Well, I picked up a pack of the new Space Marine Scout Bikes with the Space Marine Spearhead.
Space Marine Scout Bike with twin bolters
The major differences between these and the older scout bike are that
- the front wheels are open, ie less bike faring enclosing the tires,
- the mufflers, the new bike only has a single pipe on both sides and not two like normal bikes
- the scouts are multi piece plastic rather than three piece metal
- the foot plate is smaller, with no foot guards on the side to protect the marines foot and now place to rest your foot besides the primary foot pad
- the front faring which hold the weapons is much smaller also than the original bike faring.
- the seat of the new Scout bike also has no back support pad
- the back fender behind the seat is also slightly shorter than previous
I went ahead and modded some of my older scout bikes to be similar to the new scout bikes, this involved cutting and shaving the foot rests to be closer to the new scout footrests.
MiniaturePeddler's Weblog 
Well, I’ve built up 9 scout bikes now. I used 3 of the new scout bike designs, 1 Chaos Bike, and 5 standard bikes to build them. I had 3 plastic and 6 metal scouts to mount onto them. I will try to get some photos taken of them, but it started raining this afternoon and will probably continue through Thanksgiving, so I might not get photos till this weekend.
I will base them probably tomorrow and get them primed sometime this week.