Short CX/Gravel options…
Speyside Way to Kincraig, Feshie Bridge, return via Drakes Bothy and Loch Gamhna.
Logging Way to Badaguish, Beglan (ruined) village, descent to Glenmore, Back of Loch Morlich, Picadilly, Loch an Eilean
Loggers to Glenmore, ski road to Sugarbowl car park, old zig-zags to Cas. Retuen via the zig-zags and the Allt Mor path, then back of Loch Morlich etc or straight back down Loggers if time is short.
Speyside Way to Kinveachy junction, various woodsy double- and single-track options in and around the Fairy Hill. Retrun via the chambered cairn and some more nice singletrack.
You could also do the Loch Eaniach route. It’s rough in places but definitely do-able. I took @ton up there on a rented fatbike earlier this week. He tried to buy it off Bothy Bikes when he got back 🙂 Said it was the most fun he’d had on a bike in years. We did 2h45m moving time but that was “old men on fatbikes” pace.