bottom bracket sizes

[snakey_75]

hi guys, can someone give me some advice?
i need to replace my bottom bracket on my mtb. it's 122mm, can i go a few mm's smaller, if so, how much?don't know if this is the original/correct size, as i had the bike just as a frame and built the rest myself (don't think bottom bracket that was in there was original) the bike is a diamondback S-10, used for back and for work mostly, nothing too strenuous!!
another thing, how long are these things supposed to last? as the last one was only 7/8 months old!
thanks for any help....

 

[Toby_2009]

hi guys, can someone give me some advice?
i need to replace my bottom bracket on my mtb. it's 122mm, can i go a few mm's smaller, if so, how much?don't know if this is the original/correct size, as i had the bike just as a frame and built the rest myself (don't think bottom bracket that was in there was original) the bike is a diamondback S-10, used for back and for work mostly, nothing too strenuous!!
another thing, how long are these things supposed to last? as the last one was only 7/8 months old!
thanks for any help....

The one on my bike only lasted 4 or so months but apparently GIANT have a tendency to put dodgy BB's in their lower end bikes

 

[snakey_75]

cheers toby,
can't remember what the old one was, but the new one i replaced was shimano, surely these are not budget??

 

[Sittingduck]

It could have an effect on chainline. Checkout Sheldon's page relating to spingle lengths and BB sizing here.

Cheers,
SD