The Stem that's also an Aerobar: Sigma One

Today we’re going to take a close look at one of our flagship products, the Sigma One aero stem. This simple-looking little part has quite a bit going on, so let’s take a look.

Since the very first Sigma stem we launched back in 2013, we’ve had a few goals in mind. The first is to make a clean stem that itself was aero-shaped. There wasn’t really anything on the market that took care of aero shaping on the stem level. Bolts were always exposed, and even if there was some shaping to the stem body, it generally didn’t seem to care about what it looked like to the wind.

But perhaps even more important than the stem itself is how it relates to the rest of the bike. For that reason, we designed the first ever line of stems with integrated cable management. Whether you’re running cabled setups, hydraulic lines, or electronic shifting, whether your bike uses rim brakes or disc brakes, Sigma One has you covered. And there’s no crazy cable paths or delicate routing needed. What we’ve done is separate the stem’s top cover from the main body, so what you do is route all your cables or wires as normal, then just collect them underneath that cable cover, which also acts as your top cap.

There’s still nothing else on the market that does this, and it’s been something that athletes from all disciplines can benefit from. Whether you’re running a tri bike, a road bike, or even gravel to mountain, a clean front end just makes everything better.

But all of that … that’s just the beginning.

What makes Sigma One stand out from everything before it, is that we’ve integrated our patented and award-winning Alpha One aerobar stack right into the stem. See this rubber plug on the top jaw? If you want to run the stem without an aerobar, you just leave it like this. But add the optional Compatibility Kit, and you have everything you need to attach our Alpha One Dragonfly system.

This converts the continuously-adjustable Monopost from Alpha One into a series of stacked spacers. It comes with all the spacers and bolts you need to go from a slammed setup all the way to +65mm of stack. Plus, you get the same continuous tilt adjustment from Alpha One, which lets you adjust from -5 to +17.5 degrees of tilt. Add any of our best-in-class Scoops Arm Cups and Gamma Extensions, and you’re ready to fly.

And the best part about it is that it can be removed or replaced with just two bolts. Ready for that Century ride and want to make sure you have the comfort of aerobars available? Just two bolts and you’re ready to go. Back on the trail where you just want your traditional setup? Two bolts and it’s gone.

Sigma One is made primarily of carbon fiber for maximum strength at a minimum weight, with a T6-6061 alloy upper jaw, and titanium bolts on the stem clamp and bar clamp. The optional Compatibility Kit includes everything you see here, and from there you can add the Scoops, Gamma extensions, and Dragonfly of your choice to put together your perfect aerobar setup. If you want to add a computer mount or bottle cage, our own 3-in-1 Polymount or Kappa cage are the perfect complement to the system.

Head to the store and grab yours now.