Newbie - Looking for a Good Thrift Bike
 

What would be good small bikes for triathlons/duathlons that are sometimes found in thrift shops or craigslist? I'm just starting so I'm not looking for anything super high-end—just something light weight, dependable and good for beginners.

I'm a petite female distance runner who just started getting into bicycling. I helped my 9 YO train for her first youth Duathlon. She loved it so much she is continuing to run and bike through the winter and hopes to do more races in the spring and summer.

It looked so fun I was thinking of training for one of the smaller races myself. My current bike is a beach cruiser (heavy). I found some kind of 1990s Caloi with an aluminum frame for $12 (probably could use some new tires), but I'm wondering if I should keep looking around.