WHEN are you planning to do this?
right now there is flooding on the trail between dotsero and glenwood springs meaning you would need
to head south into aspen and go over the independence pass
the bicycle colorado site states the trail between idaho springs and floyd hill will be closed until "mid-summer"
I just got an email confirming the trail is still closed dont have a clue what midsummer is
meaning until then at Idaho spings you need to go up to echo lake take squaw pass to bergen park
ie you will basically need to follow the triple by pass route backwards (you could skip swan mtn) assuming
the flooding stops and you can get to dotsero