Question about Combat Cruisers

[***First of Two Latin Kings***]

Did anyone else buy these? I thought they were pretty nice. Still waiting for a review to show up on your site, TMNTman. I bought Leo and Don of the Battle Bikes sets, and was planning to only get Mike and Raph from the Combat cruisers, but seeing how nice they are I might have to go ahead and get Leo and Don if money permits.

My question: Does anyone know why Mike comes with a set of gold-painted plastic gears? Raph doesn't have them, so I'm assuming that Don and Leo don't, either. There's nothing about them on the box or in the instructions. I have no clue what they're for.