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The Tektro R556 Long Reach Caliper Brake was the key component to many of Ed's 650B conversions allowing to fit 650B wheels and wider tires on a frame originally designed for 700C wheels. In this product review Ed provides a very detailed explanation of the brakes.  Although the R556 is not in production anymore, it has been replaced by the R559 which still has all the great features Ed describes here.  In fact they've added nutted version that overcomes a potential conversion issue he describes here and in his 650B Conversion Guidelines post.

Originally Published January 11, 2007 

Every once in a while a new product comes along that looks familiar and works in a familiar manner, but it has other attributes that make it unique. Sometimes a product such as this is an "enabler", it enables things to happen that may not have be easy, or even possible, before. The new Tektro R556 dual pivot caliper brake is such a product.

The R556 caliper is a familiar looking brake. It's based on the dual pivot technology that we've seen in use for about 15 years now, ever since Shimano released the 105SC dual pivot caliper in the early '90s. The R556 has the kind of strong, progressive, stopping power and good modulation that makes dual pivot brakes so popular, and it is designed to work well with today's aero brake levers, including the STI and Ergo variants.

What makes this new brake unique is the amount of reach, or range of distance, that the caliper can span from the mounting bolt to the rim. The Tektro R556 has a whopping 73mm reach capacity, and it can be set as close as 55mm. The space between the caliper arms is also generous, and well rounded. These two attributes combine to make the R556 caliper an ideal brake for use with wide tires and fenders on bikes that have the capacity for such things.

Typically, bikes intended to fit big tires and fenders are designed for v-brakes, cantilevers, or more recently - disc brakes. All of these braking systems are more complicated for the bicycle manufacturers because they require some combination of canti bosses, disc tabs, cable hangers, etc. And the placement of the frame fitments is critical. This new 73mm reach dual pivot can allow the use of big tires and fenders, while preserving the simplicity of the caliper brake. The installation and setup is simple, too.

The R556 caliper pairs are available in the aftermarket for people who want to upgrade older bikes, or do wheel conversions. This is where the R556 enables something which was difficult before. With the 73mm reach of the R556 brake, it is easy to configure a strong, lightweight braking system on a 650B converted 700C bike which was originally configured with recessed nut attached caliper brakes. You may have seen the Trek 1200C and Trek Pilot 2.1 650B conversions in my Bikeman 650Blog.

The R556 calipers look right and provide high performance braking for these all-roads, rough-stuff machines. Similarly, this brake could enable someone to convert a 650C wheeled bike to 26inch wheels, allowing the bike to fit 1.5inch tires and fenders, for example.

Of course, this brake will not fit all bikes, obviously the reach requirements for your application need to be within the 55mm-73mm range for this caliper. And if your bike has older, hex-nut attached brakes, then it will be necessary to find a way to retro-fit the bike to accept recessed mounted brakes. It can be done, but the mechanics of that kind of installation are beyond the scope of this article. However, when the application calls for a 55-73mm reach caliper brake with recessed mounting, then there is nothing better than this Tektro R556 dual pivot. The Tektro R556 is a quality brake.

In the photos which accompany this review, you can see how the R556 caliper compares to the Cane Creek 57mm reach caliper which came as original equipment on the 2007 Trek Pilot 2.1. When viewed side-by-side, you can see that the Tektro 73mm reach caliper is quite a bit larger than the 57mm reach Cane Creek dual pivot caliper. However, despite the greater size, the Tektro brake weighs a mere 10 grams more than the Cane Creek; I weigh them at 175grams vs.165grams, respectively. The Tektro caliper arms are forged, with weight reducing recesses in the backsides. The reinforcing ribs of the forging maintain the rigidity required for minimal flexing and firm lever response. The caliper has a smooth finish, and it's polished to a fine luster. It's a good looking brake.

The hardware on the Tektro brake is all very high quality, too. And with allen set screws securing the fasteners there is no possibility that this brake will become loose in use. The quick release is a lever type rather than a traditional cam. The lever moves more cable when the release is opened, and that opens the brake further. With this quick release it is possible to adjust the brakes for good lever feel and yet have the ability to remove an inflated 38mm tire. The calipers come with recessed allen nuts and four serrated washers for mounting onto your bike.

The brake pads are cartridge type, with cast-in wheel guides, and allen retaining screws. The cartridge holders have conical washers to allow angular adjustment of the pads. The stock black pads are quite adequate, but there are dual-compound and salmon colored Kool-Stop aftermarket pads available to further tailor the braking response. I like the cartridge design because it maintains the pad adjustment when the inserts are replaced.

The Tektro R556 delivers excellent braking performance. Even when set to the limit of their 73mm reach, the calipers deliver strong, progressive, stopping power which is more than adequate to controllably lock the rear wheel on my bikes on dry pavement, even with fat 38mm tires. And they work well with top-mounted interrupter levers; those auxiliary brake levers commonly used on many cyclocross and touring bikes. There are thrust washers and a delrin type spring bushing in the brake for smooth movement. It's a light-action brake.

The Tektro R556 caliper has generous width and a rounded arch to accommodate practical fenders. Obviously your bike has to have a frame and fork design that allows the use of fenders with the tires you intend to run, but many brakes tend to crowd a fender when the caliper closes. With the R556 caliper closed across a 20mm rim, there is still 60mm of fender clearance under this brake. The SKS P-45 fenders that I have installed on my bikes have plenty of clearance with this brake.

Overall, this is a terrific brake caliper; it's well made, it works great, it looks great, and it's attractively priced. It's highly recommended!

Ed 650Braley