possible to get a 113mm Octalink V1-spline BB for fixie use?
 

So I've been thinking that Shimano Octalink road cranks (e.g., 5500-series Hollowtech 105) would be great for fixed-gear use. They're stiff, available in 165mm crankarm length, and giving proper 43.5mm road chainline with a 109.5mm bottom bracket, would give proper 42mm chainline on the inner ring if used with a 113mm bottom bracket. However, I've only been able to find Shimano Octalink bottom brackets in 113mm if they have the V2 spline, which is not compatible with 105/Ultegra/DA groups.

This scheme would work with Sora or Tiagra double cranks (which use a 113mm V2-spline Octalink crank) if used with a 118mm V2-spline Octalink crank. But I'm mainly interested in the 105 and up.

[redacted due to dyslexia]

The cranks may be OK, but everyone has abandoned the Octalink/ISIS concept because of shortened bearing life, and my guess is that fixie use would even be harder on BB bearings than standard use.

I've looked, but not too hard, for other Octalink lengths and didn't come across any. Square taper appears to be the single cog way.

Cool, thanks. I admittedly haven't looked hard (checked Nashbar, Performance, and Harris), but I mainly wanted to see if these had ever been produced. It seems that V1 Octalink is produced in 109.5mm for doubles and 118.5mm for triples, so I wasn't sure that they were ever made in 113. Octalink V2 is made in 113, of course.

From what I've heard, Shimano Octalink BB's didn't suffer the problematic bearing life. Some ISIS BB's did, but not all.

I agree that square-taper appears to be the single cog way (and I have it on all my bikes except for an FSA compact double with ISIS interface on my "fast" road bike) but it seems that this use of old Shimano cranks would be a good way to set up a fixie. If available.

Ooops. I think I'm dyslexic. I typed 113 instead of 118 a couple days ago, and I just read your 113 as 118.

Fact is, I don't know if a 113 V1 was ever made. So "Never mind!" (Sorry.)

Octalink V1 exists in 4 sizes:

109.5 mm
112.5 mm
116 mm
118.5 mm

The two middle size were intended for the short-lived XTR version, and may be difficult to find.

Another option would be to use the 109.5 with a spacing washer under the right side mounting ring. The popluar washer for this is the Sturmey-Archer sprocket spacing washer, 1/16" (1.6 mm) thick.

Why? The V2 spline is superior! That's why Shimano changed the design.

Sheldon "Octalink" Brown

Thanks Sheldon. Any BB for a short-lived XTR version is probably expensive beyond the value of a cheap conversion to a nice fixed-gear option.

And I'm interested in the V1 spline specifically b/c I've got a 105 crank with 165mm arms sitting around :)

So it looks as if the 105 crank with a 109.5mm V1-spline bottom bracket would work, if I went with 40mm chainline (which is where the inner ring would be with a 43.5mm road-double chainline, given that every crank I've measured (from old Sugino that came with 10-speed bikes to modern FSA designed for use with 10-speed cassettes, the chainrings are 7mm apart).

You haven't said what hub youll be usng, but for a 40 mm chainline, you might want to try flipping the rear sprocket over, so the shoulder faces outward.

Sheldon "Straight And Narrow" Brown

XTR should work.

have you tried it with a 109? since chainline for a double in theory is measure between the two chainrings, good chance it'll be good enough for to be gov't work, particularly with a 3/32" chain.