Power vs. Heat

POWER vs. HEAT

Some will undoubtedly wonder why Santana supplies road tandems with rear disc brakes. The answer is simple. Santana pioneered the use of disc brakes on lightweight bikes in 1976, and has remained a leading advocate of disc brakes on tandems because of heat. While rim brakes are more powerful, braking occurs as energy is converted into heat. Because of doubled weight and decreased wind resistance, a descending tandem will need to convert over three times more force into heat. On single bikes, rims can get hot. On descending tandems, tripled heat blows tires off rims. If you plan to ride in the mountains, and your team weight exceeds 350, a non-rim brake prevents predictable blow-offs. Further, one non-rim brake is all that’s needed. Unlike a motorcycle, the safest and most effective place to mount the less powerful brake is at the rear, where braking power is four times less critical than at the front.

Exceeding the Melting Point

Finally, in the interest of safety, we feel compelled to pass along the following. Santana tests brakes on a 15 percent grade that’s two-thirds of a mile long. The vertical drop is 528 feet. At the bottom of this short test course the temperature of a disc brake caliper exceeds 500°F. (On a single the heat rise would be one third as great.) Two problems: First, this temperature melts plastic. Avid disc callipers with their red plastic fittings become paperweights after the disfigured adjusters render them unserviceable. Second, because cured carbon bicycle parts are destroyed if subjected to heat greater than 225°F, mounting a tandem’s disc caliper to a carbon fork or frame is, ahem, not recommended.

BRAKE TECHNOLOGY
SEE ALSO

Understanding Braking
Power vs. Heat
Disc Brake Technology
•••Mechanical vs. Hydraulic
Avid Brakes
Hierarchy of Braking Power