Brompton SA FW retro-drive

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hoogerbooger
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Joined: 14 Jun 2009, 11:27am
Location: In Wales

Brompton SA FW retro-drive

Post by hoogerbooger »

I am continuing to regress.....getting ever more scornful of 'modern' bike stuff and progressively more retro- centric. It can't be helped....it's just an age thing.....But, " they just don't make them like they used to, you know"

I have a big birthday heading my way and I'm thinking a tour on my Brompton with some retro-alteration might be fun. Anyway I have my hybrid Sturmey up and running on the Brompton. 1965 FW internals, but with a 1980 AW shell and ballring. Double sprocket ( and Schlumpf speed drive). All working pretty smoothly on first test run....
20221205_105854.jpg
20221205_111640.jpg
old fangled
rogerzilla
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Re: Brompton SA FW retro-drive

Post by rogerzilla »

I did this but had to modify the shifter; the 4-speed trigger can't be used on straight bars as it is, because "1" is below bar level and the trigger has to go on a bend in the bar to give it enough room.

In the end I didn't like the FW much and went back to an AM.
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simonineaston
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Re: Brompton SA FW retro-drive

Post by simonineaston »

Like the brass washers :) They're taking up the slack from using modern spokes with a steel shell, I suppose.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
hoogerbooger
Posts: 672
Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

The lever is OK on the Brompton M bars..well on the bend ...like you say...which is where I had the 3 speed trigger......but your point RE flat bars is one that I had not twigged when I was reading up.

My initial impression of the FW is that it's a lot easier to use than the SRF5(w). Gears 4,3,2, seem to change almost as smoothly as the AW.....and the stiffer shift to 1st is not as bad as I'd be expecting.

With the double sprocket and the Schlumpf there's a reasonable spread of gears.....for the lumpy Welsh landscape ...but not to be honest a great advantage over the AW in the same set- up. The AW is IIRC more efficient . ..and more reliable I'm sure.....but the FW set up is mainly for fun....and because I quite like that some of the parts are virtually as old as I am.
Last edited by hoogerbooger on 8 Dec 2022, 10:03pm, edited 1 time in total.
old fangled
hoogerbooger
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Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

Brass washers: yes ....based on Brucey's past advice. As you will see from my other post on the wheel...I need all the advice I can get.
old fangled
rjb
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Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Brompton SA FW retro-drive

Post by rjb »

Here's one I built over 7 years ago using a Sturmey 36 hole AG dynohub. 20" 406 wheel 3 cross. I had to use 3 brass washers under the spoke heads on the drive side.
Image

Can one fit a FW internals into any AW shell or is there a date range when this is possible?

Anybody have an FW going spare. :wink:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
hoogerbooger
Posts: 672
Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

To fit a FW the AW shell needs to be pre-1984. I was running a 1985 AW, so have just swapped that for a 1980 shell. The issue is the internal upstand on the LH side.
1980 ( pre 1984 AW & as on FW):
20221202_134513.jpg
1985 onwards to some point:
20221108_154216.jpg
If you are thinking of building a wheel that you can swap internals you also need to think about the spacers on either side to make the centreline the same.

Brucey has a post somewhere say what internals will fit in what shell. The FW just fitted in my SRF5w shell but that would make oiling an issue as oiling via the axle not really an option.....particularly with a indicator like mine that keeps on trying to cross thread.

I have no spare FW.

(Whilst some of the parts are shared with AW's, spares are an issue. As I found out the low gear pawls are rivetted and the pawl pins are not available....so if those pawls are knackered....the planet cage is effectively dead. The indicator rod and chain are also scarce and a weakness. Pinions also need to be a matched set, so can't just take one from another hub.....& the 4 speed levers are scarcer and often apparently worn at the 'detent' for 1st gear.
old fangled
rogerzilla
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Joined: 9 Jun 2008, 8:06pm

Re: Brompton SA FW retro-drive

Post by rogerzilla »

Don't park it in anything other than "4" for long periods. If the compensating spring gets lazy, you lose "2" (it slips under load).

The spring sets vary and mixing early and late springs in one hub is a recipe for bad gear selection. The FW works by springs overcoming one another in sequence.
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simonineaston
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Re: Brompton SA FW retro-drive

Post by simonineaston »

Gears 4,3,2, seem to change almost as smoothly as the AW.....and the stiffer shift to 1st is not as bad as I'd be expecting.
i think if you can get a good FW, they're really nice! A lot depends on that shift up to 1st. And the trigger / 'bar combination can be crucial, as remarked earlier.
I had a Moulton F frame, done up racer stylee, years ago, with an FW tricked up with high quality balls, tall gearing and slick high pressure tyres the name of which escapes me (comet ?) and it flew along. I miss it.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
robc02
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Location: Stafford

Re: Brompton SA FW retro-drive

Post by robc02 »

4 speed levers are scarcer and often apparently worn at the 'detent' for 1st gear
Here is my mod to help the shifter stay in first:
ImageSA 4 Speed Lever Mod by SturmeyRob, on Flickr

A metal spacer is epoxied in place to push the spring across so that it presses on the detent directly above the ratchet tooth rather than to the side.
I routinely use an FM on my drop bar commuter cum all round winter bike, and an FG on my Humber roadster. Both bikes' shifters have this mod.
hoogerbooger
Posts: 672
Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

Noted. Not seen that lever modification before....have memory banked it. Thanks
old fangled
hoogerbooger
Posts: 672
Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

Just back from a pootle in the Hebrides. Fully loaded with tent, stove, expresso pot, flask and full size binoculars. The FW performed fine, but not a great mileage done. One proper hill done in first gear, which it survived without jumping out, so that was good for confidence in it
Brompton South Uist.jpg
I took spare spokes as I worried about my back wheel build. It stayed straight, but a front spoke went ( which explains the creaking it was doing for a few hundred miles before).
Last edited by hoogerbooger on 27 Apr 2023, 11:01am, edited 3 times in total.
old fangled
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simonineaston
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Re: Brompton SA FW retro-drive

Post by simonineaston »

Nice! Are you getting into first gear OK, with-or-without that mod. ?
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
hoogerbooger
Posts: 672
Joined: 14 Jun 2009, 11:27am
Location: In Wales

Re: Brompton SA FW retro-drive

Post by hoogerbooger »

oops. just edited my above post on that point.

I seem to be lucky so far that first gear works fine. I'm going to leave the FW on ...so we'll see how reliable it proves. I still think if I was doing a long tour I'd use an AW ( with a smaller chainring) to cover my worry that the indicator rod/spring combo may fail and leave me stuffed. I found a cap which I had over the LH axle nut in case the rod unscrewed and tried to launch itself verge-wards. Just less to go wrong on an AW and a chance of finding spares if they did.
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rjb
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Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Brompton SA FW retro-drive

Post by rjb »

Thanks to Simon in Easton who kindly passed an almost complete Moulton my way, missing the toggle chain and gear lever. I have found a bike with a 4 speed fg dynohub concreted into the ground as a garden ornament/plant stand at the far end of the village. The owner kindly let me remove the 4 speed trigger and indicator toggle which both required liberal quantities of penetrating oil to release. That indicator now sticks out from the left side of my moulton fw about 10 mm's beyond the viewing nut end. I see they came in different lengths to accommodate axle variations so mine must have come from a longer axle. Will this affect gear changing ?

I'm working my way though the Moulton so will post more as problems arise.
I suspect the front suspension is also seized so more questions will arise here as I progress.
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
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