Originally Posted by Darth_Firebolt

We had a 6'4" guy break an aluminum Felt on a trainer at the drive side chainstay / dropout joint region. Felt didn't have an aluminum 63cm frame on the continent for over 6 months so they upgraded him to a carbon model, which he proceeded to break on the trainer in the same spot after about 8 months. I believe the original frame was a Z85, but it's been 5 or 6 years at this point and I'm foggy on what it was replaced with. He was a very fit and powerful rider and might have broken both of those frames from just regular riding, but he said he was using the trainer a lot because it was over 100F a LOT that summer. After he broke that carbon frame he bought a Tarmac from us and I moved away about a month later. Not because he kept breaking frames on trainers. Lol

Edit to say this; most of the people that use trainers (and ride in general) are not clydes. They also don't do a lot of standing out of the saddle on trainers from what I've seen. They weigh less, are shorter, and put out less power. They could probably ride anything in a trainer and get away with it. Most dropouts are not made strong enough to resist the leverage put on them by trainers if taller, heavier, more powerful riders are standing and working on them. There's a LOT of leverage there. That part of the bike isn't usually held stationary and twisted like that. Set up a camera from the side of your front tire and take a clip in super high frames per second of you standing and dropping the hammer. Slow it down and watch how much your bike is twisting around the dropouts when it would normally not be doing that. Just getting a spin in to get your heart rate up is one thing and probably won't break your bike. Standing and hammering is totally different and could.