50.4 BCD TA vs. VO
On Sunday, September 1, 2019 at 8:19:20 PM UTC-7, Ralph Barone wrote:
John B. Slocomb wrote:
On Sun, 1 Sep 2019 18:12:12 -0700 (PDT), Tom Kunich
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.
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.
By gorry Tommie! You hit the nail right on the head!
You whip out these hip width measurements like they are carved on
tablets of stone... and perhaps they are. Except that you neglect to
mention that hip width in males is noticible different than in
females. To the extent thjat a female's knee joints are closer
together then her hip joints while a male's knee joints are generally
speaking the same width.
But perhaps you are telling us that women don't ride bicycles? Or the
moon is made of blue chease?
And, of course, the important measurement when discussing Q factor is how
far apart the ankles are when doing a similar exercise like walking or
The front sprockets remain in the same place. The chain line remains the same. The contact point on all of the pedal systems remain the same. So the only real difference is the depth of the crank where it attaches to the BB axle.