What pressure are you running? Three different pressure monitoring systems, put to the test

SKS’s Airspy system uses a battery-powered sensor attached to a valve stem extender. The entire apparatus threads onto an existing valve (versions for both Presta and Schrader are available) and connects with an app or a Garmin bike computer to relay real time pressure. Included in the package are several different sized brackets to connect the sensor to the closest spoke, which SKS bills as an anti-theft precaution, but also helps to stabilize the sensor unit. 

I was unable to decipher the included directions, so decamped to YouTube where I located a video tutorial from SKS. Once I made sense of it all, it was very easy to get up and running: after letting the air out, the sensor threads directly onto the valve. The bracket sits on top of the sensor and hooks around a spoke. No tools are needed for installation—in fact, SKS specifically cautions against tool use as too much torque could damage the sensor. Batteries are included as well, though I found the battery covers to be fiddly. I would appreciate having markings of some kind to help line up the cover during reinstallation.

The Airspy tool has its own place on the homepage of the SKS app and provides readouts for both front and rear tire pressures. Connecting the sensors to the app was easy enough, though the ID numbers are on the bottom of the sensor so you can’t read them easily once they’ve been installed. SKS also has a tire pressure calculator as part of its app, though I found its suggested pressures to be much too high.

On the bike, the sensors performed as expected. Pressures quickly popped up when I opened the app, and provided consistent readings throughout the ride. My tire pressure dropped 4-5 psi from indoor temps (70 degrees F) to outdoor temps (45 degrees F). I didn’t experience any alerts during testing. The apparatus is unnoticeable on the road: when installed correctly there is no rattling. I’m not sure the bracket clip will work with every spoke type out there, but the design was compatible with all of the wheels I tested it on. Functionality is very good, but it seems like the size of the sensor and bracket could be further pared down a bit so that the whole product is more streamlined and lighter. Of the three systems tested, this one as the easiest to use and had the fewest peculiarities.

Weight: 21 grams per wheel
Cost: $167 for a set of two sensors
Website: sks-us.com, sks-germany.com

Tubolito has made a name for itself producing extremely lightweight TPU tubes for a wide variety of sizes and applications. The company has recently developed a pressure-sensing system within a TPU tube, by enclosing a small NFC chip near the valve. The chip senses the pressure within the tube and then relays it to a smartphone app. It requires no batteries and adds only a small amount of weight. The chip is roughly an inch and a half long and has light padding around it for protection.

Installation is exactly the same as putting a regular tube into a tire. At the moment Tubolito only makes its PSENS chip-enabled tubes for mountain bikes (the tube is compatible with both 27.5 and 29 inch tires), though I ran them on my gravel bike without issue. I suspect that at the moment the chips are just too large to fit into smaller tubes, but Tubolito says it has plans to offer additional sizes in the future. 

If the thought of using a tube on your mountain or gravel bikes seems anathema to you, you’re not alone. Very few riders are using tubes on dedicated off road bikes these days. Even for the purposes of experimentation, it’s a hassle to need to clean out sealant and remove valves to swap back to tubes on a dedicated tubeless setup.

Tubolito’s app has just one feature. Once downloaded, it prompts you to hold your phone near to the PSENS tube and then spits out the pressure in both Bar and PSI. That is the full extent of it. It’s critical to hold your phone right against the tire for it to connect, and I frequently received an error message that something went wrong. It would be nice for Tubolito to include some additional instructions as part of the app as well as provide advice for troubleshooting issues.

I was able to check pressure mid ride using Tubolito’s app without issue, and monitored changes as I was riding. However, the fact that you need to place the phone right next to the tire to read the chip was tedious, as was the fact that you can only check one at a time. The NFC chip concept shows promise as a simple and lightweight way to relay information, but encasing it in a tube limits the real world use significantly. Putting a similar chip directly into a tire and increasing its connectivity would make it much more useful.

Weight: 85 grams per tube with built in NFC chip
Cost: $50 per tube
Website: tubolito.com

Similar to SKS’s system, Quarq’s TyreWiz uses a battery-powered sensor attached to a valve extender. The pressure sensor can then be wirelessly connected with a smartphone or bike computer. Installation requires first deflating the tire, then removing the valve core on the bike and threading the TyreWiz into the valve stem. It works with any valve with a replaceable core whether tubeless or tubed. Once installed, the sensor pairs directly with SRAM’s AXS app. Included in the package is a valve core tool.

Since SRAM’s app supports many products, it’s well-designed and fully featured. The TyreWiz(s) pop up quickly for pairing and the app gives the option to tie them to a specific bike. It also allows you to input a target pressure, as well as high and low limits around it. Should you exceed those limits, the sensor’s LED lights will change from green (within target range) to red. The app also provides pressure suggestions.

I set everything up initially and was able to get an accurate reading, then went riding. On the road I ran into some issues: the sensor has to reconnect each time you open the app and sometimes it gets confused. When I stopped to look at my pressure on the first test ride the sensor wasn’t reading accurately. I suspect the battery may have been low, as I didn’t run into any issues with the other sensor on subsequent rides.

On the bike the unit is unobtrusive and seems well-attached to the bike. While you’re riding, you can’t easily see it, though it looks a bit funny in profile. Like the SKS unit, I found the battery cover to be a bit fiddly. I always seem to end up dropping these tiny little covers on the floor and they become impossible to see. Alas.

Of the three systems, SRAM’s is by far the most expensive. It does seem to be extremely accurate, when it works, but I did have some issues with connectivity on the bike. It would be great to see this design streamlined even further. I am concerned about long-term durability with this design as it’s only connected to the bike via a threaded valve core. It seems like any minor impact or even some particularly tenacious mud would knock one of these sensors out of commission.

Weight: 11 grams per wheel
Cost: $214
Website: sram.com