lineinthewater

Ok, so after 10 years, yes 10 years, of doing most of my own wrenching, I finally broke down and bought a workstand. I was all excited, and clamped to the top tube (of an aluminum bike), only just enough to prevent the bike from moving. It was at that point that I realized it might not have been so wise to clamp to the top tube. Remember, I clamped just hard enough to secure the bike, but I didn't do any work on the bike. I quickly unclamped, and started researching.

I have a carbon seatpost, so I'm wary of clamping to that. I've read that many shops keep "dummy" seatposts around for this exact situation. I've also heard that Park actually sells a "tool" that take the place of the seatpost.

Suggestions? Comments? Ideas? Am I being irrationally paranoid? lol

FBinNY 

I clamp the seat tube just below the top tube. That's the thickest place, since you have both the frame tune and seat post. Many shops stopped clamping the frame and moved to using the seatpost for 2 reasons.

1- when clamped on the frame and especially over a decal, it was easy to mar a new bike if the frame rotated in the clamp.
2- as OS tubing became more dominant, many older clamps wouldn't open far enough, so they moved to the smaller OD seat post.

If you have a metal frame, and are careful, you have no need to worry about clamping anywhere, but the top tube is a poor choice because of cable routing and the tendency to swing the frame as you work. Plus it is the thinnest tube in the frame. For carbon frames, seat post clamping is just about SOP.

HillRider

For my steel and Ti frames I have no problems clamping the repair stand to the top tube. For Al and carbon frames I'd clamp the stand to a dummy seatrpost. Just buy the cheapest seatpost of the proper diameter and use it.

canyoneagle

+1

If the tubing is round (or even mildly ovalized), the top of the seat tube is a great spot to clamp.

TiBikeGuy

Many of the new alum frames have hydroformed tubes which are odd shaped and doesn't provide secure clamping surface.

If you are worried about carbon seatpost, it is just a quick release or allen key to remove and insert a used aluminium seatpost that can be used for repair jobs... or you can use the Park Tool ISC-4 https://www.parktool.com/product/inte...be-clamp-isc-4

E.W.G.M.B

as said above use a dummy seat post.

Bob Pringle

When using a dummy seat post to secure a carbon frame to a work stand should I be concerned about damage to the top of the seat tube from repeated loosening and tightening the seat post binder?

mconlonx

Clamping the frame anywhere could result in a crushed or dented tube, but unless you're a total gorilla, probably not. It is, however, real easy to damage the finish that way. Any wrenching of any force enough to make the bike move in the stand can result in paint scuffs.

Seatposts are designed to be clamped. Even the carbon ones. Clamp the seatpost, not the bike.

That Park dummy seatpost is one of the more frustrating tools to use...

FBinNY 

First of all you won't be tightening it as tight as you would to secure a post for riding. Secondly, do you plan to do this daily, or only when the bike needs work? How often will that be.

That said, repeated use of the seat binder clamp might cause wear and tear on the threads, so I'd keep it down unless it was a removable clamp so the worst that could happen is you were out a few bucks for a replacement.

pmt

Or just get a Park PRS-20 stand (or similar) like the Pro teams use and never worry about it again.

FastJake

Just get a POS bike that you won't have to worry about damaging

I often like clamping the top tube, because you don't have to clamp it tight to keep the bike in one place. It barely has to be snug. Seatpost is fine too though. Just make sure not to do any serious wrenching when the bike is on the stand. If you need to install a square taper crankset, remove tight/stuck pedals, etc take the bike down and let it rest on the floor.

fietsbob

get a cheap Kalloy seat post.

The Park Tool expands a wedge isside the frame to fit all round bored tubes..

TheTour Pros use a stand that holds the frame By the dropout of a removed wheel
and a support under the BB, for the very non round frames on the race Circuit.
Particularly the Time Trial Specials.

Camilo

I just clamp on my carbon fiber seat post. I do have a cheap, old ally post that I used a couple of times, then I just thought: how in the world can my Park repair stand clamp possibly damage the seat post? Frankly, the way the clamp is designed, and the way anyone with even 1/10 of a brain would use it - there's no way it would damage the post. As for torquing it - the only possilbe thing that could stress the post in a twisting way would be torquing the bottom bracket and on the rare times I remove and/or replace the BB, I tend to put the bike on the ground anyway.

I just can't understand why people think you can't use it. Pro mechanics weigh in please!

wrk101

I typically work on vintage bikes: 25 to 40 years old. I always clamp to the seat post, in part to prevent damaging decal work (I've done it before I wised up). Of course, I am not dealing with carbon posts.

AlphaV

I'm a pro mechanic, I just clamp on the seat tube, but it also depends on the bike. New carbon frames, I'll put on a cheap seat post. Steel and Alloy frames will be a seat tube, unless it's a trail bike or something with cables coming down, then it's back to the seatpost, or if the customer has too many accessories on the tube and I can't be bothered to take it off, then seat post, and sometimes I can't remove a seatpost because it's seized or there's a lock like a pinhead system in place with no key. It really depends on the bike, and each one is different. Occasionally I've had to use the top tube, just because it was my only option. Try not to because it get's in the way of cables, and I make sure I don't do a lot of heavy torquing when I do have to use the top tube.

But the key is, if you have to force the clamp close, then it's too tight. If it slides then it's too loose. You want to be just tight enough so it's easy to open and close the clamp, but secure enough that the bike doesn't slide. If you're still paranoid, then grab a rag and cover the clamp before you clamp the frame.

fietsbob

To not leave marks on the frame, I extend the seat post, grab it, then put it back down to the original marks when done.

Carbon posts, out here might have a ride the coast fast tour bike, someone in the century a day tour on the race bike type,
has shipped ahead... there are fully supported group tours to cater to them

then the seat post goes in last, substitutes to do the actual work.. we have the Park tool on hand..

Jed19

Like others have said, just get a cheap seat post for clamping. You do not have to buy, just ask your friendly LBS mechanic for old seat posts they might have. I got two from my LBS by asking nicely (but I also take xmas gifts there).

rogerstg

+1. That's what I do too. Those cf seatposts are much beefier than the bike tubes, though I don't tighten the clamp like a gorilla either.

cyccommute 

A dummy post or a Park ISC-4 ($45) is cheap insurance. You can use your carbon post if you have to but I never clamp a frame of any kind in a workstand. You have no idea what the thickness of the tubing is and a crushed frame is a rather large expense. I've seen lots of good frames crushed by ham-handed workstand use.