Folding Bikes - New BWR 6-speed hub from Brompton

Just picked up this news elsewhere:

"BROMPTON 6-SPEED WIDE RANGE HUB

Brompton is now offering a wide-range 6-speed internal gear hub as an option on all their models. Manufactured by Sturmey Archer, it will replace their current SRAM 6-speed hub. The new BWR, as they’re calling it, would make a nice upgrade for those who are currently running the S-A 3-speed or the SRAM 6-speed (which has a narrower range).

From the Brompton press release:

The new configuration for 6-speed Bromptons will feature a wide-range hub of our design, manufactured by Sturmey Archer; the present 6-speed arrangement, employing a SRAM hub, will be discontinued from 1 January 2009. We believe that the Brompton Wide Range Hub [BWR], together with Brompton’s derailleur system, sets a new standard in folding bike gearing systems. It offers:

An evenly-stepped gear range (302%) that is comparable to the leading 8-speed hubs; but
It uses only a single epicyclic gear train (instead of three), thereby maximising efficiency;
At 0.94kg, it weighs almost half as much as other hub gears;
It comes in the same small package as the current three-speed hub, allowing existing owners to upgrade easily; and
It is typically-Brompton: robust and built to last… owners can expect the same reliability as with the classic three-speed hub.
We will be supplying a 16-tooth and a 13-tooth sprocket with the BWR which, with a 50-tooth chain wheel, will give the following distances of travel:

Gear 1: 33.0 gear inches (2.63 metres along the ground)
Gear 2: 40.5 gear inches (3.23 metres travel)
Gear 3: 51.5 gear inches (4.11 metres travel)
Gear 4: 63.5 gear inches (5.06 metres travel)
Gear 5: 81.0 gear inches (6.45 metres travel)
Gear 6: 99.5 gear inches (7.94 metres travel)

This represents a gear range (top gear/bottom gear) of 302%; by comparison, the current SRAM 6-speed arrangement offers a range of 215%. Like our existing 6-speed offering, however, the gearing may be raised or lowered by fitting a 54-tooth (+8%) or 44-tooth (-12%) chain wheel in place of the standard."

[via VeloVision]

"It uses only a single epicyclic gear train"

I'd like to see how they get 6 speeds out of that.

With special Brompton fairy dust stupid... :thumb: lol

We believe that the Brompton Wide Range Hub [BWR], together with Brompton’s derailleur system, sets a new standard in folding bike gearing systems.
<SNIP>
We will be supplying a 16-tooth and a 13-tooth sprocket with the BWR


Does this help datako?

Ah, that makes sense. It was frying my tiny mind trying to work it out diagrammatically.

I should have twigged. I've got a 2 speed Cyclo cog for a S-A from the 1950s in my collection - they were doing the same thing back then.

Thanks :)

I did not see any real advantages of the 6 speed model when I was in the market for a Brompton back in late 2005. This new wide range hub, along with the new longer stronger frame, makes a Brompton even more appealing to me. When I expect to buy another Brompton in another year or two, I will look for these new things plus whatever new minor features added. I wonder why the sudden change of heart Brompton is experiencing now? I thought they swore off using Sturmey-Archer products exclusively after Sturmey suddenly went under back in 2000?

It seems like a useful, workable drivetrain, but Brompton's marketing department is clearly driving the train. Of the five shifts, two are double shifts. :( The smallest step in the Brompton six speed pattern is equal to the largest step in a Shimano eight speed. :(

It seems to be a standard three speed with a -36%, +57% gear set, but I'm interested that Brompton claims they have designed this hub. One might assume that this means it shares no similarities with Sturmey hubs produced and trusted since 1903, and has no interchangeable parts - but I'm guessing it is in fact a Sturmey with different ratio gears and Brompton's marketing is overstating their effort.

At 0.94kg, it doesn't approach weighing half of a modern eight speed hub - marketing! - but surprisingly that would make the BWR marginally lighter than Sturmey's own SRF3.

tcs

I wonder why the sudden change of heart Brompton is experiencing now? I thought they swore off using Sturmey-Archer products exclusively after Sturmey suddenly went under back in 2000?

Perhaps things have changed in the last decade. :roflmao2:

tcs

I'm a great fan of the current S-A 3 speed so I'll be interested to see one of the Brompton versions.

...but I'm interested that Brompton claims they have designed this hub. ... but I'm guessing it is in fact a Sturmey with different ratio gears and Brompton's marketing is overstating their effort...tcs

To put this speculations further: at the Sturmey booth at Eurobike they told me that brompton was closely involved into design process - and testing-period, that they paid for research and tools and that in return SA is happy to let them do the introduction into the market. That SA will like "not sell it to dahon" at least for the next few years.

I'm guessing it is in fact a Sturmey with different ratio gears and Brompton's marketing is overstating their effort.


I'd guess Brompton's marketing is accurate. SA's designer of the 8sp hub went to Brompton when SA folded. It wouldn't surprise me if he designed the wide range hub and then asked Sunrace-SA to build it.

A post on the Brompton Yahoo list notes the number of teeth on the epicyclic components. The ring gear has the same number of teeth as the current 3sp.

So wait--the 6sp is acheived through a 3sp hub mated to a 2-cog sprocket with a derailleur out back?

Anyone know how they did that--did they increase the width of the sprocket engagement groove on the hub itself to accommodate two standard drive cogs, or is it the sprocket itself that is made to fit a standard single sprocket groove typical on all IGHs?

I'm not overly familiar with Bromptons in general, so reading the press release, it rather sounded to me like a 6sp hub with two alternate single cogs for a choice out back, much like a Shimano 8sp hub comes with either 19 or 23, standard, and you choose one or the other, not both.

So wait--the 6sp is acheived through a 3sp hub mated to a 2-cog sprocket with a derailleur out back?

Anyone know how they did that--did they increase the width of the sprocket engagement groove on the hub itself to accommodate two standard drive cogs, or is it the sprocket itself that is made to fit a standard single sprocket groove typical on all IGHs?


[research]

Ah, ok... 3sp w/ 2 gears.

http://www.bikeforums.net/showthread.php?t=466395 Hub shown here looks like it has room for two rings inboard of the lockring? Do the horizontal slots on the hub mean that it takes a proprietary cog spline design instead of the usual three-spline design used on other IGH cogs?

For someone buying a new Brompton the improved gear options are welcome. However for existing owners looking to upgrade this is not exactly a giant step forward. If this has been a wide range 6 speed hub in itself rather than a 3 speed WR X 2 speed derailleur then I'd sit up and pay some serious attention. At the end of the day Brompton have not moved to a single shifter and I presume it's still those ugly shifting sticks on each handlebar! Please correct me if I'm wrong, I'd be most happy if I was lol!

... Do the horizontal slots on the hub mean that it takes a proprietary cog spline design instead of the usual three-spline design used on other IGH cogs?

Yes, proprietary. I hope the 2in1 sprockets of the actual brompton 3x2 = 6Spd will fit the new wide gear hub?

Yes, they so far stayed with the shifters (but again told me at Eurobike that they plan to change that also "sooner or later" and that they hesitate since so far shifters which combine hubgears and deraileur gears are "so big")

I hope Brompton isn't calling this a 6 speed hub, that is false.
It is a 3 speed hub, a definitely improved 3 speed, but still a 3 speed.

Although the range is as wide as most 8 speed hubs, you have 2 shifters instead of one.

Cobbling together 2 Astras does not give you a Caddilac.

I agree, a good thing for those getting a new bike, but not much of an upgrade for those who want to retrofit their bikes. I hope they change those clunky shifters soon, isn't there an aftermarket twist grip shifter available by the way?

I spoke to Steve Parry earlier this year regarding twist grips. Steve told me that there is no reason why you can’t fit a twist grip on each side.

A wide range three speed hub is fun and interesting, but a double shifter to achieve 6 speeds is still an ugly cludge. I appreciate that the reasoning is to keep the internal system simple and efficient, but I don't personally believe the minor losses involved in a proper 6, 7 or 8 speed hub are important enough to use this sort of solution, unless you plan to go racing.

From the picture the BWR looks like a Sturmey SRF hub with a new driver which accepts two Shimano freehub (cassette) spline pattern cogs. Let's hope they are not actually some proprietary pattern. BTW, putting two cogs on a Sturmey 3-speed is an idea that goes back to the 1930s. Additionally BTW, the BWR gear spread is hardly different from the wide spread ratios of Sturmey's four and five speed hubs (design dating from 1922). Also BTW, S-A has been doing a three speed hub with a special driver for Dahon for a couple years now.

Like others, with a 01/09 cut in date I'm befuddled that Brompton doesn't fit the new Sturmey eight speed instead. With its inboard shift cable it's physically narrower, has a wider range, closer ratios through the heart of the spread, and of course just the single shifter (which requires no double shifts). By the time one adds up the BWR+derailleur+two cogs+two shifters+two sets of cables and fittings, I'd be surprised if they were saving noticable weight over an SA8.


SA's designer of the 8sp hub went to Brompton when SA folded.

That hub design has proved to be the biggest liability SunRace got in the purchase. While it has some very interesting and useful design elements, the British eight speed is without a doubt the most cantankerous and short lived IG hub on today's market. SunRace has had to replace many of these, and as mentioned a new SunRace redesigned SA8 is due out shortly.

Fun fact: Every Sturmey-Archer three speed hub produced by SunRace has featured an improved internal mechanism to eliminate the old AW's dreaded "neutral" between the middle and high gears.

tcs