Brompton: 3-speed vs. 5-speed vs. 6-speed
 

I'm planning on buying a Brompton, and I am looking for feedback regarding the pros and cons of the stock 3-speed and 6-speed versions as compared with retrofitting a 5-speed SA S-RF5 hub.

What I know is that the 5-speed would give me a wider range than the 3-speed (256% vs. 178%), with an extra low and high gear, and very little weight penalty (only 150 g extra). The 6-speed would give me an even wider range (302%) at about the same total weight as the 5-speed, but with a clunky shifting arrangement using two shifters.

What I don't know is whether the 5-speed hub adds significant drag, or to put it another way, comes with a noticeable efficiency penalty. I keep reading about the inefficiencies of hubs with 5 or more speeds, but I haven't actually heard anything bad in this regard about the SA S-RF5 hub. I would appreciate hearing from anyone who has converted their Brompton to a 5-speed using the newest SA hub, or has ridden 3-speed, 5-speed and 6-speed bikes and can comment on any differences.

Also, am I being unreasonably critical of the 6-speed shifting arrangement? Not having much experience with Bromptons, it seems like it would be annoying to have to shift both shifters just to go up or down one gear. I suspect that I would probably end up staying on the smaller cog for much of a ride until I hit a hill and needed to shift to the larger cog. Is it something that I would likely get used to over time, or is it really as clunky as it looks?

If you live in a relatively flat location a 3 speed or even a 2 speed brompton will work fine on a small wheel bike. i own several bromptons a 3 speed[sram t3] a 5 speed sprinter hub and a 6 speed[sram t3 w/ 2 cogs] and a Raleigh Twenty with 2 speed duomatic and another Raleigh twenty setup as a single speed. the 5 speed i have has the old english sturmey 5 speed sprinter hub not the new chinese made SA SRF5 hub. the 5 Sprinter has the same low/high ratio as a 3 speed hub the 2 extra gears are in betweens. the 6 speed has extra low and high gears which i don't have much use and the shifter just adds complexity to shifting. the gear pulleys mechanism must be kept clean all the time otherwise you'll have shifting problems very prone to dirt contamination as its low on the ground.

as you bike daily you build leg muscle strenght and eventually won't have a need for too many speeds. my favorite bike i use is my raleigh twenty duomatic only 2 speeds high and low. If there's a sizeable grade or uphill i just stand on the pedals and I make it to the top fine. If theres a hill 1 mile long let say I just don't go tackle it and go around it its not never fun going up unless you love a real work out then you don't need gears. I don't.

my 2nd favorite is my Raleigh single speed very light and simple nothing needs to be adjusted and I just do fine on hills as well as its geared low for just cruisin.

if you keep shifting gears each time theres a little grade then you will never build leg musles. once you build them you will find you don't need gears after all not bragging but I don't

I believe in less gears less trouble !

I use the older non-wide ratio S-RF5 on my Brompton and I have a couple of X-RF5s on other bikes (the internals are the same). I find each hub behaves differently despite there being no obvious wear/damage or difference of any sort between them. The one on my Brompton happens now to be running very sweetly and it's great. However, there are fit issues to do with the toggle chain pulley extending between the front wheel spokes when folded which can cause rolling problems. . . I think it could be fixed by using the stay hook from the old 5 speed Bromptons. Generally I'm very pleased with the performance of the hub and I don't think I'd want the dual shifter 6 speed setup.

IIRC, SunRace Sturmey-Archer has gone to more efficient gear tooth profiles in their new 5(W) hubs vs. the ones used by S-A in Nottingham, UK. The S-A 5-speeds do not make use of dual stage compounding to create their ratios.

Don't mean to get in to the whole Mao Zedong/Chiang Kai-shek thing, but today's Sturmey-Archer gear hubs are manufactured in Taiwan.

Actually, probably you wouldn't. The BWR three-speed hub on it's own has vveerryy wide gear steps - far wider that the vast majority of riders have found comfortable over the last 110 years. The BWR based drivetrain is intended to be dual shifted as a matter of course.

FWIW, the 3 ratios in the middle are the AW3's .75 and 1.33
on the SRF5W, 1st is a .63.top is 1.6 (SRF5 also .67, change_ .79, 1, 1.27, 1.5

Im using a BSR / AW3 and a Schlumpf Mountain drive crankset, made in Switzerland.
there is a Brompton plug and play version of those
[CM Wasson, Brompton dealer, stocks them in Cal]

hubs 3 gears get used all over again, in low range on the crankset planetary,
for a linear six ratios, rather than the 2 cog half step 13/15 with the BWR hub.

im running a 54/15, range is about 80 to 18 GI..

when Brompton went to Sachs, since bought by SRAM,
for their 3 by 2 hub,source, [Mk 3 bikes]
the IGH ratios were unchanged ,sightly wider, .73 , 1.36 (9by3 dual drive, too)
but not as wide as the BWR, _ .64, 1.57
that they got, custom made for them at the new owners of Sturmey brand.

More recently I got a Bike Friday with a Rohloff hub,
16t cog 53t chainring 406 wheel, nearly equal steps..
low similar, 12th is like the high on the BSR/MD Brommy

just not the fold down possibility, into 4 cubic feet

There is a company in the UK that builds a 8 speed kit. http://www.kinetics.org.uk/html/8-speed.shtml

Taiwan=PRC=Peoples republic of CHINA=Formosa

Eh, no. PRC = Peoples Republic of China = (mainland) China. ROC = Republic of China = Taiwan (unofficially) = Formosa.

5-speed it is!
 

Thanks for the feedback, everyone, including the lessons on Chinese history. :)

There are enough reasons for me to avoid the stock 6-speed setup. Shifting is kludgy, as every gear up or down is two shifts (thanks tcs for pointing out how the shifting works). The derailleur easily collects road grime (thanks EM42 for pointing that out). And the extra gear range just isn't that much more than the 5-speed to offset these disadvantages.

I'm going to buy a 3-speed and spend a couple of hundred bucks to switch it over to a 5-speed with a new rear wheel and shifter. That way I can switch back if for some reason the 5-speed hub turns out not to be a good idea. In that case I might look at a Schlumpf Mountain Drive setup like tcs described, which has a great gear range.

Thanks again for all the useful feedback!

no problem

yeah we haven't even touched hong kong so hang on but I know they are all chinese they eat chinese food, and they talk chinese

Thanks! I have seen that kit (and another one here), but the 8-speed doesn't appeal to me as it adds about 700 g over the 5-speed, and apparently does involve a noticeable hit on efficiency.

Incidently, I guess the short axle (148mm?) version will fit just right. I got a 175mm axle version to fit OK but had to gamble with shortening the axle, hoping I wouldn't get through to the hollow section. . . not recommended.

I also think the older non-wide ratio version makes much more sense.

Thanks for pointing that out. The specs on the S-RF5(W) list the 119mm over locknut version as having the not recommended 175mm axle, whereas the 111mm over locknut version is the one with the 148mm axle. Interestingly, the S-RF5(N) version with the 9-spline driver only appears to come in the 111/148mm version. I am assuming that I could get the 111/148mm version and add some extra nuts/spaces to get the OLD up to 119 mm, which (correct me if I'm wrong) is what I gather the dimension of the Brompton is.

I think it's 110mm or thereabouts, I used smaller nuts and a bit of pressure to get my hub to fit.

I've now run a 5 and 3 speed. My opinion is if you can manage the 3 speed, that's what you should probably go with.

1. A bit more efficient (academic)
2. Bulletproof (more or less)
3. A bit lighter
4. Much easier to keep properly adjusted

The last point shouldn't be underestimated. I've notice with my hub that a 1/4 turn will make all the difference between it skipping / missing shifts and running sweetly. (This is my 3rd set of 5 speed internals). I've finally gotten pretty good at feeling and hearing the tell-tale signs that the hub needs adjusting. Now I usually bend over and adjust the chain at longer red lights, but it's still a pain. The real problem with this is that the hubs self-destruct if run out of adjustment for too long.

When I had the 3 speed, I adjusted it once when I first fit the wheel and then again after a few weeks to compensate for the new cable switching. that's it.

I live in Glasgow, where it's not exactly flat, & I managed fine with the 3 speed. I'm not the strongest rider in the world either. The only reason I need to stick it out with 5 speed is that I pull my two kids in a trailer pretty regularly with the bike so need the extra range. (I've also got a double up front, but that is a different topic).

So, the 3 speed is really very trouble free, and the 5 speed needs a lot more attention to keep it happy.

If you do go with the 5 speed, I highly recommend using the metal shifter. The all plastic one is horrible.

Or, you could go whole-hog and fit the S-RF5(N) with the 2 speed rear mech, and have a 10 speed Brompton... :)

Sturmey-Archer is not the only 5-speed IGH in town, although with the SRAM P5 one has to deal with a bit larger OLD and the Clickbox.

The SRAM 5 speed is a lot heavier I think.

Thanks! That's excellent advice, and not something I had thought of at all, but now that you mention it I do see comments elsewhere on the forum about the need to keep 5-speed SA hubs in adjustment, and problems that arise with them. My plan was to order a 3-speed, and then convert to 5 speeds, but maybe I'll revise that plan slightly to ordering a 3-speed, trying it for a while, and then deciding if I need the extra gears. Vancouver has some hills, but it's nothing like San Francisco or Seattle (I've never been to Glasgow, so I have no idea how it compares), so super-low gears aren't essential.

Cheers!

Brompton's 6 speed is a 2 cog external on a 3 speed , a dual range
can be set up with 2 chainrings.

[the above was probably meant in jest but just so everyone knew...]

None of them talk Chinese. Not a single one.

Chinese is only written and has no pronunciation. Chinese speak different languages which are mutually unintelligible -- they're as different as French and Italian. These languages are considered dialects only because they don't have a written form -- all Chinese *write* in Chinese but speak their own dialect. In Hong Kong they speak Cantonese for example. In Taiwan the local dialect (now fairly disused sadly) is Taiwanese. There are about 40 dialects. Nowadays most Chinese are required to know how to speak Mandarin, a dialect originating from Beijing and surrounding areas, and modern Mandarin vocabulary and grammar has been arranged to have a 1-to-1 correspondence with modern written Chinese. In Hong Kong and various Chinese communities in Vietnam, Indonesia, Malaysia, etc., there are many Chinese who know no Mandarin at all, only their local dialect and written Chinese.

Don't get me started on the diversity of food. :-) "All Europeans eat that pasta stuff".

I suspect that our terrain is pretty similar.

The only other thing I'll add is that you might need to play around with chainwheel - cog combinations to get the 'right' 3 gears. It took me a few configurations to get it right.

Good luck!

can anyone show this 2 chainrings set-up picture? thanks!

the future is eleven.........

This is similar to my setup:

http://www.youtube.com/watch?v=Ci-bMyeJVVU