Brompton 3 speed standard vs -12% vs -18% (lower gearing)
 

Does anyone out there have a perspective on the Brompton 3 speed regular vs the reduced gearing options for the 3 speed (-12% and -18%)?
I'm hoping to get a Brompton soon, and want to ride it in the Sierra Nevada foothills and in the flats. I'm pretty sure the reduced gearing is what I want rather than the regular geared 3 speed Brompton. But I don't know whether to go for the -12% or the -18% lower gearing.
I'm a little worried that if I get the -18% I may spin out and not be able to go at a decent rate of speed when on the flats in high gear. I do think I would make good use of the low gear though for going up hills in the foothills.
My latest thoughts are to go with a 3 speed just for the simplicity of it.........but picking the right gearing is tough when you can't ride the bikes before ordering. I've ridden the regular geared 3 speed a couple of times and really think the reduced geared bike would suit me mo betta.
Thanks in advance for any input.

Obviously it depends on your fitness and expectations. I'm using 39T (-22%) on my M2R and it spins out easily on flats, but I'm not planning to race it anywhere, as long as it gives me an easier time with hills. I'm pretty unfit (not exactly fat, but sporting a beer belly). I'd imagine most people who are anywhere close to fit would be happier with the -12% (44T) overall.

rather than % you can do your own ratio math .. hub cogs 13,14 or 15t factory chain rings , 44,50, 54t..

the recent 5 arm spider crank uses a 130 pcd chain ring so that 39t after market swap can be done. or any other 130 type. 40, 45,46 ,47, etc..


http://sheldonbrown.com/english-3.html

double cranksets can & have been fitted.. I tossed in a Big investment, a Swiss Made Mountain Drive 2 speed Crank .

2 versions of Florian Schlumpfs planetary 2 speed cranks are often used on Bromptons.

Mountain is a /2.5 reduction gear ala 50/20 .. the Speed Drive is an 1.65 x overdrive a 34t acts like a 56t ..



MD uses the 3 hub hears twice .. i have a 15:54t

the 6 factory options, via http://sheldonbrown.com/gears/internal.html


[TABLE]
[TR]
[TH="bgcolor: yellow"]0.75 (Low)[/TH]
[TH="bgcolor: yellow"]1.0[/TH]
[TH="bgcolor: yellow"]1.33 (High)[/TH]
[/TR]
[TR]
[TD][TABLE]
[TR]
[TD][/TD]
[TH="bgcolor: yellow"]54[/TH]
[TD="align: center"]8.0 %[/TD]
[TH="bgcolor: yellow"]50[/TH]
[TD="align: center"]13.6 %[/TD]
[TH="bgcolor: yellow"]44[/TH]
[/TR]
[TR]
[TH="bgcolor: yellow"]13[/TH]
[TH="bgcolor: white"]50.1[/TH]
[TD][/TD]
[TH="bgcolor: white"]46.4[/TH]
[TD][/TD]
[TH="bgcolor: white"]40.8[/TH]
[/TR]
[TR]
[TD="align: center"]7.7 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]14[/TH]
[TH="bgcolor: white"]46.5[/TH]
[TD][/TD]
[TH="bgcolor: white"]43.0[/TH]
[TD][/TD]
[TH="bgcolor: white"]37.9[/TH]
[/TR]
[TR]
[TD="align: center"]7.1 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]15[/TH]
[TH="bgcolor: white"]43.4[/TH]
[TD][/TD]
[TH="bgcolor: white"]40.2[/TH]
[TD][/TD]
[TH="bgcolor: white"]35.4[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TD][/TD]
[TH="bgcolor: yellow"]54[/TH]
[TD="align: center"]8.0 %[/TD]
[TH="bgcolor: yellow"]50[/TH]
[TD="align: center"]13.6 %[/TD]
[TH="bgcolor: yellow"]44[/TH]
[/TR]
[TR]
[TH="bgcolor: yellow"]13[/TH]
[TH="bgcolor: white"]66.8[/TH]
[TD][/TD]
[TH="bgcolor: white"]61.8[/TH]
[TD][/TD]
[TH="bgcolor: white"]54.4[/TH]
[/TR]
[TR]
[TD="align: center"]7.7 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]14[/TH]
[TH="bgcolor: white"]62.0[/TH]
[TD][/TD]
[TH="bgcolor: white"]57.4[/TH]
[TD][/TD]
[TH="bgcolor: white"]50.5[/TH]
[/TR]
[TR]
[TD="align: center"]7.1 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]15[/TH]
[TH="bgcolor: white"]57.9[/TH]
[TD][/TD]
[TH="bgcolor: white"]53.6[/TH]
[TD][/TD]
[TH="bgcolor: white"]47.1[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TD][/TD]
[TH="bgcolor: yellow"]54[/TH]
[TD="align: center"]8.0 %[/TD]
[TH="bgcolor: yellow"]50[/TH]
[TD="align: center"]13.6 %[/TD]
[TH="bgcolor: yellow"]44[/TH]
[/TR]
[TR]
[TH="bgcolor: yellow"]13[/TH]
[TH="bgcolor: white"]89.0[/TH]
[TD][/TD]
[TH="bgcolor: white"]82.4[/TH]
[TD][/TD]
[TH="bgcolor: white"]72.5[/TH]
[/TR]
[TR]
[TD="align: center"]7.7 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]14[/TH]
[TH="bgcolor: white"]82.6[/TH]
[TD][/TD]
[TH="bgcolor: white"]76.5[/TH]
[TD][/TD]
[TH="bgcolor: white"]67.3[/TH]
[/TR]
[TR]
[TD="align: center"]7.1 %[/TD]
[/TR]
[TR]
[TH="bgcolor: yellow"]15[/TH]
[TH="bgcolor: white"]77.1[/TH]
[TD][/TD]
[TH="bgcolor: white"]71.4[/TH]
[TD][/TD]
[TH="bgcolor: white"]62.8[/TH]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]


but as you say :perhaps your needs will be better served with the BWR3x2 6 speed, 12-16t same chainring choices up front


BWR, a wider 3 speed than BSR, takes 2 cogs ..leave it in a 12 for faster, 16 for hills ,


maybe even retrofit.. a 36-44 double crank .
[Todd, the PDX Brompton shop owner, Tours on His.. like that no FD so still just 2 levers.]

What is more important to you, speeding along the flats or having an easier time on the hills? If it was me, I would gear for the hills. Sure you might not be as fast on the flats, but nobody said it was a race, enjoy the scenery.

With that said, both gearing choices use the 44 tooth chain ring, but one uses a 13 tooth cog (-18%) the other a 14 tooth (-12%). If I am wrong someone can correct me. My point is you can go either one and change it easily if it is the wrong choice. A new cog and depending on the direction you go, maybe a new chain and you have a quick fix.

For what it is worth I use a -12% and I am a semi-strong rider as I ride everyday of the year but not on my Brompton. My wife who rides once every two weeks got the -18% and it is fine for her.

It is a tough choice to make when you don't get to test ride each version. If I had to do it all again, I would have chosen the two speed if I was just riding the bike in the city as a commuter. If I was doing long distances, I would chose the 6 speed, the range is just so much better.


Good luck with your choice.

If I get a chance, I'll try to post some figures relating the speed that would result from the gear ranges at certain cadences.

For most people the bigger concern would be having a low enough gear to climb in the Sierra foothills = -18% gearing. Then a secondary question would be how fast you want to go on the flats. 20 MPH? 25 MPH? It is pretty easy to calculate the speed resulting from the top end gear at your preferred cadence.

My personal choice in your situation would be the 6-speed - 12% gearing, which is what I have on my bike, used primarily for travel. The lowest gear on my bike gets used quite a bit, the highest gear, not very often. I'm not a racer but am a fairly fit rider, and tend to glide on downhills rather than push for speed. I am rarely interested in going faster than about 18 MPH on the flats, but can go much faster if I choose to.

The numbers below reflect the range of speeds when pedaling at a cadence of 60 rpm in the lowest gear to 90 rpm in the highest gear. While many cyclists ride at cadences outside this range these are reasonable figures for many riders to sustain for long periods.

The table is ordered as follows, with speed in MPH:
Description / Lowest Gear Inches - Speed / Highest Gear Inches - Speed

6 sp std / 33.1 - 5.9 / 100.0 - 26.8
6 sp -12% / 29.1 - 5.2 / 88.0 - 23.6
6 sp +8% / 35.7 - 6.4 / 108.0 - 28.9
3 sp std / 47.9 - 8.6 / 84.9 - 22.8
3 sp -12% /42.1 - 7.6 / 74.7 - 20.0
3 sp -18% /39.1 - 7.0 / 69.4 - 18.6
3 sp +8% / 51.7 - 9.3 / 91.7 - 24.6
2 sp std / 56.0 - 10.1 / 74.7 - 20.0
2 sp -7% / 51.9 - 9.3 / 69.2 - 18.5
2 sp -19 % / 45.7 - 8.2 / 60.9 - 16.3
1 sp std / 74.7 - 13.4 / 74.7 - 20.0
1 sp -7% / 69.2 - 12.4 / 69.2 - 18.5
1 sp -19 % / 60.9 - 10.9 / 60.9 - 16.3

So for LDier, the 3sp with -18% gearing he would ride uphill at 7.0 mph while cranking at a cadence of 60 and on the flats would hit 18.6 mph when spinning at 90 rpm cadence. With my 6 spd with -12% I ride uphill at 5.2 mph while cranking at a cadence of 60 and on the flats would hit 23.6 mph when spinning at 90 rpm cadence.

Another vote for the 6spd. If you really don't want the extra gears,you can always remove the derailleur and shifter and go with one cog. Going from a 3spd to 6spd will involve a whole new hub. Better to have it and not need it,than need it and not have it.

Looks like most of you recommend the 6 speed with the -12%. I was just a little concerned that with the front derailleur could be more troublesome than the slick 3 speed internal hub.
I've looked at the gear inches tables for the different Brompton bikes. It does seem like the 6 speed -12% would be great coverage for my riding.

You still get the slick internal hub with the 6 speed, the only difference is that is the it has a wider range between gears than the the 3 speed. Also what you call the front derailleur is actually in the rear. On the IGH there are two cogs instead of the usual one, which gives you the six gears you may need. Your left hand shifter, shifts between these two cogs. Simple design that works.

As blakcloud says, no front deraileur, just two cogs in the back shifted by a simple derailuer controlled by the left hand and even with single speed Brompton or any of the other gearing options you would have a little device back there to take up chain slack when you fold the bike anyway. The right hand shifts the internal gear 3 speed hub.

I would go with the 3 speed if I was a flat lander or did not plan to travel - maybe even the 2 sp or 1 speed. But for any but the most gentle of hills I would go with the 6 speed.

Hopefully you can try before you buy. The 6 speed takes a little getting used to because double shifts are more common than with a conventional drive train. However, the learning curve is very short. When grade changes quickly you learn to omit a left hand shift and skip a gear. When a double shift is called for I do them simultaneously. Like driving a manual transmission car it may seem confusing at firs but quickly become intuitive. I really don't think you would regret going with the 6 speed and will be glad that you made the choice.

My only other thought is that if you don't need the quick compact fold of a Brompton there are a number of other folders that could fill the bill.

Before I got my Brompton, I test rode a regular 6 speed and a regular 3 speed. Fortunately, the bike shop was located near a road that ran for fair distance at a reasonably steep grade up a hill. The 3 speed was frankly too limiting gear range wise. The 6 speed was better - fairly manageable up the hill.

When I finally bought my Brompton, I ended up going with a different shop because they had one available in the configuration I wanted and they recommended the 6 speed reduced range. I asked why? They found through experience that while you might miss the high end for the occasional speed, I would benefit much more from the lower end for hills, wind, packed sidewalks, etc.

He was right. I use the lower ranges much more frequently that I would the higher range. If you're going to be riding around foothills, you want climbing potential more than anything. Furthermore, you'll find the Brompton will be used in many more grab-and-go situations where practicality will trump speed: it's just too fun and convenient to ride.

So, if you have the option, I'd go for the reduced 6 speed version.

Quote:

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I was just a little concerned that with the...

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2 things .. Brompton 6 speed is all on the rear.. BWR Hub 3 speed with 2 external cogs.

If you choose to retrofit of a Double crank , the 'greasy finger' shifting wont need a FD.

the heel of your shoe can initiate the down shift, rolling ..

when you want to return to the big ring, stop, put a rag on the chain, and put it back on the big ring, manually.

a picture of such a setup> http://www.flickr.com/photos/cleverc...n/photostream/

My first B - a 2012 S6L, came with a 50T chainwheel/crank. I swapped that for a factory 44T: https://www.youtube.com/watch?v=hYo8Ta8SBxE&index=21...

My 2nd B - a 2013 S6L-X, already came with a reduced geared 44T chain ring/wheel. I swapped that for a 39T Dura Ace ring. By the 12:50 mark of my video is a steep hill where a lady(a lot of guys also by the way) is pushing her bike up. Meanwhile; my B'ton is cruising along nicely https://www.youtube.com/watch?v=5AT6wI_J2MI...

The only Brompton shop here charges extra for 'upgrading' to a 50T or 54T from the -12% (44T). I was pretty sure initially I wanted the 50T since my area is pretty flat, but I agree with Ozonation - I use the lower gears as often if not more.