MPLS Skyline
MENU

Space Horse Dropout Development, Part 3:  Return of the Dropout

This is the third and final installment of the series on the All-City Space Horse dropout.  We have so far covered initial concept exploration and design development both in the sketchbook as well as in virtual mediums.

After we received our rapid prototype pieces and verified their functionality, we began the process of collaborating with our dropout supplier.  Because no issues were apparent, they were comfortable with going straight to tooling.

These dropouts are investment cast.  It’s a fabulous process to use if you need to make low-volume intricate parts that are not easily made in a conventional casting mold (popular for jewelry, sewing machine and gun parts, and lugs). 

If you are not familiar with the process, here is an incredibly simplistic account of how it works in the case of this dropout:

A wax version of the dropout is molded and is attached to what is essentially a wax funnel (a sprue).  The sprue and dropout assembly are then repeatedly dipped in a fine ceramic slurry (small particles of ceramic in water) and allowed to dry.  The ceramic particles are deposited on all surfaces of the wax dropout and sprue, creating a hardened coating.  Gradually, the ceramic coating is thickened into a thick, hard shell around the wax at which time the wax removed through melting or some other process. 

What remains is a ceramic shell with the relatively intricate void of a dropout.  Steel is poured in.  The shell is broken away.  Sprue is cut or broken off. 

Bam: dropout.

(Here is a more thorough explanation:  http://en.wikipedia.org/wiki/Investment_casting)

Anyway, few months after sending files to our manufacturer this is what showed up on our doorstep:
 
01

02

03

You will notice in the image below of the non-drive side some funny seams in the surface of the part.  These tooling lines are caused when parts of the mold are uneven- they are resolved in the final product (our personal prototypes have them but your frames will not).  The lines appear around the axle pad and the AC of each dropout side and they illustrate the fact that this dropout is designed so that the branding can be removed so the dropout can be made without branding.

04

Why did we take this approach?  Well, our frame-part manufacturer also recognized the lack of attractive and functional dropouts of this type available openly to builders so they requested that we allow them to produce blank versions of this dropout to support that market.  As we are huge fans of steel hand-made bicycles (Jeff and I could easily be considered junkies) we thought this was a fabulous way to share the love.

Next, we had to produce frame prototypes to verify that our dropouts could be built into frames the way we wanted them to be.  For me, this was the most terrifying part.

05

In this picture you can most easily see that the cylindrical seat stay interface is rotated in a few degrees so that the seat stay would interface with the dropout at more of a right angle.  You can also see why we made the interface a little larger than the seat stay diameter… so that we would have just enough room for a weld bead.

07

06

08

09

10

The end!

IMG_9792

Bonus Notebook Sketch:

Dinosaur Cartoon

Comments
Guest

ari

February 15, 2012

I can’t wait for the 61cm Spacehorse to be available. I have configured my build on paper and am just waiting it’s arrival. What a fantastic machine!
Ari

Guest

Leaf Slayer

February 16, 2012

The bonus sketch should be a t-shirt. Why? I have no idea.

Guest

Steven J Braun

March 6, 2013

Are these fantastic dropouts available to independent builders? If so, how do I get a pair.

Thx

Guest

Eric Daume

October 28, 2014

How long did the adjustment range on the dropout end up being?

Leave a comment







Remember my personal information
Notify me of follow-up comments?
* Get your picture next to your comment with a Gravatar Account.

Recent Posts

Space Horse Gravel Racer

Out of all my bikes, even with having All-City’s full line at my fingertips, the Space Horse is the one I prefer for gravel races. The lower bottom bracket, slightly longer wheelbase, and generous fork rake make it an absolute demon at taming gravel descents and the smaller diameter tubing helps dampen bumps over a long day in the saddle.
Read More

New Sweatshirts in Stock Now

We are super pumped to siginficantly up our coziness game this Spring with the introduction of two new sweatshirts. Everyone needs at least one pullover and one zip up in their life, so why not make it one from your favorite bicycle company? Plus you get to buy it from a bike shop, which helps keep the local center of your cycling community in business.
Read More

Jeff & Nate’s Excellent Adventure: All-City Pacific Northwest Tour April 25-30th 2016

Yours truly and Nate (you know, our Sales Manager with the totally great hair) are loading up the van and hitting the road next week to take a tour of the Pacific Northwest. We'll be bringing the party and a whole bunch of demo bikes and coming to your town (if in fact your town is either Seattle, Tacoma, Portland, or Bend).
Read More

Archive