Xert + Karoo + NPE CABLE : Links your ANT+ devices to your smartphone’s apps.

NPE CableXert & North Pole Engineering (NPE) – More Connection Options With CABLE

This announcement got me scratching my head for a while. It seemed to offer an interesting new capability I just wasn’t quite sure how people were going to use it. Then I remembered that my KICKR 17 only has one BLE channel which restricts how I can use it and I also thought that it would be nice to connect an ANT+ device to my iPhone from time to time.

Who Is Xert?

Many of you will be happy that you have a super-accurate power meter, yet you probably won’t know that there are ‘errors’ in the TSS calculations you use. You will probably also realise that the normal usages of CPs/FTPs don’t quite help you understand the effect of fatigue on your current, instantaneous performance abilities.

Xert models power differently from the normal FTP-based approach that you are familiar with. On the occasions when I’ve been injured at running and just cycling I’ve found Xert’s predictions of my cycling abilities to feel accurate. However, its accuracy seems to be lessened when I introduce fatigue from running (Xert are working on that and have partial workarounds).

So, if you’re a triathlete it’s probably not so useful but for a cyclist, it’s definitely worth looking at.

Xert also has some very interesting (Free!) CIQ tools, including the popular ‘What’s My FTP‘ which shows your achieved FTP increasing in real-time throughout a maximal ride.

More Info: Xert Content on this site

Hammerhead Karoo 2 users will also be intrigued that the Xert Android app can be sideloaded onto Karoo 2 and essentially take it over. Voila. You have a Xert Bike Computer. Cool Stuff.

Who Is NPE?

NPE make interesting and unique sensors that do weird and wonderful things for less-than-normal uses.

Two of their other products are NPE RUNN and HEARTBEATZ. NPE RUNN (review and discount) was my favourite product of the year last year and simply turns your cheap treadmill into a smart treadmill…of sorts. It cleverly reads the belt speed and incline and transmits your pace, incline and cadence to your favourite smartwatch or smartphone app. Clever stuff.

Heartbeatz is for Apple Watch owners. A WatchOS app is installed on your Apple Watch that sends your heart rate to HEARTBEATZ which then converts your HR to ANT+ and broadcasts that so that Garmin, Wahoo, Peloton or most other sports devices and platforms can see and record your HR info. Again…cool.

NPE Runn Review


CABLE is another converter and also comes with interesting mount options for handlebars.

The supported ANT+ profiles are Heart Rate, Bike Power, Bike Speed & Cadence, Running Speed & Cadence, Crank Torque and Fitness Equipment (FE-C). The supported Bike Power profiles include Power Only, Wheel Torque, Crank Torque and Crank Torque Frequency.

Whilst almost all modern sensors transmit over both ANT+ and BLE, MANY of them are still limited to one BLE channel ie you can only pair to one other BLE device. When it comes to pieces of kit like Zwift, smartphone apps, and BLE only watches like Polar & Suunto then CABLE can essentially let you simultaneously connect to more places.

XERT comes into this because now I can use CABLE and my XERT app such that XERT can control my ageing KICKR17 whilst I zwift along to my heart’s delights.

Yes, there are other options like (IIRC) a Samsung smartphone can pair to some ANT+ sensors, the 4iiii Viiiiva converter strap and you can also buy dongles to resolve some Zwift connectivity issues.

Even cheaper: NPE also sells refurb items on their site for even lower prices. Use the discount code THE5KRUNNER



It’s great that companies are still trying to solve our perennial connectivity problems with your old tech. Not all of us can afford to buy the latest and greatest everything each year.

One day someone might think of standards that could get around all these problems. Oh…wait a minute, they already exist and mostly have for quite a long time.


Hammerhead Karoo 2 Review
Note the Xert app icon on Karoo 2

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5 thoughts on “Xert + Karoo + NPE CABLE : Links your ANT+ devices to your smartphone’s apps.

    1. doh ! ty

      edit: my understanding is that the CABLE is a GENERIC bridge whereas the viiiiva is more specific in what it can and cant do. I’ll hopefully clarify exactly what i mean in the article when i get the correct form of words . so cable IS one of a kind (it’s just the definition of ‘kind’ needs to be clarified!) eg CABLE supports VARIA, Viiiiva doesn’t

      1. There is no generic as it has to match a specific ant+ profile to the BLE equal.

        Cable requires an ios device to configure, 4iiii works on ios and android

      2. yes but, for example, the specific issue with VARIA is that Garmin has to agree to work with the 3rd party and, AFAIK, only RwGPS has that agreement as an app. CABLE is generic in that it gets around that whereas viiiiva does not.

  1. The already existing standard is ANT I guess?
    I just work with that with everything I have (3 stationary devices, 6 rolling, 3 meters and about 20 sensors). Some things could be better but that’s in the ‘advanced sector’ and in the whole data traject.

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