can a carbon frame take this?

Cycler6n

I've been training, and i have a training dvd, I was watching it to get tips, and I saw them sprinting, they were pushing their bikes really hard. I saw their frames "swaying" (not sure of correct term) left to right as they were sprinting on a carbon bike on a trainer, and my question is, could a carbon frame while on a trainer being "swayed" left to right hurt or crack the frame?

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kdelong

The term is "flexing". Every bike has a certain amount of flex, even carbon. There is less flex and it is normally not noticed when one is riding or training on rollers because the bike is free to move. It is more pronounced on a trainer because the rear wheel is held captive. I don't know how much flex was shown on your video, but you can flex carbon a fair bit over the length of the tubing on a normal road bike. A small amount of flex won't hurt the frame, but a lot of heavy flexing will probably shorten the life of the frame.

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Cycler6n

ah, thx.

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garage sale GT

Although other factors such as the type and quality of the joints can complicate things, carbon is better able to handle fatigue than many metals.

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Powerful Pete

I have been riding my bikes (steel and alu/CF) on trainers for years and while they flex like crazy, nothing serious appears to have happened to them.

Train away, my friend.

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dazman

Funnily enough my Cervelo Soloist flexes way more than my old alu Specialized Allez on the trainer. For that reason I prefer not to use the carbon bike in the trainer

Cycler6n

my tarmac flexes where I can see it, but doesn't flex too much where it affects my training.

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sogood

At the end of the day, these flexes will induce fatigue in all materials. If you aren't game to do it on a CF frame, then you really shouldn't be doing it on a steel or alu frame either. I'd think that a competent bike R&D manufacturer would already have done the necessary mechanical tests like this.

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Crankyfeet

Hmmm....It's a good point though...

Someone should be out there now designing a new trainer that has flexible supports with heavy-duty springs or something which allows the rear wheel/axle to sway with the rider. This will take the unrealistic stress off the chain and seat stays, and also give a feel that is more realistic. Patent pending...

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kdelong

Its already been done. They call it "Rollers". Why do I gotta be the f**king dictionary on this post?

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sogood

C'mon... Get your style right. No rocking the bike, keep your upper body relaxed, keep your spin smooth and efficient. I repeat, NO ROCKING!

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Crankyfeet

Have you seen a sprint finish at the end of a Pro race from the front? Tom Boonen for instance?

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Crankyfeet

Funny one dude.

Except that, whilst its fun to balance on rollers, rollers DO NOT mimick real riding physics. Wiith forward momentum a bike has inertia that makes it easier to balance. Consequently, that's why its easier to ride in a balanced straight line when going 20 mph as opposed to 1 mph. The spinning wheels do give some gyroscopic inertia though, the same phenomena that keeps a frisbee stable.

So a trainer that gives some righting force but still allows sway, may mimick real riding better than rollers possibly, and certainly would be easier to ride than rollers for the majority of cyclists. But its only going to be different when your off the saddle.... and its just an idea.

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Cycler6n

they already got those, kurt kinetic makes em, called the rock and roll, it sways left to right w/ the bike

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