Cycling UK Forum

Hi Guys

Can anyone point me to both information on and a source of spares for this obsolete gear system?

I have a bike with working gears but a disintegrated control cable for which a brief search can only find cables from Germany at £30 including postage. I can't see an easy bodge at the moment, any ideas anyone?

Cheers

Stradageek

I rescued a bike from a skip with a 5 speed positron derailleur. I spent hours trying to get it to shift successfully long term. It would be good for a short time then soon became unreliable. No wonder Shimano ditched it pdq. It relied on solid wires not stranded cables with the indexing occuring in the mech itself by its design. I don't know if the 3 speed IGH had the same arrangement with solid wires and indexing in the hub. Someone will know. Post a photo for us all to snigger at.

Would a Sturmey trigger set up work?
Or even a 3 speed twist grip shifter. Set up so middle gear is correct.

BTW if you are going to throw it out in despair, I could make use of the bell crank on my Sturmey FW 4 speed.

Yup, solid wire, using standard gear cable outer whose ends are permanently fixed into a thermoplastic 'fitting' at either end. Bell crank at the hub but not the later 3-speed style. The hubs do not have a stellar reputation, I might just built an old AW3 into the wheel instead.

Or shall I try to bodge a cable clamp at either end....

1) Is this a wire-in-tube system that operates “push and pull”?

2) is it a straight run, or does it need to include curves?

Stradageek wrote: ↑19 Jun 2023, 5:57pm Yup, solid wire, using standard gear cable outer whose ends are permanently fixed into a thermoplastic 'fitting' at either end. Bell crank at the hub but not the later 3-speed style. The hubs do not have a stellar reputation, I might just built an old AW3 into the wheel instead.

Or shall I try to bodge a cable clamp at either end....

I’d have thought it simplest and best to forget about the Shimano and to use an old SA AW instead.

Nearholmer wrote: ↑19 Jun 2023, 7:47pm 1) Is this a wire-in-tube system that operates “push and pull”?

2) is it a straight run, or does it need to include curves?

Yup, wire in tube, it operates push and pull and the cable run includes curves

OK.

This might not be beefy enough, but worth a look.

https://anticsonline.uk/Category/MerControl_N1587

You might be able to fit both the wire and the ptfe tube down the inside of an old piece of brake cable outer to give protection.

The wire is known as “piano wire”, so if this isn’t the gauge you need, maybe a piano shop is the place to ask for a thicker sort.

PS: I’ve just noticed the prices. By golly has that gone up since last I bought some donkeys years ago!

Or, this: https://www.amazon.co.uk/Control-Bonnet ... 8789&psc=1

You can buy stuff called “black piano wire” in hardware shops, very cheap, but it is piano wire in name only, basically ordinary mild steel wire, which will go rusty at the drop of a hat, and probably won’t transmit “push” without kinking.

Nearholmer wrote: ↑19 Jun 2023, 10:18pm Or, this: https://www.amazon.co.uk/Control-Bonnet ... 8789&psc=1

You can buy stuff called “black piano wire” in hardware shops, very cheap, but it is piano wire in name only, basically ordinary mild steel wire, which will go rusty at the drop of a hat, and probably won’t transmit “push” without kinking.

Thanks Nearholmer, fortunately I have the piano wire style inner, it is just the outer that has disintegrated (plastic coating cracked and fallen off). The challenge is how to take a length of standard gear cable outer and constrain it at either end to allow the 'push' to operate.

I have tried to remove the existing outer from the 'end-fittings' but it is permanently 'bonded' in place so I need to devise some sort of home made clamp/fittings that will interface with the bell crank at one end and the changer at the other.

rjb wrote: ↑19 Jun 2023, 4:24pm I rescued a bike from a skip with a 5 speed positron derailleur. I spent hours trying to get it to shift successfully long term. It would be good for a short time then soon became unreliable. No wonder Shimano ditched it pdq. It relied on solid wires not stranded cables with the indexing occuring in the mech itself by its design. I don't know if the 3 speed IGH had the same arrangement with solid wires and indexing in the hub. Someone will know. Post a photo for us all to snigger at.

4 years ago I picked up a Raleigh Nova (appr. 1982) with 5 speed Positron from being scrapped y the Community and I've never touched the gear system, only changed the chain and cogs,still works pefectly as we speak.

I've given up, the system needs the bespoke cable assembly to cope with the 'push' forces. The bell-crank indexing system requires more force than I can constrain by simply clamping onto an ordinary gear wire outer.

The plan now is to rebuild the wheel with a Shimano 3-speed hub that I rescued from an old folder. Fortunately the bike has a rear brake bridge so removing the old PPS 3-speed coaster hub doesn't leave me without a brake

Many hours of work to save £30 for a cable assembly (at best the second hand value of the bike), I must be nuts, I think the continual experimenting and learning plus the eco-warrior bonus points are what keep me going