OK, so here's what happened. Maybe somebody more experienced can tell me what to do.
I was getting ready to go riding when I noticed my rear tire was flat. I had a rear flat less than a week ago. I had an extremely hard time getting the last portion of the bead over the rim, if that is significant. It was much more difficult than I ever remember it being with this bike.
So I put the wheel back on and pumped up the tire, and got on. As soon as I started going, I could hear a really bad sound. It's sort of a clinking, popping, plinking sound. At first I thought maybe the bungee cords on my rack were loose and the plastic part bouncing off the spokes, but that wasn't the case.
It sounds like it's coming from the rear spokes, but I'm not positive. It only does it if I have weight on the bike. Turning the cranks manually doesn't produce the sound. If I lift my feet up and put my weight on the saddle I can feel the vibration of each pop.
Because I suspected the spokes, I took a look and noticed that a few of them are very loose. Could this be the problem? Do I just need to buy a new wheel?
If it's just spokes, that can be fixed very easily and cheaply. It isn't an issue getting a new wheel; I ride the same type of setup. A rear wheel can be expensive (haven't bought one recently, but they're more than fronts and one of those just cost me $50 for not even a very nice one), though, so try to fix what you have. it really sounds like the wheel just needs a good tune-up. the spokes are probably flexing quite a bit under load. if you continue to ride it in this condition, you're likely to at least get more flats and the rim may fail.
I just got back from the bike shop. At the first shop I went to, the salesman was very helpful, but he admitted they had such a huge backlog of repairs. Also, they didn't have a 27 inch rear wheel on hand to sell me. So he sent me to the second shop.
The salesman there was condescending, and wasn't willing to do business with me unless I bought both front and rear wheels ($120 for the cheapest no-name wheel set), tires, and labor . I told him my situation, that I won't get my paycheck for another 3 weeks, and I need something to commute with, but he wouldn't back down. It was all or nothing. That particular shop will never get a single dime from me.
Needless to say, I'm still without a working bike. I think the best option for me is to order some wheels online and do the work myself. What is a reputable site where I can get some wheels for relatively cheap? And is there anything special I need to be aware of?
Also, I forgot to mention. The rear hub bearings are pretty shot, so the whole wheel is pretty wobbly. I don't think I'm going to even try to ride it until I get it fixed.