Winfried

Hello,

Out of curiosity, what do you think about turning a single speed Brompton into a six-speeder with the help of a Haberstock mobility/ATS Speed Drive, and either a BSR or BWR gear hub?

The good thing is that, for the price of a conventional six-speed Brompton, we end up with the same number of gears, with a single shifter on the handlebar (for the gear hub), and no more worries about the derailleur.

The bad thing is that, without a derailleur to even things a bit, the steps between each speed are pretty wide.

All this, provided it's actually possible to stick a BSR/BWR wheel on a single speed Brompton.

Thank you.

BSR Gear Ratios
1st 75% (-25%)
2nd 100%
3rd 133% (+33%)
S-RF3 / BSR ratios-Brommieplus

BWR Gear Ratios
1st 64% (-36%)
2nd 100%
3rd 157% (+57%)
Brompton BWR Gear Ratio-Brommieplus

Meters Development ("Gear Inches")
30T chainring + 16T cog + BWR = 1.58 - 6.40m
30T chainring + 16T cog + BSR = 1.86 - 5.45m
Source: Hub Gear Calculator

Welcome to ATS
https://www.haberstock-mobility.com/
https://www.bikegang.co.uk/single-po...TS-Speed-Drive

2_i 

This makes no sense. You get pointlessly large gaps. Yes, you can ride with them, but you are inefficient and getting exhausted over longer distances. You need to combine ATS with BWR and a 2-speed derailleur, amounting to the combination of ATS with a 6-speed B. The most trouble you can get with the derailleur is that it gets stuck in one gear or another and then you are back to the combination you wanted. I hope the mounting provisions for the derailleur are there even in the single-speed Brompton triangle.

Winfried

Thanks.

The goal was to remove the derailleur from the equation, because 1) it gets jammed sometimes because of grime, especially when riding off-road, and 2) it makes for one more shifter. But indeed, the gaps are just too big, so it's not a good idea.

Alternatively, I looked at replacing the BWR with SA's S-RF5(W), but besides requiring widening the rear triangle from 112mm to 119mm, between this IGH and the Speed Drive, it's a weigthy solution.

2_i 

With my triple in the front, the corresponding gear ranges overlap, so that I shift in the front just to change the operating range, typically for climbing and descending a hill. My shifters for the rear are now in the grips, so that relatively minor movements are needed to shift there. The remaining pain is in the relatively frequent transitions where you need to apply the two rear shifters simultaneously - with 3 cogs the range is narrow. However, the latter is even worse for the original 6-sp B with just 2 cogs.

Winfried

I wish Brompton would finally wake up, and offer a 135mm OLD with a Nexus IGH. Financially, it would cost about the same compared to the BWR and be much easier to use.

bikebikebike

WHAT! and add 15 mm to the fold?!!!
and what would I do with my left hand, er, thumb?

Winfried

For those who have a widened rear triangle: Is it really noticeable when the bike's folded?