Joseph Kuosac Telescopic Extension For Brompton - Silver - 440 x 31.8mm

£44.99 Please note this product has selling restrictions to your country. was
Manufacturer : 
SJS Cycles part number : 
Manufacturer part number : 
Bottom Telescopic Extension to fit Brompton bikes. - 31.8mm
Requires 27.2mm seat post or pillar to fit saddle.
Joseph Kuosac seat post - #46148
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Questions & Answers (4)
Hope quick release compatible?
06 Aug 2018
Can I use this with a 31.8mm Hope quick release seatpost clamp? Or does it only work with the Joseph Kuosac clamp?
You can fit most 31.8mm clamps - some of them the lips will be too deep.

04 Aug 2018
Also doea the standard brompton rubber bung/stop fit this or does it come with one supplied?
Yes the bung fits but is not supplied.

Weight difference
03 Aug 2018
Is this lighter than the lower past of the steel brompton telescopic seat pillar and if so can you indicate the approx weight saving? Many thanks
The lower part of the Brompton telescopic is 440grams, the JK one is 324 grams - but is 440mm verses 510mm and the insert is 20 grams over 8 grams for the Brompton one.

Some questions about this seatpost
28 Apr 2018
1. Is it correct understood that this is the bottom part of a telescopic seatpost that will fit all Bromptons, but contrary to the original seatpost, it will allow a top part with size 27,2mm (which gives many more choices for the top part, ex. suspended seatposts)) instead of 26,6 mm on the original Brompton telescopic seatpost?

2. Are all fittings (sleeve clamp screws etc.) included with this seatpost or can I move fittings from my old original Br. tele-seatpost to this one? If not, which fittings will I then need to buy?

3. I conclude that this seatpost must have thinner walls than the Br. seatpost. Is it just as stable/stiff as the original one?


Hi there,

Yes this is a aftermarket telescopic allowing the use of a 27.2mm upper.

You simply need this post, an upper seatpost and SJS Cycles part number : 46166

We have had no issues with the strength or stability of this seatpost.