Brompton 3 or 6 speed or maybe 2 speed?
 

I'm still suffering this aspect of making a decision. I recently had a chance to ride an M6L in El Segundo, CA where it was a bit hilly and wondered if 3 speeds wouldn't really be enough for my use which is primarily paved bike paths in Idaho and SoCal. I just ride for the fun of it so as long as I can get up mild hills without walking the bike, I'm good.

Most dealers I've talked to save for NYCE seem to order their stock bikes in 6 speed, especially the west coast dealers. It's only a $100 or so but they're so dang expensive already that I'd like to save some money if I can.

the new bikes have 2 different 3 speed hubs, BSR is the continuation of the AW3 lineage.

BWR is a wider difference, between the gears, but the 2 cogs, 13/15t
are half step apart, and so the spacing between gear combinations, is tightened up .

the 2 speed is the 2 cog external gear shifter, and a 12/16t combination..

off the shelf, crank gear choices: 44, 50 and 54t
but there is no issue replacing the single ring crankset, with 2 chainring cranks.
you can kick the chain to downshift, just stop and use the greasy finger shifter
to go back to big ring..

I had a friend interested in my black M bar AW3 speed with a rear-rack, [50/13]
but they backed out .. so talk to me off list.. PM

I have no idea what you just said...

He wants you to PM private message him but I dont think you can do that yet so he needs to give you a contact information so he can tell you about a Brommie he may have for sale.

:bang:

fiestbob, you seem to know about Brompton gearing. I have a 6sp 44T and want lower gearing. How would you go about it?

one suggestion.. consider buying another crankset, & BB.. 110BCD with a double chainring ,
perhaps a 36/44t chainring combination.

then you have 2 ranges of 6.. , with no FD, the range change is manual .
keep a shop rag handy.
[Todd, owner of Portland dealer for Brommys, used that setup on a Ore, Nor Cal coast tour]

considerably lower. the Swiss mountain drive crank by Schlumpf..
A second, planetary instead of the 2nd chainring, turns a 50t into a 20t, in low range
but chain stays on the 1 chainring.
There is a model made for Brompton.
IG torque transfer is tidy, a knob sits on top of the BB just ahead of the rear pivot.

set you back in the wallet, though..

So rather than try to sell me your bike can you or anyone actually attempt answering my question? ;)

Ok , start here:http://www.brompton.co.uk/, get back to me with some specific questions.
Gearing calculator here : http://sheldonbrown.com/gears/internal.html

have you heard of sturmey archer ?
[S=standard, W=wide]
do you understand ratios ? diameter and circumference?
And the international currency exchange rates effect on prices?

sorry if I went over your head on the jargon,
been a bike mechanic for decades , ..these are really basic concepts ..

Not everyone is a bike mechanic or aspires to be. I thought I asked a fairly simple question about what gear system would make the most sense for the stated riding I mentioned in my initial post. Telling me what you did, in bike mechanic terms, doesn't really tell me if I'd be ahead with a 2,3, or 6 speed riding on paved paths with rather gentle inclines. I note on my 27 speed MB that I rarely use more than 3-4 gears and am almost never out of the middle chain ring. That's what got me to thinking about which gearing really makes the most sense *for me*.

The stock Brompton 3-speed gearing is quite adequate for most riding, especially if you're only using 3-4 gears on your 27-speed MTB (you don't say which ones though). The jumps between gears are fairly big though (roughly equivalent to 2 or 3 gear jump on a typical cassette), so compared to your 27-speed MTB, you may occasionally feel like one gear is too low and the next one is too high. Nevertheless, on my a 3-speed, after replacing the rear sprocket with a 14T from the stock 13T, my Brompton has been good for climbing short and steep 9+% stretches to 20+mph "commuter racing". If you want closer spacing between gears, I heard the new 6-speed is the way to go. Actually, for "mild hills" (whatever that is), a 2-speed may be totally adequate if you have the corresponding fitness.

CSG, your question is subjective ('what is good for me'). Here is an approach that will help you to figure this out

1. Compute the gear inch of the gears of your MB (search for sheldon gear calculator)

2. Get the gear inch of the Brompton configuration(s) you are considering (this has the GI range http://clients.squareeye.net/uploads...nt_20x20_2.pdf notice also the reduce/raised gearing options, interpolate the middle gear or get from people that know). Don't know what is your mathematical background, if you have questions feel free to ask.

3. Match the brompton gears to gears on your MB (use closes gear inch value)

4. Ride your MB using only the matching Brompton gears and see what you like.

BTW, I am using 6s reduced gearing and using all the gears.

Count teeth, do the math... what are those gear ratios?

Gear inches, ie,(# on chainring) divided by (#on hub) multiplied by diameter of wheel,
in inches,
is a conventional way of speaking of relative sizes of those ratios.

fietsbob: Your info is wery interesting for us (three of us here) wanting to buy a B in the near future. Your writing style is a bit too much "thelegraph style" and with some slang that us who do not have English as out first language and do not know the B spesifik hubs has problems understanding. Also I am guessing that those who is not familiar with gear ratios and chainwheel sizes also has a problem. I am absolutely sure you know what you are talking about but we would like to know too.. Thank you.

For the gears you use on your MTB: stop the bike and count the teeth on the front and rear cogs (chainwheels) on the combinations you use often on your MTB.

Go to the online gearcalculatot and plot in the numbers (one combination at the time) plus wheel size and the other stuff that the calculator wants to know.

Do the same for the gears available on your B. This info is needed to answer your question.

note again a calculating program http://sheldonbrown.com/gears/internal.html

input the wheel size from the menu. 16" 349-37 wheel, at the near bottom.
'gear inches' in the menu of what unit/system to use

and input the tooth counts, then find the IG hub type.

I did everything recommended here and it took me 4 Bromptons and 3 years to get the one that is currently perfect for me. Absolutely no advice will be as good as miles on a Brompton and a well defined goal, not necessarily in this order.

CSG I think you might be happy with a Dahon Curve SL , They are lightweight, small fold and have 8 gears, I think it would meet your needs for the biking you do in Idaho and California. http://www.thorusa.com/dahon/2009/curvesl.htm

I had a chance to ride a derailleur version of the Curve SL in Socal and was disappointed in it. For a bike about the same size as a Brompton, I felt it was nowhere near as good a ride. I talked to Thor about one and after our discussion, he sort of led me away from that model.

I think if I pull the trigger on the Brompton I'll get the 6 speed. For the extra c-note I'll have a little piece of mind and won't have the nagging questions as if I got the 2 or 3.

now you have to figure out if you want a 50t chainring , or something else.
factory order options : , smaller [44t] and bigger [54t]

I think the Curve SL needs a thudbuster, otherwise the short wheelbase and small wheels lead to way to much saddle-judder. And Big Apple tyres can bring a surprising amount of comfort. But the thudbuster makes it somewhat less 'SL' and the folded size a little less impressive.

I was reading the Brompton brochure and it states that the 2 speed is All you need for cycling around town. Maybe the 2 speed is the way to go, less maintenance and lighter.

You know, I wish I could convince myself of that. I'm sitting here rejecting the 3 speed in favor of the 12% reduced 6 speed and all to ride paved bike paths?? 90% of the time on my mountain bike I'm in 2-3 gears. You'd think I'd learn from that...

I chose the 3 speed model. I live in a very hilly area. Plus I have rode my Brompton on those same hills in El Segundo, CA visiting the Electric Bike LA shop a few times a while back. My little Brompton had no trouble climbing and navigating those hills (and the traffic too). If I ever upgrade, I will go for the 6 speed one. But a well tuned, well selected chainring/cog system is the "secret" of a bike that can handle those hills.

The 2, 3, or 6 speed options will all work well (although I would get the reduced gearing - Brompton low gears are still kind of high). But if you are unsure, you should just get the 6 speed (-12%) - it costs much more to retrofit than it does to buy new because you will need a new wheel (and maybe a new hub).

Also, even if you don't need six speeds for around town (and you may not), it's pretty easy to travel with a B., so you may find yourself in hillier locales.

But, seriously, if you don't know, get the 6.

I think that's what I'll end up doing here shortly. The 12% reduced 6 speed will likely be more than enough and I won't doubt the decision. If I went with the 2 or 3 or even the standard 6 with it's really tall top gear (I tend to coast on declines) I'd always second guess myself. For the extra $100-125 it's not worth the nagging suspicion. ;)