Red Mountain Downhill - West is a 5 mile technical descent. It is among the more technical trails in Vernal. Definitely bring your tools, and a spare tube. This post details the two track descent. There is also a singletrack descent, and an East descent.
The two track is a jeep trail. There are some pretty good rock drops, bumpy slickrock sections, and a few fast flowy sections of trail. This trail is techy enough to keep even good riders on their toes. There is a big double jump towards the bottom for those who dare, however you may want to check the conditions on your way up to make sure the lip is still good. Ride at your own risk. This trail is not frequenly ridden and I have never seen another soul while riding up there. It's probably best to have someone riding with you on this one.
The trick to making it up Red Mountain is to keep left at all the forks in the trail and then the opposite, keep right on the way down. If it is your first time riding it I recommend bringing a GPS with you.
If you are starting from Vernal Avenue and Main Street you will head West. Turn North onto 500 West. You will travel North to 500 North and follow the road as it turns West. Continue West to 2500 West. Turn North on 2500 West and travel north 5.8 Miles. There will be a dirt parking lot on your right. Head North on the two track which will start your climb of Red Mountain Downhill West.
* There are no restrooms, or water. Please come prepared with plenty of water.