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Brompton seatpost shim

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I need to replace the Nylon shims in my Brompton frame and in my telescopic seatpost. The shims are easily available and do not look to be inherently difficult to replace.

The frame shim is listed as both unreamed and reamed in some websites. I understand the shim should be reamed once bonded in place. I guess the reamed price is for a shop-fitted shim.

The seatpost reamer is >£100 and even I am looking sideways at spending that much for a two minute use. How necessary is Brompton frame shim reaming and is there a ghetto way of doing so?

I was completely oblivious to this need for reaming the shim when I replaced mine, so I didn't. Couldn't possibly tell you whether doing so would have made any difference!

Bonding it in place is absolutely essential though.

Jakob W:

--- Quote from: citoyen on 19 June, 2020, 01:33:02 pm ---Bonding it in place is absolutely essential though.

--- End quote ---

What did you use - are we talking UHU or epoxy?

Superglue with rubber, for use with flexible materials. Brompton’s recommended glue appears to have slow gel and setting times to allow sufficient working time to reposition the sleeve and clamp it down properly. A 20g bottle for £20 is excessive for replacing one sleeve. Loctite do a 3g bottle of suitable adhesive for £3-4, which should do nicely.

I understand that earlier shims might not have needed reaming but that all current shims have an undersized bore and must be reamed. It looks like I might have to get a third expensive, unique tool or break down and go to a shop. For philosophical reasons, I really do not want to do that last option.

I did mine without reaming and it's just right.  I scraped all the old glue out and Argos blasted the frame before painting.  I glued the new shim with Extreme Power Glue and, after making sure there was no glue on the inside of the shim, left the seatpost clamped up overnight.

I still have a spare shim if you need it.  There were two in the pack- one has a locating lug and one doesn't.  I can send a photo of the one I didn't use.


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