That they do. A little anecdote....I was being fitted by a guy who has all the latest equipment and training. Bear in mind I am 72 and have the mesomorph football player body. So, I'm on the bike/machine and the fitter comes over and says, "A good recreational rider will pedal at about 60% efficiency (perfect circles). You are pedaling at 85% with no leg imbalance. How can you do that?" I responded, "I've never owned a trainer. But, I've ridden rollers for 30 years." He simply said, "Of course."