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Monday, July 12, 2021

Bike 19, Malvern Star with Positron 2


As donated at Wecycle. In the background is Mike, helping a customer with a free bike, and in the back-background is Anna, interviewing a social worker about the value of bikes to her clients.
Positron 2 gear mech, woohoo!


This is the bike I rode home from Wecycle on July 10,  after dropping off the Giant Sedona. I changed the tube in the rear tyre, and it was ready to go really. Closer examination at home shows it has Positron 2 gear mech, indicating the bike is from the mid 1970's. It works ok but doesn't change into the lowest gear. I will do a bit of cleaning but am loathe to adjust settings on the derailleur, as I may not get it to work as well again. 

Despite its age the bike looks to have been well-serviced so there shouldn't be too much work to fix it.

Regards  Steve Nurse 

Update July 13

Managed to fix the gears so all are selectable now. Also found this website, with probably as much Shimano Positron 2 detail as you would ever need to know. This bike does not have the full catastrophe of Shimano Positron parts, for example there's no clutch on the chainrings. Its still interesting though! As well, the bike has pedals with toe straps, which I've tried and manage to get along ok with.

What does this thing do? Thankfully I turned this adjustment screw the right way and all the gears are working now. Adding a few chain links meant the chain isn't too tight on big / big or too loose on small / small cog combinations.

Handlebar controls.

Here is the serial number for those interested, M5C12936

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