Upgrading my rear derailleur - worth it?

clamps81

I've currently got a Spesh Hardrock Disc. It's a reasonable enough bike and with the fork and brakes sorted I'm almost entirely happy with it. However, even after a service I'm finding that the chain is flying off at alarmingly regular intervals. Someone on another forum (not a bike related one) mentioned that upgrading my rear derailleur would help me because it would keep the chain under a more consistent level of tension. Fair enough it would seem, since shifting is controller by the shifters and I should have no trouble with the fact that I only have a 7 speed rear cassette and would be running a 9 speed mech.

What about the chain though? Would that be ok? And is my mate right, will sticking a deore rear mech on my bike help out with chain tensioning, or this more down to a combination of other things?

If it's a goer then great, because it's a cheap upgrade and I needn't touch anything else on the bike for ages then.

Any input appreciated.

nicklouse

first off. what is currently fitted?

clamps81

Sorry 'bout that, kit is as follows :

Front Mech: Shimano Altus, 34.9mm clamp
Rear Mech: Shimano Altus, 7sp direct mount long cage
Chainset: SR SunTour, square taper spline 42/32/22 T
Bottom Bracket: Sealed cartridge, square taper, 118mm
Cassette: SRAM PG-730, 7-speed, 12-32t
Chain: KMC Z7 w/ reusable Missing Link

While a 9 speed would be nice, I'm fine with 7 at present and don't want to splash the cash to upgrade the whole lot.

nicklouse

the mech would work.

but if it would change the issue I do not think so.


where is the chain coming off and in what gear combos?

it is generally best to be somewhere in the middle of the rear cassette and the middle ring on the front for rockey descents as 1 you cant go that fast and 2 it give the chain the best chance to stay on.

Maybe check the chain is the correct length. Info can be found on Parktools.

clamps81

ah, ok, cheers.

Chain generally comes as you say on the harder areas of descents. Happened a few times at Cwmcarn and went to Afan after having it serviced and did as you suggested - keeping it roughly in the middle on front and rear and yet it still popped off. Couple of times off the back, but mostly it's actually coming off at the front. Not sure about chain length - I was hoping that's the sort of thing the bike shop would have checked and sorted.

It's it's simply a matter of me bashing the bike round too much then fair enough and it's a few quid saved, but I'll have a looksee at the parktools website as well just to check.

Cheers for that.