Personally, I would ride but not stand up and sprint on the trainer. Sprinting when the frame is rigidly held by the trainer flexes the frame in ways that look scary to me...

This question comes up every year about this time and you will hear different answers. As for me, I ride indoors most of the time year round and have had no problems with my bikes on a trainer.

I ride on the trainer all the time. I put a sweater on the handlebars to protect from sweat. Also ride with a fan blowing.

 
Always makes me nervous. I don't stand on the trainer and try to avoid any side to side motion.

Friend of mine broke both rear dropouts off a Scott Addict from riding it on the trainer. Course he weighs in around 250lbs and has a decent amount of side to side action in his pedal stroke.

Rollers are an option to avoid stress on the frame.

Your frame is flexing the same way when you sprint outside you just don't have a stationary reference to see it. If I didn't think a frame could stand up to the stresses of a trainer, there is now way I would trust it on a 50 mph decent.

I agree there's *some* flex outside and that it's harder to see, but I don't think it's equivalent to the frame being held rigidly at the dropouts. Outside, the frame can tilt side to side and the wheels can flex a little, too, so I suspect the loads are both lesser and different. Repeatedly stressing the frame by sprinting on it indoors seems like a bad idea to me, but to each his or her own...

From our online bike owner's manual:

"When clamped to a trainer, your bicycle experiences high forces that are very different from the forces that occur in normal riding. In extreme cases, the unusual forces applied by a trainer can actually break a frame. Avoid extremely hard efforts on a trainer, such as applying high side-loads when sprinting or climbing. Especially avoid trainers that rigidly hold the rear triangle of the frame while constraining movement of the rear wheel."

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Carl Matson

What's this mean if you don't mind? KICKR?

What does "constraining movement of the rear wheel" mean in this context?

Hello Carl and All,

What is your opinion regarding trainers that take the back wheel off like Wahoo Kickr ..... for likelihood of bike frame damage .....compared to those with the back wheel attached to a roller?

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Cheers, Neal

+1 mph Faster

It means trainers that prevent the rear wheel from moving in a more natural "outside, on the road" manner are to be avoided. Something like a KICKR doesn't involve the rear wheel, obviously, but it still rigidly holds the rear triangle. As the manual says, avoid extremely hard efforts such as applying high side loads [as] when climbing or sprinting.

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Carl Matson

Meaning the rear wheel can't move (more) like it does out in the real world on the road.

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Carl Matson

Hi Neal-

Answered above. If it prevents the rear triangle from moving naturally then it's best to avoid simulations of climbing, sprinting, etc.

Cheers-

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Carl Matson

Perhaps you could cite a specific example or two? Wheel-on trainers generally hold the dropouts rigidly but the wheel can move side to side, and the wheel doesn't support any of the weight of the rider. Wheel-off trainers like the KICKR seem effectively the same, i.e. the dropouts are rigidly held and supporting the rider's weight, it's not clear to me the lack of a wheel actually changes the forces on the frame at all. Are these examples of situations where the wheel can't move like it does in the real world? If not, what are examples?

Yes, wheel-on trainers let the rear wheel move slightly, but not in the same manner that you'd get riding outdoors where the rear triangle is free to move as well. in fact, if anything, the wheel motion relative to the frame that you see in wheel-on trainers is likely increased over what you'd see outdoors because the rear triangle is fixed.

As you point out, the wheel isn't really handling any significant (vertical) load so the fact it's absent in a wheel-off trainer doesn't change the potential concern: avoid high-output efforts that could induce large lateral loads if the rear triangle is held rigidly in place.

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Carl Matson

I'll confess to being confused, I can't figure out what these trainers that Trek is telling us to "especially avoid" actually are.

Also, a fixed rear triangle means the wheel might move more than outdoors? I'm not following.


Agreed, lateral loads seem to relate to the bike being rigidly held at the dropouts, so this concern seems to apply essentially equally to almost all trainers, and the big thing to avoid is standing up and putting huge lateral forces on the frame.

Aside from the direct-drive models, isn't this ALL trainers?

You've got the answer in your last couple lines, pretty much...in red:


Rollers don't have this issue. Trainers that clamp the rear triangle but allow the rear end to pivot (e.g. Kurt Kinetic Rock and Roll) are better than fully rigid trainers but I personally would still exercise caution with something like that when it comes to laying down the megawatts.

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Carl Matson

See below (above).

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Carl Matson

Maybe I'm dense, but what's a fully rigid trainer? The wheel-on trainers with which I'm familiar are all like the Kurt Kinetic Rock and Roll, i.e. they rigidly clamp at the drop-outs but the non-load-bearing wheel can move laterally a little bit on the roller.

And I completely agree that on any trainer than clamps the bike in place (as opposed to rollers), standing up and really flexing the frame seems like a bad idea.

I have a computrainer and have used it for the past three years with my Argon E118, I don't bend cranks but do put out wattage doing intervals and I ride hill courses on it all winter. I have not done any damage to my bike.

They all allow the rear end to rock side to side like the Kinetic? Have you watched a video of that trainer in action?

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Carl Matson

Ah, that's right, that's the one that literally rocks back and forth (hence the name). I was confused by your assertion that this was an example of a trainer that rigidly holds the rear at the dropouts while not constraining the movement of the wheel.

So that Trek policy could be summarized as "especially avoid all trainers that rigidly clamp the rear at the dropouts, which is true of the vast majority of all trainers, both wheel-on and wheel-off, on the market."

Do you have an option for another back up or cross bike to ride? Put some clip ons & ride. I kept my old titanium QR TiPhoon around for trainer riding but wouldn't use my carbon frame in the trainer.