brompton 12 speed

[rogerzilla]

It's only really a 10 speed! If they couldn't make the hub ratios wider*, they should have made the derailleur ratios closer.

The old Sachs-based 6 speed gave no gaps and was easy to understand - to go up the gears you went 15L, 13L, 15N, 13N, 15H and 13H, the numbers being the sprocket teeth and the letters being the hub range (low, normal, high).

*it does get challenging to make a 3 speed hub gear that deviates much from the usual 1.33 internal ratio, as this gives really durable and smooth-running sun and planet sizes. in the BWR, the planets get rather small, as do their pins, and it must be the practical limit for a single-stage mechanism in the standard size shell.

 

[TheDoctor]

12 speed, yes, but with two sets of close duplicates (45" 47" and 70" 73" and an all-but-useless 115" top gear, I struggle to see what you'd gain over a home-brewed 9 speed using 12T 14T 17T on the existing BWR.

 

[Origamist]

This has been a few years in development and was 'quietly touted' at Eurobike last year. It's not for me, but with a 44T (or smaller) front chainring it kinda makes sense in a typically idiosyncratic Brompton manner...

 

[tinywheels]

would it not be easier to just widen the rear frame and fit a hub gear as our friend up north does?
Surely that's far simpler than this mash up. Also a hub gear set up would be nigh on maintenance free,plus get rid of the fear of rear wheel punctures.
Clunking up and down my six speed is bad enough let alone this setup.

 

[brommieinkorea]

Tend to think Alfine 8 or 11 would be a great idea, and you could put a trp spyre on the rear and save some rim metal. Not that this looks dreadful, maybe just a little more complicated than neccesary.

 

[dimrub]

I think I'd be happiest with just an 8-speed SA. Enough gears, no servicing, simple shifting - the Brompton way. Why don't they do that?

P.S. I was not familiar with Shimano Alfine. Yep, sounds like a great idea. For completeness sake, here's the conversion kit for it, by Kinetics.

 

[Kell]

While this piques the interest of my inner-engineering junkie, in practice I find the 2x3 setup absolutely fine for the riding my Brompton gets.

Looking at the gear-range chart from @tom73's Cyclist review, it seems that while some additional derailleur-shifted-range and resolution has been added to each of the three ratios available on the hub, inexplicibly much of the additional "benefit" is at the high end; which I very much doubt many will use on a high-drag, utilitiarian city bike..

View attachment 719578

As someone who typically remains in the mid-hub gear and switches between high and low on the back end I can see the appeal of the greater range and resolution provided by the 4sp setup on the rear, however the top end seems a bit silly and I'm not sure how intuitive / straightforward shifting would be with nearly the same amount of speeds available front and rear.

At the "right" price I'd consider this as an upgrade on my C-Line, however I suspect it'd need a new rear triangle in addition to the cassette, derailleur, shifter.. while Brompton prices for big bits tend not to be shy.

All things said and done I don't think this release will do much to undermine the utility that I already get from my 6sp

Comparing like for like the additional top end doesn’t work for me. At least not any more.

Four or five years ago I was two stone lighter and hadn’t had both pneumonia and Covid. Back then, I’d regularly spin out on the top end of 6th on a 50T chainring.

Now I’m heavier and have lost 80 watts from my FTP it rarely happens. I still use 6th, but I never really get over the top of it anymore.

However, there will be plenty of people that would appreciate the extra top end - as I discovered when I did the Brompton World Cup and had people coming past me at about 30mph.

However, the 50T can still be swapped out for the OEM 44T and you’d get more ‘hill capability’. Maybe this would retain a similar top end to the current 6-Speed?

I’m not clever enough to work it all out.

 

[T4tomo]

Comparing like for like the additional top end doesn’t work for me. At least not any more.

Four or five years ago I was two stone lighter and hadn’t had both pneumonia and Covid. Back then, I’d regularly spin out on the top end of 6th on a 50T chainring.

Now I’m heavier and have lost 80 watts from my FTP it rarely happens. But I still use 6th.

So there will be plenty of people that would appreciate the top end - as I discovered when I did the Brompton World Cup.

However, the 50T can still be swapped out for the OEM 44T and you’d get more ‘hill capability’. Maybe this would retain the top end from the current 6-Speed?

I think it would make more sense with a 44T chainring. that gives you similar top end to current 50T 6 speed, but a much lower low gear, circa 25inch from what i can tell from that chart.

I’m not clever enough to work it all out.

take the gear inches shown, divide by 50, times by 44 - thicky

 

[Tenkaykev]

Mrs Tkk plans to convert one of her Brommies to a 14 speed Rohloff. The donor bike is a custom built tourer from Chas Roberts.

 

[wafter]

Comparing like for like the additional top end doesn’t work for me. At least not any more.

Four or five years ago I was two stone lighter and hadn’t had both pneumonia and Covid. Back then, I’d regularly spin out on the top end of 6th on a 50T chainring.

Now I’m heavier and have lost 80 watts from my FTP it rarely happens. I still use 6th, but I never really get over the top of it anymore.

However, there will be plenty of people that would appreciate the extra top end - as I discovered when I did the Brompton World Cup and had people coming past me at about 30mph.

However, the 50T can still be swapped out for the OEM 44T and you’d get more ‘hill capability’. Maybe this would retain a similar top end to the current 6-Speed?

I’m not clever enough to work it all out.

You make an interesting point. Granted I'm not a strong cyclist and very rarely bother 6th; although I do sometimes find myself in 5th on the flat. I guess there's an argument for catering for strong riders / down-hill-nutjobs.. however it's a very upright, draggy bike so I'd still question the benefit of such-high gearing... maybe the lower flat-bar varients are a bit better suited to this.

Good point about the 44t - this would basically reduce every gear by 12% relative to the 50t. I'm dubious of spending the time to draw any more conclusions from the previously-posted gearing chart however as there seems to be a discrepency - both 4 and 12 speed setups are listed as 11-18t with 50t chainring; however the 12 speed's range in the middle of 1:1 drive of the hub shows lower gearing than the 4sp; when it should be the same.

I did wonder if the 12sp data had been calculated for the 44t chainring; however the discrepency with the 4sp info doesn't seem large enough for this to be the case..

Viewed in isolation the gear spacing of the 12sp over the whole range seems pretty nice; however in reality I'm not sure how user friendly this would be to access - on the 6sp you only ever need a maximum of one prod of each shifter to get to the adjacent gear (either just one on the sprockets, or one on the sprocket on the hub) while doing so on the 12sp would potentially require as many as three consecutive shifts on the sprockets and one on the hub...

 

[simongt]

Of course, as with most things cycling, nothing new here. Cyclo were offering a three speed derailleur integrated with a three speed hub back in the fifties; apparently very popular in Britain & the Continent. Marry that to Huret or Simplex double chainwheel derailleur and away you went - !

 

[Kell]

Of course, as with most things cycling, nothing new here. Cyclo were offering a three speed derailleur integrated with a three speed hub back in the fifties; apparently very popular in Britain & the Continent. Marry that to Huret or Simplex double chainwheel derailleur and away you went - !

Am I reading that right - does that mean three shifters?

Might as well add a Schlumpf drive too.

 

[Schwinnsta]

Am I reading that right - does that mean three shifters?

No, you're not.

 

[simongt]

Am I reading that right - does that mean three shifters?

One for the hub gear, one for the derailleur and one for the chainring shift. Although this is assumed based on 'logic' - !

 

[a.twiddler]

It all seems a bit excessive just to get 12+ gears on a folding bike. However, since I entered the weird world of the recumbent Darkside, I have come to accept all sorts of things which I'd previously regarded as improbable. Hence three shifters on my recumbent, one for the hub gear, one for the rear derailleur, one for the front derailleur. Presently a choice of 42 gears, with a double on the front. If I reinstated the third chainring it could be 63 gears. Other posters will no doubt have more, especially on trikes. If it works for you, why not?