General Cycling Discussion - something that is not discussed nearly enough: seat post clamps or collars!

So I just busted the bolt on my Surly stainless seat-post clamp, 30.0mm (http://www.amazon.com/Surly-Stainless-Seatpost-Clamp-30-0mm/dp/B001P9EVTQ/ref=sr_1_3?ie=UTF8&qid=1322019862&sr=8-3). I have a loaner until a permanent replacement can be ordered but now that I have the the option to get a new one, I'm having trouble choosing one and discerning which ones have better features. Seat-post slippage has been a problem before and aesthetics are important.

These are the ones I'm considering.

Surly Stainless seat post clamp (http://www.amazon.com/Surly-Stainless-Seatpost-Clamp-30-0mm/dp/B001P9EVTQ/ref=sr_1_3?ie=UTF8&qid=1322019862&sr=8-3), a simple replacement for $20

Surly Constrictor (http://www.amazon.com/Surly-Constrictor-Seatpost-Clamp-Black/dp/B001GSQJC8/ref=pd_sim_sbs_sg_2) (tall and thick wall for stronger grip, aluminum) for $15.

Salsa Lip Lock Seat Collar (http://www.jensonusa.com/store/product/SE299F02-Salsa+Lip-Lock+Seat+Collar.aspx) for $18.


Any other recommendations? Any non-stock seat post clamps chosen for a build? Help me pick a good looking, strong clamp.

Have you considered posting this to the Bicycle Mechanic's forum? Breaking bolts on seatpost collars indicates that something is amiss with the setup- simply replacing the collar may not fix the problem.

I'm guessing that 'collar' means non quick release. Anyhow, I'm using a black anodized Salsa collar on one bike. It does seem to have solved any problem with slippage, though I'm not sure why. Also, it not only looks good, but if someone wants to steal the seatpost and saddle, at least they will need an allen wrench.

So, I just busted the bolt ..

You need another bolt, you can find higher grade steel bolts,
but they may not be stainless.

Or chromed finish.

perhaps the fit tolerances of the seat post in the frame is too loose ,
and you over-tighten it to compensate.

Types with Barrel nuts like the 'Lip Lock' uses offers a steel thread,
and will not flex the bolt, as it is tightened, as it rotates to stay aligned.

I guess: it broke across the threads.

I broke my allen bolt collar, so I went to the LBS, and all they had was the QR kind. It has worked great so far (even for a 280lb clyde).

On my normal touring/city bike I use a regular middle priced bolt on collar(?). Works really well, does have some slippage (a few mm) over the course of a few weeks. On my MTB I use a Salsa QR seat clamp (no theft worries..the bike is under me or inside). Even though it is pricey it works brilliantly. Tightened correctly I usually have 0 slippage, and I use it at least twice during my normal route. I noticed for it to work right it has to be cleaned and re-greased about once a month.

I like the Salsa lip lock collars. I'd go with that or Thomson.

Surly Constrictor, not bad looking and will defiantly help with slippage. You may also find that an application of carbon assembly past, even if the parts are not carbon, will help stop the slippage.

No matter which one you use, grease the threads of the bolt when assembling. That'll help you tighten it enough to prevent slippage while allowing it to turn easily enough that it doesn't break.

Yeah, something is wrong. Those just don't break. I've been riding 30 years and never had it happen. Nor has my post ever slipped on any bike.

My guess is you aren't matching up the right collar with seatpost size. You are over-tightening the clamp.

My guess is you aren't matching up the right collar with seatpost size.
The seatpost clamp should be matched wit the seat tube diameter (on the top end of the seat tube), not with the seatpost diameter.

Yeah, something is wrong. Those just don't break. I've been riding 30 years and never had it happen. Nor has my post ever slipped on any bike.

My guess is you aren't matching up the right collar with seatpost size. You are over-tightening the clamp.

I disagree. I've had slipping occur. I've also known several people that broke the bolts. This is with stock components on a bike.

I disagree. I've had slipping occur. I've also known several people that broke the bolts. This is with stock components on a bike.

+1. Seat binder bolts and seatpost clamps are the one spare that I carried with me on our Santana tandem.

So I just busted the bolt on my Surly stainless seat-post clamp, 30.0mm (http://www.amazon.com/Surly-Stainless-Seatpost-Clamp-30-0mm/dp/B001P9EVTQ/ref=sr_1_3?ie=UTF8&qid=1322019862&sr=8-3). I have a loaner until a permanent replacement can be ordered but now that I have the the option to get a new one, I'm having trouble choosing one and discerning which ones have better features. Seat-post slippage has been a problem before and aesthetics are important.

All one need do is replace the defective bolt not the whole clamp!! Try your local auto parts store or local hardware store.

When any bolt is tightened it goes into what's call a "plastic" state which is the bolt being stretched like rubber to hold the torque you put into it when you cranked it down.

Once in the "plastic" state some low grade bolts will simply pull apart like taffy under the torque load. At that point going to a higher grade bolt will hold the clamping force at the torque level you leave it at.

Have you considered posting this to the Bicycle Mechanic's forum? Breaking bolts on seatpost collars indicates that something is amiss with the setup- simply replacing the collar may not fix the problem.

I should have mentioned how I broke it. Usually I tighten it with an allen key on my multi-tool. There's not much leverage there, so I usually get some stiff resistance and I know it's tight enough. The other night, though, I used a long Park Tools L-wrench from the bike co-op I volunteer at. I was able to keep tightening and tightening and then it just snapped and the seat post slid down all the way. I wasn't used to an allen wrench with that much leverage. Anyways, the collar is trashed...the bolt is stuck and there's no way to get it out. We tried getting it out but it's done.


Just to be clear: I broke the bolt because I used a more powerful allen wrench. The seat post collar is a stock Surly Stainless steel clamp that is fitted correctly to the seat-post. I'm just looking for recommendations now for a strong, good-looking 30.0mm collar.

Like I said , look for a higher grade steel Metric machine screw,
Same size, and it will go in place of the broken one.
:rolleyes:

I should have mentioned how I broke it. Usually I tighten it with an allen key on my multi-tool. There's not much leverage there, so I usually get some stiff resistance and I know it's tight enough. The other night, though, I used a long Park Tools L-wrench from the bike co-op I volunteer at. I was able to keep tightening and tightening and then it just snapped and the seat post slid down all the way. I wasn't used to an allen wrench with that much leverage. Anyways, the collar is trashed...the bolt is stuck and there's no way to get it out. We tried getting it out but it's done.


Just to be clear: I broke the bolt because I used a more powerful allen wrench. The seat post collar is a stock Surly Stainless steel clamp that is fitted correctly to the seat-post. I'm just looking for recommendations now for a strong, good-looking 30.0mm collar.

You shouldn't be able to break a normal seatpost collar bolt with a hand-held Allen wrench under any circumstances. My guess is that something is undersized and the bolt was bent when you tightened it that far.

As before: there is something that's not fitting correctly. Either the collar is too large for the OD or the seatpost is too small for the ID of the seat tube. Since the seatpost slid down when tension was released, I think the seat tube may have been reamed a smidgen oversize. Normally a seatpost requires some force to be moved up or down.

You shouldn't be able to break a normal seatpost collar bolt with a hand-held Allen wrench under any circumstances. My guess is that something is undersized and the bolt was bent when you tightened it that far.

As before: there is something that's not fitting correctly. Either the collar is too large for the OD or the seatpost is too small for the ID of the seat tube. Since the seatpost slid down when tension was released, I think the seat tube may have been reamed a smidgen oversize. Normally a seatpost requires some force to be moved up or down.

Supposing the seat tube is reamed a little big, can a strong clamp fix the slippage problem? It's not a constant problem but it would slide down a bit on rough bumps if the collar was a little loose. I mean I've ridden it for over a year. It's just a small annoyance.

Supposing the seat tube is reamed a little big, can a strong clamp fix the slippage problem? It's not a constant problem but it would slide down a bit on rough bumps if the collar was a little loose. I mean I've ridden it for over a year. It's just a small annoyance.

It's more than a small annoyance if the bolt broke. The seatpost should require a little pressure to drop it lower.

I'd create a shim to fit between the seat post and seat tube. Good hardware stores have shim stock if the bike co-op does not.