Seatpost clamp bolt loosing torque

[R3awak3n]

So I have been having a bit of problems with this damn seatpost slipping. Have tried 2 seatposts, 2 clamps. Carbon paste. Different Carbon paste and now I have put loctite on the seatpost clamp bolt. I have noticed that I torque the bolt to 6nm and when I get back from a ride (and gravel bumpy gets worse quicker) it will have lost torque. I am thinking that this is the reason the seatpost will slip. Totally fine when torqued properly but as it looses torque at the end of a ride it will start slipping. After I put the loctite it lasted 100 miles of rides before slipage so it definitely helped but I don't think I solved the problem.


Is this common? What is the solution? Maybe higher strenght loctite? Different clamp? This is driving me CRAZY.

[AngryScientist]

what kind of clamp do you have?

if you have one where the bolt threads into aluminum, get rid of it, instead look for one where the bolt threads into a stainless steel barrel like this:

https://www.universalcycles.com/images//products/large/19513.jpg

[R3awak3n]

I might try the salsa but what I have now seems pretty nice, wolftooth. The one that was there before also super nice, says dkg on it and from reading on the internet its one of the best. Im stumped

[Peter P.]

If you had the same problem with the Wolftooth AND the dkg, then it's not the clamp, with the below exception.

Is the post aluminum or carbon?

Could be the seat tube I.D. is milled oversize. The other issue I've seen is, the seatpost collar usually has a lip which rests on the end of the seat tube to prevent it from sliding down. If this lip is too small in its I.D., it will contact the seatpost before the seat tube, and clamping area will be severely reduced.

It's easy to measure or visually inspect. If that's the cause, the solution is to sand away some but not all of that lip. A piece of sandpaper taped around a broom handle will do the trick.

I agree with angryscientist, if you have to get a replacement, get one with the self-aligning threaded insert.

Also, dkg (http://www.dkg-cnc.com/bicycle.html) sells a mountain bike version of your clamp which takes a higher torque load (uses a larger bolt) than the road version. It might be worth a shot. I have a road version on my road bike and it works fine.

[David Kirk]

Is the bolt actually backing out? You can check by putting a tell-tale make on the face of the head with a sharpie of dab of paint. Try that and see if the bolt is moving or if you have a different issue.

dave

[bikinchris]

Maybe even a double clamp like this one:

https://www.ribblecycles.co.uk/ribble-seat-clamp-twin-bolt/

[buddybikes]

Worst case (ugly of course) short term solution is hose clamp on seatpost

[R3awak3n]

If you had the same problem with the Wolftooth AND the dkg, then it's not the clamp, with the below exception.

Is the post aluminum or carbon?

Could be the seat tube I.D. is milled oversize. The other issue I've seen is, the seatpost collar usually has a lip which rests on the end of the seat tube to prevent it from sliding down. If this lip is too small in its I.D., it will contact the seatpost before the seat tube, and clamping area will be severely reduced.

It's easy to measure or visually inspect. If that's the cause, the solution is to sand away some but not all of that lip. A piece of sandpaper taped around a broom handle will do the trick.

I agree with angryscientist, if you have to get a replacement, get one with the self-aligning threaded insert.

Also, dkg (http://www.dkg-cnc.com/bicycle.html) sells a mountain bike version of your clamp which takes a higher torque load (uses a larger bolt) than the road version. It might be worth a shot. I have a road version on my road bike and it works fine.

Post is carbon so I don't want to overtorque it. wolftooth clamp says max 6nm and have not been able to find post but usually carbon anything 5-6nm max. Its a ritchey superlogic so its light. I have the same post on 2 other bikes with no problems what so ever. I also tried another post, same result (was also carbon post). The clamp I got is a 29.8, its not very tight when I put it on, I think I mesured the ID of the tube at 29.2 so too big for a 28.6. I need to check the lip though, that is a good point.

Is the bolt actually backing out? You can check by putting a tell-tale make on the face of the head with a sharpie of dab of paint. Try that and see if the bolt is moving or if you have a different issue.

dave

this is a good idea David, I will do this. Put it at top and see if its actually rotating. I am out for a ride in a few minutes and it will be a big one, ti will be a godo test.

Maybe even a double clamp like this one:

https://www.ribblecycles.co.uk/ribble-seat-clamp-twin-bolt/

I have been thinking about one of these

Worst case (ugly of course) short term solution is hose clamp on seatpost

:P on my new cielo? no way ahha

[Peter P.]

If the I.D. of the seat tube is 29.2mm, then there's no Ritchey seatpost that will fit that frame. At least, not according to the Ritchey web site.

Typical 27.2 seatposts mate with 28.6 O.D. seat tubes.

Unless you're referring to the I.D. of the clamp you're using. Then you need to measure the O.D. of the seat tube, and the I.D. of the seat clamp at the inner lip I mentioned.

You could also try an aluminum post, just for test purposes, to see if you have the same slipping problem.

Another possibility I've run into: the relief slot on the back of the seat tube could be too short, preventing the tube from compressing sufficiently under clamping force. I had this happen to me with a Salsa Ala Carte (brand new). My solution was to yes, drill a new strain relief hole 5-10mm further down the seat tube, then use 2 hacksaw blades taped together to lengthen the existing slot to meet the new relief hole. It worked and it wasn't noticeable to anyone.

From my measurements, for a 28.6mm seat tube, the slot, to the bottom of the relief hole, should be at least 25mm. I'm guessing the slot should at least equal the O.D. of the seat tube.

[AngryScientist]

saw these and thought of this thread.

drew is an engineering mastermind, and if he makes something, you can pretty well guarantee it will work as intended. this is just an example, he has more on his site. not cheap, but made by a guy who knows how to make stuff.

https://www.ebay.com/itm/New-ENGIN-34-9-dropper-seatpost-clamp-NAHBS-made-in-Usa-BLUE/401837071034?hash=item5d8f5b1aba:g:9RgAAOSwZuhdRsQ B