lost on BBs

[Jebb]

Hi, just started commuting to work but my bike is in need of a few up grades, as the chainset is making not to nice noises.

Think I sort of got my head around how to change the cassette but the chainset has left me totally confused with the BB and what chainsets are compatible with it, think I remeber my LBS saying my BB limited me to only a few chainsets or was it the frame to only a few BB? anyway the bike is a GT avalanche 1.0 2007 spec http://www.bikeradar.com/gear/category/bikes/mountain-bikes/product/review-gt-avalanche-1-0-9265/ with a Power Spline BB, could you please explain to me what BB and chainset I can fit on this bike, as I would like to change the whole drivetrain but totally confused!

 

[fossyant]

It will be one of these

http://www.tweekscycles.com/Product...tom Brackets&gclid=CLHn6qKTrr4CFbDJtAod1EsAGw

You ideally need to remove the BB, and find out the axel length. The BB's shell will most likely be 73mm (68mm is road bikes). So you'll need the axel length and the shell width. Both are usually printed on the bottom bracket.

You will need a power spline removal tool - it looks similar to Shimano, but it may not be.

 

[Jebb]

thanks,

it's not so much the size of BB I'm confused with as the BB may not need changing, I'm confused with what chainsets are compatible with it, what do I need to look for? a chainset that says it's compatible with "Power spline" ?and also if the BB does need changing what can I swap it with? just another power spine or something else?

I'm asking as I would like to do the work myself to save some money but if it works out too expensive by the time I research what tools I need, I will just purchase the parts and get my LBS to fit them but again I need to know what to buy.

 

[cyberknight]

I doubt the LBS will be happy to fit something you have bought or they will charge you an extra rate to do it , if you want the LBS to do the job just let them replace it as getting on the good side of the LBS people is a boon, i have free spacers, indexing and odds and sods over the years .
Don`t get me wrong , i have a set of tools that cost me about £40 for a basic kit to which i have added a few bits and bobs and try to do my own repairs to save money but if i am stumped then let them do it .
By all means ask how its done and they may be kind enough to explain so you can do it yourself next time .

 

[Jebb]

My LBS has done work for me before, when I provided the parts, they charge an hourly rate, I also bought the bike from them and go there for other bits, and they have serviced the bike in the past too.

In fact if I remember rightly it was them that suggested briningg parts in as they would have to order them in and it would be at full RRP.

But even if I were to take the bike to my LBS to do the full work, I would still like to know what parts I can use, so I have some understanding what options Ihave.

 

[boydj]

If you need to change the chainset, then it may be worth changing the BB at the same time, so you can be sure of the compatibility and have a wider choice. Modern external BBs are not expensive and are easy to fit.

 

[Jebb]

If you need to change the chainset, then it may be worth changing the BB at the same time, so you can be sure of the compatibility and have a wider choice. Modern external BBs are not expensive and are easy to fit.

which do I buy tho? I have no idea what will fit my bike.

 

[RecordAceFromNew]

which do I buy tho? I have no idea what will fit my bike.

If you are keeping the Deore front derailleur you should get a chainset with roughly similar tooth count and a 50mm chainline. Unless you really want to minimise weight I would not get one with an outboard bottom bracket, but something like this and a UN5x square tapered bottom bracket that matches the chainset requirement for spindle length and your frame's bottom bracket shell width (likely 68mm).

 

[boydj]

which do I buy tho? I have no idea what will fit my bike.

Just about any standard BB will do - as long as it's the correct width, which you can measure for yourself. The width of the BB shell should be 68mm or 73mm. Some of the newer standards, like BB30, BB386 etc won't fit. I'm not familiar enough with mtb's to advise further.