Originally Posted by
Dave Mayer
Q has been increasing - this is obvious. Look at the Dura -Ace numbers posted previously. And this is for a performance-oriented gruppo, where the desired Q is as tight as possible. Higher Q is caused by wider stays, which during my riding days has increased on road bikes from 120mm - to increasingly 135. Preventing heel strike is why higher OLD gets translated into higher Q. The silly trend to external-BB bearings is another driver.
BTW: chainline and Q are not the same; I don't know how this got introduced to unnecessarily clutter this debate.
Frame design drives the trend to higher Q. The component vendors have to follow.
I would be surprised if the performance penalty of a high Q is only a few %, as cited earlier. I assume this from a test with a bike mounted in a trainer. In real life, wide crankarms cause the bike to rock back and forth with each pedal stroke, robbing power.
Okay, if you guys are going to keep insisting that chainstays have caused Shimano to make its cranks wider, please cite examples and where the crank makers agreed to a new clearance standard and what organization made this possible.
Chainline and Q aren't the same, but they are certainly related as chainline is a limiting factor in Q. When chainline changed with the introduction of 126 spacing and 135 moutain spacing, minimum Q definitely increased.