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Old 11-01-05, 05:50 PM   #1
dragonflybikes
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Where to clamp bike with a repair stand?

I have a new Orbea Onix bike. It is all carbon and I have a carbon seat post. I am concerned about where to clamp onto the bike with a repair stand. I am worried about damaging the frame or the seat post. What is the best and safest way to clamp a bike? I have even thought about making my own stand that would the top tube would rest on both at the front and the back. Am I just being paranoid or do I have to be extra carefull?

Thanks
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Old 11-01-05, 06:13 PM   #2
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Quote:
Originally Posted by dragonflybikes
I am worried about damaging the frame or the seat post. What is the best and safest way to clamp a bike
A cloth in the jaws will protect the surface and finish of the seat post. Not overtightening the jaws will ensure you won't crush the post.

If you're very very paranoid, do like I do with my bents: hang it to the ceiling with a soft cotton rope by the bar ends and by the saddle. Sure it'll be wobbly to work on it, but at least you'll be extra sure it won't be damaged.

Last edited by ppc; 11-01-05 at 06:22 PM.
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Old 11-01-05, 06:15 PM   #3
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You are being paranoid, but correctly paranoid.

Never clamp your bike by its tubes. Don't clamp it by its CF seatpost, either.

Buy the cheapest seatpost that will fit your seat tube and use it as a "build post." Clamp your bike by that build post.

Works every time. Prolly find something for ten bucks. Cheaper than either a new frame or a new CF post....

EDIT: Here. Three bucks in 31.6mm dia. Prolly something for not much more on the same site if yours is of a different diameter: http://www.jensonusa.com/store/produ...e.aspx?sc=frgl
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Old 11-01-05, 06:20 PM   #4
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Originally Posted by neil0502
Don't clamp it by its CF seatpost, either.
Is that common practice? I've never owned a carbon bike, but I can't see why a carbon seat post wouldn't stand the torque of the bike being lifted by it. After all, it can surely withstand the weight of the rider pushing backward or something.
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Old 11-01-05, 06:31 PM   #5
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Quote:
Originally Posted by ppc
Is that common practice? I've never owned a carbon bike, but I can't see why a carbon seat post wouldn't stand the torque of the bike being lifted by it. After all, it can surely withstand the weight of the rider pushing backward or something.
It's not the axial load of lifting the bike (or supporting you) that's the problem. It's the radial load from the repair stand's clamp. Frame tubes and carbon seatposts don't have a large amount of "crush" strength since that's not what they are designed for.

The recommendation to buy the cheapest proper diameter seat post you can find and use it with the repair stand is a very good one.
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Old 11-01-05, 06:47 PM   #6
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what about for simple adjustments and cleanings? The bike is allready built (I did it without a stand) I just want to be able to do a better and easier job at adjusting the derailures as the cables strtch and make other adjustments.
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Old 11-01-05, 06:55 PM   #7
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I agree, clamp on the seat post. I disagree that a cf seat post is too fragile. I was at my LBS the other day and they told me they just prepared a new Cervelo for Dave Zabriski and I know their "world class" mechanics clamp on cf posts all the time. These guys are top shelf mechanics and prepare bikes for guys like Zabiski, Levi Leipheimer, etc. BTW, they are the largest Orbea seller in the U.S.

The seat tube clamp exerts a lot more concentrated pressure on the post than a repair stand ever would. You won't crush it with a repair stand clamp. If you're concerned about protecting the finish, go ahead and put a rag around it. My stand (Ultimate) has nice soft jaws, so I don't bother. Have clamped my and my wife's Bontrager Race X Light cf post all the time and no marks, no problems.
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Old 11-01-05, 06:59 PM   #8
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I noticed that my LBS clamped my (freshly painted) fixed gear conversion by a seat-post-surrogate. I appreciated their consideration!
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Old 11-01-05, 07:03 PM   #9
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This one's pret-ty simple, folks: clamping to anything other than a build post (or the expensive equivalent sold by Park Tool) = some risk, no reward.

You can do what you want with your bikes. I'll continue to use the low-$ seatpost with mine. Takes about six extra seconds. Takes risk down to zero.

Don't mean to sound like my answer's the only one worth beans here. It's far from that. But I don't take chances with expensive frames or expensive components. Not sure why anybody would. As to Dave Zabriski, incidentally, if something does happen to his seatpost (or any other piece), they run to the van and grab another one off the shelf. It's not always fair to try to translate what team wrenches do into what you or I should do.

Just my $0.02. YMMV.
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Old 11-01-05, 07:05 PM   #10
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Quote:
Originally Posted by HillRider
It's not the axial load of lifting the bike (or supporting you) that's the problem. It's the radial load from the repair stand's clamp. Frame tubes and carbon seatposts don't have a large amount of "crush" strength since that's not what they are designed for.

The recommendation to buy the cheapest proper diameter seat post you can find and use it with the repair stand is a very good one.
You couldn't crush a CF post with a bike repair stand. The concern would be that the bike not get bumped around while being held by a CF post.
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Old 11-01-05, 07:12 PM   #11
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Quote:
Originally Posted by Expatriate
You couldn't crush a CF post with a bike repair stand. The concern would be that the bike not get bumped around while being held by a CF post.
That's probably correct. The poster who said that the frame's seat post clamp puts much more force on the post then a repair stand makes a good point.
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Old 11-01-05, 07:20 PM   #12
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If you're still looking for a repair stand, look into the types that don't have a clamp. Minoura and Park have repair stands that cradle the bottom bracket and clamp the fork.
Park version.
Minoura version.
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Old 11-01-05, 07:25 PM   #13
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The CF seat post cannot tolerate much in the way of bending. Apparently, one of the guys in The Aussie Thread just busted one. He avoided a core sample though.
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Old 11-01-05, 08:02 PM   #14
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i'm a fan of these:



http://www.parktool.com/products/det...=24&item=ISC-1
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Old 11-01-05, 08:20 PM   #15
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i'm a fan of these:
They're fine for some new builds. But not convenient to remove your post for maintenance, and the expander would be a concern in some frames.
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Old 11-01-05, 08:24 PM   #16
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As a point of interest, Trek uses a standard Race c/f seat post on the captain's seat. Go here if you're interested: http://www2.trekbikes.com/bikes/bike...d=1492000&f=11 The stoker's stem and handle bars are attached to this seat post, usually quite a way up on the post. That's a lot of side load and clamping force, too. Certainly, if you're at all concerned about clamping on your Orbea's post, do as suggested. It's always a good idea to error on the side of caution, but I strongly doubt you'd be able to hurt it, even if you tried! Just my $.02 and worth every penny...
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Old 11-01-05, 08:31 PM   #17
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Quote:
Originally Posted by Old Hammer Boy
Certainly, if you're at all concerned about clamping on your Orbea's post, do as suggested. It's always a good idea to error on the side of caution, but I strongly doubt you'd be able to hurt it, even if you tried! Just my $.02 and worth every penny...
I don't doubt you're right, by the way: that it's highly unlikely that you'd ever break a CF post under normal clamping with caution not to knock into the bike once clamped in that manner.

We agree on the notion that a build post simply provides an "abundance of caution."
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Old 11-01-05, 11:04 PM   #18
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Well put!
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Old 11-02-05, 07:50 AM   #19
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So, can I conclude that for other frame and seatpost materials (steel, ti, al) it's okay to clamp on wherever I like (seatpost or toptube)?
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Old 11-02-05, 10:31 AM   #20
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I'd go with the steel build post and avoid clamping carbon seat post or any of the frame tubes.
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