evilmikeJoined: 19 Apr 2006Posts: 640Location: Capitalist Hill
I need to buy a bottom bracket for my new bike, but I'm unsure of what length I should get. Here's the deets:
130mm spaced campagnolo freehub w/ a 9 speed cassette
Shimano Deore LX 94bcd mountain crankset, set up as a wide compact double
I'm thinking that I should shoot for 110, but I'm wondering if anybody else has some opinions on this. I don't think I'll have any problem with the cranks clearing the chainstays, and I think I prefer more moderate tread.
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joeball
Posted: Fri Mar 23, 2012 9:52 am
Joined: 24 Jul 2005Posts: 6037Location: Ether
Well it's one of those two, lengths, but what is 1.5mm of chainline between friends?
In some ways it makes sense to go with the 110 since you will probably be in the big ring more.
I'll try to be a good guy and go take my cranks off measure for you tonight if I remember.
I suggest you have one of every BB length in your parts bin just for cases like these.
lantius
Posted: Fri Mar 23, 2012 11:05 am
1337Joined: 22 Jul 2005Posts: 6705Location: right over
Sheldon lists the Deore LX 94bcd as 107-113mm BB for a 47.5-50mm chainline. If you're running it as a compact double on the outer spider only I'd tend towards the narrower side of the range.
limpyweta
Posted: Fri Mar 23, 2012 11:23 am
Joined: 23 Sep 2008Posts: 740Location: North Beach
Remember the chainline margin of error with different crank press fit standards if you go to the used market. I think Sheldon wrote the margin of JIS-ISO square tapers is like 5mm, mix matching clean, dry, bottom brackets and cranks of those two standards. And Sutherland's 6th ed wrote there's like 5 more square taper standards.
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Alex
Posted: Sat Mar 24, 2012 4:48 am
Joined: 18 May 2006Posts: 3128Location: Roosevelt
I have 103, 107, and 110 bottom brackets if you want to try all three and see how it goes. None are for sale, but they are here for test fits. I'll be in the basement until 11:30 today.
Since you are running a triple as a double you want to go 7-10mm shorter than stock. However if you go too short the crank might bottom out on the BB splines before it is tight on the taper. That is why it is important to experiment.
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evilmike
Joined: 19 Apr 2006
Posts: 640
Location: Capitalist Hill
Joined: 24 Jul 2005
Posts: 6037
Location: Ether
1337
Joined: 22 Jul 2005
Posts: 6705
Location: right over
Joined: 23 Sep 2008
Posts: 740
Location: North Beach
Joined: 18 May 2006
Posts: 3128
Location: Roosevelt
