You should be aware that carbon timing belts are used on higher end tandems and handle tandem torque fine. They will, in
tandem service last in excess of 20k miles. Tandems are available with belt drive on the timing cogs and the rear wheel
drive with 10-11 spd hub shifters. Such a set up would be very low maintenance, just clean the bike now and then and
once per year drain and add 5 ml oil to the hub.

Gates will be or is getting some competition from at least one European belt maker. They use a different tooth
configuration however.