Originally Posted by timcupery
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.
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.