Hard work with big rewards on a popular section of the Colorado Trail.”
— Mike Ahnemann
This trail can be ridden in either direction, although it flows a bit better and the climbs are more climbable heading down from Georgia Pass, as mapped here. I've chosen to map this one from Georgia Pass because many people connect this to the Colorado Trail: Kenosha Pass to Georgia Pass, creating a big shuttle ride from Kenosha Pass to Breckenridge. You can also ride this up from the trailhead by Tiger Run on Rte. 9, which is where this trail ends as marked.
In this direction, you'll find yourself at 11,900' for the start, with about 6.5 miles and 2000 vertical feet of descent. Don't take this section lightly though - although it's a fantastic singletrack descent, it does have some rocky sections. One section in particular is one that less advanced riders will consider walking - big rock step downs on top of loose rocky trail make for some sketchy moments.
Once you finish the first big descent, you'll find yourself at an open spot along the Swan River. If you've brought a water filter, this is a great place to use it. Otherwise, it's a nice place to eat a snack and cool off. You'll want to catch your breath here, because the next 3.5 miles bring a big uphill grind with over 1000' of climbing. This section gets quite a bit of sun, and it's granny gear climbing in spots, making this a real grunt, especially if you started the day at Kenosha Pass.
However, more reward is in store after the climbing is done. The next descent is beautiful riding - less technical than the first descent, and flowy enough to let it rip. It's good enough to restore your energy, which is good because you're not done yet.
The rest of the trail has changed quite a bit due to big clearcut logging operations that have changed the character of the area and reduced the amount of shade available. Although the rest of the trail trends downhill, there are a couple of short and sharp climbs which you can see on the elevation profile below.
Keep an eye on the MTB Project mobile app for this one, because there are a couple of unmarked trails that branch off this one, and it's possible to get yourself headed in the wrong direction, although you'd eventually pop out to the road and make it back to the trailhead either way.