BB spindle length?

[Stressed]

Mmmm, interesting. I've yet to find any definitive guide for this voodoo!

 

[goshow]

107 is the standard M900 bottom bracket for a 47.5 chainline at the time.

113 if you need to go for the 50mm chainline

For a prestige or clockwork, the. 107 is your length, with recessed cups too.

Alu-O/Elite should be able to use the same as they only use middle diameter front mech bands. That and it’s what I use on mine.

Excellent. Thanks. Just so happens I’ve got a UN91 with a 107mm in my stash.

 

[FluffyChicken]

Mmmm, interesting. I've yet to find any definitive guide for this voodoo!

The guide is read the instruction manual.
If no manual, take a best guess from the profile of the crank (axle to pedal offset).

Then tweak, as needed, to get a centre of frame to middle chainring of between 47 to 50 mm, aiming nearer the 47.5mm

Then worry about NDS offset, some may need the inbetween sizes to put that size a little bit further out etc.

I do have a picture from way back when, that I put up, that shows you what I mean by profiles.

Though you could read the sutherland or Barnett big thick book pdfs as sure they explain it very well.

 

[Stressed]

The guide is read the instruction manual.
If no manual, take a best guess from the profile of the crank (axle to pedal offset).

Then tweak as needed to get a centre of frame middle chainring of between 47 to 50 mm, aiming nearer the 47.5mm

Then worry about NDS offset, some may need the inbetween sizes to put that size a little bit further out etc.

I do have a picture from way back when, that I put up, that shows you what I mean by profiles.

Though you could read the sutherland or Barnett big thick book pdfs as sure they explain it very well.

Thanks Fluffy (for making my head hurt)

 

[Repacker]

Sheldon Brown is usually very helpful:

https://www.sheldonbrown.com/bbsize.html

 

[Stressed]

This was useful!

 

[FluffyChicken]

That looks like Bikepro.com

 

[Tootyred]

Its a good use for those dead bottom brackets! Just hang onto them....you can then pop one in as a starting point at least.

Same with crappy seatposts

 

[Stressed]

That looks like Bikepro.com

Correctomundo!