Sigma ROX 4.0 by Sigma - 2.4-Inch GPS Bike Computer

Sigma ROX 4.0 puts a 2.4-inch display, GPS and GLONASS positioning, and barometric altitude measurement in one compact bike computer. The unit also uses a rechargeable 550 mAh, 3.7 V battery and carries an IPX7 rating.

What The ROX 4.0 Adds

The ROX 4.0 supports more than 30 functions, including turn-by-turn navigation, re-routing, speed, distance, and training time, according to Sigma's product page. The same page says the computer can be positioned on the handlebars without cables or sensors and can connect to up to 3 sensors.

Sigma's short manual lists the battery type as a rechargeable 550 mAh, 3.7 V battery and names Bluetooth Low Energy and ANT+ for sensor links. It also lists an operating temperature of 0 C to 60 C and a transmission power of less than 4 dBm.

Price And Market Position

A US retailer listing puts the ROX 4.0 at $68.99 as of 09/07/2026, while Riding Gravel said the base unit was around $70.00. That places it below many higher-end GPS head units that add maps, touchscreens, or larger color displays.

Riding Gravel also described the ROX 4.0 as a GPS cycling head unit with Sigma Ride app support, plus optional cadence, speed, and heart-rate sensors. The review measured the screen at 2.4 inches and weight at 51 g, matching Sigma's own product materials.

Compatibility And Setup

Sigma says the ROX 4.0 works with the SIGMA RIDE app, the SIGMA DATA CENTER, and third-party route files in FIT format. The product page also says komoot tracks can be loaded through the app, and the manual says the device can pair with one smartphone at a time.

The manual adds a USB-C charging port, a charging time of about 2.5 to 3 hours, and support for e-bike data on compatible systems. It also says only original Sigma mounting systems were tested in the lab and in the field.

Where It Fits

The Sigma ROX 4.0 fits riders who want GPS guidance, sensor support, and basic training data without moving to a heavier navigation unit. Its 2.4-inch screen, 25-hour battery claim, and IPX7 rating keep the focus on ride data and route prompts rather than a full mapping suite.

For riders who want color maps or touchscreen control, the ROX 4.0 sits lower in the hierarchy. For riders who want a lighter unit with GPS, altitude, and sensor support, it keeps the spec sheet focused.