Q: On a recent outing our ride took us down a descent with grades in excess of 15% on a hill that was over 4 miles long. We have disc brakes but the rotors and pads must have over-heated because by the end of the downhill it took all of my strength just to stop us. How do I prevent this in the future?
A: Due to the unique nature of tandems, including riding style, total weight, and long wheelbase, the various components are stressed to their maximum. For example, it is not uncommon for a mountain tandem team to go through 2-3 free-ride specific bottom brackets in a season. The example descent in your question, although extreme, represents a relatively common occurrence for most regular tandem teams.
If you plan on taking on downhills of the nature described in your question then follow the recommendations below:
- Install downhill type disc brake systems. These systems include 4-6 independently operated hydraulic pistons, regular DOT brake fluid and full hydraulic activation. The rotors should be the 8″ type with slots to dissipate heat and allow debris to clear the rotor path.
- While descending practice modulation of the brakes (varying the amount of force applied) including the complete release of a brake to allow passing air to cool the rotor and pads. When fully releasing a brake wait for a straight away or alternate full release with the application of the other brake.
- Brake fade as described in your question is more the result of super-heating brake fluid. When this condition occurs you are increasing pressure within your brake lines. It is best to stop and allow the system to cool. Water can be splashed on the rotor and caliper to facilitate the cooling also.
- Regularly replace your brake pads (even if they still have pad remaining). Heat and moisture conspire to harden the friction material and deteriorate braking performance.
- Ensure your tires are appropriately suited to the terrain and properly inflated. Incorrect traction can increase the amount of braking force required to control your tandem.
- Use more of your body to slow yourself. Create a large profile in the wind to limit your velocity.
Learn more about tandem disc brakes here