Introducing the TriRig Sigma Stem
article & images by Nick Salazar
Sep 28, 2012  hits 152,810

Sigma is here! Get yours in the TriRig Store!
Intro + Aero

TriRig's next manufacturing project is a stem. Yep, the lowly, boring stem is getting our full attention. Why are we tackling a stem? The same reason we do anything else: we see some vast improvements to be made over what the rest of the industry is offering. Our new stem, called the Sigma, follows the same theme as the Omega brake in that it was designed in response to a void that the market simply wasn't filling. A standard stem is one of the ugliest components from the perspective of frontal area. It's a component ripe for improvement. The traditional stem is an aero problem, and the Sigma is TriRig's answer.

Moreover, as we'll explore in this article, it works beautifully in concert with our Omega brake. They can be used independently, but the combination of a Sigma and an Omega will be a pretty potent and beautiful upgrade to the traditional front end, allowing older bikes to compare more favorably to the so-called superbikes than you may ever have dreamed possible.

Aero Features

The Sigma is clean, aero, and integrates with centerpull brakes like the Omega.

As is the case with many such products, the Sigma is deceivingly simple in appearance, but actually has quite a bit going on. Because its primary advantages are the aerodynamic improvements it offers, it seemed best to go over those first. So here they are, in no particular order:

  • Ultra-narrow profile, for the smallest possible frontal area, and an ultra-smooth shape from front to back, no bulges or protrusions that you find on standard stems. All the bolts are hidden and recessed into the already-small design. The Sigma is totally flat on top and bottom for smooth airflow - no sharp corners or crevasses that would act as wind traps.
  • Elegant, simple cable management - All of your bike's control cables, whether mechanical or electronic, route through the Sigma stem. But instead of requiring a difficult, cumbersome install, the internal routing is achieved by the use of a bolt-on piece that is installed as the final step in the process. That means that you don't have to go through the hassle of fishing cable lines, or recabling anything to achieve this clean routng. You just install all your cables like normal, then tuck them together and bolt on the stem cover. It's as easy as that. This also means the bike will still be very simple to break down for travel - removing the stem cover gets you a lot of extra cable slack that can be used to tuck the aerobars next to the frame with a minimum of fuss.
  • Integrated cable routing for center-pull brakes - PERFECT for use with the TriRig Omega. For the first time, a commercially-available stem will have integrated center-pull cable routing. It's utterly simple to use, and again, is always easy to access due to the bolt-on stem cover (mentioned above) which can be installed or removed at any time without requiring that you re-cable your bike. In the case of the Omega, it means you don't have to use the Omega's integrated hanger - you can run bare cable all the way down the head tube, WITHOUT needing to add a headset cable hanger. This can be especially useful for individuals with an ultra-low position who can't afford the extra stack height added by a headset hanger. And although the Omega's integrated cable hanger is not an aerodynamic penalty, there is something to be said for the absolutely beautiful aesthetic created when it is eliminated, and nothing but bare cable runs straight into the brake. The images in this article certainly show you what I'm talking about.
  • Integrated window for Di2 or EPS control boxes. A window on top of the removeable stem cover allows you to tuck in the control box of an electronic drivetrain, keeping it out of the wind, but also allowing it to be accessed at any time. There is also a fairly large cavity within the Sigma itself which can be used to tuck excess amounts of electronic wires if need be.
  • Integrated computer mounts will make it simple to attach your Garmin or other computer without clutter or compromise.
  • Optional integrated computer mount. In recent months, I've seen athletes spent a lot of time trying to come up with sleek ways to attach their bike computers to their aerobars without making it look like a complete mess. People seem particularly interested in getting a Garmin installed without adding a ton of frontal area. So we just took away the hassle for you, and created a simple, bolt-on solution that makes the mount a cinch. A single bolt allows you to attach or remove the computer mount at any time, without affecting ANY of the rest of the stem setup. So if you want the computer there, it's super easy to attach. But if you're playing with BTA setups and aren't sure you want your computer between the arms as well, it's easy to change your mind. And at just 15 grams, it may be the lightest solution out there too. Moreover, the mount is future-proof. It is relatively easy to create new mounts as different computers are released to the market. All it takes is a little time to sort out the mount interface, and then manufacture it. But since they're all plug-and-play, you don't have to worry about it ahead of time. Just bolt them on whenever you get them, and you're good to go. Be vocal in the comments below, or on our facebook page, and let us know what brands you want to see supported as far as compuer mounts go.

So that should give you a general sense of what the Sigma has to offer in terms of an aerodynamic advantage. We plan to quantify the aerodynamic properties using the same wind tunnel that Dr. Andrew Coggan developed, and report it in the same white paper format we presented for the Omega. But that's not all a stem is about. It is, first and foremost, a critical component of your bike fit! It links the aerobars to the frame and fork, and it must allow you to maintain your particular fit coordinates in order to make sense on your rig.

So hit the jump and we'll talk about the design features of the Sigma, including not only the fit issues just mentioned, but also in terms of how you wrench this thing, and how it will work with today's bicycles.


Tags » sigma,  stems,  tririg
  • This image should give you a good idea of what the Sigma is all about. But the best part about it is, this is a PHOTOGRAPH, not a computer-generated graphic. This image is true to scale, and shows the rather striking difference in frontal area between the Sigma and a traditional stem.
  • Here's the Sigma installed on a bike. You can see how the cables are managed quite neatly to keep them out of the wind. But that stem cover can be removed at any time for easy access to the stem cavity or the cables themselves.
  • A window on the top of the stem cover is built to allow access to control box buttons. Positioning the control box is up to the user - the Sigma is meant to be flexible enough to allow a variety of options, but it's up to the user to dial that in.
  • Integrated centerpull cable routing sets the Sigma apart as the ideal choice for using with brakes like the Omega.
  • From the front, the side, or the rear, the Sigma is clean and elegant.
  • The cables tuck into the stem and route out the rear. The removeable cover makes everything dead simple to set up.
  • The closeup of the rear half shows how the stem cover helps to manage the cables in a very simple, effective way. There's also a large cavity inside the stem to house electronic control boxes for bikes with Shimano Di2 or Campagnolo EPS.
  • Another angle on the Sigma
  • Believe it or not, this bike was built up from an open mold frameset that cost $400. But with the simple upgrades of the Omega brake and Sigma stem, it looks absolutely stunning. The bike in this photo is fully cabled and working, it's just that none of the cables are visible to the wind!
  • Here's a profile shot of that bike, showing you how the Sigma helps manage the bike's cables and keep them out of sight and invisible to the wind.
  • The TriRig Sigma stem, coming soon.
  • Sigma and Omega - a dynamic duo.
  • This is the prototype computer mount, which is being refined and finalized. It attaches with the single M4 bolt shown, and makes it simple to attach your bike computer without excessive hardware.
  • The tiny feature on the bottom half of the stem is where the computer mounts attach, via a single M4 bolt.
  • Here's the Sigma  with the computer mount attached.
  • The mount is designed to sit within the frontal profile of the stem, staying out of the wind.
  • Here's how your computer might look attached with the Sigma's integrated computer mount. Slick.
  • The Zero Rise stem will be released first, with a 35mm version following later in 2013.

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