The most fragile part of a carbon tandem is the paint job; just knocking one over that leaned up against a post or tree can fubar the finish. Beyond that, they're just like any other bike, perhaps even a bit more durable in that they don't dent and it takes a really hard knock to actually do any damage to the composite materials.

However, because it's a composite frame all but the most mangled frames can be fixed. Moreover, if a frame turns out to be a bit too whippy -- such as a frame originally built for a 260lb team that's bought by a 360lb team -- the frame can be reworked to add more material to beef it up. Now, to be fair, there's only one company that's well known for reworking busted carbon frames and that's Calfee. In fact, there's a photo somewhere on the net that shows a shop area where frames are queued up for repair and you'd be amazed as how many Scott, Orbea and other brand name frames were in there for repair.

Finally, Craig Calfee will tell you that when he has gone off into the wilderness he'll take along a small frame repair kit -- I'm guessing it's some sheets of carbon fabric, epoxy components, a swizzle stick and a Dixie cup -- so that he can make any field repairs that might come from a major shunt. If I recall correctly, the way he characterized it was short of any crash that sent the rider to a hospital or worse, he can't think of any crash damage that couldn't be field repaired to get yourself home. Now, while I suspect there's probably only one person riding around with a carbon field repair kit, it does underscore the repairability of a composite frame.