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Introducing the Pursuit Special

We’ve been working intensely on cross product and the JYD lately, so I was beyond stoked when All-City Global Product Manager Amy “The Hammer” Kippley gave me a track chainring to design.  Images of track bags full of All-City chainrings danced in my head.

Because there are so few components on a track bike, each component becomes more visually and functionally critical.  Basically, fewer components means that you just become more obsessed with the look and functionality of the components you do have. 

This obsession is exacerbated by the fact that due to the track conditions (clean, dry, smooth) there are very few environmental factors between you and your components.  There aren’t bumps in the course or obstacles (trees, cars) to distract you from your drivetrain grinding or being not stiff enough.  Likewise, there aren’t derailleurs or extra gears or brakes to distract your eye.

Because chainrings are so front and center, they easily become one of the most visually and functionally critical parts of a track bike.

On to design requirements:

The rings must look amazing.  This wasn't too much of an obstacle as I was working closely with the other half of the All-City Crack Creative Team, Saisha Harris, seen here giving thoughtful feedback.

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The rings must function amazingly.  These rings are designed for velodrome application, first and foremost.  The tooth count would range up to 52T and as low as 46T.  While the design is track specific, we know people will throw them on street bikes. Noted.

The larger rings would benefit from a thin outer web to help maintain stiffness.  Also, pie plate-style chainrings are hot. 

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This web would not be as beneficial to the smaller rings, only really adding weight. 

I added a short reinforcement ring to the back of all size rings to also assist with stiffness.  We did not add this ring to the front, however, as a reinforcement ring would interfere with many potential final machining processes we could use for making the outer face as shiny as possible.

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Tooth profile must be butter.  I took a crack at designing my own profile, but when we started collaborating with our domestic chainring manufacturer, it was clear that I was not the expert in the relationship.

We looked at a lot of options for general form, but we arrived at this saw-tooth profile.  It worked well in simulation.  Also, it deviates from the common radially symmetrical forms that currently dominate the chainring game.  

Anyway, here are the initial concepts we came up with, fitted to cranks.

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And the EXTREMELY rough concept and ride prototypes.

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Lastly, here is my personal ride test prototype installed on my Koochella track frame (built up for Enduro TT night at NSC) with ample track slack.  

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I don’t care how heavy my Vigorelli crank is, I think it’s a riot... and that the solid plainweave carbon spider is totally hot with the chainring.

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And yeah, my drive train is filthy from our Midwest World Tour a few weeks ago.  I know.  I know.

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The feedback from the test riders, and from my personal experience, is that this guy rides like butter on the track and on the street.  It's light and stiff to boot. 

The rings will be ready for you lovelies soon.  Look for them.

Comments
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Dave Scrod

July 24, 2014

Hell yeah, can’t wait!

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