Hi Fodorites,
I'm going to Strasbourg for 3.5 days in a couple of weeks and since it will be my first time there, I need some help. I've decided to use Strasbourg as my base city and would like to do day trips to Colmar and 1 other small picturesque town while I'm there. I also would like to do some biking in the "countryside" if possible (won't have a car so will travel by train). (Ie. any short easy trails that I can do while enjoying the Alsace scenery)

The hardest, and most boring, part of your biking program will be riding OUT of Strasbourg. Try to avoid this. I suggest that you catch the train (with your bike) to COLMAR and start from there. Ride to, and visit, KAYSERSBERG, then go through Bennwihr and Zellenberg to visit RIQUEWIHR. After that, the next place to visit is RIBEAUVILLE, then through St Hippolyte to Selestat, where you can catch the train back to Strasbourg. The ride would be about 30-40k, and you would visit at least three very picturesque towns, not including the old centre of Colmar. The ride is gently undulating, and mainly follows the famous Route Des Vins, which is on the western side of the Vosges Mountains which form one backdrop. The other backdrop is the Black Forest Mountains across the Rhine in Germany. Alsace is a splendid spot at any time of the year, but particularly when you will be there.

Okay, this will sound really stupid, please forgive me....but when you rent a bike, do they also give you a lock? I'm thinking that could be a nice (albeit wobbly!) way to visit a few wineries there, but would then need to make sure the bikes are safe... is that easy to do? It sounds like a lot of people bike there, so I'm guessing this isn't a problem?

I don't know about the lock, but you could easily get one cheaply at one of the many '2€ Shops'.
If you were to follow the route I suggested above, but wanted to concentrate on wineries, then I would recommend Hugel, Dopff et Irion, and Dopff Au Moulin in the centre of RIQUEWIHR, and, best of all, Marcel Deiss, perhaps the top Alsace producer, whose tasting rooms are on the righthand side of the road as you enter Bergheim, having cycled from Ribeauville. Tasting are free, but there is some expectation that, having sampled a few bottles, you will buy one or two that appeal. Carrying your purchases on a bike might be a good trick!

Ah yes!!! I forgot about buying wine, which i will certainly do. Hmmm....must think on this. Thank you for your reply!