Before grad school I raced in a handful of Olympic distance triathlons and during grad school I practiced off and on with a great club team here on campus. After getting in the habit of using aero bars during a few races I always wondered if it would be possible to combine the two positions (aero and outstretched) of the standard setup. If the outstretched position could collapse into the aero position then maybe the overall setup could be improved by:

- Eliminating drag of the outstretched bars while in the aero position
- Keeping the brakes and gears together and available in both positions
- Make the transition between positions smoother

I decided to give it a shot. We have really nice shop here on campus so I had access to some great prototyping tools. I started with some quick crappy prototypes in wood, and then moved to a working 2d mechanism using laser cut acrylic. I put a very unstable prototype on my trusty old campus cruiser and had a few short test runs without working brakes or gears. Two big lessons learned: 1) the bars need some way to lock and unlock from the outstretched position 2) the entire mechanism should be sprung so the bars always want to return from the aero position to the outstretched control position.

I increased the resolution of my next prototypes with the use of our CNC (Haas Mini-mills) and FDM (Stratasys) machines and some CAD/CAM software. I added springs around the main pivot and used a few small spring plungers to allow locking and unlocking. The plungers were put right under my thumbs on the hand grips. Several iterations and many prototypes later I had a working prototype in ABS plastic. The CAD drawing above shows a pretty refined view of the overall functionality. The working prototype was a bit messier. The bars attached to my road bike using a BMX bike stem. They integrated a set of Campagnola brakes/shifters onto some custom grips made with the FDM machine. In the prototype, the forearm pads are stationary and attached to the headset instead of moving with the bars. The video below (compliments of the crotch cam) shows the working prototype in action.

The carbon fiber renderings above and below show one idea of how the handlebars might look if implemented by a real manufacturer. To keep the design a little cleaner, the secondary bars of the four-bar linkage would be concealed within the hollow tube of the primary bars. The brakes and gears would ideally integrate cleanly with the trigger mechanism.

Enough engiNerd talk. Do these things work? They definitely work. I was worried about the weight shift being really cumbersome but it’s actually really smooth. They move forward into the aero position really well and with the spring tension they snap back to the outstretched position when needed. I’m not sure if that’s the right action but it worked for the prototype. When you engage the aero position it feels pretty awesome, like you’re readying for take-off.

Will they ever find their way to market? Not sure, but I’d love to see it happen. Regardless of their future, it was really fun to take a crazy idea and make it work. The entire project was a great way to engage the design process and a fantastic learning experience. Now I need to get off my designer ass and get back into triathlon shape.

This entry was posted on Sunday, January 13th, 2008 at 9:00 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.