I was in there in April for 2 days, when it wasn't very crowded. My first stop was the Reims TI at 10 a.m. on Sunday, and they booked a Martel tour for me for later that day. Some tours at some of the caves were already completely booked. I took the Tattinger tour as a walk-in, then the Martel tour. The next day in Epernay I took the Mercier tour - first come, first serve basis, but the tour was far from full. Though I'd toured Korbel in California and was familiar with the méthode champenoise, all three tours were interesting. Only a very little of each tour was duplicated information and the caves themselves are worth seeing. I enjoyed learning about the families, the region, the grapes and so on.
In Epernay, I walked about a kilometer long the Avenue de Champagne from the TI to Mercier (about the farthest out). I passed the champagne houses of every name I'd ever heard of and several I didn't recognize. It looked like several had tasting rooms, but by the time I left Mercier I didn't think I'd be up to drinking more.
At Tattinger and Mercier . You have a choice of tasting 1, 2 or 3 wines (and paying for the pleasure). Tattinger was the most expensive, but their poured their reserve wines. . Martel was the most generous, with smaller tastes (less than the usual 1/2 glass) but lots of them.
You can drink champagne by the glass at restaurants and cafes. Even at the train station cafe, there was a choice of 3 or 4 from the large producers.
I don't know if France has any laws governing cyclists, and in particular regarding any limits on blood alcohol limits (the limit on drivers is 0.5 %). In any case, it's unsafe to cycle "under the influence." If you are staying in Reims and in Epernay, you can easily visit all the champagne houses in the towns on foot.