Bike Fit Evaluation: Can It Help Diagnose And Prevent Cycling Injuries?
- Volume 19 - Issue 12 - December 2006
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Keys To Optimizing The Shoe/Pedal Interface
Shoe/pedal interface. Serious road and mountain bike riders should use a dedicated bicycle shoe that offers a rigid sole. Bike shoes should fit well and have adjustment straps to aid in fine-tuning the fitting process. There are two options for maintaining the bike shoe on the pedal in the most appropriate position. These options are older style toe clips and the popular, in-vogue clipless pedal systems.
Toe clips consist of a cage and attachment straps controlling only the fore/aft position of the shoe on the pedal by using various sized cages. Clipless pedal systems involve mounting a cleat onto the bike shoe sole and then clicking the cleat of the shoe into the clipless pedal. Some pedal systems allow for rotation on the pedal and some fix the foot to the pedal in the desired position. The clipless pedal systems allow for fore/aft and side to side adjustments as well as some internal and external rotation.
Make all adjustments with the cyclist in his or her shoes with cleats loosely attached and shoes clipped into the pedals. Generally, the ball of the foot is centered over the pedal axle. Specifically, we recommend adjusting the cleat on the bike shoe so the bunion area, which is easy to identify, is directly over or up to 1 cm proximal to the pedal axle.
If the cyclist walks with a foot position that is in-toed or out-toed (for whatever reason), one can reproduce this position to some degree at the shoe/pedal interface. For an intoed cyclist, position the cleat on the shoe as far medial as possible and then internally rotate the shoe on the cleat, usually up to 10 degrees. For an out-toed cyclist, position the cleat as far lateral on the shoe as possible and rotate the shoe externally up to 10 degrees. Take care that the medial malleolus does not contact the crank arm in this position.
After establishing the desired position, firmly fix the cleat to the shoe. There are commercially available systems to assist with the shoe/pedal setup. The Fit Kit® (New England Cycling Academy) has a rotational adjustment device (RAD) that is useful in determining proper transverse plane positioning on the shoe. One can make additional adjustments to the shoe/cleat/pedal interface that include medial and lateral canting of the forefoot and buildups for limb length discrepancy. One can accomplish these adjustments within the shoe, sometimes between the shoe and cleat and rarely on the pedal itself. Address excessively everted or valgus heel positions with medial (varus) cants or wedges. Address excessively inverted or varus heel positions with lateral (valgus) cants or wedges.
One can add buildups for limb length discrepancies within the shoe up to 1/4-inch to 3/8-inch. Larger discrepancies will require a pedal or shoe sole buildup. It must be noted that accommodating limb length discrepancy for cyclists is a challenging topic and strategies to address the discrepancy depend on the level of discrepancy (e.g., femur (proximal) vs. tibia (distal)). Distal discrepancies usually require in-shoe, shoe sole or pedal buildups for the short side whereas proximal discrepancies may require asymmetric crank arm lengths in addition to shoe or pedal buildups. We have found limb length studies (sequential X-rays of hips, knees and ankles with a grid) to be helpful in determining the exact amount and level of discrepancy before deciding if and how to accommodate it.
What About The Handlebars?
Handlebar height and handlebar reach. These are subject to comfort and personal preference. Most cyclists place the handlebar height 2 to 4 cm below the saddle height. Recreational cyclists prefer a higher handlebar height whereas racing enthusiasts will tend to lower their bars for a more aerodynamic position. Evaluate handlebar height in relation to seat height by placing a yardstick on the seat and extend it over the handlebars. One can then easily measure the difference in height.