Question: I have a question that keeps popping up when someone checks out our Tandem. All and all most comments are positive on chosen components except for the “hubs”, which are XT Deore. The opinions are that they will probably be the first thing to go out on the bike. I realize that things will break down quicker than a normal due to heavier abuse but why the hubs? And, which hubs are better so I can prepare if necessary.
Response: The rear hub is likely the single most stressed component on a tandem mountain bike. It must handle the vertical, horizontal, and rotational forces applied by a tandem team. The long wheelbase of a tandem allows tandem teams to climb grades barely manageable by normal bikes. When combined with the double power and torque applied via the gear ratios the rear hub, specifically the freehub mechanism, receives extreme stress.
Standard Shimano freehubs use interlocking metal wedges and springs to allow the mechanism to operate. These small pieces fail regularly on single bikes and will fail when used for any extensive mountain tandem work. All hubs except the internally geared and Chris King use a form of the standard Shimano freehub and associated wedges and springs.
In contrast the Chris King Rear Hub eliminates the springs and wedges in exchange for a type of screw drive. The screw allows the free hub to rotate freely during coasting and almost immediately engages when pedaling. They also offer steel upgrades replacing the lighter but weaker aluminum internals for super strong steel. Link
For the majority of tandem teams the freehub body of a standard shimano type will see a premature failure. Upgrading to a Chris King type rear hub will result in the best possible outcome.