Do try to find a shuttle to skip the A87 seciton. It's an extra 500 ft of climbing on a busy road and there is no reason to do it on a mountain bike if you can avoid it. If you don't like boggy sections and it is rained recently maybe skip the Strath Mor
Skye John Muir trust 30000 acres
First section was very boggy... Probably walked more than rode. Plan on getting feet very wet as they sink 3-6 inches into the "ground". Ride through at your own risk as it is difficult to know beforehand whether you'll sink 1-2 inches or below the axle. Trail for the second loch skirts the edge of the lake and at times goes through it. But than might be easier than the boggy ground because the Lake seems to have rock bottom. Once writeup said plan on riding through up to your top tube.
Transfer to opposite side of river... just after the pen... another site suggests to do it just at the end of first loch
After B road, a steep, rocky climb (but no bogs for now) awesome view at the top as usual.
Drop down on the other side down to the beach is cool. Do some rock surfing on the way down, but you are a long way from help. Turn inland at the well marked derelict stone cottage. From here it is all singletrack back to Hotel Sligachan, although sometime multiple routes around bogs (yes, a few more on this section, but not as many and not as deep; most of trail is rideable) or rock obstacles.
Technical descent with lots of rocks: big, small, loose, embedded, gravel, but not too bad a ride.
Another loch on this trail and awesome views of the Cullen mountains all the way to the north side of Skye. Several waterfalls visible along the way. After the loch, you roughly parallel a creek back to Hotel.