The stuff used for dirt bikes is excellent. The stuff for skateboards and the top of tennis racquets is also good and slightly cheaper.
I use the latter because it is enough to do the job unless you want to cover the whole chassis of course. Due to the weight factor I only cover the front and back ends as well as a strip down both sides.
If you choose to use the protector film used on motorbikes they also make it in a carbon fibre pattern which is way cool....and at first glance looks just like the chassis itself.