Review: Zipp Vuka Shift AXS 90 Extensions

 May 8, 2020 article & images by Nick Salazar

There is a new frontier in the aero arms race, and it's at the front of the bike. Specifically, there have been some really exciting developments regarding the complex of arm cup, pad, extension, shifter, and the rider's arm. Several different companies have come to the forefront to pioneer this space, including SpeedBar, MOST, WattShop, Drag2Zero, LOOK, and others. But this space isn't just about speed, it also has a lot to do with comfort. To that effect, TriRig has its own product in this space, our Scoops arm cups, and (hint hint) we are always interested in exploring how we can improve, especially at the front end.

The revolution in this space really began, in earnest, with Speedbar. This company makes bespoke one-piece cup/extension units that not only eliminate a ton of hardware, but more importantly integrates all that front end material into one shape that fairs the rider's arms and forms a single aero shape. Lots of air that normally became disturbed significantly around the rider's arms could now flow more cleanly around them. Eyes and ears really perked up early in 2019 when the first news and images of these things began to surface. We noticed that in Kona, no fewer than seven athletes were using Speedbar, and a couple athletes (Jan Frodeno and Patrick Lange) using similar systems by other companies.

Of course, the Speedbar solution is a one-off, molded individually to each rider, and locking each rider into one definitive position, arm orientation, and hand angle. And it's extraordinarily expensive, at about $3000 per set, plus any travel expenses incurred traveling to Speedbar themselves, in the Netherlands. Not exactly an off-the-shelf product, as Speedbar is quick to admit. It also is completely static, non-adjustable, and best-suited for top-end riders trying to optimize a single racing season. It is absolutely NOT the right choice for athletes looking for versatile equipment that can endure incremental fit changes over time. So far, the only thing that holds a foot both in the Speedbar "hug the arm" camp and also maintains any semblance of adjustability is the LOOK Aergo extensions. WattShop is about to release their Anemoi extensions, which will fit that description as well. And if you watch this space, I'm sure you'll see other such products coming soon.

Introducing Zipp's Vukashift AXS 90 Extensions

So where does the instant product fit in? Well, Zipp's marketing language wouldn't really tell you. Zipp says to "Think of it as a supremely efficient solution to house 'the brains' of your SRAM RED or Force eTap AXS time trial or triathlon bike." So at first blush, these guys are meant to eliminate the big old BlipBox (which they do), ensure cleaner wire routing for your AXS setup (they do that too), and leave you with a nice clean front end (to the extent that extensions alone can do so).

Before we go any further, how well do they do at their stated goal? Well, they do a great job. They pair and connect to your AXS group as easily as the old BlipBox did, with a minimum of fuss. Of course, now you have two gizmos to worry about, each with its own battery. So you've got double the batteries to worry about running out. Fortunately, it's the same CR2032 coin cell that the BlipBox it's replacing takes. So if you bought some spares, they will work here too. And we do recommend keeping those spares with you on your bike. Despite SRAM's claim that they will last for months (or years), we've had them run out very quickly. In any event, make sure you carry some CR2032's on your ride, along with at least one eTap derailleur battery, and any wrenches you'll need to access the battery casing. In the case of the VukaShift AXS 90 extensions, that means you'll need a Torx 25 wrench, in an L-shape short enough to wedge between the extensions, should you need to replace a battery mid-ride.

About the cleanliness, the extensions really do make it more convenient to create a clean front end. On the bikes we're showing you here, that was never really a problem. Our Omni frame can store the BlipBox either in the integrated storage box just aft of the stem, or affixed directly to the Dragonfly on the Alpha One aerobars, which is where we hit it when we reviewed the AXS group. Of course, many folks have bikes incapable of easy hiding spots for the BlipBox, and for them, these extensions may be one of a very few good alternatives to keeping the front end clean.

Fit and Comfort

Overall, the fit and comfort of these extensions is good, but there are some caveats. With a rise of 90mm and a terminal grip angle of about 14 degrees, it's a nice bend and very comfy in the hand. The extensions also cant inward about 25mm. That is to say, when viewed from above, if the extensions are not rolled in at all (their axial plane is parallel to the vertical plane orthogonal to the horizon), the hand grip of each extension is about 25mm closer to center than the end of the extension. This is intrinsically neither good nor bad, but has important consequences depending on your bike setup.

Zipp includes a custom rubber grip which I'm of two minds about. On the one hand, the grip mates very nicely creating a beautiful integrated shape. On the other hand, it limits user choice, and I might like to try something a little cushier like the new Silca offerings. I suppose nothing would stop you from adding tape on top of the rubber bit, or removing it and replacing with tape. It is a pretty piece of kit all sewn up.

The other thing about the bend is that it stays pretty close to your arm, without touching it. This was an explicit design goal, as publicly stated by Zipp. Sadly, I don't think they get close enough to really enter the new aero frontier described up top. Nor do they have any particularly aerodynamic cross-sections anywhere; they're rather boxy as the wind sees them. Still, their inward cant and wider surface area do seem to help shield the rider's arms a little more than most traditional extensions, and on that front they may be better aerodynamically than the plain variety.

All-in-all, I'm happy to see Zipp working on things like this, it's a welcome innovation in this space. For an AXS-equipped bike, this would be a very nice cherry on top, assuming you don't have a Speedbar or similar.


Tags » axsgroup,  components,  extensions,  sram,  zipp

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