There's nearly no shade along this whole route, and it's on pavement, so it's not a great midday run.
Of the myriad bike paths in Summit and Eagle counties, this stretch of paved trail between East Vail and Vail Pass is very popular, but not really the best. It is, however, often the top choice of locals looking for hill climb training, and for tourists, who arrange for a shuttle to drop then off at the pass and amble downhill to Vail.
To start this path in the downhill direction, find the large parking lot off I-70 exit 190 on the west side of the interchange. From the north end of this massive parking lot, follow the paved road that parallels the freeway on the west side. Pass two reservoirs (Black Lake 1 and Black Lake 2, popular with fishermen). After a gate, the road becomes paved path at this point and is set apart from the highway. It is quite pleasant here with good views of Black Gore Creek.
The next stretch of path immediately adjacent to the highway is much less pleasant. Oncoming trucks are noisy and a little scary (there's not even a guardrail here). Soon enough, you swing around, go down steeply, then make a sharp right turn and go under the freeway. Accidents occur here regularly - so watch for bike traffic!
Past the freeway, run slightly uphill and into the forest. Cross over Polk Creek, then go a little further until you meet the Old Vail Pass Road. This road was abandoned long ago and is now just a nice wide, newly-paved multi-use path. Head steadily downhill until the path ends at Bighorn Road and the Deluge Lake
trailhead parking area.
To continue to the town of Vail, follow Bighorn Road for a mile or two until you find the Gore Creek Valley Trail (East)
turning off to the left. It is right near the East Vail highway exit #180 on the southwest side of the freeway.