slipping seat post

Check first of all that the seatpost diameter matches the spec for the frame. There are a lot of sizes and some differ by only about 0.2mm, but that is more than enough to cause slippage.

It could be the wrong size post as stated. You might try wrapping the post with some teflon tape and then tighten. I can't guarantee this to work but it will be a cheap fix if it does.

If the seatpost is the right size, give some carbon paste a try. Like so.

jhuskey said:

It could be the wrong size post as stated. You might try wrapping the post with some teflon tape and then tighten. I can't guarantee this to work but it will be a cheap fix if it does.

Yep, that'd probably work.

Or you could try wrapping some plumbers tape around it. The kind you use when you intall a new shower head. I'm not sure, but it might be made of vinyl.

64Paramount said:

Yep, that'd probably work.

Or you could try wrapping some plumbers tape around it. The kind you use when you intall a new shower head. I'm not sure, but it might be made of vinyl.

Teflon tape = Plumber's tape = anti-seize tape. Not made of vinyl, that is Electrical tape.

kdelong said:

Teflon tape = Plumber's tape = anti-seize tape. Not made of vinyl, that is Electrical tape.

Right, and teflon tape is specifically designed to reduce friction and seal tiny gaps on threaded joints so they can be tightened without galling. It's really low-friction, malleable stuff, with no adhesive at all.....so I'm not sure how it'd make for a good solution on a slipping seatpost. 😕

Vinyl/electical tape would actually be better IMO, since it would adhere to the seatpost and be durable enough to withstand some force without deformation. Can't say I've tried either, however.

Revds said:

I built up my first carbon frame this Spring. It's sweet, except it's [censored] and doesn't work. Help!😕

Put the seatpost in the seat tube. Before you tighten it, there should be some resistance to it going up and down. Try and wiggle it side to side. If you can feel movement it's too small. If you have a 27.0mm seatpost in a 27.2mm seat tube you will feel movement side to side. You'll be able to feel movement even if there's less than 0.1mm consistently across diameter of theinserted seatpost.

Don't ar$e around with tape - it'll end in tears. One day your saddle will be on the top tube and the resulting "quick" stop at the end of the saddle "descent of doom" will likely make it seem like your testicles have been jammed into the bottom of your ribcage.

If there is no movement then try some paste as recommended above.

Pray that someone hasn't been in there with a seattube reamer. If they have then your frame may be farked.

Check that 'the slot', which is normally at the back of the seattube isn't jammed with something. If it can't close slightly then you're not going to be able to clamp the seat post.

If the clamp doesn't, well, clamp, don't apply lots of force - get a better clamp. You typically need very little force when clamping a seatpost in a carbon frame. A torque wrench is handy as "feels nice and tight" is normally way too much. 6Nm is typical.

If you got the frame from a 'shop' on eBay that ships from Neverheardofitdingdang in deepest Taiwan, pray that it's not a reject that missed the garbage skip and ended up on a FedEx plane going towards your house.

frenchyge said:

Right, and teflon tape is specifically designed to reduce friction and seal tiny gaps on threaded joints so they can be tightened without galling. It's really low-friction, malleable stuff, with no adhesive at all.....so I'm not sure how it'd make for a good solution on a slipping seatpost. 😕

Vinyl/electical tape would actually be better IMO, since it would adhere to the seatpost and be durable enough to withstand some force without deformation. Can't say I've tried either, however.

I suggest the teflon tape since it is thinner and you have a better chance of getting the correct thickness. Electrical tape is thicker and I have had very little luck using it as a bushing material, it seems to alway wag up on me. I can't say either one will work since i have not tried that specific application for either but I guess it's worth a try. If it had been an aluminum seatpost I would suggest a piece of beer can. Malleable and won't rust.

The only wedging material which is guaranteed to work is a relatively non compressible shim (which come in standard sizes). As alluded to by Swampy, these will still only work if the post/frame conform to particular (though non-matching) specs. This is still not an ideal solution though. The best option is to make sure the post is the right diameter for the frame (something the thread starter still hasn't told us).

Tape (plumbers/electrical/whatever) will eventually deform and compress and allow relative movement of the post and frame. Plumbers tape is designed as a seal/lubricator for threaded piping connections, why it should be expected to work here (where there is no thread and no sealing requirement) is beyond me.