Cyclocross?
 

I've been an avid MTBer now, but now as I am getting older-17- I am riding my fuel on cement 90% of the time I am not out on an official trail. My friend got interested in it, and now he got me interested in it. So what is it exactly? It seems like a road bike with knobbs on the tires. Looks fast and fun. Browsing around at your CX bikes on here, it appears most bikes are pretty custom. One can take these bikes off roading too? Hm.

if you're asking what cyclocross racing is, it's like an on-road/off-road obstacle course race. sometimes you have to get off your bike to get through stuff.

getting older - 17!!!?? Get on those trails young man!!!

Watch out! You're looking down the barrel of 20 years old! Beyond that is nothing but the cold grip of death!

Ride, ride, RIDE!