Machine Tech Zero-Flex Cantilever Brake

There are few brakes, for the price, that are as innovative as the Zero-Flex. The Zero-Flex arms are machined from billet aluminum to leave just a thin wall supporting the piece. Because of the arm thickness the brake pads mount to the side of the arm.

Mechanical explanation of the Zero Flex. Each arm is 14.51mm thick and has a finished overall height of 78mm Each arm through the mounting area is 22.5mm wide, and broadens to 35mm making the lower arm section at 45mm from the bottom. The arm narrows again to 11mm at the top of the upper arm. The rear of each arm piece is milled leaving between a 2mm and 3.7mm wall thickness around the perimeter. The front face of the Zero-Flex is largely milled away but not as aggressively as the un-seen rear of the arm. The width near the inner side is just 1.15mm thick. The Zer-Flex is bored on the back side to make a cavity for the spring. A polished brass tube is machine pressed into a hole through to the front.

A machined stainless steel bushing with polished inner and outer surfaces slides into the brass tube which also acts like a bushing. This steel bushing is what slides over the frame or fork's mounting stud. Each of the internal tension springs is independently adjustable and replaceable. A small hole drilled upward into the brake arm anchors one end of the brake spring. A machined cap that covers the covers the spring compartment making an 8mm stand-off for the brake arm. The inner side of this cap has a hole for the other spring end to anchor in. The cap is drilled for the mounting bolt to pass through and there are two cuts made across the cap that leave parallel flat surfaces for a 15mm cone wrench to grip while adjusting the spring. When the proper tension is reached the mounting bolt is tightened down to hold the tension while still allowing the brake arm to rotate smoothly. Slots are milled through the sides of the remaining brake arm walls. These 6.27mm wide slots permit the brake pad mounting post to extend into the core of the arm. The Zero-Flex is one of two cantilever brakes we reviewed to use a threaded post brake pad. Machine Tech sends the brake with Kool-Stop Eagle Claw 1's.

The post passes through a serrated convex washer then through the inner wall. The washer and the Eagle Claw's concave pad mount allow angle adjustments. Once through the wall, a steel flat washer is used to reduce friction and a 6mm by 1mm recessed nut is used to hold it in place. The recessed nut is made of steel, looks like a tube with threads inside it and a 5mm hex fitting at the non-thread end for a hex wrench to turn tightening the pad in place. This recessed nut weighs 3.5 grams but is not replaceable with the SRP recessed nut because the mounting post are too long to grip fully without a spacer. The Zero-Flex comes with a 300mm long Dia-Compe straddle cable. The cable has a lead anchor at one end and has a lead finger grip for quick release use. The other cable anchor is a cable end clamp, machined of steel tube that has interior threads with a set screw tightened into it. A hole drilled through both sides of the tube allows the straddle cable to pass through and the set screw clamps the cable within the tube. The tops of both brake arms are milled to accept either cable end.

Machine Tech makes a beautiful and elegant cable carrier. Machined from aluminum plate in an arched triangular shape it measure 42.5mm across is 8.75mm thick where the set screws tighten and 6.32mm (1/4") thick in most other areas. The piece has a 3.3mm wide kerf cut through most of it for the straddle cable to lay. At each end of the carrier is a core left to be drilled and tapped with threads for the cup point set screw used to hold the straddle cable in place. At the top of the triangular carrier is a stainless steel clamp bolt with a hole drilled through it for the brake inner wire. A steel washer and an aluminum nut are used to tighten and hold the brake inner wire. The steel bolt has a 5mm hex fitting, the nut is made for a 10mm socket to grip. End of mechanical.

A pair of Titanium mounting bolts and stainless washers are included with the Zero-Flex. The brake pads without the custom nut weigh 42 grams a pair. We found the Zero-Flex to have a Bike-Pro brake profile measurement of 20mm. The brake weighs 130.5 grams (including 42 grams of brake pad). To this add 7.5 grams for the mounting bolt set and 11.5 grams for the cable carrier for a total weight of 149.5 grams. The Zero-Flex is made with the arms caps and carrier anodized the same color, choices are Blue, Black, Lavender or Silver.

For the money, what's included with the brake, (Ti bolts, carrier) workmanship and weight, this has got to be one of the best deals ever. Made in USA.

Color-B-BK-L-S $ Price in Catalog

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