSITIONING INSTRUCTIONS

  1. Find out what level and type of riding the person will be doing. Make sure you ask the person what the majority of their riding will be. For beginners, you will need help with determining common speeds and terrain that is common for your area. This will be an imporant reason for re-adjustment sessions with riders whose riding levels or types of riding change over time.
  2. Choose the speed and gear you will run in the position evaluation. Here's a table you can use to select speeds for different groups.
    Level Suggested Speed Suggested Gear
    Beginner (mountain biking) 8-12 mph 42 X 18-21
    (hilly road)
    (road) 12-14 mph 42 X 18-18
    Intermediate (mountain biking) 10-14 mph 42 X 14-16
    (hilly road)
    Recreational Racer (mountain biking) 12-16 mph 42 X 14-16
    (hilly road)
    16-20 mph 53 X 16-18
    Expert (mountain biking) 14-18 mph 46 X 15-18
    (hilly road) 53 X 18-20
    (road) 20-24 mph 53 X 16-18

    Try and choose a gear that the rider can steadily pedal at about 80 rpm.

    1. Configure the CompuTrainer for the course reflecting the specific type of riding. Set up three six-mile courses (flat, 3% grade, and 6% grade).
    2. Check the screen to be sure the profile (top of the screen) reflects the course profile you want. Become familiar with CompuTrainer configuration processes.
    3. Set the rider's weight (include the weight of the bike)
    4. Do a general bike positioning setup. Experienced riders should already have a general setting they are comfortable with. New riders should stand next to the seat of the bike facing forward (toward the handle bars with the bike level on the ground.) Then set the seat height about an inch below the rider's hip bone. You should be able to see the rider achieve a flat back when the elbows are bent 90 degrees (this should give the rider the beginning of an aerodynamic posture). You shou ld also see maximum leg extension between 150-170 degrees (from thigh to shin over the knee). Once you do the general setting, you should allow the rider to sit in the posture that is most comfortable for the type of riding you're adjusting towards.
    5. Put the bike on the CompuTrainer and perform the spin-down calibration of rolling resistance. If the handlebar controller does not accept the setting, reduce the pressure on the rear tire friction roller. A setting between 2.0 lbs an d 3.0 lbs is typical.
    6. Have the rider mount the bike, ride easy, clip on the earlobe heartrate sensor, and select the appropriate gear.
    7. Start the person riding at the chosen speed.
    8. When the rider's heartrate has stabilized, note the heartrate and watts, and have the rider dismount. Be sure the person is riding at a level that the rider will be able to repeat through the adjustment sessions.
    9. Mark the position of the component you will be adjusting, make a modification, then repeat steps 9 and 10.
    10. If the modification shows lower heartrate, go back through steps 9-11 repeatedly, making modifications in one direction (up/down/front or back) at small increments (about 3mm) until you no longer see a continued drop in heartrate.
    11. If your first modification does not show a drop in heartrate, go back to the original setting and modify in the opposite direction, going back to step 9.
    12. When you observe a rise in heartrate, having modified in both directions, you should be able to identify the optimum setting for the component.

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