On Sunday, September 1, 2019 at 6:12:14 PM UTC-7, Tom Kunich wrote:
On Friday, August 30, 2019 at 7:49:45 PM UTC-7, AMuzi wrote:
On 8/30/2019 9:07 PM, Don Gillies wrote:
If a vintage crank needs an offset on one side, you can just add the offset to the other side and substitute a symmetric crankset, so a 116 R+5 bottom bracket can be substituted with a 121 symmetric bottom bracket (120 or 122 would work fine.)

- Don Gillies
Palo Alto, CA, USA


Which makes your tread ( aka "Q") wider.
Deal breaker for some riders.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

The iliac width is why the BB50 has become so common. People's legs do not have to spread so wide and the length of the BB shaft is narrower and consequently stiffer. Average hip breadth is 13" or 33 cm. So the narrower the BB the more angularly correct a pedal spacing would be.

Time for Frank to tell us all that I don't know what I'm talking about.

BB50? What's that? My BB30, BB86 and BB90 bikes all have Shimano cranks with the identical tread or Q-factor. Same Q-factor as my threaded BB/outboard bearing Shimano equipped bikes.

-- Jay Beattie.

-- Jay Beattie.