Some folks prefer a mtn bike on the Highline Canal, although certainly not challenging in any sense of the word, and totally travelable by hybrid or road bike.
Lee Gulch Trail in Littleton provdes a slight challenge Available off of the Platte River Trail/Mary Carter Greenway. Also, the Big Dry Creek along Dry Creek Road and the Little Dry Creek. The Willow Creek Trail through northern Douglas County - right off the C470 trail at Park Meadows.
There are trails on the west side of Chatfield west of the ponds that you need a mtn bike for, and, when it reopens, hopefully, Waterton Canyon. Both are easily accessible by bake path from Wash Park, if desired.
You can ride through Parker and use the Hidden Mesa trail, 7 miles of more challenging mtn bike only trail.
At the east end of the Sulphir Gulch Trail in Parker are 4 miles of mild mtn bike trail.
But, let's face it - most of Denver Metro is pretty flat.
All of the above can be reached from Wash Park by bicycle.
Last edited by DnvrFox; 01-16-12 at 04:46 PM.