Originally Posted by hhnngg1

Rollers do not help my power one bit. They don't make me more efficient, and if I use them exclusively, they make me SLOWER because it's so much harder to maintain high-power efforts (like threshold+) for significant periods compared to a fixed trainer so that I don't develop the power anywhere near as well.

I also think the smoothness=efficiency or more power is a placebo (mental) effect. If you're not riding in the higher power zones regularly, and more often, you're not going to get as fast. Even a choppy pedalstroke will smooth itself out when you do a lot of time on the bike, fixed trainer or not. Someone who puts out 250watts with a powermeter on a trainer will bust his same self at 225watts on a nondraft TT every time, and it won't even be close, even if the 225watt guy is a buttery smooth as silk pedalstroke. Unlike swimming, it's hard to discard lots of extra watts on a bike, even if you're intentionally trying to pedal 'in squares'.

As well, the smoothness factor isn't gained because of lateral motion on the rollers - it's the fore/aft motions (on nonfloat rollers- floating rollers remove a lot of the challenge of this part.) Seriously, once you even get mildly comfortable about not going off the side on rollers, which doesn't take too long at all, the biggest challenge is not going off the front when you accelerate hard or stand up and crank. If you get really comfy on rollers, you'll find it has almost nothing to do with lateral motion - I spend almost all my mental energy on rollers avoiding going off the front and virtually zero time worrying about going off the side.