Originally Posted by
wobblyoldgeezer
should an additional drag brake be part of the spec? I see this as a lifetime bike, and have Alps/ N Cal Sierras/ Sri Lanka from the tea plantations to the coast (5000 feet steady downhill) as some of its future tasks!
Unless your dealer is offering you a special discount and/or won't extend the discount to you at a latter time, I would suggest buying the tandem with the stock brakes and then evaluate what might work best as you have at least three different configurations to consider:
1. Dual calipers with supplemental Arai drum / drag brake running off a bar-end shifter: ideal for sustained speed control on very long, steep descents for any team and almost necessary for heavier teams or teams that will be riding with loaded panniers, etc...
2. Dual calipers with supplemental Avid BB Road 203mm mechanical disc brake set up as a light-duty drag brake running off of a bar-end shifter: good enough as a "just-in-case" supplemental brake for those occasional tours or rides when rim brakes alone may not be sufficient for speed control on a challenging descent for lightweight or middle weight teams. Note that the use of the Avid BB as a "drag brake" is not recommended or endorsed by Avid; however, teams who have used it that way with good success: YRMV / PAYOR.
3. Front caliper with full-time rear Avid BB Road 203mm mechanical disc brake running off of the right front STI brake lever: perhaps the best of both worlds for light to middle weight teams who find themselves in hilly terrain or wet conditions on a semi-regular basis. While not a true drag-brake that provides the benefit of the set-it-and-forget-it bar-end shifter for sustained speed scrubbing without cramping your hands, for aggressive teams who like to make spirited descents it provides superior downhill braking power to rim brakes with the added benefit of having a very high heat capacity that doesn't drive additional rim-brake heating into the rims and tires.
When last I checked, the Bontrager Race Lite Tandem wheels still came with left-hand threading that allows it to work with either the Arai drum or a thread-on disc rotor adapter which is what gives you the choice of brakes. You'll want to verify that this is still the case before making your decisions. However, assuming that is the case, you can see that you have the ability to change your mind and your brake configuration without too much trouble or expense beyond the cost of the brake hardware, a bar-end shifter, and a cable splitter that allows you to mate two regular brake cables together for the very-long brake cable run. The latter is recommended as it also seems to cut down on the amount of elasticity that you'll find on very-long brake cable runs.