I biked around the Alsace wine region for three days, all based out of Colmar. It was utterly fabulous.
Here are a few tips maybe not covered by others.
1) Rental bikes in Colmar were surprisingly scant. A few places listed as rental shops were really just small independent bike shops with just a few randoms to rent and short business hours. I checked with a few of these and they'd rented their entire (small) fleets already. So I rented a somewhat leaden and clunky but solidly operational city bike at the place in the train station for something like 10 or 12 euro a day for my whole trip. I rode 30-60km a day on it and was fine, but a better bike would have been fine too. Folks working there nice but not proactive about offering extras. I asked after a pannier and they instead were happy to put a basket on for me. I asked after an extra tube and the guy opened a cupboard full of repair kits and handed me one.
I've read that there's more bigger rental outfits in some of the bigger villages - search that up. I stopped by Cycles Wagner in Turckheim too - bigger US style bike shop that had a decent rental fleet.
The issue then is getting out to the villages if you are staying in the city. I love to rent a bike as soon as we get to a city, ride it out of the city in various loops, use it to tour the city during during quiet hours - so magical! Maybe asking your hotel would be a good move?
2) Some of the best villages, and the finest wineries, are separated by some hills. It is because of these hills that these are great villages with great wines - the sloping terroir of the four grand cru vineyards produces the best fruit. And it's also the most beautiful landscape in the area. You are going to want to ride from Ribeauville to Kayserberg for sure, and in the process you'll ride up some moderate hills, maybe 1k feet of climbing in the day, nothing super steep but a can be hot. Take your time, pack some water, and take a break or two. But do it.
3) Mind the traffic even in the country - there's a lot of easy, safe riding on country lanes, but occasionally you're on road, and occasionally a local man (always a man) will come flying through in a 25 year old Peugeot with shot suspension like he's racing the 24 Hours of Le Mans, caroming out of his lane as his car bounces and rifts around blind turns. Rare but I saw it a few times, and all it takes is once. Don't be afraid, but do remember to always stay well to your side of the road as you gawp at the gorgeous scene.
4) as for tasting, it's like most anywhere else, from giant COME ON IN signs, to find us around the place and we're happy to pour for you, to by appt. only, to by appt. only and YOU will never get one, to you can taste our wine when you pay $80 for a bottle somewhere else.
5) Picnicking on a well-place bench way out in a serene vineyard on top of a scenic hill is sublime. The bigger villages are chock-a-block with gourmet/artisnal take-away food outlets, so shopping as you go is a fun way to build your lunch. As is sitting at a restaurant out there- tough to go wrong!