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 [url= http://www.parktool.com/blog/repair-help/rear-derailleur-overhaul ]here[/url] 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 -
[url= http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/RD/EV-RD-M751-2506_v1_m56577569830609152.pdf ]exploded view[/url]
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?