Aluminate Prototype Parts

I picked up the prototype batch of CNC parts for the Aluminate project and all I can say is they turned out awesome. The dropouts are lower yoke are stout but not overly heavy. Interest in track frames has been increasing since I started posting about this project - looking forward to next steps in getting some frames built!


Aluminate Prototype Dropouts and Yoke

Today I was stoked to pickup the Aluminate prototype parts. All of these parts were used to validate CNC tool paths and won't be used on an actual bike frame. The fit checks between mating parts went very well and I hope to have a small batch ready early next week. Next step is gathering the 7005 aluminum frame tubes and getting some frames built.

The aluminum-bronze insert slides tightly into the 7005 aluminum dropout body for a snug fit. This design provides an all-encompassing wear surface for the rear track hub...if the insert gets chewed up it's easy to replace - this means a longer lasting frame. I've sourced M3 Torx head screws for attachment - these are difficult to find in the US and special thanks to my contacts at Pencom for the hookup...these little metric screws came straight from Singapore!

The lower yoke is dainty but will provide ample clearance for a 35mm rear tire. I slid the yoke over a 37mm high air volume tire and it was snug getting past the yoke entrance, but after that no problem. My feeling is that it will also work well for some criterium frames I plan to build later this year.

The AHRENS engraving also turned out nicely - great job to the machining masters at Alta Design for their fast turnaround and high-quality work. I will never get bored of designing parts in 3D and watching billet get transformed into highly functional products. F*cking awesome.


Aluminate Project

For the last five years, I've worked very closely with Jason Montano, owner of Montano Velo in Oakland, on a variety of steel track frames under the Broakland brand. In this role, I took design direction from Jason Montano, the architect of the Broakland brand. Jason's vision for his track frames came from many years of riding experience and the desire to build a well-balanced bike with very specific ride characteristics. I came into the picture by offering computer-aided design (CAD) skills to translate the initial hand-sketeched concepts to the computer and ultimately onto paper. I must emphasize that Jason Montano communicated his vision to me, in terms of geometry, tubing selection, and aesthetic. In turn I used my engineering background in product development to model the track frame concepts into manufacturable form. I truly value the working relationship that has evolved with both Jason Montano and Jason Grove in developing so many unique frame designs.

The high-end Broakland frames became popular immediately due to their precise geometry, neutral balance, distinct aesthetic and nearly flawless craftmanship by Jason Grove of El Camino Fabrication. While studying the nuances of track frame geometry I knew I wanted to design my own version using aluminum as the base material. I absolutely love steel but I also love the challenge of designing new frames - I knew this one would be special.

My main challenge would involve a new rear dropout design that was functional and durable since rear wheel swaps can chew up even steel frames after a while. After sourcing some aluminum dropouts with questionable origin, I knew I could design something vastly better. The 'off the shelf' dropouts had stainless outer plates that I knew would slip under heavy load - obviously not good. The next issue is that they were very thin and the inside surfaces of the dropouts were raw aluminum which would wear for sure.

To alleviate the wear issue, I designed an insert that cups all critical surfaces of the dropout. This insert is made from aluminum-bronze, a common material found in ship building due to its excellent corrosion and wear resistance. The material is harder than aluminum yet soft enough for the axle bolts to bite and remain tight. If the insert gets worn out after dozens of wheel swaps, it can be replaced with (2) M3 bolts located on the inside dropout faces. The dropouts measure 9mm across the faces and weigh in at 130 grams per pair.

Last fall I met with local rider Nate to bring him into the project. Nate had direct experience riding production aluminum track frames and I wanted to pick his brain. It's no coincidence that Nate also home brews craft beers - thus the ALUMINATE name was born.

Nate's frame is a 55.5cm with 55.5cm top tube and parallel 73 degree head and seat angles. The BB drop is 50mm and the overall geometry is snappy but not too aggressive. The horizontal dropouts have a sweet spot at 395mm but can be adjusted in either direction easily. We plan to run an 1-1/8" Wound Up fork, King headset and a bunch of custom bits to round out the build.

The lower yoke is similar to my other yoke designs but smaller to meet the needs of this application. It has a hollow box-section behind the bottom bracket to provide added stiffness during pedaling. The angled surfaces accommodate 25mm tall rectangular chainstays commonly found on my mountain frames. Why rectangular? Because the shape is stiff as hell and minimal power output is lost while pedaling.

This approach also provides enough clearance for 175mm cranks (Nate plans to run 172.5mm) and 46T front chainring. Larger chainrings will require the chainstay to be shaved slightly, but since they are fairly thick walled, I don't see any strength issues at this point. This approach also allows for a fairly large 32mm rear tire to be used - and I think a 34mm may be possible with some subtle tweaks to chain length.

This will be a busy month getting the Aluminate parts machined and the frame fabricated. Looking forward to seeing this project materialize into a highly functional bike!