Prototype Adjustable Stem

Another mountain biking project, this one is a proof of concept. To explain the problem simply, bicycles have different geometries for different riding conditions. “Downhill” mountain bikes have very tall handlebars. This is because when the bike is pointed down a steep hill, you want your handlebars to be set higher, else your weight is too far forward (less stable). When climbing steep hills, however, you’d really prefer the handlebars to be lower. Having them set too high will shift your weight to the rear wheel, unload the front wheel, and make steering very difficult.

In my mind the solution is simple: an adjustable “stem”, the part that the handlebars attach too.

Now, adjustable stems have been around for decades, but their adjustability is severely limited. I wanted to be able to set my handlebars lower than anything on the market, while also being able to set them as high as a “downhill” bike.

A few measurements, a couple hours in Solidworks, some flying chips, and I had a testable prototype.

I have been running this setup for over a year now and the benefits are clear. The next step is to improve the adjustment mechanism as well as address some flaws in the initial prototype.

• Design time: 2 hours

• Manufacturing time: 3 hours