I'm a longtime cyclist but just started commuting about 6 weeks ago. About 5 weeks ago i switched out the tubular wheelset on my bike for some 36 spoke clinchers. Last saturday I went back to have my LBS make sure the wheels are still true.

I've put about 380 miles on the wheels since i bought them; 95 of those in the week since my LBS trued the wheels. Today on my way home i broke a spoke on the rear wheel. Thankfully i was only about a mile from home and was able to limp back.

I ride with a pannier strapped to my rear rack. it probably weighs in at 20-25 lbs most days. Could the extra weight have contributed to the spoke breaking after this little time? Or, could this have been some issue with the wheels themselves or with the way the wheels were trued by the LBS? I'd just like to figure out whatever I can to make sure it doesn't happen again in the future?

I think one of my mistakes is not knowing how to true wheels and replace spokes on my own. tomorrow that will change.