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Hayes Prime Disc Brakes – Power and Leverage Tech Comparison

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Hayes Disc Brakes’ new Prime has been building hype for weeks now, and they’ve yet to unveil the full tech specs behind their Poppet Cam Lock.  However, we’ve managed to pull some test data out of them showing how they compare in in-house tests.  Hayes says they’ve used these tests during development to ensure that the new Prime is tuned to excel in all trail conditions at a wide range of speeds and temperatures…but a big focus has really been placed on brake feel and consistency.

On the chart above, the Hayes Prime is compared to three of the top brands’ hydraulic brakesets.  Their testing shows the Prime produces the same or more braking torque at 15 lb/feet of force, which they say is a fairly aggressive grab that would haul a bike down to a stop quickly on a paved surface.  Trail conditions and surfaces will of course alter how aggressively you grab it, but for purposes of comparison, they went with an aggressive stopping

Wheel Torque is how much friction force the brake pads are putting on the rotor based on the Mu of the pads and rotor material.

LEVER INPUT FORCE @ SAE basically means that the finger position was the same for all brakes tested so that leverage was the same.

“At this level, everybody’s brakes are really good,” says Joel Richardson, product manager for Hayes Brakes. “What we did with the Prime was focus on a very consistent feel.  Throughout the entire stroke, as you squeeze the lever harder and harder and harder, the torque and the lever feel are perfectly linear.”

This translates into a more predictable feel when braking, whether your feathering it or “holy crap I’m going to die” grabbing the lever, eliminating the need to micro-adjust the lever to compensate for changes in performance.

On the chart above, the lines that skew downward near the top right mean that the pad material hit a point where it couldn’t cope with the heat and/or the pressure.


On the second graph, you’re looking at the amount of lever input force versus the distance you’d have to pull the lever.

Lever Distance Traveled @ SAE is the amount of lever travel at a set point on the lever, which was the same point on all levers for all systems testing.

Dead Stroke is how far the lever travels before it starts building pressure in the system.

On this chart, the Prime is shown with the lever set at the maximum stroke adjustment (that secretive Poppet Cam…).  Setting it at the minimum stroke level would simply shift the Prime’s graph (purple) to the left, allowing you to customize where in the lever travel you want it to start making pad contact.  In other words, you can change the lever throw from short to long.  Avid’s Elixir CR offers similar stroke adjustment.  The starting point on this chart is irrelevant here…this chart shows brake “feel”.

“What you’re looking for in this graph is the slope of the line. This is where we get into the feel of the brake,” Richardson says.  “If the line was vertical, you’d have very little stroke and the brakes would ramp up very quickly…it would have almost a wooden feel.  A relatively flat line, however, would feel really squishy and you’d be pulling the lever back to the grip with little effect.

“With the Prime, we’re not the firmest and we’re not the softest, we’re just right.  We have a very supple feel while providing solid lever feel…it’s going to be just a little softer than the Stroker platform.”

All brakes were tested with a 160mm (6″) rotor.

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