"Swaying" isn't enough info to have us give anything but wide and generalized suggestions. So can you help us help you? We need to know if the sway is actually slop/looseness in the BB, crank arm attachment or ring mounting. Or is it the natural flex of a frame (that you never spotted before).


With the bike stationary but stable grab each crank arm end. Try to wiggle/rock the crank with your hands. Does it rock back and forth? Or does it only rotate a tiny bit as you try to keep the motion as cross directed as possible? Next straddle the bike and with the brakes pulled firmly place your strong leg on that side's pedal 9at about the mid point of the down stroke) and apply significant pressure. Can you see the pedal/crank flex away from the side you're pushing on?


Trainer stand frame of reference is a poor one for real life reference. While the axle is somewhat stabilized (it does usually move within the stand's axle cups) the rear tire is scuffing side to side over the roller with each pedal stroke (which doesn't happen on dry roads in real life). Not knowing how to separate out the different motions (trainer VS road) can lead some to wrong conclusions.


1/4" of frame flex at the Bb is not a wrong amount. Andy