Bremsen für Tandems: Unterschied zwischen den Versionen

==Bremshebel==

If your tandem has upright (straight) handlebars, you need to match your brake levers to the type of brake calipers/cantilevers you're using. This boils down to the fact that you either have direct-pull cantilevers, or you don't. If you have direct-pull ("V-type") cantilevers, you need to use levers made for that application, levers that pull a lot of cable.

If you use conventional levers with direct-pull cantilevers, there will be too little cable travel, and too much mechanical advantage. The lack of travel can mean that the brake shoes will drag on the rims even when the brakes are released, or, it can mean that you can squeeze the levers all the way to the handlebars without having the brakes engage...it all depends on how they're adjusted. If you get this setup adjusted just right (wrong) the brakes will work but grab too abruptly, possibly causing skidding.

Brake levers for upright handlebars bend away from the handlebar; levers for drop handlebars bend toward the handlebar. They are not interchangeable.

At present, thw Dia Compe is the only drop-bar brake lever designed to work with direct-pull cantilevers. Due to the nature of drop-bar levers, it is not so easy to make a suitable lever that can be operated both from the drops and from the hoods.

Since the mechanical advantage change occurs at the cantilever-end of the cable, the cable-stretch benefits of the direct-pull system are lost, but this can still be a very worthwhile system, especially for rear brakes on small frames.

Drop-bar levers fall into two families, traditional and "æro" styles.

*    Due to the slightly different location of the pivot point, you can actually stop by applying the brakes from the hoods, as well as from the drops. This was not the case with the older style.

Yes, you can have too much of a good thing. The greater mechanical advantage of æro levers comes at the cost of reduced cable travel, especially when they're used with newer "low-profile" cantilevers. If you wind up with insufficient cable travel, you have to choose between having the cables so tight that the brakes drag lightly on the rims even when released, or, having the cables so loose that you can squeeze the levers until they bottom out against the handlebars. Neither of these adjustments is satisfactory.

Since the mechanical advantage of conventional cantilevers can be adjusted, the usual cure is to raise up the cable yoke, as described in my Cantilever Adjustment article. This is generally not a serious problem with the all-important front brake, but the added stretch of a long tandem rear brake cable may preclude a satisfactory adjustment of the rear brake. If the suggestions in my Cantilever Adjustment article don't solve this problem for you, you may need to buy levers made specifically for cantilever use, such as the Dia Compe 287, or convert to a direct-pull system with a pulley.

"Æro" levers have no place to install adjusting barrels for fine-tuning the cable length as the shoes wear. This is not a problem when they are used with caliper brakes, but cantilever brakes these days are designed more with MTB applications in mind. Since MTB-type brake levers always have built-in adjusting barrels, there may be no provision for cable adjustment when cantilevers are used with drop bars. This is un-acceptable. A bicycle that doesn't have brake adjusters is dangerous and defective, and no manufacturer or retailer should let such a bike go out of the store. This applies especially to bikes with drop-bar levers and cantilever brakes, because this combination is particlarly finicky about cable adjustment.

Fortunately, inexpensive adaptors are readily available to let you add a cable adjuster anywhere the cable runs through housing.

== Siehe auch ==