The Critical Role of Tandem Forks
Besides doubled rider weight, other factors make a tandem fork work 4-5 times harder than a single bike fork. First, tandem forks take more hits. On single bikes we “lift and sail” over bumps to reduce impact. Tandem forks, however, must withstand the full force of every bump. Second, because tandems can descend 40% faster, the force required to stop a tandem (f=mv2) is up to 400% as great as a single bike descending the same hill. Because front brakes provide 80% of the stopping power on any vehicle, maximum braking can occur only if a tandem’s fork can withstand quadrupled braking force without shuddering or failing. Our concern for your safety is why Santana uses larger tandem-specific fork blades and stronger Evolution-sized steerer tubes and crowns.
Do forks fail?
Fork failure is the #1 justification for bicycle recalls. On a single bike with a standard fork an incipient failure can sometimes be spotted. Unfortunately, when a fork with this sized (11/8”) steerer tube is used on a tandem the expected failure point (just above the lower bearing race) is completely hidden from view. Most bike component failures won’t cause an accident. Tandem fork failures nearly always cause an accident which puts both riders in an Emergency Room. Do to the need for doubled design strength Santana not only insists on Evolution sized (11/4”) steerers, we verify adequate strength through independent lab testing. Do other tandem builders bother to lab test their forks for doubled resistance to impact and fatigue? If they did, they wouldn’t rely on standard 11/8” steerers.
