Brompton Forks & Rear Frames

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imageThese Brompton-compatible rear triangles were designed for my Rohloff Brompton kits, but are suitable for fitting most standard rear hubs to a Brompton. The design has been refined over 10 years of making hundreds of Rohloff Bromptons.

Made entirely from 304 marine-grade stainless steel, they won’t rust – you can have one in brushed stainless steel finish, or powdercoated to match the rest of your bike. They have a lifetime warranty, like everything I make.

The rear frame has a 135mm OLN width (the Brompton normally is 115mm) so will work with most standard hubs like the Rohloff and Alfine. It has IS disc brake mounts and has enough space for a 160mm rotor They work with normal Brompton frame rollers and Eazy wheels, brakes, and the standard elastomer. Standard mudguards and rear rack will also fit, and if you use a Rohloff it also uses the standard Brompton single-speed tensioner.

Brompton-compatible rear frame – £395 Add to your basket

Brompton-compatible rear frame, integral rack – £485 Add to your basket

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brompton forksI also make Brompton-compatible forks – designed for my disc brake kits, these are suitable for fitting standard 100mm-wide front hubs into the Brompton – not just disc brakes but electric motors and standard-width hub dynamos will fit.

They are made from Columbus Zona tubing with investment-cast crowns and fork ends, and come with the correct fittings for the Brompton mudguard and handlebar catch.

I normally make them with IS disc brake mounts, post mount is possible if you prefer. I then have them powder-coated in any colour you like.

Brompton-compatible forks – £295 Add to your basket

22 Responses

  1. Paul says:

    How do the weights of your rear end and fork compare with the stock Brompton parts and the titanium alternatives?

    • admin says:

      My rear triangle is about 100g heavier than the standard steel Brompton one. My integral rear rack is lighter than Brompton’s rack, so my rear triangle with integral rack is about the same weight as the Brompton rear triangle and rack.

      My forks are the same weight as the standard Brompton forks.

      The Brompton titanium part are, in total, about 740g lighter than their steel ones – that’s counting the folding pedal bolt and mudguard stays.

  2. jkguess says:

    What size rotor can this set up take – I would be planning to use Avid BB7. Also are the new type Brompton levers compatible with the BB7 mtn?

    • admin says:

      They’re built for 160mm rotors. The Brompton levers work well with the BB7 Road version, the Mountain version has the wrong leverage ratio.

  3. Hugo Schröder says:

    Why not titanium to make it even lighter ?

  4. Hugo Schröder says:

    Do the Brompton shock cords fit on your Brompton rear frame + integral rack ?

    • admin says:

      I’ve never tried – they should do, as the bolt sizes are the same – they would attach on the outside of the rack not the inside, though.

  5. Ike says:

    Ben, do you offer your rear and frame in titanium please. I see an option in the full build for Ti but I’m unsure at this stage if I want th full build. So I wanted to get the rear frame and fork only.

    Builtiful bikes though.

    Thanks

  6. nosely says:

    Hello- Do you know the max size tire that will fit your fork and rear triangle (349 and 355)?

    • admin says:

      For 349, the limit is really the usual Brompton sizes – so up to the Marathon Plus in 349. The problem is the chainstay bridge which has to be where it is otherwise the seatpost hits it when it folds. I’ve never tried 355 wheels, but I’d guess they’d work with thinner tyres – not sure why you’d want to, though.

      If you go smaller, you can go fatter – the 16″(305) x 2″ Big Apple tyres fit okay.

      • nosely says:

        That’s extremely helpful, thanks very much for the info. Is the rear triangle available with a derailleur hanger? thanks in advance.

        • admin says:

          I can make one with a derailleur hanger, but no derailleur takes up enough chain to allow the bike to fold without the chain becoming slack.

  7. Jus says:

    Hi Ben ! Do you make stainless forks ?
    (I ask because it would be great to have both triangle and fork in brushed stainless steel finish)

  8. Deserthawk says:

    Can you make your forks 110mm at the dropouts to fit some of the newer electric hubs?

  9. ismail says:

    I want to convert my 6 speed brompton rear brakes to disc brakes only keeping my current gears wheel etc. Is this possible if i purchase the rear triangle and disc brake kit ?

    • admin says:

      No, your current rear wheel is not disc-ready – the only way to do it is to get a new rear hub – Alfine, NuVinci or Rohloff.

  10. Neil Dewhurst says:

    Hello,

    Have you ever thought about up-sizing fork and rear triangle to take 20″ wheels?

    Obviously its a major modification, a new bicycle pretty much, and so would require some careful planning/testing to get it folding okay and to maintain BB height (perhaps 1 or 2 cm higher). Still I think that it would be an interesting compromise. I would be interested, for a start, perhaps others too… Folded, the package wouldn’t be so small and neat as a standard Brompton, yet I am sure that it would still retain a huge advantage over other 20″ folding bikes (Dahon, Tern). With a slightly bigger drop cover it would still be easily stowed on the train, perhaps too on the bus and in the Metro.

    After some experience with a 20″ folding tandem (Pedal Power Butterfly), which make with 50-405 Big Apple and is now on 55-406 Big Ben, and I really appreciate having such a choice of tyres, which I would like for my solo bike too. Touring two-up on the tandem, with my daughter, we can easily roll over loose gravel where the Brompton would get stuck, running 35-349 Marathon Plus, even with my wife riding (and she’s anything but chubby…).

    In the meantime, I have well noted your suggestion of using 16″ wheels so as to have a better choice of tyres (50-305) while still using standard frame. I’m not too sure if and how I could get the rim brakes working again on such a set-up (rim diameter nominally reduced by 22 mm). Perhaps that suggestion pre-supposes using a bike that has already been converted to disc brakes?

    Neil Dewhurst – Lyon France

    • admin says:

      I have been considering it. The back isn’t too big a challenge, I can make a longer rear triangle, it’s the front that’s tricky – fitting longer forks for 406 would raise the front by about 6cm, which is quite a lot. So the way to do it is to probably modify the front of the main frame too, changing the head tube.

      As with most of these things, it’s a project that has to wait for someone to actually order one – I don’t have time to build these things on spec 😉

      The 16″(305) wheels only work with disc brakes, yes – they don’t fit the standard frame anyway, they only fit my rear triangle and forks.

    • Ariel Richtman says:

      I too was interested in the upsize to 406 wheels

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