Sliding Brompton Seatpost

[bryanattewell]

Hi

My Brompton seatpost has started to slide and rotate when I go over bumpy ground. The clamp bolt is as tight as a tight thing. Any ideas on how to fix this?

[Wesh-Laurence]

Hi,

That was one of the reasons I didn't like the Brompton which I got rid of after 2 months.

Try and fit a seatpost shim to fit the seatpost and seatpost hole. The shim in effect increases the diameter of te seatpost. Remove the seatpost and measure its external diameter, that will give you the internal diameter of the shim you need. Release the seatpost clamp completely and open the seatpost hole up slightly, it's probably deformed to a smaller diameter when you clamped it tightly. Measure the internal diameter of the hole that the seatpost goes into, that will give you the outer diameter of the shim you need.

If you use EBay just search for seatpost shims and from the list find the one with the correct dimensions.

Good luck.

[Ugly]

Only once had that problem with my Brompton, after an over zealous cleaning with WD40, cured it with a thorough cleaning of both the seat post and inside the frame.

In the unlikly event of the seat clamp distorting the seat post will show damage. the clamp is much stronger than the comparative thin wall of the seat post

[epicurus]

Remove seat post
Wash thoroughly with fairy liquid and warm water
Replace seat post
Done

[bryanattewell]

Thanks guys, that cure sounds a lot less expensive than I feared

[rogerzilla]

You probably don't want to hear this, but the titanium seatpost is less shiny and less prone to slipping

[MLJ]

Brompton are using a new Aluminium alloy seat post which is lighter in weight and unlikely to slip: it also has markings so that the post can be put back to the same position every time.