Originally Posted by T-Mar

The OP is talking about a circa 1984 Turbotrainer. Back then, the trainers typically locked into the front wheel dropouts and had a BB support that could be moved forward or backwards and raised or lowered to accommodate the BB shell position. On the Turbotrainer, the BB shell was held down onto the cradle support only by a bungee style cord. The front supports weren't very rigid and the BB support even less so. The bungee attachment would allow some bouncing.when pedaling hard. It was very common to see lateral movement of the rear wheel due to flex and movement of the trainer stand and bouncing of the frame. It is inherent to the Turbotrainer design and has little, if anything, to do with frame flex..