The Kinetics 8-speed Brompton conversion uses a Sturmey Archer hub gear with a very wide range – the X-RF8(W) has a 325% gear range*. Compared to Brompton’s 6-speed option, it is a wider gear range with only one gear shifter – a low profile twist shifter. All 8 gears are in sequence, so it’s easier to use than the 6-speed’s twin-shifter system, and any gear can be selected while stationary. The smaller front chainset keeps the drivetrain further inside the folded package. No modification of the frame is needed.
I can fit the 8-speed to an existing Brompton for you, or I can send you a kit. The kit includes the complete back wheel, chain tensioner, gear shifter and cable, and replacement chainset. You’ll need a few spanners, and a few allen keys – fitting is not hard, and takes about 30 minutes (see the instructions here).
Brompton 8-spd Kit – £395 – delivery takes around 4-6 weeks.
Thumbshifter instead of twist – £25
*I normally use a 20t rear cog and 33t front chainring, to give ratios of about 29″ to 95″ (2.3m to 7.5m).
hi
i have a 3 speed brompton.
i can use 8 speed kit?
Yes, the kit will fit any standard Brompton.
This can be fitted in a carbon wheel (ORZ, etc…) instead of a regular wheel?
I’ve never tried, but as long as it’s a 28h rim it should be fine.
Hello,
what is the weight difference in comparison to the standard 6-speed (3-speed hub + derailleur) setup?
Thanks.
It’s around 750g heavier.
J have a 2 speed, light titanium version, 2012 I would know if the dimension is correct without modification of the frame.?
could you tell me the dimension for my bike shop in France for installation
thanks you
The axle width is fine, but some titanium frames need a little bit filed off the chainstay where the cog is.
If I ordered the kit for a titanium version (2017) is this something I could deal with myself? Do you have any pictures of this?
It needs some metalworking, so depends on your skill level – it can be done with care with an angle grinder.
Hello,
Can you offer this kit with 30t front chainring and new chain to fit?
Thank You.
I just acquired a 2 speed S model. Would this be the genesis of a 16 speed, or is that just silly?
The cog sizes are different, I’m afraid – the 8-speed hub will only take a single 20t cog.
I’m glad to find this before ordering my first Brompton. Needn’t bother with any of their gearing options now, none of which appealed to me. Gear range appears to be comparable to my current Sachs Super-7 bike (31.8″ to 96.5″), and I use all seven.
Will this work with a single-speed Brompton?
Yes, it will work with any Brompton.
What is thje over locknut distance distance of the hub you use ?
Is it the standard 120mm of the standard X-RF8(W) hub that requires a slight widening of the Brompton rear triangle or do you reduce the hub over locknut distance distance to 110mm ?
I reduce the hub to 115mm to fit the Brompton frame with no spreading.
Hi, do you ship to Canada? Will The local Brompton retailler Know How to install it?
Yes, I ship all over the World. Any decent bike shop should have no problems fitting it.
I have a 6 speed brompton. If I buy the kit, is there anything else I need to install it?
Depending on the age of your chain, you might need a new one.
I got your 8-speed SA kit very quickly (very fast shipping to the USA) and I had the bike shop DIAMOND CYCLE in Monclair New Jersey install it (which they did in a day). I love this setup over the dual shifter 6-speed and I can more easily take on hills with the lower overall gearing.
I have a 6 speed if I put this kit on will this make it a 16 if I use the derailleur with ?
No, the derailleur cannot be used with this hub, the sprockets are completely different.
Does the kit come with a 20 cog?
Yes, that’s the only cog that fits.
How much weight does the 8 speed
kit add to a 2017 M2L?
It adds around 1kg.
can you fit a smaller chainset than the 33t to make the gearing smaller?
Suitable chainsets are quite hard to find – in theory it’s possible to go down to about 30t without causing problems, any lower and the chain hits the wire cable loop on the chainstay.
What is the metres of development?
Thanks
It’s 2.3m to 7.5m.
I’m interested in the 8gear conversion, How would it work on a P-type handle bar?
The twist shifter works pretty well on a P-type, unless you’ve got the older plastic brake levers – in that case, the thumbshifter is probably better.
Yes but how will it work? I.e. Where on the bar it will be fitted ? On top/ around the curl…?
It’d go on the top – it won’t fit around the curve.
Hi would you have a photo of how it will look like for me to visualize on how it can work? I’m assuming that it’s been done before…
Can I order the kinetic 8 speed kit with twist shifters on a brompton from you? I didn’t see it as an option on the custom bike form.
No, I don’t build complete bikes with the Sturmey kit, only with Rohloff, Alfine or NuVinci kits.
I’ve done the conversion, it only took an afternoon but if you aren’t handy with spanners, I reckon any local bike shop would do it in a 1/2 day.
Hi,
Would this kit work on an old Brompton that does NOT have the lug on the rear triangle for mounting the derailleur? I presume there is a single cog on the rear hub?
Thanks
Paul
Yes, this kit does not need the derailleur mounting – on old frames, the dropout spacing is a couple of mm narrower so you might need to spread the frame a little bit to get the wheel in.
Hi,
I have a 6 speed with a Schlump mountain drive. Would this 8-speed-kit work on my brompton? Would the Schlumpf Mountain drive have the same effect on the 8-speed-kit as on the 6 speed?
Thank you for your answer!
I have built bikes with the 8-speed kit and the Mountian Drive – it works fine. It depends what chainring you have, but typically a 50t would give a very good range.
I have a 6 speed Ti Brompton with the +8% gearing option(54T) chainring. I believe this give sa 108″ gear with which I’m happy. Would the 8 speed be able to obtain this gearing?
Yes, with a 38t chainring.
If I go to Glasgow, is it possible for you to assemble this 8 speed hub the same day?
Yes, I did one today, it takes about an hour – but I need some time to build up the kit first, I don’t usually keep them in stock.
And is it ok for a Brompton M1E? Is it possible to use the same rim? I saw also something you did with a Alfine 11 speed. Is it possible to assemble something like it without disk brake? How much shall I pay for the Rohloff and/or the Alfine?
Hi there,
I’m very interested in buying a 1-speed M-type Brompton bike and then add your 8-speed Sturmey kit to it.
I’ve got two questions:
1. When I buy the bike, which front chainring shall I opt for? Standard? -7%? Or -18%? (as displayed on the official Brompton website)
2. With your kit, will the size of the bike increase when folded? (for example, in comparison with the official 6-speed kit)
Many thanks and keep up the good work!
Vlad
The 8-speed kit comes with a new chainset, as it needs a much smaller 33t ring, so it doesn’t matter what your bike has.
The folded size is the same – the standard left wheel nut that comes with the kit is a little longer, if that bothers you then you can use one of the original wheel nuts.
We recently bought two used 5-speed Bromptons, dating from around Y2000 (so it’s probably the shorter wheelbase type).
On one of the bikes, the Sturmey 5-speed is a bit wonky. Assuming I’m not able to get it to shift reliably: how much weight would your 8-speed setup add, approximately?
It’s roughly 750g extra.
Am I right in thinking I’d need a 28T front ring to get something similar to a 22” hill climbing gearing? That would give me a range of 22-72” is that right?
Are you able to supply a 28T or 30T front ring…?
The problem with going smaller than 30t is that the chain hits the cable keeper loop on the chainstay.
Hi. Is there any reason why a 32 tooth chainring will not work with this set up? If I was to try and do a conversion myself the 32 size is more commonly available. Are there problems with crank length bolt hole diameter chain size chain line etc? Are there any parts problems when reducing locknut dimension and chain tensioner mods?
No reason why not, it’s just that single 32t chainsets are hard to find. The chainring needs to be pretty close to the chainstay, so fitting a standard ring to a double or triple chainset might not work.
You must have fitted quite a few of these by now. How reliable is the eight speed hub?
Over a hundred I think! The early hubs were a bit fussy about adjustment, but the current wide-range ones are very good. The only problems I have sometimes are with the twist shifter, it’s a bit plasticky. The aluminium thumbshifter is great.
Is it possible to fit a front ring small enough to get a bottom gear about 20″ (top would I guess be about 65″) with the SA 8 speed?
I think it’d be tricky – that would need a chainring of about 23t, and anything smaller than 30t causes problems with the chain hitting the wire cable loop on the chain stay. Of course you could remove that.
Hi there, I’ve just bought a new Brompton (one of the nice looking Nine Streets special editions) and have realised that the M type handlebars have changed quite radically. The brake lever, gear shifter and bell are all integrated and the shape of the handlebar is subtly different.
Have you had any success fitting the eight speed kit to a 2018 Brompton with the redesigned M handlebars?
Yes – the gear shifters are removable, and the bell can be moved to the other side. But the thumbshifter is a better option than the twist on H and M bars.
This will fit on a Dahon presto with Sram T3?
No, it’s only for Brompton folders.
What are the pros and cons of using your 8 speed system? I am looking to buy a 2018 or 2019 Brompton. Either six speed or possibly yours with buying the one speed version to swap.
If there’s issues with your system what would my repair or replacement options be? Say for instance five years from now you’re no longer in business and my 8 speed gets issues, would local bike shop be able to install or fix these parts?
I’ve been here for 20+ years, hopefully that won’t happen! But if it does, the hub is a standard narrow-shell Sturmey one, the internals can be replaced by any decent bike shop with the correct tool. The tensioner is modified, but uses standard jockey wheels.
Dear Sirs,
the kit including what? may I have a picture what parts inside the box? thanks
The kit is a new rear wheel with cog and fittings, new chainset, new tensioner, gear shifter and all the parts you need.
Do you install the S-RF5 W) with 28 Holes, 111mm O.L.D. & 148mm axle ?
No, I don’t use that hub.
I have a 6speed that has the gear shifters with integrated brake levers (2017 black edition). Do I have to purchase new brake levers as well or can I just remove the shifter part from my current set? Kind regards – Marko from Germany
The shifters can just be removed from your brake levers by undoing the two small bolts.
Hi there.
Is the thumb shifter a souped up version of the Sturmey Archer 3-speed changer or more like a shimano click and release type?
It’s an aluminium one on top of the bar, not the Rapid-fire-type under the bar.
Hi I the kit available with a Black Rim/ Spokes/ Hub to match a Black edition as much as possible?
No, sadly the hub is not available in black in the right drillings.
Hi will the 8 speed fit a 1995 5 speed
Yes, though as your frame is 112mm wide rather than 115mm, it will need a bit of squeezing to get the hub in – or you can spread the frame slightly by wedging a block of wood between the chain stays.
Hi, I am just looking at purchasing a Brompton on the C2W scheme and converting it to Alfine 11. I take it I should just buy the cheapest as your conversion fits them all. Also, I have never had an Alfine 11 but have had an Alfine 8 on 700c wheel and it used to break spokes quite often. Do you know if that is an issue with the 11 on the smaller wheels?
Yes, the kit will fit any Brompton, so just get the cheapest one you can find with the right bars and colour. Spoke breakage has never been a problem, perhaps because small wheels are much stronger than big wheels.
Hi there, I’m really interested in this 8-speed kit. I live in the Peak District and currently ride my Brommy on a 46T chainring and 14T sprocket on the standard 3-speed hub. The lowest gear is still too high for me to comfortably climb the hills and it feels like I need like a MTB granny ring or something. So, my question, do you think your regular combo of a 20/33 set of ring and this hub would supply that sort of ratio (sorry can’t quote the exact one, but something I can spin fast to get up short/steep hills)? My maths says so but it’s hard to imagine it without riding it.
With the much bigger range and the lowest gear being number 1, I might be tempted to try something like a 25t sprocket, keep my 46T chainring and see how it goes.
Do the smaller chainring fit the standard Brommy crank? If so and they’re not too expensive I could try a smaller ring as well.
Sorry for so many questions!
Unfortunately, only the 20t rear cog works on the Brompton. The 33t chainset that comes with the kit is a Shimano Nexus one, they’re also available in 38t for higher gearing.
hi,
I look for the lowest gears setup for climbing steep with a Brompton .
can you please compare lowest setup of the 6speed vs the 8speed ?
thank you
The lowest gear is about the same – 29″ for the 8-speed and for the 6-speed with 12% reduction. For lower gears, I have the Alfine-11 and Rohloff kits.
Hi
I just bought the a B75.
1. Can I use yours 8 speed conversion kit on my rear frame? I don’t know what is the clearance of the rear frame. 112 or 117?
2. Can I use the 44 chainring that B75 currently use?
3. How long will it take to ship to Singapore?
Hi, the 8-speed kit will fit your frame. You could use the 44t, but it will be quite high-geared – it might be better to try the 33t that comes with the kit. Delivery is about 2 weeks.
Hi, will you make the whole brompton with 8-speed? I mean just telling you the specifications of the Brompton. Thank you.
No, sorry – I only sell the 8-speed kits.
Will a 23T or 25T sprocket fit this hub?
For example:
https://www.sjscycles.co.uk/sprockets-hub-gear/?brand=sturmey%5Farcher&teeth=25
If not, why not?
Thanks
No, there isn’t enough chain stay clearance for a bigger rear cog.
Ben sent me a rear triangle with a Sturmey Archer X-RD8(W) 8-speed drum brake hub, to match the existing Greenspeed-modified SA X-FD front drum brake hub I had installed on the factory fork of a Brompton. My friend will keep using this bike for utility transport in the DC area, multi-modally and now even less bothered by rim and brake wear, with easier inline shifting of more steps over a wider range than the original M6L configuration provided. Thanks, Ben!