Gear Review: Speedfil Z4 Bottle Cage

As Tested

Among a handful of prototype testers for the last month was Canadian pro triathlete Donna Phelan and a small handful of sponsored Wattie Ink age group triathletes...aaaand this editor. I used it both with the Speedfil A2 bottle locked in place, as well as moving standard bottles in and out during training.

For a month I used a few different versions with different levels of cage stiffness or flexibility, ease or stiffness of bottle entry and exit. I must say I kept coming back to the fact that I love the minimal design of the Z4, specifically the lack of a baseplate or any other hardware, using just zipties to affix it to the extensions.

The zipties of the Speedfill Z4

Beyond that, it's great addressing basic needs. The integrated Garmin mount frees up the extension real estate and places it right in line with the eyes while in the aerobars. Stiffness or flexibility in either of the prototypes we played with was never an issue; the fairly closed-off design of the cage itself is going to keep the bottle where it's supposed to be. We never had an issue with bottle security in testing. The cage top has a pronounced notch that helps lock the bottle in by the neck. And it was easy-in, easy out.

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The only suggestion would be to "lead" the zipties with a few loops of electrical tape around your aerobar extension as a stop. While this may not be a big deal on those with alloy aerobar extensions (as the plastic zipties and roughed alloy surface tend to "grip" one another better), keeping the cage fixed in place horizontally on typically slick, glossy carbon fiber aerobar extensions would be a challenge; a few loops of electrical tape, acting as a "stop" will solve for that, allowing easy in-and-out of bottle swaps during a race.

All told, with just four zipties affixing it to our bike, the Z4 is to our knowledge, and at this point, the lightest dedicated BTA setup with function feature on the market. On heavy tri bikes burdened with enough extra "stuff," it's a nice feature...and a rare time that the lowly ziptie becomes a "feature" per se.


Inviscid will be selling the patent-pending Z4 cage (which includes the Garmin arm and zipties) for $40. For those looking to pair the unit with their existing Speedfil A2 bottle, an upgrade version of the Z4 will also include a new new straw clip that allows the straw to lay alongside the bottle and out of a rider's face while riding, along with a new silicone-backed Velcro fixing strap. That setup will retail at $50.

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About the Author

Jay Prasuhn

LAVA magazine Senior Editor Jay Prasuhn has served as a technical, feature and destination writer for more than 13 years, covering and photographing events including the Hawaii Ironman, the Olympic Games and the Tour de France, as well as IndyCar and NASCAR motorsports events. An Ironman, ultramarathon and Leadville 100 MTB finisher, Prasuhn makes his home in Encinitas, Calif. You can follow him on Twitter at @jayprasuhn.

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