1) Nobody just "tastes" wine. Everybody swallows. Yes, everybody. Only weenies spit it out like you see in the movies.
b) I have done a bike tasting tour. Even for a short distance (<10 miles) it's fairly challenging, especially after the 3rd or 4th winery (why lie? wine is great!).
iii) My conclusion is: wine and cycling just don't mix very well, unless the wine comes *after* the cycling. Before or during is just a little bit too much excitement, especially along the popular wine routes (drunk cyclists + drunk drivers = !@#$%^!!!).
I will say, though, that I thought it was a good idea at the time (I was young and childless), and I had a great time doing it. My conclusion in number iii) comes from the lack of wisdom acquired through aging gracelessly, so take it with a grain of salt (and pepper).
Also: all of the wineries we visited (Sonoma area) were bicycle-friendly and we didn't feel at all out of place with our cycling gear on.