I thought I'd bring this here to see what you guys and girls think or would do yourself. I have a Trek 2200 (aluminum frame) thats several years old. Right now while I'm in college, it's the road bike I have. I haven't let my brother ride it because he's not real good about not wrecking things like that, or paying for them once he does wreck them. I recently bought a trainer and now he wants on it too. He weighs around 200 pounds, I'm around 170. What I'm concerned about is all of that extra use might be more wear and tear on the bike than I want, but I haven't had a trainer for long so I don't know how "rough" it could possibly be for a bike on a trainer, I guess as rough as you make it (and my bro is not one to be gentle on things, especially if you're not standing over him). I definately don't want any hardcore cranking on it in the trainer as I feel with the bike unable to flex as much hooked onto the trainer that it would be harder on the frame, and I'm not sure that I can trust him not to do it when I'm not around. So am I being stingy, or am I justified?

Well I recommend removing the seat, just keave the seat post, he'll think twice about trying it.

I have heard that trainers are hard on a frame, but I have only heard that. I know they can certainly wear down a tire fast (my experience). I use my road bike on a trainer, oh, for about 3 years now. No ill effects yet, but I am NOT hard on it, and I just spin, no hard pushing, standing, sprints, etc.

Digger

Tyres suffer on the trainer, so he might want to fit a (slightly wider) cheapo tyre for trainer use.

If you're worried about stresses, then probably the best thing you can do is fit a cheapo quick-release spindle on the back wheel. That will save your better quality one from possible deformation.

I'm not entirely sure how much increased risk there is on the other componentry though.