Hi Gang,
Yesterday I joined the ranks of Tandem Riders with the arrival of our new Co-motion Speedster. Ever since I saw one at a Century some time back I have been lusting after one. I'm hoping this will shorten my wait, at the top of hills, etc., for my wife. :D
Anyway, I'm getting ready to put together my tool kit and I seemed to recall reading somewhere if one was in need of a chain breaker to stop a tandem- they always have one. That got me to thinking; do I need to carry one of these on my tandem?? With my standard DF road bike I've never had occasion to use one, nor have any of my friends. So, Do I need to carry one and if so what am I likely to need it for?
Thanks in advance, Bone

I recommend that any who rides a tandem have either a multi-tool with a chainbreaker, e.g, Crank Brothers Multi-tool (http://www.pricepoint.com/detail/11909-325_CRBBT2-2-Accessories-42-Tools/Crank-Brothers-Multi-17-Tool.htm) or an honest to goodness mini-chainbreaker like the Park CT-5 (http://www.universalcycles.com/shopping/product_details.php?id=1132&category=746) AND a reuseable chain link like a Sram Powerlink, Forester Superlink II, or Wipperman Connex.

As for what you'd use it for, basically if you have it you won't need it: consider it a good luck charm. However, if you don't have the tools and parts needed to repair a chain, the probability that a late rear derailleur shift on a steep climb in one of the taller sprockets (28, 32, 34) causing a rear chain to pop a rivet becomes much higher. Seriously, a tandem generates a lot of power at the rear hub and a marginal Shimano one-time-use rivet installation or any other weak link that happens to pass between your rear derailleur's jockey pulley and one of the larger cassette sprockets could pop under a high load.

We broke the timing chain once, a few km's from our house. Now we carry a chain breaker and a few spare links. Beats having me push from the back on my wife's low seat, while she tries to brake and steer. We carry the Topeak Hummer with a chain breaker, but I understand Crank Bros has the best warranty, so I'd go with their Multi 17.

Chain breakage is a bit rare on a single or tandem.
Have broken only one chain on a single and half dozen breaks on a tandem. However that is in 30+ years (200,000+ miles) of tandeming and about 50,000+ miles of single bike riding.
Having said that, better to have it and not need than to need it and not have it!

Call it Boy Scout Insurance.