We have experience on a Tandem, but we have a new C0-Motion Supremo. We have less than 400mi on it and we are still getting used to it's handling characteristics. We came to a steep downhill yesterday. I'm guessing 16%-18% for about 3/4mi. with some gentle turns. We got off and walked down because I was afraid. We have Dura Ace caliper brakes. We are 275lb team weight. I'm afraid of popping a tube due to excessive heat build up. I just don't know where that point is. I'm good with the brakes. I know how to feather them and alternate them. I like my technique. I just don't know at what point i will exceed the capabilities of the brakes themselves. I'm not going to get a drum brake because I would rarely use it. Can I ask you to share your experiences and offer suggestions?