Just removed a 68mm x 108mm splined bb and want to replace with square taper but can only find 107 or 110mm versions!
Can spacers be used to achieve 108mm using a 107mm bb or would a 110mm work?
Why didn't I just get a hollowtech 11!
Why are you trying to get the same length as the splined bb you've removed? The length is determined by the chainset, not the previous bb.
Pure choice .. assuming the chainring clears on 107mm and chain line will be probably be acceptable with +2 on 110 but you could add spacers/washers on the inside to bring it in but I'd just try it 1st. The splined BB was probably just nominal anyway +/- 1mm
As above, the axle length will depend on the cranks. You can't add a spacer. If you go too short the cranks will bottom out before the taper engages. Too long isn't a problem (other than q factor). A few mm will make little difference.
As above, you need the correct axle length for your cranks. That should give you a good chainline for a 3x setup. You should be able to Google the part number of your cranks and find the correct BB length.
Just look at 1mm on a ruler. Honestly how much difference to clearance or chain line angle do you think that will make over the distance between the crank and hub axles. Just whack the closest on and give it no more thought.
My DayOne has a slightly too long BB on it, and that's a fixie where chain line is more critical and I can't see any offset by eye.
I've gone 110mm after some further research and off the advice of above. Cheers all!
Good job.
Re your hollow tech II comment. Wait until you realise that bottom bracket has been in your bike for ten years with out any issues. Absolutely bomb proof.
107 and 110 are pretty the same length on the drive side of the axle. 0.5mm difference! Think 107 is able to have a etype front mech fitted behind the driveshaft cup.
So either is fine
There’s 1.5mm difference at either end of 107 vs 110. And the e-type compatibility is down to whether you’ve got an e-type BB, not the spindle length, because the drive side part is correspondingly different. If you fit an e-type mech or equivalent to a non-e-type BB then both cranks will be offset to the right (which will affect chainline of course but may exacerbate clearance issues at the left chainstay).
Chainline often doesn’t need to be bang-on, for sure, but at the end of the day cranks are designed for a specific spindle length, and BBs are designed for use with or without specific spacers, and if you diverge from any of that then you change the chainline accordingly. (If you wanted to use an MTB crank with a road rear hub or vice versa then you’d generally want a +/-5mm change in spindle length, but mostly it’s best to stick with the designed setup.)
Realistically, most modern square taper cranks use 110 or 113mm spindles, I think, in which case as you say, a 110 is probably fine either way—it’s not like the old days when some were well into the 120s and you could get it miles off.
I suppose the questions up front should really have been what sort of bike is this for?
What sort of and drivetrain setup? (numbers of sprockets, chainrings, etc)
What kind of chainline do you need to achieve?
it’s not like the old days when some were well into the 120s and you could get it miles off.
Quite a few current shimano square taper chainsets use 122mm bottom brackets.
I suppose the questions up front should really have been what sort of bike is this for?
The main question is what are the cranks and what axle length were they designed for?
122m tends/tended to be for track chainsets used on 120mm spaced frames doesn't it?
Assuming this is for a geared MTB, If you've got something 135/142 (same position for the cassette relative to frame centreline) it would often be something in the range of 110-113 for Square taper shimano MTB chainsets.
Useful old BB tables from sheldon
And Sheldon explains chainline...
Edit:
The main question is what are the cranks and what axle length were they designed for?
Well yes that's what I'm driving at, but the axle length isn't set in stone for every crank, it often depends on desired chainline, and that really depends on frame spacing, hub and relative sprocket positions... (discuss).
122m tends/tended to be for track chainsets used on 120mm spaced frames doesn’t it?
Not really, no.
For example, the current M2000 triple chainset is designed for a 123mm bottom bracket...
https://bike.shimano.com/en-EU/product/component/altus-m2000/FC-M2000.html
As is the MT101
https://bike.shimano.com/en-EU/product/component/altus-m2000/FC-MT101.html
Quite a few current shimano square taper chainsets use 122mm bottom brackets.
Crumbs, it’s come to something when I’m out of touch with even square taper kit 😂
it’s not like the old days when some were well into the 120s and you could get it miles off.
My Voodoo Hoodoo came with a square taper chainset and used a 73x127mm BB so longer setups are out there. I never found a replacement for it so ended up having to put an old RaceFace chainset on there instead, it originally cost more than the sodding bike!
Crumbs, it’s come to something when I’m out of touch with even square taper kit
Chuckle 🙂
longer setups are out there. I never found a replacement for it
Schroedinger's bottom bracket
My Voodoo Hoodoo came with a square taper chainset and used a 73x127mm BB so longer setups are out there. I never found a replacement for it so ended up having to put an old RaceFace chainset on there instead, it originally cost more than the sodding bike!
Would this one not work @reluctantjumper ?
https://slam69.co.uk/products/sealed-bottom-bracket-cartridge-73mm-x-127-5mm
Re your hollow tech II comment. Wait until you realise that bottom bracket has been in your bike for ten years with out any issues. Absolutely bomb proof.
Not what I found. I ran square taper (Token) for around 6 months a year or so ago, including a lot of winter riding, and when I took the BB out it is pretty rough to turn by hand.
Well that was a rubbish bb then!
Shimano square tapers last forever.