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Old 02-20-14, 11:26 PM   #1
keyven
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Brompton Gearing - which did you choose and why? Is -12% good for urban commuting?

For some reason, the shop here starts at 44T (-12%), and charges US$35 to change it to the regular (52T?). Singapore is relatively flat (we only have a few decent hills and no mountain to speak of).

I can't say I'm very fit, though I do very light running/cycling/swimming several times a week. I'm wondering if I should go with the regular gearing or stick with the lower one?

From some reviews online it seems the -12% is fine for city transport. Anyone has a good experience with it?

Last edited by keyven; 02-21-14 at 02:05 AM.
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Old 02-21-14, 12:18 AM   #2
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bromptons 3 sizes are 44,50, & 54t

I run a 15t cog on a BSR, and a 54t chainring 2nd is a 58 gear
[TABLE]
[TR]
[TD][TABLE]
[TR]
[TH]43.4[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]57.9[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]77.1[/TH]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]

higher? 14 or 13t cog

a 44:13 may be fine [TABLE]
[TR]
[TD][TABLE]
[TR]
[TH]40.8[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]54.4[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]72.5[/TH]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]


I have hills Schlumpf Mountain drive crank offers a Low range
H......L
1
2
3
[TABLE]
[TR]
[TH]43.4[/TH]
[TH]17.4[/TH]
[/TR]
[/TABLE]
[TABLE]
[TR]
[TH]57.9[/TH]
[TH]23.1[/TH]
[/TR]
[/TABLE]
[TABLE]
[TR]
[TH]77.1[/TH]
[TH]30.8

[/TH]
[/TR]
[/TABLE]

Last edited by fietsbob; 02-21-14 at 12:23 AM.
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Old 02-21-14, 01:46 AM   #3
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What is the hub you are using, and how many teeth are there on the rear sprocket?
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Old 02-21-14, 02:19 AM   #4
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Quote:
Originally Posted by fietsbob View Post
bromptons 3 sizes are 44,50, & 54t

Oh ok thanks. I'm not sure how to interpret your numbers though. So the Brompton 44T gearing is just fine for flattish land with the occasional hill?
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Old 02-21-14, 02:49 AM   #5
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If your bike is equipped with the Sturmey Archer Brompton special 3 speed wide ratio hub, and assuming a 15T rear sprocket, 44T chainring, and the standard 349 tyres, your gear range (in inches) is: 30, 47, 74 - first to third gear. This is quite low for SG.

Upgrading to the 52T will bring you to 35, 55, 87. Much more reasonable but still low.

If hills are only occasional go with a 56T chainring: 38, 60, 94.

My bike lowest gear is 40 inches. This has been fine for me.

If you are going to be climbing Mt. Faber like hills everyday then go with 52T. Otherwise try to source a 56T chainring. I do not know if the Brompton accepts standard chainrings - better check.
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Old 02-21-14, 09:54 AM   #6
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the Math 44/13x16 = 54.153.. an equivalent to a wheel that diameter, in inches.
thats the 2nd gear.. of 3

The BSR is on the 3 speed (same as traditional AW3.. 3/4,1,4/3)

BWR is the 3 by 2, 6 speed .. Wider spread 2 cogs.

only the 3 spider crank options for chainrings , I mentioned would include the extra guard ring
to keep your pants out of the dirty chainring teeth

52, & 56 will come from other sources , not Brompton.

Last edited by fietsbob; 02-21-14 at 10:02 AM.
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Old 02-21-14, 10:55 AM   #7
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My 3 spd Brompton has a 50T chainring and 13T cog on the BSR hub... ~46-62-82 GI. It's fine for my urban commute.
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Old 02-21-14, 11:15 AM   #8
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I guess that it depends on how you ride.

I am at a different computer but have a spreadsheet that I use to determine speed as a result of gear inches and cadence, and I could work up some figures for you if that is helpful. I went with the reduced gearing because 1) I live in hilly Seattle, 2) I wanted to use the bike for travel and did not know conditions of destination and 3) My riding style. In fact, I wondered if I may wish to go lower than 44T, but decided to start with that.

Some riders want to get to their destination as fast as possible and prefer to ride in the higher gears and expend more energy. I do that on my "workout bike". But on the Brompton, my emphasis is more on conserving energy and not breaking a sweat. I wear regular dress clothes, with a rubber band around my pants leg as a precaution for keeping it out of the chain. I often don't peddle on the downhill and just glide, unless it is a gentle grade. I have used my #1 gear far more than I have used my #6 . In the end, if you get it wrong it will not be expensive to swap out a chain ring. Your local dealer may have learned from the experience of selling Bromptons that the 44 ring is best for most. For me, whenever I am not sure, I save the money, then spend it after I have learned that I need to make a change.
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Old 02-21-14, 12:15 PM   #9
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Quote:
Originally Posted by DoubleDiamonDog View Post
I guess that it depends on how you ride...

... on the Brompton, my emphasis is more on conserving energy and not breaking a sweat. I wear regular dress clothes, with a rubber band around my pants leg as a precaution for keeping it out of the chain...[/COLOR]
+1. Since last summer I've had a commuting partner (a co-worker) and she helps slow me down and keep my commute in perspective. Basically my Brompton stays in second gear during my commute, first is for hills and third is for the times I'm partner-less and feel like picking up the pace on the ride home or the very few instances that I actually have a nice tailwind. As for not sweating, no chance. There were several times this year that the temp dropped below 0 Fahrenheit and I was still sweating with just jeans, a shirt, hoodie and a GoreTex rain shell on.
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Old 02-21-14, 12:35 PM   #10
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FWIW, the 9 spline driver on the hub of the 6 speed takes the 12t , .. their 2 speed is the same type spline..



Rebuilding the wheel with the S-RF5(N) which is also a 9 spline driver , may offer more options

the 2,3,4 gear is the same as the 3 speed , now, on the 5 speed hub.1 a .63, 5 a 1.6.
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Old 02-21-14, 04:59 PM   #11
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keyven: are you looking at a 3spd or 6spd? I live in hilly DC,and only once did I wish I'd gotten the lower gearing on my standard 6spd. If your city is flat,either should be fine,the 6spd might even be overkill. If you already own a bike,you can plug the numbers in here to see what your current gearing is,then compare those to the numbers for Bromptons here.

Quote:
Originally Posted by Shahmatt View Post
If your bike is equipped with the Sturmey Archer Brompton special 3 speed wide ratio hub,
The BWR is only on the 6spd. 3spd models have a regular(BSR) hub.
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Old 02-21-14, 06:24 PM   #12
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Okay I am at a different computer. I don't know is this will help you but for the 6 spd w/-12 gearing, the gear inches in 1st thru 6th speed are as follows, per Brompton: 29.1, 35.8, 45.6, 56.2, 71.5, 88.0

For different cadences the speed in each of the gears from 1 thru 6 is:

Speed @ 100 rpm: 8.7, 10.7, 13.6, 16.7, 21.3, 26.2
Speed @ 80 rpm: 6.9, 8.5, 10.9, 13.4, 17.0, 20.9
Speed @ 60 rpm: 5.2, 6.4, 8.1, 10.0, 12.8, 15.7

That is a pretty good cadence range - obviously you can grind slower or spin faster. But regarding the question of needing higher end offered through the standard ring, I don't really feel a need to go faster than 26 mph on my Brompton. Backing off a bit for a more sustainable, for most, cadence, 90 rpm in 6th gear will move you @ 23.6 rpm - still pretty fast.

Just for reference, there are a couple of guys here who have mezzos and are very happy with the gearing. I don't know what models they have but from the mezzo web site, the gear inches for the mezzo D9 are:


[TABLE="width: 901"]
[TR]
[TD="width: 288, colspan: 5"]GEAR INCHES
Gear Ratios for 54 x 12-26 are:
11t: 78.9 17t: 51.0
12t: 72.3 19t: 44.0
13t: 66.8 21t: 41.3
15t: 57.9 23t: 37.7
26t: 33.4

[/TD]
[/TR]
[/TABLE]

So even with the -12 gearing option on the Brompton, the high gear of 88.0 gear inches is still higher than the highest of the mezzo, which is 78.9, a little closer to 5th gear on the Brompton than 6th. The Brompton gives you a little lower gear for climbing @ 29.1 vs 33.4 on the mezzo. The point of this is simply to suggest that even with the lowered gearing, the high gear is comparable and probably higher than most standard configuration for other bikes. I think you will not find many that exceed the 88.0 gear inches. If ytop end speed is paramount, get the standard or an even bigger ring.
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Old 02-21-14, 06:59 PM   #13
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Quote:
Originally Posted by keyven View Post
For some reason, the shop here starts at 44T (-12%), and charges US$35 to change it to the regular (52T?). Singapore is relatively flat (we only have a few decent hills and no mountain to speak of).

I can't say I'm very fit, though I do very light running/cycling/swimming several times a week. I'm wondering if I should go with the regular gearing or stick with the lower one?

From some reviews online it seems the -12% is fine for city transport. Anyone has a good experience with it?
Can you test ride both, 44T and 50T? Do you own any bike now, what kind of gearing does it have?
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Old 02-21-14, 08:04 PM   #14
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Thanks for the helpful tips guys. I stuck with the 44T (-12%), since it wasn't going to cost me extra. TBH, the space I had to test the bike is ridiculously small (forget parking lot... more like long narrow hallway with people walking), so gear changes were essentially impossible.

That said, I've ridden my bike for about 2 hours and it's "fine", though I can forget about charging up the highway or anything - not that I want or need to. By my (crappy) estimates, on flat ground I'd probably be doing less than 20MPH before the highest gear gives up.

I'd definitely make more use of the lower gear when I go over to Australia, but for now I'll get used to it and pay the added costs if I can't take it.
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Old 02-21-14, 09:49 PM   #15
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Quote:
Originally Posted by dynaryder View Post

The BWR is only on the 6spd. 3spd models have a regular(BSR) hub.
Hmmmm. I was using Sheldon Brown's IGH calculator and they had this hub on the list. So perhaps at one time a 3 speed wide ratio hub was available. I do not know what is in the market now. My numbers were assumption until the OP (or TS) confirmed model/hub/sprocket size for the calculation to be made.

On a side note: It's quite a startling range though for just 3 speeds.
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Old 02-21-14, 10:37 PM   #16
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Quote:
Originally Posted by keyven View Post
For some reason, the shop here starts at 44T (-12%), and charges US$35 to change it to the regular (52T?). Singapore is relatively flat (we only have a few decent hills and no mountain to speak of).

I can't say I'm very fit, though I do very light running/cycling/swimming several times a week. I'm wondering if I should go with the regular gearing or stick with the lower one?

From some reviews online it seems the -12% is fine for city transport. Anyone has a good experience with it?
YES. I have a Brompton M6R with -12% gearing. I live in Southern Ontario, Canada. We have no hills really either; it's flat. The shop I bought it from was in British Columbia - very mountainous. They sold -12% gearing, so I assumed that it was because of the hilly terrain. He actually advised that the -12% gearing was good for all around riding.

He was absolutely right. I find the lower gearing very suitable for high winds (very common here) and even though there may be no natural hills, there are man made ones, such as when cycling overpasses or underpasses - those grades are often steeper than you think. And if you do travel, you might find yourself in a place with hills. I actually find I don't travel in the highest gear, even if the terrain is flat. The reduced gearing is very useful in stop and go situations.

If you plan to go as fast as possible all the time, then don't bother with the reduced gearing. However, I bought my Brompton for everything: commuting, traveling, etc. In other words, traveling at all speeds in different scenarios. So, in my experience, I feel I have the most versatility. You can always pedal a little harder to go faster, but you might need a lot more help going up hill.
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Old 02-22-14, 08:31 AM   #17
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YES. I have a Brompton M6R with -12% gearing. I live in Southern Ontario, Canada. We have no hills really either; it's flat. The shop I bought it from was in British Columbia - very mountainous. They sold -12% gearing, so I assumed that it was because of the hilly terrain. He actually advised that the -12% gearing was good for all around riding.

He was absolutely right. I find the lower gearing very suitable for high winds (very common here) and even though there may be no natural hills, there are man made ones, such as when cycling overpasses or underpasses - those grades are often steeper than you think. And if you do travel, you might find yourself in a place with hills. I actually find I don't travel in the highest gear, even if the terrain is flat. The reduced gearing is very useful in stop and go situations.

If you plan to go as fast as possible all the time, then don't bother with the reduced gearing. However, I bought my Brompton for everything: commuting, traveling, etc. In other words, traveling at all speeds in different scenarios. So, in my experience, I feel I have the most versatility. You can always pedal a little harder to go faster, but you might need a lot more help going up hill.
Thank you for the personal insight. I too "bought my Brompton for everything" and plan to use it that way, so I agree!

Tonight I just did my first proper ride - about 20km on mostly flats with a mix of long gentle climbs and some short intermediate ones. Man I'm definitely out of shape because I was panting by the 2nd climb. That said, the max speed of the bike on flats is somewhat limited, but I'm getting too old to be hurtling down the freeway. Most of the time I was comfortably on the mid-gears.

The bike is great to ride overall and bringing into malls and the trains were a breeze. It was so unobtrusive that I didn't feel self-conscious pulling it around. I seriously doubt any other bike could get away with this! Most definitely a worthy investment.
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