Nearly all prefocussing – the AF isn’t fast enough. Some of them (if you click thru to the set) are continuous AF mode (ones with panning mostly), but it seems a bit hit and miss. I need to experiment more to work out which situations it works reliably in.
Some I did try AF on, but I was getting more hits with prefocus. It depends a bit what angle you’re shooting at – shooting into the rider up close at (relatively) wide apertures the DoF aint that large, so you miss focus. Other angles where you keep a more constant distance to the rider it’s fine.
Basically use a bit of common sense and you can work it out. In general, the ones where I pre-focussed I probably would’ve on a “proper” SLR too… but then I’ve not tried any of the more modern properly fast AF pro DSLRs.