Quite the adventure ride, which I rode solo at a fairly slow and easy pace; I stopped a lot to take pictures and to check things out since I doubt I'll be back. The dirt riding is not difficult until near the end, but the washboard roads are an issue from the start of the dirt to the zip line facility. Not far from the end of the dirt section there was an area with a fair number of steeper and very rocky pitches which are quite challenging on a road bike with 25mm tires. They would have been easy on my 29'er mountain bike and would not have taken any technical skill to blast straight up, but to maintain traction and continue up on the road bike with normal road tires requires an increase in speed and cadence and care in picking a good line up the pitch. I could have made it through any individual such pitch (one might have taken a couple of tries) had I been fresh, but as things were I had to stop and unclip maybe 5 times, and actually walked 10-15 yards through two of them: one because I had not looked ahead to pick an advantageous line, and the other because the continued effort was not worth it when I had no idea how much there was still to go (i.e., I wimped out!). This section eases with a drop in the average grade and there is no more true difficulty. Anyone that is comfortable on a hard packed dirt road can do this and just jump off and "hike the bike" up any technical sections and still do this ride; such sections are short and no time would really be lost. (See: the "dirt" segment or annotation on the left panel.) I should have taken care to refuel more than I did and the skimpy breakfast I had in Oracle was insufficient to get me up to the observatory. Two nights of too little sleep and plenty of drinking both nights with Jessica Taylor et al. in celebration of her graduation did not help. Regardless, this is a very satisfying ride. The Ski Run Rd was evidently not paved beyond the ski area until a couple of years ago, but there is no reason not to go all the way up to 9,000' now. There is a "road closed" gate with a gap to the left which I was able to ride through and continued all the way to the observatory facility which has a more serious gate that does not permit passage (and also has a sign indicating access is restricted to authorized people only). There isn't any scenery to see on this last short section beyond the earlier "road closed" gate; the only reason to bother is to finish off the climb "to the top"; when you are at the "road closed" gate, you can see the road continues up! The scenery and the ride is well worth it, but if you only have one chance to ride up Mt. Lemmon, I think I'd recommend the regular, paved road up the front side because of the amazing scenery of the hoodoos, etc. I saw the scenery while descending, but not to the extent you can when riding up the mountain at a much slower speed. If I have reason to drive through Tucson and have my bike with me, I'll certainly take the time to ride up. I had originally planned to stop and get a slice of pie apple pie à la mode at the Sawmill Run restaurant on my way back from the observatory, but I was hungry and was giving serious thought to stopping there before riding up Ski Run Rd -- only, there was a lot of thunder developing and I thought I should get up the rest of the way before any deluge from a thunderstorm overtook me. On my way back down, just past that "closed road" gate, there was a turnout with an amazing view and I could clearly see a couple of areas where it was raining fairly hard, so I skipped the pie altogether in order to head down the mountain in the hopes of getting to lower elevations before possibly getting soaked. I did get soaked, and the water drops were so large that they stung if they caught me in the cheek; it was on the cold side for a short while, but the temperatures started to rise fairly quickly with the drop in elevation and I was pretty much dry (except for my suede shoes) by the time I got back.