Carbon Bike on Trainer....... Safe?

[borinomi]

It is fine.

[goodboyr]

Wow. I was waiting 3 weeks for your answer. Thanks for that.

[11.4]

Somewhere else, Nick Crumpton said that he's fine with any of his bikes being ridden on trainers. That says a lot.

I'm curious, though. Relatively speaking, if one cranks a frame around on the road, there is some flexion and give -- the bike can change position for one thing, and any stress is absorbed at least partially by flexion in the wheels. That would apply both to relatively continuous (greater than fractional second) loads and also very transient shock loads. So relatively speaking, I'd expect the trainer is the bigger load. Both may be acceptable, and note that its important that most people don't exactly beat up their trainers all that much so this is moot in those cases. It would be interesting to see some actual stress studies. In the end, especially since my favorite carbon frame is a Crumpton anyway, I'm happy to accept Nick's warranty extension to trainers. Lol.

[5DII]

Lennard Zinn says the stresses on the bike using a trainer are far smaller than the stresses on associated with riding it on the road.

http://velonews.competitor.com/2009/04/ ... outs_90568

[11.4]

Lennard Zinn says the stresses on the bike using a trainer are far smaller than the stresses on associated with riding it on the road.

http://velonews.competitor.com/2009/04/ ... outs_90568

I wish he had shared his reasoning. The one thing that a frame faces on the road versus on the trainer is the frequent vertical impact of road irregularities. And of course many people ride a bike harder on the road than on their trainer. But some evidence would be interesting. I haven't really seen anything that looks like valid torque data on stay ends (which is presumably where we need to be looking?) when doing maximal efforts in a trainer.

[jooo]

Some trainers can be clamped down much harder than any normal skewer, which could certainly cause cracking issues, but this isn't a problem with carbon frames as such, just heavy handed users - the same kind of people who over-tighten posts, stems, bars etc.

An issue I've read about is pulling dropouts out of the stay ends, but this sounds like something that is far less common on modern or high end frames. The fact that aluminum dropouts are less common on a lot of bikes these days makes this less of an issue in general. Frames that do still use aluminum generally seem to have less problems these days too, maybe because the epoxy used in mass produced bikes is better than 12-15 years ago and also that manufacturers are far more careful to prevent corrosion, isolate the aluminum from the carbon fibre etc. Think of how many bikes would have been warrantied for this say 10 years ago - probably quite a few. Again if you're having problems with this, chances are it's not that trainer's fault as such, just that whoever made your bike has probably been a bit sloppy.

[Calnago]

Yeah, I'm not sure I buy that either. Not to say a trainer is going to break anything, but it's kind of like clamping your dropouts into an immovable vice then putting sideways force on it. On the road, the bike moves and leans with the rider and the forces. I'd also be curious to hear Zen's reasoning on that one.

[jooo]

Sorry, that's not what I'm talking about, but rather just crushing the dropout. Using your vice analogy, just imagine you put a dropout in a vice and kept tightening the vice until the dropout cant deal with the compression any more. Or if you had threaded axles like a track bike and just kept tightening the nut as hard as you possibly could with massive breaker bar or something stupid like that. Does that make sense?

[Calnago]

@jooo: I must have posted the same time you were. I was actually referring to 11.4's post that I too would like to hear Zinn's reasoning. As to your question, I don't know how much force it would actually take to crush the dropouts from sheer claiming pressure. I would suspect quite a lot, however. With enough force I suppose anything can break.

[goodboyr]

I'm totally missing the point of this discussion now. Are we still questioning whether it's OK to use a carbon bike on a trainer, or are we into some more esoteric and theoretical discussion? Because using a carbon bike in a trainer, from both theory and actual empirical experience is totally safe.........

[AlpeDHuez]

Unfortunately I'm resurrecting this topic with real world experience using a carbon frame with a direct drive trainer. During a steady out-of-saddle effort while riding up the radio tower climb on Zwift mountain (likely a familiar experience to many of you) a dull pop rang out from the rear of the bike, which simultaneously leaned sharply to one side, with the frame impacting against the flywheel housing of my trainer. Experiencing the odd sensation of crashing on a trainer, I managed to unclip just as the frame popped off the skewer at the opposing dropout. Looking over the bike afterwards, I discovered the source of the initial problem—the chainstay snapped on the side of the bike where the lean occurred. In case any of you may be wondering if I'm a heavyweight, that's not the case. 140lbs tops.

Considering I can't seem to find many similar stories of carbon frames failing on trainers, I can only guess my experience can be deemed a statistical fluke (albeit an expensive on).

[dim]

I'm not so sure .... it depends how you pedal

My son uses Zwift and I've had a go a few times on his setup (he uses his Canyon Endurace)

I tend to rock sideways when I pedal, and never realized that till I used the trainer

it must do damage after a while?

[AlpeDHuez]

When on climbing on a trainer, it's best to use an up and down motion (like Dan Martin) and not side to side (like Fabio Aru).

[BikeAnon]

....Considering I can't seem to find many similar stories of carbon frames failing on trainers, I can only guess my experience can be deemed a statistical fluke (albeit an expensive one)...

Does your frame need to be repaired now? I snapped a seat-stay last year. Repaired it for under $30, and a little bit of work. It's held up well.

[AlpeDHuez]

Yes--the frame will need to be repaired. Currently being assessed by a carbon guy (as the manufacturer will not warranty).