The bike is original and I fitted a a Brompton kit. I followed the instructions exactly (except for wheel removal). The front of the rack mounts on the rear brake bolt. I have checked several Brompton documents to verify that everything that the bolt passes through is in the correct sequence with no extras. One concern is that there was nothing, ie. no spacer, to be discarded from the original assembly to make space for the thickness of the rack. With the increased stack length there is now barely enough protruding thread to fill a standard 6mm nut. That would be a bare minimum in my eyes, but of course I can't even see to verify this because that "nut" is actually part of a 40mm extension that helps keep the bike folded when picked up. I don't know why, exactly, but I'd feel better if it had a few more threads to screw on to.
My other concern is that the rack mount, which is a good 1/8" thick is supposed to be located between the caliper and the brake cross member. I'm no structural engineer, but surely this will increase the bending load on the brake bolt? Perhaps not the best arrangement? There must be a lot of Bromptons about built just this way, so I guess it's "ok", but I can't see any real reason why it couldnt be fitted in a neutral location on the other side of that cross member. Installation would be simpler too even though I might need to chamfer the mounting lug to clear the curved cross member. I'm considering experimenting soon. If I like it I may well swap over.
There has been a direct consequence which the instruction sheet made no mention of: becauses the callipers had been repositioned I had to do the same for the brakeblocks - they were now too close to the tyre. Because the shops were shut
I found that I could not do this to my satisfaction. I was unlucky enough to have bought a bike built in early '18, when, for a few months, they fitted some rather naff onepiece blocks. They worked OK, but now fine adjustments are problematic because the metal cup washer has indented the plastic body, and I personally found it a real challenge to align silver grey blocks against a silver grey rim under domestic lighting. Proper blocks in the post - but this was a whole load of hassle that would not have arisen if the rack was located on the other side of the strutI'm planning to write to Brompton about this, but first I thought I'd ask if others have had similar experiences, or indeed, if you think I'm being too picky. Living on a steep hill my view is that brakes are things to get picky about, but, of course, YMMV!