After a bit of advice - Need to change bottom bracket, presently have a square taper type, but need to change tpye due to new chainset.
Do I only need to know the correct diameter of frame and not the length as with the square taper?
Would you also recommand renewing casette, chain and chainset at the same or is this a myth?
Have around £150 to renew the lot , any suggestions on what to get would be appreciated.
By the way the bike I ride is a Giant XTC 2009.
Thanks in advance for any help.
Your new chainset will come with a BB which has 3x 2.5mm spacers to allow fitting to a 68 or 73mm frame with/without a BB device (front mech/chainguard).
As for whether you need a new chain, cassette and 'chainset' I think you have partly answered this by stating you are going to fit a new chainset.
I would fit the chainset and see if it all played nicely...if not then it is time for a cassette and chain (those I would do together).
New Deore chainset will work with 9 or 10 speed, Deore 9-speed cassette and a 9-speed KMC chain (better with its quicklink than Shimano's dinosaur rivet).
To go 10-speed would involve shifter, rear mech, cassette and chain.
Unlikely within your budget.
PaulD