Some people's shoes are very big, with all the podiatric equipments like splints. In this case, we make the straps long on the pedals. We sometimes better to re-shape the pedal on the heel, too.
On the other hand, for the people with small shoes, strap may need to be shortened. We sometimes apply thin slices of sponge on the heel, too.
Keeping knees straight is important to pedal COGY effectively.
Some people's knees tend to fall out. In this case, use the leg strap to hold 2 knees in certain distance.
Some people's knee tend to fall in. In this case, use the leg strap to hold the leg and yellow frame together.
For some people, the leg strap is not enough to keep the legs from falling out. Additional metal work may work in this case.