No singletrack to speak of (so far as I know), but if you're content with jeep roads the possibilities are endless. Below are some reports I've written up of previous trips. Click the links for lots of pics.
: (1) Blue Sky/Skyline summit at the core of the refuge, (2) through the Coyote Hills to Colvin Timbers, Abert Rim overlook and back, (3) very short ride up to Warner Pond, (4) mostly paved ride from Plush to Lakeview.
: (1) short trip from refuge HQ to Poker Jim Ridge overlook, (2) along the Nevada/Oregon border to an overlook of Hawksy Walksy, (3) flat cruise along Campbell and Bluejoint lakes at the base o Poker Jim Ridge - NOT doable at wet times, probably including this year, (4) bike+hike to Hart Mountain summit.
: Sorry, many of the pics from this one have gone missing, but still some great stuff ... (1) loop ride from park HQ around Spanish Lake, up Guano Creek, Blue Sky and Skyline, (2) short out-and-back from near the OR-NV border to the Sheldon antelope refuge -- LOTS of future potential here too!
I've had lots of great rides out there, but if I had to recommend ONE ride it would be the ~28 mile loop I did in September 2002. VERY approximate directions - please verify on a map and use your own best judgment: starting at Park HQ, ride clockwise around the main park loop to the eastern "summit" of the main Blue Sky road, descend (east) down a couple miles to a jeep road and follow it and several other roads (S, then SW) across several dry lakebeds (staying a couple miles below the main graveled road to Blue Sky) to Guano Creek road, then (north) up past Blue Sky to the saddle where you meet Skyline. Ride (east, then N, then east again) up Skyline to the summit and enjoy the blast back down to the Blue Sky road and return to park HQ.
The rides I have actually done in this area barely compare to the ones I still hope to do before I die:
1. Start near deadhorse (horsehead?) lake, accessed off OR140 east of Plush, and ride up Guano Creek to Skyline and back down. Almost certainly a 2-day trip -- if you did it right you could camp at Hot Springs the night before, drive to Horsehead first thing in the AM and you'd have a camp set up for yourself that evening. You'd be riding through the area in this photo:
2. Ride north from park HQ to the edge of Orejana Canyon. I've backpacked in this canyon before (see pic below), and it's a great spot, teeming with wildlife (in addition to cows) including bighorns.
3. Ride east from somewhere along Blue Sky road out to Beattys Butte and back. This is a looooong trip, at least 2 and possibly 3 nights. There are several possible routes, including the possibility to explore a number of jeep roads along the east side of the refuge without going quite so far.
4. There are at least a couple roads that go the top of Warner Mountain or nearly so, including at least one that descends down the other side (near the main access road). I'd love to explore these more, but they are gated and marked "no vehicles". I haven't talked to any officials at the refuge in quite a few years about this, but I'd love to get a clear ruling as to whether they really mean "no motorized vehicles" and bikes might still be allowed -- which I suspect might be the case, but they probably haven't had many inquiries. If so, the trip to the summit of Hart that I did in 2004 would be a LOT easier than the way I did it (which was to ride to the gate partway up the mountain -- I think since then they may have moved it further down -- and hike from there). The "road" does
reach the summit plateau, and it would be awesome to be able to bike up (and down) the whole way.
And remember, if you spend any time at all out there you are certain to see pronghorns. Lots of 'em: