Q Factor

[GParkes]

I recently installed a FSA Gossamer crank with a Power2max PM unit on a friends tri/TT bike. It replaced a Shimano 105 (5800) crank. Both spec with a Q Factor of 146, but she swears her left leg (calf all the way up) is off. Both cranks are 165's, same pedals. Mind you, she has podiumed in her last six events- she knows her body. Before I get sliding cleats in/out on her, or putting the spacer in the BB, anyone have thoughts on this? Anyone else have this experience?

[dustyrider]

Maybe her cleat slipped? :confused:

[GParkes]

Forgive me, she claims no movement in cleat. But I need to verify.

[BdaGhisallo]

An easy way to check her feeling, without disturbing her cleat position, would be to put a 1mm pedal washer on the left pedal and to see how it goes. If she's happy with the mod, that's all you need to know.

[carpediemracing]

Also clip in the shoes (without her in them) and measure heel to frame clearance at various points. If floating cleats then twist the same, like max it out with heel to inside.

I'm guessing the Q factor may be the same but the arms moved over to one side? Or the Q factor measurements may simply be off.

[David Kirk]

I've found Q numbers to be anything but accurate.

I would measure things to quantify before messing with other variables and making it more confusing.

I would set the crank so that right hand crank arm is parallel to the drive-side crank arm and then measure from the pedal face to the chainstay. Write that down and then turn the crank 180° and do the same on the left side.

Now put the old crank back in the frame and do the same thing and then you will have solid numbers to compare the two cranks and this should point you in the right direction to make things feel better for the rider.

dave

[wallymann]

yeah, dave is spot-on. fwiw...the Q specs should be symmetrical, too.