For the majority of people the foot, knee and hip are not correctly aligned. In cycling this can lead to biomechanical inefficiency and a loss of power. In many cases this will lead to hip and/or knee pain.
One way to affect the alignment of the foot and knee is at the foot pedal interface. Before we talk too much about alignment, we need to define some terms.
Varus forefoot angulation- more than 85% of people display this. The forefoot is angled up slightly so the big toe is raised off the pedal. Pedaling causes the big toe to descend and contact the pedal. The tibia rotates internally bringing the knee towards the top tube of the bicycle.
Valgus forefoot angulation-occurs in 5% of the population. The outside of the foot is tilted higher than the inside. Pedaling causes the little toe to descend and contact the pedal. The rider will display the classic bow legged look.
Neutral forefoot- 10 % of people have a neutral foot. In many cases these riders will still benefit from varus angulation correction. A neutral foot can never have too much support.
Shimming is one way help a rider who is suffering from alignment problems. It can also help maximize power output and efficiency while minimizing the chance of knee pain or injury. Having proper hip/knee/foot alignment is paramount to successful cycling. Many cyclist report feelings of more power, reduced knee pain, and the most common report is “my legs feel like pistons”.
The purpose of the shim is to support the natural angulation of the foot. There are two types of shims. The first type is the Specialized BG shims. They are placed inside the shoe between the footbed and the insole. They have the advantage of being able to be transferred to other shoes with no tools and minimal time. Some times BG shim can take up too much room in the shoe, crowding the toe box. In this case, the rider may need the second type of shim known as the Lemond LeWedge. LeWedge shims are place between the cleat and the shoe. They have the advantage of not crowding the toe box. They do require a little more precision with the installation (tools , cleat placement). These shims can also be used for correcting leg length discrepancies.
Often shims are used to cure nagging injuries which are usually the result of improper alignment. If you suspect you might have alignment issues, feel free to contact us at Collins Cycle Shop and speak with a certified fit technician about the problems your facing.
And remember, Everyone may not have a custom bike, but everyone can have a custom fit!