Gear problems

andyturner28

Hi guy's.

My dad has an 02 Giant Boulder which has 21 gears. The rear hub went belly up so i thought i would upgrade the gearing to 27 gears at the same time as replacing the wheel and hub. Just got it all fitted and i can't get it to go into 8th at all, and the rest of the gears are a little clunky. I fitted my old 9 speed Shimano Doere mech ages ago, and It still has the old chain, so do you think this has to be renewed as well? What is the difference between 7sp and 9sp chains, apart from the length? I have seen a lot of pictures of DH bikes with very short chains, so i assumed i would get away with it.
Also what about the chainset? I have a spare Truvative Isofow but i wanted to avoid fitting that to my Dad's as the chainset on my mum's is pretty dodgy.

Cheers,

Andy.

nicklouse

you need a 9spd chain as they are different widths to 6-7-8spd chains.

and dont forget to reset the stops on the mech.

the shifter is new?

andyturner28

Hi Nick.

The shifter is an 05 Doere. The stops havn't been changed since it came off my bike. I think you are spot on with the chain width though, as i just had another fiddle and it is missing virtually every other gear, so obviousely it is too wide.

Do you think i would be OK sticking with the same chainset? There dosn't seem to be any chain line issues, or is there any other reasons why some chainset's are 9 speed specific?

Cheers,

Andy.

nicklouse

the chain set rings may cause a problem due to the new required thinner chain. But then again they might be OK you will know when you fit the new chain as it will or will not work.

Dont for get you will need to shorten the new chain to fit.

see the how to get the correct chain length on parktools site or with the instructions that come with the chain.

andyturner28

Thanks Nick. I'll see how it goes with the new chain.

Cheers,

Andy.

andyturner28

Ok, got new mega 9 compatable chain now and have fitted my old 9sp Truvative Trueshift chainset. The rear gears are now perfect, better than mine in fact :?, but i am having problems sorting the front out. I can oly get it to behave when the rear is in 1-3rd, when the chain line is at it's worst! When i try to change the front with the rear in a high gear i can't get it onto the big ring, just the granny and middle. I have left the old front mech on, could this be the problem, or is it the chain line? Is it possible to move the bb over to the non drive side i little by adjusting the bb cups? I have already decided to get a new front mech for my bike and stick my old one onto Dad's, but i just need to know if changing the mech will solve the problem.

Cheers,

Andy.

andyturner28

Sorted Got a new 9sp mech, gears now perfect.