I would probably go 1080x960, try and fiddle with your ISO (light) and balances. There's a sweet spot somewhere, you just need to find it. Start with a setting, test it on bike, check it, adjust accordingly, test again. Take like 20 second clips for your test, enough to get up to a speed and turn so you get multiple light and shifting situations, for best appraisal of your settings and adjustments to make.
Pondered upon a rainy plateau, with a coal forge, and many dragon.