Fixing 50 bikes, 35, Oxford with Shimano Positron

 

As traded, by this stage I had removed the completely stuffed gearchanger and twin cables, and got the bike working in high gear.

Positron gearchanger.

Hi

A while ago, I fixed and documented working on a Malvern Star bike with a Positron II groupset, and have now brought home from Wecycle an Oxford International bike with a twin cable rear derailleur Positron. Anyway, this shows a few pics. Will post more soon, but meanwhile here is a forum post about another bike with a similar (ok, crap) setup, and another one, and another one. The Disraeli Gears site has a full service manual I can access, that's good!

Update, 24 October 2021

Spent much of today working in the bike. As the photo of the gearchanger shows, the change has 2 cables going to the rear derailleur, one pulls it left for low gears, the other pulls it right for high gears. From the link above to the manual, I found that cable assemblies (Shimano 6060010) are still available, and that would repair the bike simply with its original changer. And its likely that with a tandem gearcable, and 2 new cable outers, the same fix could be made, with maybe a small abount of finneagling. Another possible mod would be to drill or file out the changer so 2 cables would fit under the  pinning screw.

Anyway I did none of these, see photos below:

3

4

5

6

7. Steel Plate on stand bracket,

8

9

10

11

1. Took off and cleaned the stand, and made a small steel plate which is bolted onto the top of the stand bracket. It has an m6 bolt coming out of it. (Photo 7)

2. Ran a cable outer from the left derailleur cable position to the boss on the chainstay, then ran an inner cable and spring up to the bolt in the stand. After a bit of checking and spring swalling, I had the spring doing its job, moving the derailleur to the right. (Photos 4 and 9)

3. Mounted up a 5 speed gearchanger on the stem and ran a cable to the right derailleur position (4). A bit of fiddling later and all 5 gears are rechable.

4. Went for a test ride and it works well. Found a rack on hard rubbish and I will probably fit it to the bike soon.

Regards

Steve Nurse

Update Nov 22

I delivered the bike to Wecycle and its for sale now, probably not the sort of practical bike a refugee would want.