Brompton 8-spd Instructions

For general reference, here’s the instructions I wrote for fitting the 8-speed. The chainset bit might vary depending on what chainset I can get hold of.

Fitting the back wheel:

– Take off your old back wheel, and swap the tyre, tube and rim tape onto the new wheel.
– Take off the original tensioner, and all gear cables, including the pulley for the gear cable on the right side.
– Slide the new wheel into the dropouts – it should go with the cable guide pointing upwards – it can only go in one of two ways, so it should be obvious which way is right.
– Slide the two tabbed washers onto the axle, with the tabs going in to the slots in the dropouts. Important: use the new washers supplied with the kit, not the original ones from your old wheel. Fit a Sturmey nut on the left side, and the plain nut on the right, and tighten.
– Slide the chain tensioner on on the right, then fit the thin washer, and the other Sturmey nut. Only do this nut up hand-tight, you’ll want to take it off again when you fit the cable.
– Pump up the tyre.

Fitting the chainset and chain:

– Take off the pedals and chainset.
– Fit the new chainset, and fit the pedals.
– the chain may not be the right length – with the standard 20t sprocket, 33t chainring, and latest tensioner, the chain should be 100 links long.
– if you fit a new chain, fit either a 7/8-speed derailleur chain, or a narrow single-speed one like the SRAM PC-1.

Fitting the shifter and cables:

– Fit the shifter to the right handlebar – you’ll need to cut down the handlebar grip a bit, and it should go with the cable to the front of the brake lever, not behind. If space is cramped, you can usually move the brake lever inboard a bit too. Make sure the shifter doesn’t restrict movement of the brake lever.
– Thread the outer gear cable through the plastic cable gatherer behind the stem, down alongside the other cables, behind the chainset and through the cable guide there, through the cable guide on the chainstay (going from outside to inside, like the brake cable) and up through the square tube that used to hold the plastic pulley, before curving down towards the cable guide on the hub – depending on your handlebars, you will probably need to cut a bit off the cable to make it the right length.
– Thread the gear cable through the outer cable. It’s easiest if you don’t put the outer cable into the cable guide on the hub yet, you can do this later.
– Fit the cable clamp as in the Sturmey instructions – put the shifter into 8th, and fit the clamp 105mm along from the end of the outer cable. Cut off the spare cable.
– It’s easiest if you take the tensioner off again for this bit – push the plastic cable clip on the hub backwards so you have some slack, and clip the cable clamp in place. Try operating the shifter to make sure the cable clip rotates around the hub correctly.
– Adjust the gears as per the Sturmey instructions – in 4th gear, make sure the yellow dot is in the centre of the window, on the back of the hub on the right-hand side.
– Re-fit the tensioner, and try again – operate the shifter a few times while pedaling, and check again that the yellow dot is in the centre of the window – adjust the barrel adjuster on the gear shifter if necessary.

That should be it 😉

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19 Responses

  1. jonathan mellish says:

    I have a late sturmey archer 3 speed Brompton circa 2000 so would your conversion go straight On. Concerned about the oln dimension. Thanks Jonathan

    • admin says:

      Hello, I’ve fitted the kit to bikes of a similar age with no problems – I think it might need a slight pull to get the wheel in, but not much.

  2. bob says:

    I have a really nice NOV chain tensioner. Can it be used with the 8 speed Sturmey Archer Kit?

  3. Joel says:

    Hi is this conversion suitable for Ti rear frame?

  4. Kurt says:

    What chainring sizes can be had? I note you use a 33, can I get a 32, or a 31? And I assume I can order the 25 T rear from you?

    • admin says:

      Sturmey don’t make other sizes, but it could be done with a different chainset and replaceable chainrings. The largest cog that’ll fit an unmodified Brompton frame is a 20t, so a 25t won’t fit.

      • Kurt says:

        Thanks for the info. I don’t have a Brompton but am considering one and am fairly picky about gearing. If the 20T rear is my only option, I am wondering how small I can go in the front to get the same gear ratios as a 25 x 33. Are you saying the 33 x 20 is my only option? If so maybe I need to consider the Alfine 11 or the Rohloff 14.

        • admin says:

          It’s not really possible to go much lower with the Sturmey, no – can get higher gears easily, but the smallest front ring that’ll work is a 30t. An Alfine or Rohloff could go much lower.

  5. steve m says:

    Hi, I’m ordering a Titanium Brompton this week from a local bike shop (Colorado, USA). Your 8 speed conversion is the best solution I’ve found. Are there any other shifters that could possibly work? I have SunRace / Sturmey thumb shifters on 3 other bikes, and I love them. If they don’t work, is it because of a different pull ratio?

    • admin says:

      Yes, the pull ratio is different – but I’ve used the Travel Agent device to alter the ratio and allow Rapidfire shifters to work. An Alfine 8-speed shifter might work too, and there’s the J-Tek shifters.

  6. Daniel says:

    Hi
    In there any problem to install with P handle bars?
    Thanks
    Best regards

  7. Kip says:

    Following from Steve m’s question on shifters: i’ve gone the “full Brooks” on my Brompton and would prefer to retain the Ergon gp1/brooks grips. I see the suggestion that the Rapid-fire 8-speed shifter should work with an added travel agent device. Given this will be a self-install, any concerns or compromises you’re aware of?

    • admin says:

      The only thing to check is that the cable doesn’t get too close to the chain, as the Travel Agent turns it through 90 degrees. It might help to move the cable arm on the hub to the other position (open triangle instead of filled triangle).

      Another option is that J-Tek make shifters for 8-speed hubs, but I haven’t verified if they work with the cable pull of the Sturmey yet.

  8. Mahesh says:

    hi,
    I have a 2015 H2L (2 speed) brompton and would like to get the 8 speed sturmey archer conversion kit.
    Questions
    1) Is it possible to do this without any frame modification?
    2) Is the sturmey archer hub as reliable as the alfine or does it require frequent maintenance?
    3) I have read about some problems with fold that comes with the front chainring change. Do I need any specific spacers?
    4) Are there any other options to the rotary shifter for the hub? Can I get something like the low maintenance bar end shifters for the hub?

    thanks
    Mahesh

    • admin says:

      1. No frame modification will be needed on your bike, the only ones that sometimes need a little modification are titanium frames.
      2. They seem as good, yes – I have almost no problems with either. It’s not quite as efficient as the Alfine, though.
      3. A few Bromptons have a slightly shorter bottom bracket which causes problems – a spacer under the bottom bracket to move it right by a few mm usually solves it, worst case a longer bottom bracket is the solution.
      4. I have used derailleur shifters using a Travel Agent to alter the cable pull.

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