Bike polo mechanics & fixing

Change the gear to compensate for the crank length difference.

Go find what Sheldon says about Gain ratios.

Or don't as it's not a big enough difference to worry about.

I'm on a Hija, 120 rear, 1.35 Duranos. 68 shell.

Changing the crank length doesn't do that much to the q factor. The main problem is that ex bb have a set width (and therfore 'q factor') unlike square taper. I would go 170 to help.

I've said it before but this is a nice little resource http://www.maxpowercycles.de/technical-stuff/