We have a Co-Motion Speedster which we have had for a year. We had no prior Tandem experience and we still consider ourselves novices...although improving. Our bike came with Avid Shorty 6's. It has no drum or disc brake. Our combined weight is 270lbs. People in our club always comment that we need a drum or a disc, but so far, we have not had any problems stopping. The LBS said that because we are not that heavy, we would be fine with the cantilevers. We prefer hilly rides, but we don't live in a mountainous area. What do you think? On a seperate note, while our Avids stop fine, they have a crazy, loud squeal that cannot be adjusted out. Apparently the squeal is common in this style of brake, but more of a problem with Avids. We are considering the Tektro CR-720. Any suggestions?