Aspen's Maroon Bells road climb is a tough one-way ride all the way up 17.6km to the foot of an incredibly beautiful wilderness area in the Rocky Mountains. Not one for weekend warriors; you'll need to have done a bit of hill training before you tackle this two-wheel challenge.
Chicks with picks
If you're a member of the fairer sex and want to learn the basics of climbing or, as the website says, "how to kick axe", check out Chicks with Picks. They offer tuition in rock climbing, bouldering and ice-climbing - think crampons and ice tools - so their wanna-be climbers can breathe in that fresh air and enjoy the wondrous views from some of the Rockies' peaks.
Backcountry huts
Enjoy tramping or mountain biking between Colorado's mountain huts with San Juan Huts. The firm helps health-conscious independent travellers wanting to go hiking, mountain biking or backcountry skiing into remote areas of southwest Colorado and Moab.
You can move between huts or use one as a base for day trips. Walk in summer, backcountry ski in winter. The huts have bunks and stoves. There's varying terrain for all levels and it is recommended skiers use a guided service.