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Space Horse Dropout Development, Part 2:  The Reckoning

This is the second installment of a three-part series on the development of the All-City Space Horse dropout.  Today, we go from the physical sketchbook to the virtual 3D modeling program.

From the 2D sketches shown in the last post, I created this very rough first 3D model:

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This is a good opportunity to point out that our axle interface is shorter than many (but certainly not all) semi-horizontal dropouts of this type and all track ends.  Track ends, such as our Hennepin Bridge dropout, are designed around the user’s need for several gear configurations without having to adjust chain length.  As a result, that style dropout tends to have a lengthy axle pad.  The Space Horse dropout was sized so that a single-speed or fixed rider would have sufficient tensioning capability in a single-gear configuration without having to use a half-link in their chain. 

The overall shape of the dropout was driven by its need to be as visually and as structurally compatible as possible across all sizes of Space Horse frames.  Below, there are several quick screen shots of the dropout applied to geometries across the size range.  

46cm
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55cm
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61cm
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For the next step, I dropped in the rack and fender mounts and added a web between then to make them more robust.  Also, I re-surfaced the dropout to add the indexing stop at the front of the axle pad (to be discussed more later).

Before prototyping the dropout, I rendered the dropout on a complete frame.  In case you were wondering, all of the steel frames and frame parts I render are shiny red with stainless accents.  Like any reasonable human being, I have always wanted a shiny red bike (I have never had one).

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Here are some emotional photos of the resulting rapid prototype:

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After a few minor tweaks to the design based off of the rapid prototypes, we started to collaborate with our dropout supplier.  

In the next episode I will discuss the tooling process and final development.  

Comments
Guest

Mark

February 6, 2012

I really enjoy reading these. Thanks for posting!

Guest

Tim

February 7, 2012

Cool stuff, thanks for sharing. Those renderings with the reflections and antialiasing are super slick. I really like the front stop for running geared.

Guest

jonathan

November 30, 2012

Really nice blog on dropout design. Its hard to find decent technical information and I think you cover the basics well. What CAD software are you using?

Guest

Wes

April 20, 2014

“Like any reasonable human being, I have always wanted a shiny red bike…”
As the oh so proud owner of a red Mr Pink, I wholeheartedly understand!
I am loving these posts. I need to get back in touch with SolidWorks.
Keep up the fine work!

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