Slightly, but often not as much as one might imagine. It will of course vary between users, depending upon each persons available range, fitness and strength.
The Retroflex Adjustable Cranks and Comfort Cranks is simply facilitating making outdoor exercise accessible and enjoyable, to be able to enjoy fresh air, and to be able to reach a café. However, we have had elite cyclist use our system whilst injured, simply so that they can maintain their fitness, and some have still been able to perform well whilst racing.
Our Retroflex crank systems fit to all types of bike including electric assist bikes.