If you want climbing and dirt roads, try these routes:
• Head up Sunshine Canyon for about 8-9 miles of paved solid climbing. After this it turns into dirt road running all the way up to the peak to peak highway. Some awesome mountain views.
• Same with riding past Jamestown (small town). Ride up Lefthand Canyon, through Jamestown and continue on. Eventually turns to dirt, roadies ride it but you'd enjoy it more on a good cross bike. Some steep climbs.
• There's also some great dirt/gravel trails by Wonder lake that run up North. You can take these trails all the way over to the Boulder reservoir, all on dirt.