Crisp’s elegantly simple disc brake caliper

June 2, 2014

Straightforward, self-adjusting, and heat-tolerant.  Will it see production?

Crisp Brake 1
Simple, airy design

Given the long history of the sport of cycling (to say nothing of motorsports’ parallel products), it’s not surprising that there are few truly new concepts floating in the ether, just looking for the right noggin to land in.  All the same, when we came across Australian Crisp Engineering’s modified scissor-type brake caliper, the concept was so elegant that we wondered why it hadn’t been tried on discs earlier.

Hey- when was the last time you belt a disc caliper from scratch?
Hey- when was the last time you belt a disc caliper from scratch?

Looking very much like a Magura HS77  road bike caliper that’s seen the angry end of a shrink ray, Crisp’s disc caliper uses a single hydraulic slave cylinder to spread its arms, which in turn drive a pair of pads to the rotor.  Easier seen than explained, the design is very straightforward, claiming to address several issues with current models.  Without more common designs’ pistons, there are fewer seals to leak and less liklihood of a sticky piston causing uneven pad wear.  As the pads and much of the mechanism is exposed to the air, there’s plenty of opportunity for braking heat to dissipate before causing any hydraulic fluid to boil or otherwise degrade.

A spread at the top becomes a squeeze at the bottom
A spread at the top becomes a squeeze at the bottom

The rough prototypes seen here aren’t necessarily pretty- but they are a solid proof of concept and are functional enough to have allowed designer Allan Crisp to ride them in a local enduro event-  on his rigid singlespeed.  Crisp’s CAD renderings look considerably more substantial- though are said to weigh a competitive 110g (roughly the same as a current Shimano XT caliper).  The design is said to work with Shimano hydraulic brake levers- though Crisp is also working on their own.

The pivot axis can easily be seen from the side
The pivot axis can easily be seen from the side

The floating design is said to be self-aligning- which, depending on how the system is set up, could conceivably be effective at accommodating bent rotors, rub-prone and noisy, or both.  Because the pads travel in an arc, the top edge will, at rest, sit closer to the rotor than the bottom edge- but with the right amount of friction in the mount, this could also be an effective self-alignment feature.  Come replacement time, a simple pin is all that holds the pads in place and access should be very straightforward.

Crisp Brake 5
An interesting design with some promise

As any engineer will attest, the heavy lifting comes between concept and series production, so while the idea may have merit, execution will be what makes these brakes successful- or unsuccessful.  Crisp’s project is currently seeking funding via Kickstarter- though is 98% shy of its goal with five days left. While further development and demonstration may be needed before crowdfunding is a viable option, it’s encouraging to see mountain bike tinkerers continuing to build and try new ideas.

More at Kickstarter and Crisp Engineering’s website.

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