Very nice stop action photo. The contrast is good, it's sharp and the background is pleasing.
I'm pretty sure someone has already mentioned this but just in case not, I think you made a mistake shooting this landscape style instead of portrait. As is there is no sense of height. Had you shot this as a portrait with lots of negative space below the bike I bet this would have scored a lot higher. However with that said, I still give this an 8. You can always easily change it for print purposes with that nicely even background.
Nice sports action shot. Grays look a bit flat to me. A bit more contrast and perhaps a bit of sharpening would make this pop even more, but very cool photo.