Seat shim dimensions for Brompton I have seen a great seatpost online that i would like to fit to my brompton. The only trouble is that the OD is 31.6mm instead of 31.8mm.

The  Brompton seat mechanism uses a plastic shim to help the seatpost rise and lower smoothly. 


Anyone know the dimension of the brompton seattube and if it is possible to buy a new shim and fit to brompton frame so that I can fit this seatpost properly?

thanks!
It might fit perfectly as is. If for some reason it doesn't fit perfectly, you could make a shim out of a soda can (which is about 0.1 mm in thickness). I don't think anyone makes a commercial shim of that size.