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Old 02-24-10, 07:56 AM   #1
DougG
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Carbon Bike on Workstand

I know that I won't be able to clamp my workstand on a frame tube of my new carbon bike when I get it, but is it generally OK to clamp on the seat post if it also has a carbon post?

As a former engineer, I would like to clamp the bike as near to its center of gravity as possible, and clamping on the seat tube always seemed counter-intuitive since it cantilevers much of the weight of the bike (bike in horizontal position), putting bending stresses on the seat tube. But maybe carbon posts are strong enough and it's OK to do that. Is it?
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Old 02-24-10, 08:12 AM   #2
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I believe carbon seatposts are plenty strong enough to be used as clamping points for your workstand. They take more stress from your weight while riding than from the bike's weight.

That said, unless your seatpost is a non-round design, why not buy a cheap metal seatpost and dedicate it to workstand use?
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Old 02-24-10, 08:28 AM   #3
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Use the seatpost, never the seat tube. Be sure the post is below the minimum insertion line. Clamping my seat tube mars the finish on my 1000$ paint job.
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Old 02-24-10, 11:42 AM   #4
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Take the seat post out and look inside it. It may be Al. with a carbon wrap. I think you can clamp those. Some of the manufacturers make rubber inserts that allow you to clamp the seat tube. Be careful as plastic is very notch sensitive.
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Old 02-24-10, 11:57 AM   #5
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What kind of work will you be doing to the bike while it's on the stand? If just simple maintenance like adjusting deraillers and brakes, you can get away clamping pretty much anywhere. Just don't clamp very hard. If you are torquing BB cups or crank arms, I do those tasks with the bike on the ground regardless of frame material. Not worth the risk and having the bike on a stand doesn't offer much benefit in those situations.
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Old 02-24-10, 12:09 PM   #6
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Quote:
Originally Posted by DougG View Post
I know that I won't be able to clamp my workstand on a frame tube of my new carbon bike when I get it, but is it generally OK to clamp on the seat post if it also has a carbon post?

As a former engineer, I would like to clamp the bike as near to its center of gravity as possible, and clamping on the seat tube always seemed counter-intuitive since it cantilevers much of the weight of the bike (bike in horizontal position), putting bending stresses on the seat tube. But maybe carbon posts are strong enough and it's OK to do that. Is it?
You need to tell us what workstand it is and what clamp.

For example the park extreme range clamp - you should be able to clamp almost every single seatpost (aero, semi-aero, round etc. out there (with the exception of seatmasts) without problems:



We've never broken or damaged a post and we've never had to swap one of for an AL one for fear of damaging it (not even possible with half the bikes we sell anyways).

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Originally Posted by mkane77g View Post
Use the seatpost, never the seat tube.
+1 for carbon
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Old 02-25-10, 09:35 AM   #7
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The new Park clamp was practically designed for this. Clamp pressure is easily adjustable. Cheaper than the clamp operator posted, but not as versatile.
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Old 02-25-10, 09:40 AM   #8
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Originally Posted by helicomatic View Post


The new Park clamp was practically designed for this. Clamp pressure is easily adjustable. Cheaper than the clamp operator posted, but not as versatile.
Yep, that's the home mechanic version of the clamp and they're clamping on a seatmast in that picture as well.
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Old 02-25-10, 09:57 AM   #9
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Quote:
Originally Posted by HillRider View Post
I believe carbon seatposts are plenty strong enough to be used as clamping points for your workstand. They take more stress from your weight while riding than from the bike's weight.

That said, unless your seatpost is a non-round design, why not buy a cheap metal seatpost and dedicate it to workstand use?
+1 on a round carbon seat post. I clamp onto mine without any problems. Realize you need not clamp with gorilla like strength. The jaws on padded with rubber and the coefficient of friction is pretty good between the two surfaces.

I never clamp on the any part of the frame, whether carbon or aluminum. The ratio of wall thickness to diameter of a frame member (say seat tube) is rather small. The ratio of wall thickness to diameter of a seat post is much greater. I cannot quantify this, but seems like the latter would be harder to crush.

Also, I agree with the OP, that clamping at the center of gravity would be best. However, realize the frame is designed to hold the rider's weight plus dynamic loading, I can easily convince myself the forces in the frame members due to the static weight of the frame on a stand is rather small in comparison.

BTW to the OP - you're never a "former engineer". You're always an engineer, perhaps just retired and having fun! I am a "current engineer" and having a little less fun.
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