1988 Brompton Model L - how do the gears work?

[templehead]

Hi, I've just bought two very old Brompton folding bikes, which are fitted with what look like the old Sturmey Archer gears the Raleigh Chopper I had as a kid had (the little chain thing going into the hub). Thing is, there's one on each side of the hub, so my question is how do the different ratios work? Thanks!

 

[a.twiddler]

If you google Sheldon Brown Sturmey Archer hubs there's a wealth of information there. Also, if you look at the hub shells there should be model numbers and date codes which will give you a better idea if you compare them with the info on Sheldon Brown's site. I've not owned one of the 5 speeds but my recollection is that the earler 5 speeds had two toggle chains and shifters, the later ones had one, which seems a simpler set up. Older models have an oil port so a drop or two of oil can be dripped in each month. If they've been standing for a long time they might be a bit gummed up, but getting some oil in there can help free them up and avoid the need for dismantling. Mostly, it's about getting the cables and shifters working properly, unless something drastic has happened inside the hub, then everything should work. Hope that helps.

 

[T4tomo]

Hi, I've just bought two very old Brompton folding bikes, which are fitted with what look like the old Sturmey Archer gears the Raleigh Chopper I had as a kid had (the little chain thing going into the hub). Thing is, there's one on each side of the hub, so my question is how do the different ratios work? Thanks!

Essentially a 3 speed with a high and low (but the middle gear is direct drive, so the high low cable does effect it)
Unreliable and fragile hence being replaced with a "normal 5 gear hub" which wasn't that much better.

If they work all well and good, if not I'd look for a more modern 3 spd rear wheel and shifter to replace it.

 

[Chris S]

If they work all well and good, if not I'd look for a more modern 3 spd rear wheel and shifter to replace it.

Or just remove the left-hand toggle chain to give an ultra-reliable 3-speed. The troublesome gears 1 and 5 will no longer select, but if they didn't anyway then he won't have lost anything.

 

[templehead]

Thanks for this, it's really useful. I know a bit more about them now... frame numbers are 6xx and 8xx, so they are from 1988 as per the leaflet taped to one of them from which I'd assumed that date. The hubs on both are stamped 87-4 and 'Five speed'. I've only tried one of them, and the gear shifters are both quite stiff, but it did seem to work. Everything on it looks bone dry, although they aren't rusty, which is in keeping with what I was told, namely that they'd been under the stairs for 20 years before being disposed of on the owner's death.

Thanks again for all the info, I am a relatively recent returner to cycling - I got a 2nd hand Dawes Boost Suburbia during Covid, the first since the aforementioned Chopper! - so it's much appreciated. I reckon it's a good service for these two this weekend, we'll see how well (or if!) the other one's gears work and take it from there!

 

[T4tomo]

that makes sense "87-" is the year on a SA hub, which ties with being built into a 88 bike.

Assuming they have oil ports, a good flush with GT 85, then left with the port open downwards to drain and then dribble so "proper" oil in there should help free up the hub mechanisms without the complex operation of dismantling.
I would probable treat them both to a new set of cables all round - check the lengths of the old ones against the new ones as too long or too short can effect the fold.
I would imagine the tyres will be perished or on the point of too after 20 years, so new tyres and tubes too.

 

[templehead]

The Sheldon Brown site seems to have gone offline, but it is still available via the Wayback Machine:

https://web.archive.org/web/20240403052926/https://www.sheldonbrown.com/

For the benefit of anyone else arriving at this thread wanting to know how the (frankly weird) gearchange works on their ancient Brompton, here it is:

Sorry, should have said that mine have the S5/2 hub fitted.

 

[T4tomo]

The Sheldon Brown site seems to have gone offline, but it is still available via the Wayback Machine:

https://www.sheldonbrown.com/