In reply to ElvisMax1:
depends where your're starting from. If from loch muick, then you'll not save much in approach beyond the river fording (though up to there will be much quicker) and it's not a pleasant cycle beyond. In descent from the coll path junction you'll be a LOT quicker and it's not nearly as horrible to descend as ascend! If you're coming from Deeside, it's a pretty easy cycle in from the north to the Coll and back out again on a good landy track and doesn't take long.
Dubh lock and eagles rock are both best approached on bike as far as path junction.
Cheers,
Stu