DISC BRAKES: HAYES VS. SHIMANO

DISC BRAKES: HAYES VS. SHIMANO


Hayes had been manufacturing hydraulic disc brakes for the motorsport industry for decades before they turned their attention to developing the ultimate mountain bike braking system. Shimano, on the other hand, had only played with the concept, producing a limited supply of hydraulic rickshaw stoppers in the late ?70s.
When core mountain bikers were begging for lightweight disc brakes, the only large manufacturer that responded seriously was Hayes. While Shimano wasted time perfecting an overweight expanding roller brake, Hayes cranked out a self-adjusting, open-type hydraulic disc brake that remains the standard to beat today.
Four years later, Shimano abandoned the roller brake and put every engineer they had on a disc brake development program. Prototypes emerged in late ?98 and versions were raced in national and World Cup events throughout the ?99 season. Now, after a couple of false starts, the production version of the Shimano Deore XT disc brake is ready to sell.
AMP, Magura, Hope, Formula and Cannondale had third-generation disc brake systems in production by the time Shimano released their new stopper. Now, the zoot-factor of Shimano’s hydraulic masterpiece is moot?the burning issue on everyone’s mind is: ?How does the new Shimano disk brake stack up against the established leaders?? In this feature, MBA chose Hayes? latest braking system as a counterpoint to compare the possible benefits and deficiencies of the Shimano Deore XT disc brake.

THE HAYES SYSTEM
The Hayes is also a self-adjusting, open-type hydraulic system. The right- and left-hand master cylinders are exactly the same item, and you can reverse the levers without inverting the reservoirs, unlike with the Shimano brake. The lever blades are new for ?00 and they are very comfortable?early levers were exactly the opposite. Hayes uses a double-acting caliper with a single pair of pistons. Hayes brakes come preassembled and charged with fluid. The hoses are hard plastic and can be easily cut and shortened.
Split perches allow you to remove the Hayes levers without yanking off the grips?a plus if you ride motorcycle style. Hayes has its own type of ?B? mounting bosses, but will supply an ?A? mounting adapter when requested.

THE SHIMANO SYSTEM
The Deore XT brake is an open system?its lever/master cylinder is a sort of pump that recharges the caliper with fluid as the pads wear and allows excess fluid to return to its reservoir when it expands with heat. The reservoirs protrude from the perch of each lever at about 45 degrees to keep the brake fluid level higher than the bypass ports inside the master cylinder. Braided stainless steel covers the plastic hoses to prevent abrasion. Cutting the braided line is problematic, so Shimano offers eight different hose lengths for OEM customers that are preassembled with the calipers and levers.
The Shimano system is your textbook disc brake with one twist: the double action caliper (that means it has retractable pistons in both sides of the caliper) has smaller pistons on the trailing side to cause the trailing part of the brake pad to squeeze harder than the leading edge. This, we suppose, is to prevent undesirable brake squeal.
Shimano designed their system to be compatible with the Hayes-type hub’s six-bolt pattern, and to mount to universal ?A?-type bosses.


 

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