# Talk to me about Brompton gear upgrades ...



## CopperBrompton (30 Jul 2013)

I have an M3L, bought because it was only ever intended for use around central London, where three gears are plenty. 

I'm now making more use of it in hillier territory and thus looking at a gear upgrade of some kind. I definitely need more lower-end and more steps, and a little higher-end would also be nice.

Options I'm at least vaguely aware of, together with my current impressions of pros & cons, are:

1. Brompton 6-speed upgrade
Pros: The cheapest option, reliable
Cons: I had a 6-speed before and am not a fan of the two-lever system

2. Sturmley Archer 8-speed hub
Pros: Not that much more expensive than 6-speed, twist-grip (which I love), greater range
Cons: Reliability of the SA hub seems to get mixed reviews?

3. Nuvinci CVT hub
Pros: Stepless, twist-grip, large range
Cons: Expensive

4. 11-speed Alfine 
Pros: Range, reputation
Cons: HOW MUCH???!!!  Not twist-grip?

All input welcomed.


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## Rohloff_Brompton_Rider (30 Jul 2013)

2nd hand schlumpf mountain drive.


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## CopperBrompton (30 Jul 2013)

Wouldn't that again be a two-lever system?


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## jackthelad (30 Jul 2013)

6 speed upgrade about £250 if you go for the lower 44t at the front add another £50 total £300
8 speed hub supply and fit about £300
I dont think the mountain drive,alfine 8, alfine 11 or the Rohloff hubs are worth the extra cost,but then everyman to his own.Cheaper getting fitter,


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## Night Train (30 Jul 2013)

I have been thinking along similar lines and looking out for a SA 8 speed to 'DIY' convert onto my Brom.

Same issues as the OP, a lower gear and a higher gear would be really nice to have but not keen on the twin lever system, much preferring a twist shift or a single 'up/down' trigger.


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## Rohloff_Brompton_Rider (30 Jul 2013)

Trikeman said:


> Wouldn't that again be a two-lever system?


No, 1,2,3....kick button 4,5,6 all nice and sequential.


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## CopperBrompton (30 Jul 2013)

jackthelad said:


> 6 speed upgrade about £250



I've seen this for £200 fitted, but would happily pay £100 more for twist-grip even without the extra range of the 8-speed SA provided it's reliable. Some reviews say it is, some say it isn't, so wondering if that's indicative of variable quality-control ...


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## CopperBrompton (30 Jul 2013)

bromptonfb said:


> No, 1,2,3....kick button 4,5,6 all nice and sequential.



Do you have a link to the Brompton fitment of this?


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## Rohloff_Brompton_Rider (30 Jul 2013)

http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm


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## Rohloff_Brompton_Rider (30 Jul 2013)

Hub gear calculator for the Brompton...


http://xldev.co.uk/bgc.html


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## CopperBrompton (30 Jul 2013)

Thanks. From what I can see, that only gives lower gears, so I'd have my three existing ones, plus three lower ones. That would address the bottom end, but not give me the extra top-end I'd like.


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## CopperBrompton (30 Jul 2013)

bromptonfb said:


> http://xldev.co.uk/bgc.html



Thanks, that confirms the mountain drive isn't the best option for me - it would give me a gear 1 I'd never use, gears 3 and 4 would be duplicates and no higher-end than now.


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## Rohloff_Brompton_Rider (30 Jul 2013)

Increase the ring size. You can go up to 60 teeth without it affecting the fold. There is a M.D with an arm for the Brompton so no special cutting of the frame.


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## Rohloff_Brompton_Rider (30 Jul 2013)

Trikeman said:


> Thanks, that confirms the mountain drive isn't the best option for me - it would give me a gear 1 I'd never use, gears 3 and 4 would be duplicates and no higher-end than now.


No repeats on the BSR hub.


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## Rohloff_Brompton_Rider (30 Jul 2013)




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## CopperBrompton (30 Jul 2013)

Ok, tried with the 60 and that looks like a good range, but I think I'm missing something about how this works ...

I start in MD and go through gears 1, 2, 3. To get gear 4, I surely have to press for DD *and* go back to gear 1 on the lever to get gear 4? It's that double-shifting that's my objection to the standard Brompton 6-speed.


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## Rohloff_Brompton_Rider (30 Jul 2013)

Ah ok fair enough, I've come from a Brompton M6L with speed drive so it's lot lot easier for me.

I see what you want now....the 8 speed sturmey is the cheapest modern kit but the old 5 speed might do you?


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## CopperBrompton (30 Jul 2013)

Yeah, I have actually owned the 5-speed in the past (not a deliberate selection, just a very good secondhand price) and that was a decent range, so that would be another option if it's easily available as a conversion?


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## Rohloff_Brompton_Rider (30 Jul 2013)

If you want to go that route, I know a man who will defo have a 5 speed wheel and kit. If you'd like I'll PM you his email address.


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## CopperBrompton (30 Jul 2013)

Thanks


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## T4tomo (1 Aug 2013)

Trikeman said:


> Ok, tried with the 60 and that looks like a good range, but I think I'm missing something about how this works ...
> 
> I start in MD and go through gears 1, 2, 3. To get gear 4, I surely have to press for DD *and* go back to gear 1 on the lever to get gear 4? It's that double-shifting that's my objection to the standard Brompton 6-speed.



It's one double shift in the range as opposed to standard 6 speed where every shift is a double shift - odd gears on one cog and even on another. It basically fills in the jumps in the 3 speed range and adds one gear higher or lower depending on what sprocket you were running on your 3 speed.

I briefly looked at the SA 8 speed hubs - if you go that route make sure you get a kit with a smaller chainring, otherwise you end up with a crazily high geared range.


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## CopperBrompton (1 Aug 2013)

Thanks. Comparing what I have to what I want:

- Want one gear lower than 1st
1st
- Want a gear between 1st and 2nd
2nd
3rd
- Want at least one higher gear
- Ideally two

Based on that, what chainring would you recommend with the 8-speed SA?


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## T4tomo (1 Aug 2013)

No idea as you haven't said what size chain ring and sprocket you currently run. 

The hub gear calculator linked to half way up page 1 of this thread will tell you, just pump thenumbers in there. Kinetics in Glasgow seemed to do a sensible sized sprocket, although anecdotally his service can be haphazard timewise when he is busy. 

Also double check the 5 speed hub, that might give you what you want for cheaper with or without a change of sprocket.


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## CopperBrompton (1 Aug 2013)

Ah, didn't realise there was more than one standard setup with the M3L. I am not mechanical. :-)

I shall investigate when I'm next home.


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## CopperBrompton (2 Aug 2013)

Ok, so I have the 50-tooth chainring. Can't see an easy way to count the rear sprocket teeth but as the bike is standard, I assume it's 13-inch. That means I currently have:
47.7​ 63.7​ 84.7​ 
I now see what you mean about the SA-8, as with the same chainring that would give me
63.9​ 83.0​ 94.5​ 107.9​ 122.6​ 140.5​ 159.7​ 207.6​which would be just a little silly. :-) Even with a 44-inch chainring, it would start at 56", and only gets sensible with a 44-inch chainring and 20-inch cog - is that even possible?

The 5-speed actually looks the most sensible way to do it:
42.4​ 50.3​ 63.7​ 80.8​ 95.5​ 
I assume any Brompton dealer could quote me a price for an upgrade from SA 3-speed to 5-speed?


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## Rohloff_Brompton_Rider (2 Aug 2013)

No, the 5 speed isn't available anymore....hence me sending you pete's number, he deals in second hand b's.


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## CopperBrompton (2 Aug 2013)

Yeah, I emailed him but no reply


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## rualexander (2 Aug 2013)

5 speed Sturmey hubs are still in production.
Have a look at www.sturmey-archer.com/


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## CopperBrompton (2 Aug 2013)

Thanks, do you know which of those is the one Brompton fitted?


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## rualexander (2 Aug 2013)

No, sorry I don't know which if any of the current models were used by Brompton.
Best bet for an upgrade would be the x-rf5(w) which according to Sheldon Brown's gear calculator gives a range of 25 to 64 gear inches, using a 50 tooth chainring and a 20 tooth sprocket.
The 119mm over locknut version would probably be the one to fit a Brompton.


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## CopperBrompton (3 Aug 2013)

Ok, thanks. That one would be too low for me with that particular setup - I currently have 47/63/84 and am looking to get a little lower and somewhat higher.


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## Rohloff_Brompton_Rider (3 Aug 2013)

Trikeman said:


> Yeah, I emailed him but no reply


Sorry, forgot to say..he's on holiday...oops.


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## Rohloff_Brompton_Rider (3 Aug 2013)

rualexander said:


> 5 speed Sturmey hubs are still in production.
> Have a look at www.sturmey-archer.com/


Yeah, I meant already built wheels, sorry I should have been clearer.


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## CopperBrompton (3 Aug 2013)

bromptonfb said:


> Sorry, forgot to say..he's on holiday...oops.


 
Ah, ok :-)


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## rualexander (3 Aug 2013)

Trikeman said:


> Ok, thanks. That one would be too low for me with that particular setup - I currently have 47/63/84 and am looking to get a little lower and somewhat higher.


Ok, well you'd just have to change your chainring and/or sprocket size then.
For example, a 50 tooth chainring and 14 tooth sprocket would give you a range of 36 - 92 gear inches, or with a 13 tooth sprocket 38.6 - 98.9 gear inches.
Sheldon Brown gear calculator is here http://sheldonbrown.com/gears/
Note, the Sturmey Archer 5 speed x-rf5(w) seems to 36 holes so you probably need to change the rim too.


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## CopperBrompton (3 Aug 2013)

The Sheldon and Brompton calculators seem to give totally different results <Confused>


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## Night Train (6 Aug 2013)

rualexander said:


> Note, the Sturmey Archer 5 speed x-rf5(w) seems to 36 holes so you probably need to change the rim too.


I don't know if you can get 36 hole 16" rims. I've tried looking for some to build QR trailer wheels and haven't managed to find any.


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## rualexander (6 Aug 2013)

Yes 36 hole 16" rims are available, St John Street Cycles sell them, Sun CR18 model 
I'd post the link but for some reason this website doesn't let me paste into posts when using the browsers on my tablet.
Just Google 349mm rim 36 hole and it will come up.


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## Night Train (7 Aug 2013)

rualexander said:


> Yes 36 hole 16" rims are available, St John Street Cycles sell them, Sun CR18 model
> I'd post the link but for some reason this website doesn't let me paste into posts when using the browsers on my tablet.
> Just Google 349mm rim 36 hole and it will come up.


Cheers.


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## rualexander (7 Aug 2013)

2585677 said:


> 36,spokes between a SA hub and a 16" rim would leave very little space to get a pump onto the valve.


Shouldn't be a problem if the wheel is laced properly with the valve hole in the right place, see this picture of a 36 hole Brompton rim with an electric motor front hub,


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## CopperBrompton (1 Sep 2013)

Thanks for all the input on this. The gear calculator was wrong about the SA-8 - it actually gives 33-107 gear inches with a 50T chainring, which gets me everything I wanted: greater range at both ends, and smaller gaps, and with my preferred twist-grip shifter.

The upgrade would have cost a little shy of £300, but Tiller had a ready-converted brand-new one on offer. Buying that one and selling my existing one meant a premium of only £150 to get a brand-new bike, so decided to treat myself. :-)


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## Messenger88 (25 Sep 2013)

Hi Trikeman,

I wrote the Brompton Gear Calculator, so would like to know where it went wrong with your SA-8 calculations. Could you tell me how many teeth you have on your rear sprocket, and let me know the model number of your hub? I'm keen to iron out all the bugs.

Many thanks


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## CopperBrompton (26 Sep 2013)

Hi Messenger, I'm rather non-mechanical, but I believe the rear sprocket is whatever is standard for a 2013 M3L.

The hub is, from memory, the SA SRX-8, but if that doesn't make sense I can check when I get home.


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## Messenger88 (2 Oct 2013)

Hi Trikeman,

Thanks. I can't find any information for the Sturmey Archer SRX-8, and my calculator only has data for the wide-range Sturmey Archer 8-speed hubs. However, all the 8-speed Sturmey Archer hubs I know of have direct drive in gear 1, so with a 50 tooth chainring and a 13 tooth rear sprocket, the approximate 1st gear ratio is easy to calculate: wheel diameter x (chainring / rear sprocket) = 16 x (50 / 13) = 61.5 inches.

However, I don't think the Sturmey Archer hubs support the standard Brompton rear sprockets, so to get your gear ranges you must have a larger rear sprocket - perhaps 25 teeth? I don't know what's possible, but that's the combination required to get your gearing.

If you've got a completely different hub, please let me know.

88


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## CopperBrompton (2 Oct 2013)

It is definitely a Sturmey Archer, but it would probably make sense for you to talk to the man who knows: Graham at Tiller Cycles. http://www.tillercycles.co.uk/page6.html


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## Messenger88 (2 Oct 2013)

In which case I'm guessing you have a 25 tooth rear sprocket; I believe the SA8 can take either 23 or 25 teeth.
If you set the 'rear' value of my calculator to 25, it returns your 33 - 107 range for the SA8 & 50T - which also matches the figures on the Tiller site.

Thanks for all your help.

88


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## CopperBrompton (3 Oct 2013)

Having had a quick look, that seems about right, so I think you've cracked it. :-)


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## T4tomo (12 Jan 2014)

So how are you getting on with the SA8? I'd be interested to know. 

I have an S3L (I think that's the right code for it) which has the higher choice of gearing 54T chainring as my commute used to be pretty much flat. Now moved house and have a much hillier route. Approx 400ft of vertical rise, either steady gradient over 5 miles or over 2 miles including a little section of 10-12%, depending on which train station I use. I can honk up it out of the saddle in 1st but could do with a lower gear tbh plus the gaps between gears are quite large for the steady but varying incline piece. Always feel like I need gear 2 1/2 or 1 1/2.

I do like the efficiency lightness and reliability of the SA3 though, so If I'm adding 10% to the weight of the bike I don't want to sacrifice efficiency and reliability.


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## CopperBrompton (12 Jan 2014)

I absolutely love it.

There are two small downsides. First, you need to rotate the pedals a full turn forward before you fold the rear wheel, to tension the chain. If you don't do this, the chain can come off, but once you know about it it's not an issue.

Second, the twist grip effectively loses you half the right handlebar. I'm planning to get an extender so I can fit Ergon grips.

Otherwise, it's perfect. Virtually infinite gears with tiny steps. 1st is low enough for stupid hills, and 8th lets me reach 30mph on steep downhills. Twist-grip is effortless. Lots of fellow Brompton riders on group rides have commented on the fact that I'm able to maintain a constant cadence at all times, and I beat everything away from the lights.

Get one.


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## Kies (12 Jan 2014)

I have a twist shifter on the Dahon - very easy gear changes


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## T4tomo (12 Jan 2014)

I'm not a big fan of twist grips to be honest, reminds me of my old raleigh commando ( yep parent too poor to get me a chopper). I have twist grips on a cheapo tandem we have which I occasionally change gear without meaning to. 

Explain more what you mean about extenders. I currently have micro bar ends on my S bars ( great for the flat bits off my commuye and or when it gets windy, as it allow you to flex your elbows and get lower / more aeroand moved the brake levers and gear changer in a bit to accommodate them (plus trimmed the foam grips slightly). Is the twisty grip a big intrusion? You are on M bars I think.

Plus do you notice the extra weight of the SA8?

Thanks


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## Pale Rider (12 Jan 2014)

T4,

Easy - and cheap - enough to put a smaller chain ring on the front.

Or/and you could convert your Brommie to BWR - Brompton Wide Range - 6-speed.

http://www.sjscycles.co.uk/brompton-gear-upgrade-set-3spd-to-6spd-bwr-exccables-prod19449/


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## CopperBrompton (12 Jan 2014)

It's not much cheaper than the 8-speed conversion, though, which is a lot slicker and gives wider range.


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## Pale Rider (12 Jan 2014)

Trikeman said:


> It's not much cheaper than the 8-speed conversion, though, which is a lot slicker and gives wider range.



I wondered about that, although I believe the BWR is quite a bit lighter.

The 8-speed twist shift is slicker.

I'm used to my Brommie's six speed, but changing sequentially is a bit cranky.


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## ufkacbln (12 Jan 2014)

Trikeman said:


> Thanks. From what I can see, that only gives lower gears, so I'd have my three existing ones, plus three lower ones. That would address the bottom end, but not give me the extra top-end I'd like.



There are three versions

Mountain drive: Reduces front ring by a factor of 2.5 
Speed drive: increases the front ring by a factor of 1.6
High speed drive, increases the front ring by a factor of 2.5

What you need to do is sort the gearing ti suit your normal riding and then fit the Schlumpf to accommodate the difficult bits.

For instance, I have a 34T front ring on my Gekko which suits me perfectly for city riding (stop and start) however I wanted the third of my riding that I am faster to be more efficient so fitted an HSD to give me an 85T front ring for these times.

Had I been a racer and the majority at high speeds then I could achieve the same withan 85T front ring and a Mountain Drive to reduce the gearing for the occasional hill or trafic interaction


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## CopperBrompton (12 Jan 2014)

Pale Rider said:


> I wondered about that, although I believe the BWR is quite a bit lighter.
> The 8-speed twist shift is slicker.
> I'm used to my Brommie's six speed, but changing sequentially is a bit cranky.


Yes, it's true the BWR is lighter, but given the speed with which a Brompton accelerates and the fact that I hardly ever carry it any distance (either unfolding and wheeling, or trundling on the EasyWheels), the weight difference is a very small price to pay in my view.


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## T4tomo (13 Jan 2014)

yes I'm not keen on the non sequential gears on the six speed. so trikeman - are you saying you can't fit bar ends once you have the twistgrip shifter for the SA8? or is it just a case of sliding all the shifter & brake gubbins a little more central on the bars to accomodate

pale rider - switching to 50T whilst helping me out up steepest hill - loses me the top gear for the downhills and flats and I still have big jumps between gears. It is the cheapest option though!


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## CopperBrompton (13 Jan 2014)

T4tomo said:


> I have twist grips on a cheapo tandem we have which I occasionally change gear without meaning to.


I love twist grips - have them on my trike too. Have never changed gear without meaning to.



> Is the twisty grip a big intrusion? You are on M bars I think.









Bar ends are no problem, but to replace the entire grip I need to be able to extend the bar.



> Plus do you notice the extra weight of the SA8?


It is heavier, but notice it - no. If I'm walking any further than up/down stairs or across a platform, I either wheel it on the EasyWheels or unfold it and push it. For me, the fold/unfold is so fast I can't understand why anyone chooses to carry it any distance.


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## CopperBrompton (13 Jan 2014)

T4tomo said:


> so trikeman - are you saying you can't fit bar ends once you have the twistgrip shifter for the SA8?


See above - you can add bar-ends but I want to replace the entire grips with Ergon ones, and that needs a bar extension.


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## T4tomo (13 Jan 2014)

Ah understood helpful photo too. That would work for me, I only use the foam grips anyway, not expensive leather ones! Plus S bars make sit easier to move the controls inwards to make some extra handroom to accomodate bar ends. Maybe it's just the cheaper Revoshift controller on he tandem that is an issue is you haven't had any problems


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## Paulus (23 Jan 2014)

I have just read all the posts here as I have decided to upgrade my M3L to a 5 or 6 speed, thanks for all the info. Paul.


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