This is very bizarre. Riding on Sunday, I hear a "ping", stop and find one of my rear spokes has broken...and in the center. Figure I'll get it fixed the next day. So next morning I'm riding and, again, "ping" another rear spoke popped. This one broke closer to the hub end. I brought it to the LBS and they replaced the 2 spokes and trued it for $25. Mind you, the bike isn't very old and the spokes don't appear corroded (I don't beat on my bikes). The bike is a Bianchi which I only ride on pavement. I've had some bikes for 20 years and never popped a spoke, not even my MTB! So, 2 new spokes, wheel trued, I'm doing a 25 mile ride today when at around 10 miles, "ping"; then on my way home, another one (both back wheel, again). WTF! Two questions, any idea what would cause this? All broken spokes have been on the freewheel side of the rear wheel. Also, I only weigh 170 lbs., so weight isn't the issue. The only recent change (can't imagine it would have any effect) is new tires, which take considerably more pressure than the old. Second, should I rebuild the wheel (all new spokes) and approximately what should that cost. I'm thinking a new wheel might be cheaper, but there's nothing wrong with the current rim and hub. TIA.