@berlinonaut
>>FAG type bottom brackets are the absolute opposite of "non standard". Just not as common today as they used to be. But your bike obviously has some years on the counter already.
Well I suppose after a few adventures in the outer reaches of biketech I tend to favour Shimano bits and bobs. If a standard FAG clearly wasn't a standard to last if, as I understand, you can no longer get those old bits. I have several bikes older than that brommie - no issues with their bits. Yep, mine is getting on - it's not actually done too many miles.
>>Why? There's absolutely no reason to do that.
I've always understood that it's good practice to take BBs out periodically to degrease the threads. I have definitely had one stick. Factory fitted stuff is also often I think rather lacking in grease so I always take BBs out of new bikes soon after buying.
>>No. As said before on older Bromptons you do have have an ISO bottom bracket and these are close to impossible to get hold of for some years already. For quite some years it has been replaced with JIS, you can use them with the old cranks but it is a bit off. Never change a running system... BTW: The Brompton manual recommends replacing the cranks every 5k miles.
Thanks for the info. You seem to be an expert on this stuff. If you could recommend a Shimano BB and a crankset from whoever that would fit I'd be very interested/grateful. Won't be doing until I need to obvs.
As a sign of how much I have thought about all this on this relatively lightly used bike it was only your comment on the cranks needing to be swapped every 5,000 miles that alerted me to the fact that chainrings can't be replaced. That wasn't very clever of them was it? And definitely not green.
So down the line I'll be looking for a new crankset with a standardish BB and a replaceable chainring.
Thanks for your post.