My rear derailleur (Shimano XT) failed during last weekend’s ride and so I took it apart in order to investigate and give it a good clean. (For anyone interested, the Park Tools guide found here was really useful).

I’ve discovered that there is little or no tension in the cage spring for the first 3 or 4 cms of travel when rotating the cage. Comparing this to a similar derailleur on another bike and the difference is significant. The derailleur in question is about 7 years old and has seen a good number of miles and associated abuse, but has been well looked after and as a consequence is otherwise serviceable, I’m hoping therefore to avoid spending the £50 on a replacement.

I’ve searched a little online for replacement springs for the derailleur, but can’t find any on offer. Anyone know if replacement parts can be bought, and if so where from?

Cheers

I have had to guess at the model number from your description but I think this diagram should show your mech –

exploded view

Do you mean the spring labelled as part number 8?

Mister P, yep, part number 8 on that diagram.

Madison are expecting a couple of those into stock around 14/9/11 and they have an SRP of £1.49

Part number is 5UF 1410 if you want your local bike shop to order you one

Thanks for a really helpful response, Mister P. That’s above and beyond what I expected.

Off to speak to the people at my LBS now!

You might get one from a borked mech from your LBS.

I’d be surprised if a 7 year old mech had much life left in it though.

Have you compared a new and old spring to check it is the spring and not some other factor?