Brompton Chainring Bolts

[PaulF]

It seems that Brompton was supplied without the long bolt that attaches the chainring to the spider - the normal chainring bolts are all there.


The only way I can find to buy a replacement is to buy a full set - which seems a little wasteful. Does anyone know the spec of the long bolt? Or even better have a spare in their parts drawer?

[rogerzilla]

Have you tried removing the ring and trying one of the other bolts in the thread?  They will be M8 fine (M8 x 0.75).  The head size can be important to prevent it getting in the way of the fold.

[PaulF]

Have you tried removing the ring and trying one of the other bolts in the thread?  They will be M8 fine (M8 x 0.75).  The head size can be important to prevent it getting in the way of the fold.

Yes I tried the other bolts but the one that fits the crank is not a standard chainring bolt it has a longer thread. It's the one in the centre of the image here: https://www.condorcycles.com/products/brompton-chainring-bolt-set-for-spider-crankset?variant=896749535242&wgu=281345_196673_16485677486163_748ac13cce&wgexpiry=1656343748&source=webgains&siteid=196673

[rogerzilla]

But is the thread the same?  If so, you can order a bolt of appropriate length.  Finding a shallow domed head allen bolt might be a challenge, though; these are pretty unique to bikes.

[drossall]

Don't suppose you solved this? I replaced my Brompton's chainset some time ago with a little-used second-hand one. Just noticed, when stripping the bike to replace the transmission, including the ring, that that bolt is missing. Can't say whether it's fallen out, or was never there.

Edit - oooh

[PaulF]

Don't suppose you solved this? I replaced my Brompton's chainset some time ago with a little-used second-hand one. Just noticed, when stripping the bike to replace the transmission, including the ring, that that bolt is missing. Can't say whether it's fallen out, or was never there.

Edit - oooh

Yes, but the hard way; by buying a full set. Think I may have found the one you linked to but with their postage it worked out cheaper to buy a set.

[drossall]

Luckily, for me, they are just an excuse for a bike ride

[PaulF]

Luckily, for me, they are just an excuse for a bike ride

I should have used you last time

[drossall]