F&@£ing bottom brackets!!!

[Jimmy oldskool]

Can someone help me please!?

I'm normally not too bad at picking the right bits and screwing a bike together and I think (you may think differently!) that shows...However...

I have 2 builds in the stand at the minute that are doing my absolute swede in with regards to my choice of cranks and bottom bracket length!

The first one is my Mongoose Amplifier. I built it with M900 cranks on a 110mm BB length, which was perfect. I then purchased a set of NOS L&M Stardrive cranks, which hit the lower pivot at the back of the BB shell, so I bought a 115mm BB, which now JUST skims the pivot, but is unrideable! I could put a 118mm BB in, but then I'm questioning the chainline!

Second one is my Ballistic/ Ritchey build...Same thing, A set of Topline cranks are absolutely wedged to the chainstay on a 110mm BB!

HELP!!!

 

[BerthaPog]

BB axle length is crank dependant, from memory, the Toplines needed quite a long BB axle (127mm rings a bell). Had them on my ‘94 Explosif, no issues with shifting, though I never bothered to check the chain line. Used shorter with Shimano cranks.

 

[Vesatoro]

A crankarm-spindle length-chainline database would't be a bad thing to exist. The Sheldon Brown database is quite useless except for Shimano https://www.sheldonbrown.com/bbsize.html

 

[1552]

Topline use a 127.5 from memory

 

[MCA4President]

A crankarm-spindle length-chainline database would't be a bad thing to exist. The Sheldon Brown database is quite useless except for Shimano https://www.sheldonbrown.com/bbsize.html

I agree, I have some Race Face cnc cranks I need a bb for. I'll be buggered if I know which length I need.

 

[hamster]

It's irritating but far less awful than the modern standards: BB30, BB86 etc.

Fit the crank to a longish bottom bracket, measure its chainline, calculate the error and correct length.

 

[gtturbo]

As above topline is generally 127mm.

 

[scant]

yup. differing brand square taper chainsets required differing length bottom brackets, per frame brand, making it often trial. luckily the bullseye patent expired, so shimano released hollowtech2 which made life considerably easier & thru axle become the new standard

 

[provdes]

I feel your pain. Going through the same thing with my Middleburn RS-3s on a Trek 990. But have discovered they need a 122, however the chainline doesn't seem right so I now need to faff with chainring spacers...

 

[hamster]

yup. differing brand square taper chainsets required differing length bottom brackets, per frame brand, making it often trial. luckily the bullseye patent expired, so shimano released hollowtech2 which made life considerably easier & thru axle become the new standard

The new standard being:
BB90, BB95, PF86, PF92, BB30, OSBB (road), BB30A, BB30-83 Ai, PF30, OSBB (mountain), PF30A, PF30-83 Ai, BBRight, BB386 EVO, T47, Threadfit 82.5, SRAM DUB

SImples.