Hi folks!

I broke a spoke for the second time on this wheel, but I don't think I'm overstressing it. I'm wondering if it was poorly built or if I need to ride differently. Here are the details:

The bike is of unknown make: it's either custom or had a custom paint job. It's a 54cm lugged touring frame w/ Columbus Tubing as the only decal. Originally 27 1/4, it's sporting 700c rims, but backwards from what I would expect: 36h in front, 32h in back! Naturally it's the back one that's giving me trouble.

The decal calls the rear wheel a Mavic Open Pro with smaller text reading Maxtal S 5000 (or maybe 6000); also, "SUP" with smaller "UB control". The hub is Shimano 600. It's driven by an 8-speed 11/28 freewheel (?). I need to spread the stays slightly to install the wheel. I've got 28c Continental Gatorskins running roughly 100psi. (The front wheel is an Araya with a Sansin hub (which was beat to hell when I repacked it 3 months ago, but still rolls well enough)).

Total bike + rider weight is maybe 190lbs: 30 of it bike, 160 of it rider. On occasion I have a trunk rack that adds 10/15 lbs, but I wasn't riding with it either time I broke a spoke. I commute to school 2.5 miles each way on city streets at 25+ mph 4 days a week and run random errands with it. I go for longer rides when I can: 60 miles is a good outing for me. I put a little over 1100 miles on it since I got it in October last year.

The first time I broke a spoke was towards the end of a mellow 25ish mile ride with my girlfriend. I don't remember any particular stress before I heard the snap. I certainly hadn't been riding hard. I had REI replace the spoke and true it and figured I was golden. This was somewhere around March. On Friday after slightly less than 60 miles I made a right turn at a not-unreasonable pace and heard a snap. Same thing: chainring side spoke. I removed the broken spoke and trued the wheel enough to get home, and now I'm wondering what the hell I should do.

Does my wheel suck? Do I have bad luck? Am I too fat? (Really?) I can't really afford to buy a new wheel, nor can I afford to have my primary transportation tied up in the shop for 3 days every time this happens. I think I can replace the spoke myself and just true the wheel on the bike, but what are your thoughts on this? Also, any thoughts on continuing to ride for a day or two with that spoke gone?

Thanks for looking at my long-winded question! And, even more, thanks for sharing any thoughts you might have!