FlippinFlags

I've read about people doing both.

-12% lower gearing for easier climbing..

+8% for faster speeds and walking up steeper inclines..

Brompton's are already severely limited in gear inches..

https://brompton.zendesk.com/hc/en-u...es-and-ratios-

What would you do and why?

tds101 

avole

I did nothing, used the standard gearing, it was just fine. More concerning was the state of the roads. Small wheels aren't great on rough surfaces.

pinholecam

Has to be the -12%.
I don't have a Brompton, but I do tour with a 18" Tyrell IVE.
On my bike which spans 26.6GI to 87.5GI, I'd still want perhaps 1 lower gear (perhaps 25GI) for a fully loaded bike.
If its only loaded for credit card touring, then 27-87GI is fully sufficient unless in very hilly places.


To get over the harsh ride, go for wider tires.
I generally use 1.5" or 1.65" and vary the pressure depending on terrain.

avole

Wider tyres on a Brompton? Not sure you can.

The harsh ride is common to all 16" wheels, and is usually on gravel, pitted road surfaces etc. You can use the lower end of the tyre's pressure rating, which helps. However, the one road where the bike vibrated so much a couple of fitting (later add ons, not original - water bottle, lock etc) fell off was a recently laid sealed one leading to a temple group just outside Ankor Wat. They'd used larger than normal stones on the surface, and it made the 3 or 4 kms or so agonising for both me and the bike. Didn't stop me repeating it the next day, however, the temple complexes and the country round Ankor I found fascinating.

I had no probelem with a heavily laden bike going up the odd steep incline, more with strong headwinds, but that was just going slower than I'd calculated.

berlinonaut

With a little love you can put the Greenpeed Scorchers on the Brompton. 40mm/349, so a bit wider and cushier than the standard tires.

berlinonaut

Obviously depends on the purpose of the bike and on the gearing chosen.

With the six-speed I recommend the 44t chainwheel (-12%) as the stock 50t is way too long, even in the flat and w/o luggage. the more for loaded touring in a hilly terrain.
With the 2-speed I'd stick with the stock 54t as it is a pretty good compromise in my option. Alternatively use a 60t (afermarket) and add a 39t for touring, acting as a granny gear on hills.
Avoid the 3-speed, especially for touring as it has no advantage but serveal disadvantages.

fietsbob

then there are 2 speed single chainring cranksets...
Some made For Brompton, not made by them..

the gears are between the arm and the chainring.

so arm rotates at a different rate than the chainring.

1.6x overdrive a 34t in overdrive acts like a 54t,

I went the other way, 2.5 :1 reduction gear, so my 54t acts like a 21.6t
and I go through my BSR gears twice , 3rd, high in low range, 4th low in high range..

both planetary, so shifts at any speed, even bogged down on a hill..

Over the bar shifter shifts easily from 1 to 3 or 3 to 1..




...



...

avole

That's interesting, berlinonaut. I would have agreed with you at the start, but later I found the 54t, even with a loaded bike (you've seen the picture) useful on the flat where you can charge along at a decent rate. I think that's mostly because I got lighter and fitter. I assume that's what I have on the bike, by the way, never checked to be honest.

berlinonaut

Your bike is a 6-speed, right? With this (with the BWR hub) with the stock 50t the shortest development is 2,65m, which is not too bad but for loaded touring in hilly terrain clearly too long in my opinion.

With 54t it would be 2,86m (which is definitively to long for hills), with 44t you have 2,33m. For loaded touring I'd consider the first gear being below two meters to be good/helpful, lower than 1,50 is in most cases not necessary for most people, at about 1m it starts to become unrideable. So even with 44t the Brompton is not very well suited for steep ascents and way worse with 50t and 54t.

On the higher end with 44t you have 7,05m, with 50t 8,02m, with 54t 8,66m in the highest gear. At a healthy, not very sporty cadence of 75 you in the highest gear you'd ride at 32kph with 44t, 36kph with 50t and 39kph with 54t. Trouble is that with a Brompton barely anyone is riding faster than 30kph in the flat over a distance, most people (including me) ride way slower. Thus the highest gears are not of much use with 50t and 54t but limit your ability to climb (as at the same time your shortest gear becomes longer).

Touring is not about high-speed, at least for me. I prefer to pedal at a healthy cadence and to be able to climb hills and accept to spin out downhill. Cadence is an individual thing - many sporty drivers feel fine at a cadence of 115 to 120 (which I would never achieve) Those would reach 62 kph (!) with the 54t chainwheel on the BWR. Nobody does that.
On the other hand below about a cadence of 70 things start to become unhealthy for your knees as you put too much force on them. And at the same time typically the ratio of energy and endurance becomes worse this kind of pedaling takes too much energy for the same distance in comparison to a higher cadence.

This is why I advocate the 44t and why I have converted my BWR to 9-speed: I get a liitle longer than the 7m of the standard 44t but maintain the short first for hills. Plus I can keep the cadence around my personal perferred cadence of 75.

fietsbob

IMO, tooth counts are clearer..44, 50 or 54

non brompton any 130bcd 39t & upwards..

39 40 42, 46, 52, 53.. etc..

substitute a double crank, and the options increase.
'Greasy finger shifting' mean no derailleur just stop
put the chain on the other cog , then go again..





.....

avole

berlinonaut, I climb hills with the slowest of them, often passed by OAPs on the steepest of them. The other side, however, is a different story

1nterceptor

Test ride and/or rental might answer your question(s).
If still unsure; go with bigger ring. Then if you decide to
swap to a smaller one - just cut chain shorter. If you go
the other way(small to big); will need a new chain as well.

There's another smaller ring option.

Winfried

Install a 50/34 double-chairing and be merry.

https://www.bikeforums.net/folding-b...-brompton.html

fietsbob

Longer BB axle, and you can get a 130 -74 triple-izer chainring [TA]
and put a smaller chainring on the 74 circle of bolts.

old 50t, had holes for a 2nd chainring , but the swaged crankarm connection,
had a chance of coming loose from the chainring , on a steep hill.

BromptonMan

Hi all.

I have a 3 speed Brompton with the -12%. I think in 2 years ive only ever used the lowest gear once! Ive ordered the front chainring and longer chain to make it +8% Hoping that it gives me usage of all the gears 🚲 Its pretty flat terrain though, occasional hills, but having both gives options.

FolderBeholder

When the Missus and I set-out to order our Brompton 6 speeds we thought the -12% gearing would be a no-brainer. Our San Diego area Brompton retailer had a few Bromptons in stock and allowed us to try a -12% back to back with a standard gearing 6 speed. To both of our surprise, and despite our age ("60's") the -12% was sooo low, we couldn't imagine living with them since the lowest 2 or 3 gears were too low to ever be used (egg-beaters).

That said we selected the standard range models, and have had NO regrets for doing so and in fact 1st gear on these very rarely gets used but when it does it provides a pleasing blend of ease of pedaling AND some modicum of resistance/feedback at the pedals.

Thats our experience anyway.