Seatpost Clamp for slipping post?

[Lewis Moon]

The Syncros seatpost in my 2005 Poprad keeps slipping down. I've gone through three clamps and the only one that works is the OEM one. The problem is, the OEM clamp is more than a bit cheesy and probably won't last many more clamp/unclamp cycles. It's a simple threaded aluminum clamp and probably pretty soft.
Can anyone suggest a good clamp (31.8 tube, 27.2 post), possibly a double bolt design that will hold the post under my 180 lb ass? Weight is not really that important.

Yes, I've addressed the too much grease issue and the Syncros post should be rough enough to stay in place.

[ultraman6970]

To start with, add some carbon paste, that will help with the gripping.

Secondly, there is a double clamp, it is a clamp that is divided in two sections. The bottom one will do the same than the clamp you have right now and the top section will clamp straight in the seat post. No matter what that thing wont move.

Like this one...

[AngryScientist]

almost any clamp should work if the two clamping surfaces are prepped right.

that said, anecdotally speaking, i've had good luck with both salsa and thomson clamps.

[scrubadub]

I just got a Thomson clamp to replace some generic OEM one. It's really well made and tightens down with a very small amount of torque.

[54ny77]

get the campy post clamp. it's got a lot of surface area and can put the squeeze on, as it were. not the prettiest looking thing, in my opinion, but highly effective and i have 'em on various bikes for whatever that's worth. i don't worry about seatpost slippage.

this one:

[jr59]

Salsa lip lock!

[thegunner]

if you don't have carbon paste -- give it a squirt of toothpaste. it'll smell minty too

[Dave Wages]

In my experience the Salsa Liplock clamps about as tight as anything I've used. I've never seen that double clamp before, but that would probably fix it too, although it's a bit ugly, imo.

Another tip that might help is to reverse the slot of the clamp 180 degrees from the slot in the frame, so if the frame's slot is in the back of the seat tube, have the clamp's slot facing forward. Not sure why this helps, maybe the ears of the clamp are better supported and less likely to bend inward toward each other? It does work though, I've been able to stop some Gunnar frames from slipping simply by taking their existing clamps and reversing them.

Good luck,
Dave

[djg21]

Get a Thompson. The knurled surface stops it from slipping. Use carbon assembly paste to avoid the need for over tightening.

[ultraman6970]

Is this for real?? some toothpaste have some tiny balls inside, besides that it will dry hmm... kind;a natural glue or so?

Originally Posted by thegunner

if you don't have carbon paste -- give it a squirt of toothpaste. it'll smell minty too

[Peter P.]

If your post is slipping, particularly since you're running a steel frame and an aluminum post, then something is wrong.

ANY clamp should do the job. As long as the clamp's ears aren't touching there should be clamping force being applied to the post.

You could have an issue of a post that is slightly undersized and a seat tube that's slightly oversized, stacking tolerances. Just a guess, but a possibility too.

I had a similar problem with a Salsa Ala Carte steel ATB frame with a Salsa Liplock seat collar and a Salsa Shaft seatpost.

I concluded the relief slot cut into the rear of the seat tube, which allows the seat tube to flex and clamp around the post when the collar is tightened, was too short. I compared it to other bikes and found it 5-10mm shorter; I forget.

So, I merely drilled a new strain relief hole 5-10mm below the existing hole then extended the slot to meet the hole using a pair of hacksaw blades paired side-by-side. A little sandpaper smoothed out the inside of the seat tube.

Problem solved.

I measured 2 of my bikes and the slot is 30mm from the end of the tube to the bottom of the strain relief hole.

Perhaps this solution will help you rather than using brute force with the clamp.

Seat clamps should require only 4-6.75 Nm of torque to secure the post.

[oldpotatoe]

Originally Posted by Lewis Moon

The Syncros seatpost in my 2005 Poprad keeps slipping down. I've gone through three clamps and the only one that works is the OEM one. The problem is, the OEM clamp is more than a bit cheesy and probably won't last many more clamp/unclamp cycles. It's a simple threaded aluminum clamp and probably pretty soft.
Can anyone suggest a good clamp (31.8 tube, 27.2 post), possibly a double bolt design that will hold the post under my 180 lb ass? Weight is not really that important.

Yes, I've addressed the too much grease issue and the Syncros post should be rough enough to stay in place.

Add carbon paste, if aluminum have a decent LBS 'knurl' it and use a Salsa or Campagnolo clamp. The suggestion to turn the clamp around to be opposite the slot in the frame is a good one also.

[dlui]

carbon paste works for me!

[thegunner]

Originally Posted by ultraman6970

Is this for real?? some toothpaste have some tiny balls inside, besides that it will dry hmm... kind;a natural glue or so?

yep for real. i'm not sure what pastes you're talking about, i'm just talking about the old school colgate ones. a racing buddy of mine kept a travel sized tube in his seatbag for just this reason.

[bambam]

Carbon Paste +1

Had this problem on a bike with a built in clamp.

a packet of what I assume was carbon paste was given to me. I clend the pst and tube and it worked. (Steel Bike and Aluminum post.)