Author Topic: Brompton rear triangle compatibility  (Read 603 times)

Brompton rear triangle compatibility
« on: 16 June, 2024, 04:54:17 pm »
I need to replace the rear triangle of my Brompton (as it's very badly rusted). My bike is one of the older 'short wheel base' models (orignally the budget C3 model). Does anyone know if there are compatibility issues, or will any rear triange fit (for example https://www.ebay.co.uk/itm/155410319284)?

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton rear triangle compatibility
« Reply #1 on: 16 June, 2024, 07:34:17 pm »
I am not sure about the top-off-the-range Ti models but otherwise SWB and LWB rear triangles are interchangeable at the hinge and suspension. There are minor differences with dropout shape as the hub changed (e.g. SA vs. SRAM) and whether there is a derailleur fitting.
Wheel meet again, don't know where, don't know when...

Re: Brompton rear triangle compatibility
« Reply #2 on: 06 July, 2024, 12:24:28 am »
Thanks! Following inspiration from an earlier thread, I got in touch with Ben at Kinetics, and he had a rear triangle he had just taken off as part of a new bike build, which he was happy to sell. Someone on ebay was also selling the reamer kit (a piloted one, with a short cutting section). I heated the countersunk screws, they came out without too much difficulty (using the trick recommended by Kinetics of jamming in a long 5mm allen key in the side where the first screw has been removed). Interestingly, Brompton specifically specify a low strength threadlocker (Like purple loctite 221/222). Now all back together, and feels good. The only frame specific parts I had to change from the old rear triangle were the anti-rotation washers for the hub, but fortunately I had the new style (tabbed steel) ones from a previous hub swap!