I've just acquired my second Birdy -- a black Speed. I'm loving it, but I still need to tweak it in a few ways. The first is that I think I need to get a green elastomer. The red one is a little soft to my taste, and the bike squeaks and bounces too much, especially if I'm up on the pedals and trying to accelerate up a hill or the like. I weigh 185 lbs., and the green elastomer worked well for me on my old Red. I'm not sure where to acquire one easily in the US. Any thoughts?