Yep, got one of those too..and mountain biking (or cycling in general) is a good cross-training method.

And it makes your legs look fabulous.
I found out the hard way that motocross takes muscles too..a lot more so than I had thought and most people suspect.

I guarantee I'll spend the next few weeks tending to sore muscles that I haven't used in years.
I ride in closed-course competition and designated practice and riding areas, I'm too chicken to do the desert races..

In buying this bike, I did have a choice between street and mx....but mx racing's safer than the California roads any day.

And since my nickname's mxslick, well.....