Alex Moll wrote:
> It seems the return spring in the rear Jubilee has lost all tension.
> It'll downshift to the larger cogs, no problem - but it won't upshift
> to the smaller.
It's pretty unusual for a spring to lose tension. Contrary to popular opinion, proper springs don't "go soft" from use -- ever. (Though a particular part may have missed its heat-treatment and gotten through quality-control in a very soft state, in that case it was soft from day one -- it didn't get that way later.) More likely the spring has been bent, or come unhooked at one end. Or most likely of all, the spring is fine but one or more of the pivots of the parallelogram have gotten tight. This can happen from crash damage or from road grit getting in.
It's easy to check the pivots -- just unhook the spring from the lower attachment, which is exceptionally easy on the Jubilee, it can be done by hand without a tool. Now the parallelogram should move back and forth easily; ideally it should feel almost frictionless.
Here's a picture of the spring:
http://bulgier.net/
If there's not extra friction in the pivots and you really do just need the spring to be stronger, this can also be fixed almost instantly by hand -- just bend the spring. Grab the end you just unhooked at its lower attachment point and bend it up, towards the dropout. Trial and error will tell you how much to bend it -- bend a little at first, then hook the spring back under its peg and give it a try. You have to bend it enough beyond where it needs to be for it to permanently yield ("take a set"). You'll know if it yielded because it won't return to the same place when you let go.
If it looks like extra friction in the pivots is the culprit, you could try flushing any gritty contaminants out with your favorite solvent, then oiling them. I doubt you'll be able to disassemble the pivots for proper cleaning, they're smashed together at the factory and not meant to be disassembled.
Working the oil into the pivots can take a while. Work the parallelogram back and forth (with the spring unhooked), with an excess of oil on the pivots, until the oil has penetrated throughout. Though you'll never know for sure if the oil made it everywhere, hopefully you'll feel a reduction in friction.
If they're tight due to crash damage, chances of fixing that are slim.
Mark Bulgier
Seattle, WA USA