Brompton Unique Gear System

[T4tomo]

I know someone who uses a Mountain Drive on a fixie, which has to be quite rare. He stops to change gear - not sure exactly why, but maybe the device isn't supposed to be shifted when the cranks are moving.

and also its probably pretty difficult to kick the switch button with your heel whilst pedalling clipped/ strapped in.

I think you are supposed to freewheel to change.

I remember looking at them yonks ago but decided it was a very expensive upgrade I couldn't really justify and it would add weight to iits man use a cycle train cycle commuter bike.

 

[berlinonaut]

I know someone who uses a Mountain Drive on a fixie, which has to be quite rare. He stops to change gear - not sure exactly why, but maybe the device isn't supposed to be shifted when the cranks are moving.

On a Fixie a Speed Drive would make much more sense usually as the jump in gears is not as massive as in a Mountain Drive. The Schlumpfs are from 2009 models onwards ok to use on fixies as since then they can deal with the torque in both directions. According to the homepage, Schlumpf drives can be shifted at standstill as well as under load, so possibly your collegue just developed a habit - it seems not to be a technical necessity.
I did never own a bike with a Schlumpf and only have ridden one once for a short test ride out of curiosity (and that was ages ago), so no own relevant experiences about the shifting.

 

[shingwell]

I did never own a bike with a Schlumpf and only have ridden one once for a short test ride out of curiosity (and that was ages ago), so no own relevant experiences about the shifting.

Oh no, expensive upgrade time?!

 

[berlinonaut]

I was never keen on the additional weight that a Schlumpf would bring in and neither on the complexity of dealing with three shifters (3-speed hub, 2 speed derailleur, Schumpf). I do know a couple of people who are totally happy with their Schlumpf, on the Brompton as well as on other bikes. On the Brompton the MD works best with the older generation Sachs-6-Speed due to the spread of the hub compared to the BWR. Personally, I went towards the Rohloff and didn't look back.

 

[rogerzilla]

On a Fixie a Speed Drive would make much more sense usually as the jump in gears is not as massive as in a Mountain Drive. The Schlumpfs are from 2009 models onwards ok to use on fixies as since then they can deal with the torque in both directions. According to the homepage, Schlumpf drives can be shifted at standstill as well as under load, so possibly your collegue just developed a habit - it seems not to be a technical necessity.
I did never own a bike with a Schlumpf and only have ridden one once for a short test ride out of curiosity (and that was ages ago), so no own relevant experiences about the shifting.

It was definitely a Mountain Drive as the ratio was huge: 70" and 28". He used it to get up the hill out of Bath. A 28" fixie would be a bit of a liability downhill, or even on the flat!

 

[Kell]

Each to their own, but it seems odd (to me) that that would be the solution on a fixie. Why not a rear hub?

I guess it's neater and has the unusual-ness factor to give him pub bragging rights, but it doesn't seem like the most obvious solution.

 

[T4tomo]

Each to their own, but it seems odd (to me) that that would be the solution on a fixie. Why not a rear hub?

I guess it's neater and has the unusual-ness factor to give him pub bragging rights, but it doesn't seem like the most obvious solution.

Well a rear hub can't be both geared and fixed for starters....

 

[Kell]

True - but many run flip flop wheels and most 'fixies' are actually just single speeds.

 

[LittleWheelsandBig]

Well a rear hub can't be both geared and fixed for starters....

Sturmey would like to have a word with you.
https://www.cyclingweekly.com/reviews/gears-drivetrain/sturmey-archer-s3x

 

[T4tomo]

there have been a few niche attempts over the years. I don't think the s3x was much of a commercial success. it weighed more than most frames.....

 

[LittleWheelsandBig]

Most internal gear hubs are heavy. The shell isn’t full of air. That wasn’t the question.