I have walked the lockside path, and whilst I reckon you would be on and off the bike a lot, It would be a nice ride, especially when you throw in the scenery. Don't know if you guys are interested but just found this:
''Not only was there a path running up over the pass and into Gleann Unndalain, but it was one of the nicest paths imaginable. The impression I got was that it was an old packhorse road, but it was certainly old and blended very well into its surroundings.
Often clinging to the edge of the hill, it wended its way oh so gently up to our high point of the day of just under 550m.
I already had a grin on my face, and was skipping along, but didn't expect the path to continue down the other side.
It did, and with stunning views opening out over Barrisdale Bay we made our way down to Barrisdale''
Sounds promising right? I guess there is only one way to find out