The B9007 / A939 are both fine for road bikes, the OMR isn’t really up to much.
Another, longer, route I enjoy is NCN7 to the Findhorn bridge, up the Strathdearn road to Garbole then the climb up past the windfarm and down to Farr. The B851 then takes you to an underpass at the A9, onto the B9154 and back via NCN7. Few food stops but the Strathdearn Hub in Tomatin is worth a visit.
Oh – an hour gets you from Aviemore to the ski centre car park at Cairngorm. Much quicker on the way back of course 😁
Bothy Bikes and Aviemore Bikes both do MTB rental. There are a couple of others but I’d stick to them.
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