Brompton cycles choices

[mercalia]

The Brompton 6 speed uses a BWR 3 speed hub ( who is BWR?)- is this a solid design? and how does it differ from the BSR hub they use on their 3 speed bikes? Why the need for 2 different 3 speed hubs?



https://www.brompton.com/brompton-gbr/uk-store/parts/rear-wheel-incl-fittings-for-6-spd-bwr-3-spd-(silver)/c-24/c-75/p-1616

[Tiberius]

BWR = Brompton Wide Range.

BSR = Brompton Standard Range.

I guess that is a start to answering your questions.

[Brucey]

the 6s setup uses the derailleur to make a half-step between the IGH gears. You can make this all work with a standard 3s hub but the gears are (for Brompton-eque purposes) then too close together. Thus the BWR hub with its more widely spaced IGH ratios with 6s gives you both a much bigger range and gears that are closer together than a 3s hub.

The BWR hub has ratios of ~0.64, 1.0, 1.56, compared with AW ratios of 0.75, 1.0, 1.33.

Internally the BWR and BSR are based on the same architecture as the current AW hub, i.e. there is an NIG type driver, and the gear selection works in the same way. It may be possible to interchange AW/BSR/BWR internals and hubshells to some extent (but I think it is possible that some combinations result in the internals fouling the LH bearing protrusion inside the hubshell from an AW hub).

The differences in a BWR include that

- the 6s hubs have a longer driver to accept more sprockets, with an HG type spline fitting (BTW this driver will fit into lots of other SA NIG-type hubs too) and
- the planet cage and pinions are different from a standard AW. IIRC the BWR planet cage is made of aluminium and is bolted together. The pinions have just 12T
- the BWR axle is different and is fitted with a 34T sun pinion

there may be others too. However all the small parts including (AFAICT) bearings, cones, locknuts, labyrinth seals, sliding clutch, pawls, actuator plate, ring bearing parts, ring gear, control toggle, toggle key, clutch spring etc are the same as AW(NIG) ones.

cheers

[Gattonero]

The Brompton 6 speed uses a BWR 3 speed hub ( who is BWR?)- is this a solid design? and how does it differ from the BSR hub they use on their 3 speed bikes? Why the need for 2 different 3 speed hubs?



https://www.brompton.com/brompton-gbr/uk-store/parts/rear-wheel-incl-fittings-for-6-spd-bwr-3-spd-(silver)/c-24/c-75/p-1616

To answer the first question,yet it is reliable. The percentage of faulty hubs is very low, the ones that will become unusable is always due to complete lack of service (read: bikes/wheels never ever been cleaned while always exposed to elements, and hub never serviced/lubricated) so it's fair to say that it will fail if one wants to. With a minimum of care, they will last some long time and many miles, the weakest point seems to be the race/cone in the driver, either by contamination/lack of correct lubrication/wrong bearing preload.

[mercalia]

the 6s setup uses the derailleur to make a half-step between the IGH gears. You can make this all work with a standard 3s hub but the gears are (for Brompton-eque purposes) then too close together. Thus the BWR hub with its more widely spaced IGH ratios with 6s gives you both a much bigger range and gears that are closer together than a 3s hub.

The BWR hub has ratios of ~0.64, 1.0, 1.56, compared with AW ratios of 0.75, 1.0, 1.33.

Internally the BWR and BSR are based on the same architecture as the current AW hub, i.e. there is an NIG type driver, and the gear selection works in the same way. It may be possible to interchange AW/BSR/BWR internals and hubshells to some extent (but I think it is possible that some combinations result in the internals fouling the LH bearing protrusion inside the hubshell from an AW hub).

The differences in a BWR include that

- the 6s hubs have a longer driver to accept more sprockets, with an HG type spline fitting (BTW this driver will fit into lots of other SA NIG-type hubs too) and
- the planet cage and pinions are different from a standard AW. IIRC the BWR planet cage is made of aluminium and is bolted together. The pinions have just 12T
- the BWR axle is different and is fitted with a 34T sun pinion

there may be others too. However all the small parts including (AFAICT) bearings, cones, locknuts, labyrinth seals, sliding clutch, pawls, actuator plate, ring bearing parts, ring gear, control toggle, toggle key, clutch spring etc are the same as AW(NIG) ones.

cheers

so how does that affect using the controls? in order to go thru the gear range do you have to "toggle" back and forth the derailleur before you go onto the next hub gear? what sort of learning curve then for some one used to using standard derailleurs?

[Gattonero]

...

so how does that affect using the controls? in order to go thru the gear range do you have to "toggle" back and forth the derailleur before you go onto the next hub gear? what sort of learning curve then for some one used to using standard derailleurs?

None really, you could get a pre-2017 Brompton shifter and it just clicks in position to select a gear. It's pretty simple.
Have not tried the BWR with older "Torpedo" shifters and the Brompton ones work ok though they feel "plasticky" and maybe's not easy to replace a gear wire if this is frayed at the end.

[Mick F]

You don't start off in first gear and go up through the "box" like in a car.
You treat the two cogs as a high ratio set of three, or a low set of three ............ or that's the way I'd do it.

I have a moulton TSR90.
That is a triple chainset and a 10sp cassette with a 3sp SA.
No way do I go through all the permutations of ninety ratios.

[Brucey]

so how does that affect using the controls? in order to go thru the gear range do you have to "toggle" back and forth the derailleur before you go onto the next hub gear? what sort of learning curve then for some one used to using standard derailleurs?

if you want to use the gears sequentially then yes as you upshift you use the derailleur control every shift and the IGH control every other shift. But from a standstill you can block shift using the IGH instead (moving or not), and then fine tune to get the right cruising gear. Folk who have used this system say it gets to be second nature after a while. You don't need to look at the controls, you will know what gear you are in from feeling the lever positions.

There is a learning curve with every form of bicycle gearing; they are all different. IMHO no single form of gearing is markedly more sensible or compellingly easy to use vs others; they all have quirks.

cheers

[Gattonero]

You don't start off in first gear and go up through the "box" like in a car.
You treat the two cogs as a high ratio set of three, or a low set of three ............ or that's the way I'd do it.
...

I think that is the most easy explanation.
After all, it's a city bike for A to B, one would just choose the gear he can push without having to think if he'll be up to the Strava segment

[Mick F]

I modified my 3sp Hercules back in the mid 1960s to have two sprockets.
Can't remember the tooth sizes, but I can remember that it was 1st 2nd and 4th on the big cog, and 3rd 5th and 6th on the small cog. As a 15 year old, I used to delight in going up through the box 1st all the way to 6th.

In 2010, I modified my Raleigh Chopper to have a double chainset and a double sprocket with the 3sp SA.
Excellent system.

[mercalia]

on another matter is the small carrier option worth the money or are there better other market ones? The Brompton one costs £65 and the mudgaurds also £55 which seems a lot - can these also be got cheaper other market?

looks like the 6 speed with -12% gearing option is the one for me to go for = similar to my dawes 1-down with 11-30 rear and just using the front 36 chain ring which would cover much of the use i intend

[Gattonero]

For "carrier" you mean the rear rack?
IMO, the front bag block is hard to beat, it's super-practical and dedicated bags are very well made. Carradice too makes a couple of models, both will stand up years of use.
The big advantage of having the bag in front of you is the ease of taking things while riding (i.e. a water bottle, map..) and you can park the bike -by folding the rear triangle- with the bag still on. Also you have a better distribution of the overall weight.

[Si]

Never use the rear rack on mine...the front bag is just so good youll wonder why every bike doesnt have one.....and youll end up fitting a basket to your carbon racer!

However, if touring you will want the rack if carrying a lot (tent etc) as its easy to sit a big rucksack on the rack and attach the top to the backof the saddle.

[rfryer]

On gearing, the fact that the sprockets are sized to give you gears in between the BWR ratios means that it's well worth learning the pattern to achieve sequential shifts. It soon becomes second nature, and the distance between gears works well for me.

Regarding the rack, it's useful, but not as much as the front carrier. I use it with the rack pack to increase my carrying capacity, with bungees to lash a French horn on the back, and to provide a more stable base when rolling the folded bike.

[JakobW]

The advice I've had from Brompton-owning mates is that the rack is well worth it. Not so much as a load carrier (though it does work as that), but because it makes it far more stable in the folded position, whether rolling or standing; it also protects the mudguard.

(Edited to add): alternating the gear shifts only takes a short journey to become second nature, though as others have noted you don't tend to go through all the gears when setting off; the main thing to remember is whether you should be pedalling (derailer) or easing off (hub gear) on the shift.