Adam suggests moderately-steep hills which take 5 minutes to climb but are not too steep going back down. Here are suggestions:
Remington Rd. uphill from Boynton JHS, after the first steep S-bend. This is a steady grade up till the elbow below the steep pitch up to N Sunset.
Snyder Hill Rd. up from Pine Tree.
Renwick Rd. from above the IHS track to the intersection of N. Sunset.
Several others are good pitches but maybe < 5 minutes for faster folk? Dodge, Game Farm.