Shimano Positron 5 Speed Derailleur

[wheres_my_beard]

Anyone got any experience of setting up this type of derailleur?

It is about 1/4 a chain width out, but does change gear, and stays in it once selected. It's just clunky and slips a little before fully engaging.

 

[Pennine-Paul]

This used a solid piano wire rather than a cable for shifting
more info here... http://www.disraeligears.co.uk/Site/Shimano_Positron_II_derailleur_(DG-200).html
best of luck with that one!!!

 

[wheres_my_beard]

I wonder what my LBS would make of this if I took it in for a service?!

The bike is totally rideable, but it would be nice to get the gears perfect.

 

[Goldie]

You need Bendo: http://feelofsteel.blogspot.com/ His Viscount Aerospace Victor runs 5 speed Positron...

 

[raindog]

There was one on my son's old heap of a bike that he brought back from Austria, it worked well untill the cable broke, couldn't find one anywhere, even on the internet, so we chucked it away and got an ordinary old mech to replace it.
I should think you set it up like any other mech? Disconnect the cable, line mech up with smallest sprocket (or, as there's no return spring on these, even on the largest sprocket?), screw cable adjuster into zero, make sure gear lever is in zero position, reconnect cable blah, blah etc etc as usual?
I would think.

 

[wheres_my_beard]

There are plenty of Positron cables around, so I think the system may be viable for some time.

Luckily I've never had a reason to setup, or replace a cable on a rear or even a front derailleur.

I guess I'll just have to get on with it a see how it goes, thanks for the advice.

 

[raindog]

OK, this is what I'd do.
Disconnect the cable at the mech end.
You can now push and pull the mech back and forth as if the cable was doing it. You'll see that there's no return spring, but the mech clicks into place under each sprocket and stays there.
Set the mech under the smallest sprocket
Set the gear lever in the zero position
Pull the cable so that it's under slight tension and reconnect
I think you'll still need to play with tension adjuster screw to get it working properly.
If it still doesn't work as it should, it could well be worn chain and/or sprockets which are the culprits and not the mech itself.
Good luck.