Fitting new chainset and bb

gkf9

I have a Octalink BB and a Shimano crank dont know what sort? Think its deore? They was on when i got my GT Avalanche 1.0 bike.

Can anyone tell me if its possible to upgrade to a SHIMANO XT HOLLOWTECH CHAINSET
what would be involved, would i be able to fit it myself (ive got some slight mechanical skills )and would i need a different BB...My frame is 68mm wide...its all very complicating with the talk of spacers,external and internal BB's etc etc!

Thanks for any easy understandable advice.

supersonic

Need the model of the crankset ie M7xx Usually doable at home, but in the case of HT2 cranks, you will need the bottom bracket shell facing.

nicklouse

yes no maybe. More info needed. which Hollowtech version?

have a read of parktools as well.

CraigXXL

I'm thinking of doing the same. The crank is a Shimano F-M422 if it's the same as my 2008 Avalanche 1.0. Only reason I will be changing is that I am quite punishing on the drive train due to my weight. I am wanting the extra strength of the cranks and BB without the weight of a downhill chainset. Any advice is welcome.

This is the chainset I have in mind http://www.wiggle.co.uk/ProductDetail.aspx?Cat=cycle&ProdID=5360031021&N=Shimano%20XT%20M770%20Hollowtech%20II%20Triple%20Chainset

supersonic

Craig, keep what you have until it dies. Its probably plenty strong enough! If its not broke yet,,,

The chainset you mention comes with its own bottom bracket, and will fit your frame no problems. The bottom bracket shell will need facing. Tools to fit:

http://www.chainreactioncycles.com/Mode ... delID=4062

You'll need a different set to take off the old stuff though.

gkf9

supersonic wrote:

Need the model of the crankset ie M7xx Usually doable at home, but in the case of HT2 cranks, you will need the bottom bracket shell facing.

Whats shell facing mean?
How much would it cost for a LBS to fit?

Think my crank is the same as CraigxxL
Thanks

supersonic

Facing removes a bit of material from the faces of the BB shell. With the crank and BB you link to, the bearings sit in external cups, so the faces of the shell need to be flat and parallel.

Its a nice upgrade, save a bit of weight over ther old stock, but the old stuff is still good and reliable. I wouldnt bother.

A shop will charge about 20 quid to remove the old crank, face the shell, and fit a new one. If take in a bare frame, 10 quid to face it. You will need a new chain with new chainrings.

CraigXXL

I will keep it until it does break. I've changed bottom brackets before but will probably get my LBS to face the shell and fit the chainset to make sure it's done right then buy the tool for changing future brackets if required.

Thanks for the help.

gkf9

supersonic wrote:

Facing removes a bit of material from the faces of the BB shell. With the crank and BB you link to, the bearings sit in external cups, so the faces of the shell need to be flat and parallel.

Its a nice upgrade, save a bit of weight over ther old stock, but the old stuff is still good and reliable. I wouldnt bother.

A shop will charge about 20 quid to remove the old crank, face the shell, and fit a new one. If take in a bare frame, 10 quid to face it. You will need a new chain with new chainrings.

Ok think i will hold fire then on your advice!! Not had the bike to long so might just replace the
BB when it goes..the octalink BB seems to be more easy to remove and refit!! Just really liked the look of the Xt Hollow chainset..

Thanks again think i grasp the ins and outs a bit more now.