Yes and no.

You're a 310lb team which falls on the left hand side of the bell curve for tandem team weight. Therefore, the need for the drum brake is somewhat questionable UNLESS you:
A. are doing a lot of long, steep, technical descents and like to keep your speed in check...
B. plan to do loaded touring or will be pulling a trailer in hilly terrain... or
C. are otherwise not inclined to make spirited descents and don't want to risk overheating your rims.

Assuming one or more of the above apply, then an Arai drum brake is the only "true" drag brake for those applications.

However, if you'd just like to have a rear brake with a bit more heat capacity than a rim brake for the occasional steep hill that makes you feel as though you're pressing your luck with rim brakes, a 203mm Avid BB Road mechanical disc brake hooked up to your right front brake lever as the primary rear brake may be the ticket. That's what we and many other teams have migrated to who have found that a dedicated drag brake just isn't needed; however, still find ourselves on descents where we know weve pushed against the edge of our dual rim brake's performance envelope. There are a few tricks to getting them set-up correctly, then there is the break-in time, and they do require a bit more attention than your rim brakes relative to keeping the pads properly adjusted for heavy-duty users. However, at least for us, they have been a vast improvement over rear rim brakes or any other combination of rim and drum brakes... noting we're a 285lb team that likes to bomb the descents.


That depends on what you ultimately decide to go with for a rear brake and/or supplemental brake. Your Co-Motion has 145mm rear spacing so there are several options. At the high end, Chris King will sell you a disc compatible rear hub, but doesn't offer one that is threaded for the Arai drum brake. Phil wood also offers a disc hub, but it's rather massive: just not their niche IMHO. However, their threaded hubs are fine for the Arai and will also accept a thread-on disc rotor adapter. Although, be mindful that any of the thread-on disc adapters are a bear to get off once you've been using the rear disc. In the mid-range, the
White Industries hubs are very nice and come in both threaded and disc mount versions and there is of course the threaded Shimano HF08 hubs. I believe the DT/Swiss hubs are all black these days so that doesn't fit your spec. I'm sure I'm missing a few, but those are the big names in tandem hubs.


I'd check with Mark Johnson at PrecisionTandems.com, Mel Kornbluh at TandemsEast.com, Rich Shapiro at GTGtandems.com, or perhaps even the folks at the Bicycle Outfitter in Los Altos, CA. Mark will most likely have what you need, particularly if you're considering the disc set-up ILO rim + drum. Mark and the others will all have the drum brake components and you can sometimes score a barely used Arai drum brake on Ebay for not a lot of dough.