Orange Aluminium Elite bottom bracket: Suntour MD / Shimano?

[Dave_B]

I'm sure there are gurus out there who can help with this one. I'm building up an Aluminium Elite frame, 1992. The bottom bracket seems in good condition but it's Suntour Microdrive. I've measured it at 23mm wide but from what I've read the Shimano spec for this frame is 68 x 118mm for a square taper BB. The Suntour BB looks like it offers the right taper but the Shimano cranks don't seem to go on far enough and they sit way out from the frame. The crank arms clear the chainstays by a country mile.

I'm going to need to replace the BB with a Shimano spec, right? :roll:

 

[ishaw]

Re:

suntour micro drive bb is usually 115mm iirc, non md is usually 122.5 I think.

Any shimano taper compatible bb in the right length and bb shell width should be fine.

 

[Dave_B]

Re: Re:

suntour micro drive bb is usually 115mm iirc, non md is usually 122.5 I think.

Any shimano taper compatible bb in the right length and bb shell width should be fine.

Thanks, that's helpful. I'd guessed the BB is Micro Drive as there was a MD front shifter on the frame, but it could be non-MD. I measured with the calipers at 123.0 but I could have been out. I know Orange offered MD on the Aluminium back in the day.

 

[Incworks-1969]

BB length is a product of which chainset you are going to use to keep the optimal chain line with a 68mm BB shell and 135mm OLND rear hub spacing. Examples: Shimano Deore LX, FC-M560 (1994) Low profile crank set required a 68 x 113mm. Shimano STX-RC FC-MC36 (1996) crank set required a 68 x 110mm.

Suntour Micro Drive groups required a shorter length bottom bracket spindle to pull the cranks in toward the frame appreciably, to reduce the Q-factor. The standard Suntour XC Pro spindle, for example, was 125.5mm long. The Suntour MD spindle was 115mm long. Shimano did a similar thing in the mid 90's with it's low porfile MTB cranks (reducing the spindles from 122-118mm down to 113-110mm)

If you are fitting a Shimano crank set go with a Shimano compatible BB to avoid any chain line issues and to maintain the optimal Q-factor. Current modals are the BB-UN300, BB-UN55.

Here's a link to Sheldon Brown's Bottom Bracket Size Database:

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

 

[Dave_B]

BB length is a product of which chainset you are going to use to keep the optimal chain line with a 68mm BB shell and 135mm OLND rear hub spacing. Examples: Shimano Deore LX, FC-M560 (1994) Low profile crank set required a 68 x 113mm. Shimano STX-RC FC-MC36 (1996) crank set required a 68 x 110mm.

Suntour Micro Drive groups required a shorter length bottom bracket spindle to pull the cranks in toward the frame appreciably, to reduce the Q-factor. The standard Suntour XC Pro spindle, for example, was 125.5mm long. The Suntour MD spindle was 115mm long. Shimano did a similar thing in the mid 90's with it's low porfile MTB cranks (reducing the spindles from 122-118mm down to 113-110mm)

If you are fitting a Shimano crank set go with a Shimano compatible BB to avoid any chain line issues and to maintain the optimal Q-factor. Current modals are the BB-UN300, BB-UN55.

Here's a link to Sheldon Brown's Bottom Bracket Size Database:

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

Really helpful stuff, thanks a million. I've now found the Shimano PDF spec sheet for the chainset and it recommends a 110 or 113 mm BB width.

 

[FluffyChicken]

ooh Alu Elite. normally I would say go for 110, but your mech a larger band, only mid band so I would still try 110 first as it give the shorter 'correct' chainline. Use 113 after that if you have no choice. (or are going to fix up with 9speed+)

But it's ben nice of Shimano to add the back catalogue of info to there archive over the past years, makes it much easier than 10 years ago.
Take a picture of the bottom bracket when you take it out. Suntour made decent ones.
(as a side If your bb measured at 122, then it was not a microdrive crank, but the larger size, still very nice. Probably has D-3SB (which is 121.5mm) is XC-Pro. XC-Comp/LTD would normally have the 128.5 axle as D-3TS marking, at least in 1991. 1992 MD was introduced, but you could still get both

 

[Dave_B]

ooh Alu Elite. normally I would say go for 110, but your mech a larger band, only mid band so I would still try 110 first as it give the shorter 'correct' chainline. Use 113 after that if you have no choice. (or are going to fix up with 9speed+)

But it's ben nice of Shimano to add the back catalogue of info to there archive over the past years, makes it much easier than 10 years ago.
Take a picture of the bottom bracket when you take it out. Suntour made decent ones.
(as a side If your bb measured at 122, then it was not a microdrive crank, but the larger size, still very nice. Probably has D-3SB (which is 121.5mm) is XC-Pro. XC-Comp/LTD would normally have the 128.5 axle as D-3TS marking, at least in 1991. 1992 MD was introduced, but you could still get both

Thanks, more really helpful advice. I'm sorted!

 

[FluffyChicken]

Re:

I should really check the autocorrect and missed characters more often too.