Reddit mentions of Riddoch on the Outer Hebrides

I'm from Scotland, but haven't actually done anything like this myself, so I can only provide some preliminary information.

The main distillery regions are Speyside and the Western Isles. You should look at the Speyside Way - http://www.speysideway.org/ - which is about 80 miles long, passes quite a few distilleries and will provide a decent starting point for your route.

The Western Isles are also a popular cycling holiday destination, but will require a bit more planning. There will be plenty of guide books on cycling there, though, which you may want to take a look at. I know Lesley Riddoch wrote one - http://www.amazon.co.uk/Riddoch-Outer-Hebrides-Lesley/dp/1906307865/ref=sr_1_2?ie=UTF8&qid=1412441134&sr=8-2&keywords=riddoch - although I think it's more a memoir style book than a guide book.

I'd suggest figuring out which distilleries you most want to visit, figure out a route between them, and then stop at a few others on the way.