Crank help - compatibility issues?

[lillerj]

Hi, I'm having a chain suck issue after replacing the chain and cassette on my old rockhopper so I'm thinking that I need a new crank set.

It currently has an old XT crank set, like this one:

viewtopic.php?t=156540

But I think the teeth are worn out hence the chain suck, anyway, I put on a new IG chain and bought an HG cassette so I'm wondering what chain set will work with these? It's an 8 spd if that makes any difference?

Any advice on what chain set to buy would be appreciated! Looking to spend up to about £60 or so.

many thanks

 

[xerxes]

Are you having problems with the outer ring?

If it's only the middle or granny ring, replacement chainrings will be cheaper: http://www.ebay.co.uk/itm/Shimano-32t-C ... 3f31141db3

 

[lillerj]

It seems to be on both the middle and outer ring. Will check.

I'm sure that this crank set has an outer ring which is attached to the spider so it makes replacing the rings a little tricky.

 

[integerspin]

It seems to be on both the middle and outer ring. Will check.

I'm sure that this crank set has an outer ring which is attached to the spider so it makes replacing the rings a little tricky.

I messed about swapping rings last time I changed the chainset, but if the outer ring needs replacing the next time I change any of the chainset on my other bike with an M739, with original outer rings, I will probably buy a set of the LX cranks that you see for about 30 quid, I think they even go on the same bottom bracket.

The outer ring is held on by a large nut, when I swapped my rings last year I couldn't find a decent outer ring but found a 5 bolt chainwheel adapter. The adapter replaces the outer ring, then you can bolt a normal compact 5 bolt set of rings to it. I got the adapter with some knackered M569 cranks.

 

[xerxes]

I'm sure that this crank set has an outer ring which is attached to the spider so it makes replacing the rings a little tricky.

I think you're right - probably not one of Shimano's greatest ideas. :?

You can pick up granny rings and middle rings for £10 - £15, so I'd replace them. If the outer ring is only slightly burred or "shark-toothed" you could have a go at fixing it by filing the teeth: http://www.mountainbikerides.co.uk/fett ... -suck.html

However, if the outer, with that integral spider, is really far gone then it probably is going to be better to replace the whole chainset.

 

[lillerj]

Thanks for all the replies so far. I'm thinking that I'd rather just replace the chainset as it sounds like a hassle to replace the outer ring! Can anyone recommend a chainset that will work with an 8spd set up? Or will anything work? Apologies if this question sounds dumb, I just haven't bought any new stuff for a bike for a long time so feel like I don't have a clue what will or won't work. Bear in mind that this rockhopper is from circa 1997.

 

[hamster]

Anything will work with 8 speed. Remember to buy a bottom bracket of width to match the chainset.

 

[lillerj]

probably best if I pick up a chainset and BB at the same time then

 

[xerxes]

Square taper, octalink and isis type bottom brackets come in different lengths to suit different chainsets to give the correct chainline: http://sheldonbrown.com/bbsize.html

You'll also need to check the shell width of your bottom bracket, most likely 68mm, but might be 73mm: http://branfordbike.com/articles/bottom ... s-pg59.htm

You can pick up a new Square Taper chainset: http://www.chainreactioncycles.com/shim ... prod106885

And suitable BB: http://www.chainreactioncycles.com/shim ... -prod71369

For well within your budget.

Or you could buy a new style external chainset with BB included, you don't have to worry about spindle lengths with these: http://www.chainreactioncycles.com/shim ... -prod40496

The only thing you can't fit is any of the new style press fit bottom brackets and chainsets, like BB30, BB92 etc.

The new style external bottom brackets and hollow axle chainsets are generally lighter and supposedly stiffer than square taper type, but I think the bearings last longer in square taper bottom brackets. Shimano UN54 and UN55 bottom brackets are cheap as chips and virtually fit and forget, I've got one that's done 2 to 3,000 miles in all weathers and is as smooth as the day I fitted it, whereas the external BB on another bike gave up the ghost after about 1,200 miles.

 

[lillerj]

good info and advice Retro Guru, many thanks