Shundong SD-558A Mountain Bike Speedometer with Blue Backlight and 28 Functions for Bicycles E-Bikes and Motorcycles

Knowing your speed, distance, and riding time helps you train smarter and ride more safely. The Shundong SD-558A code table delivers all this data clearly on a two-row, four-window LCD display. Designed for a wide range of two-wheelers, it fits wheels from 4 to 40 inches, making it suitable for bicycles, electric vehicles, and even motorcycles. The built-in backlight uses a high-brightness cold light source so you can check your stats at night or in tunnels. With 28 functions in total, this speedometer replaces guesswork with accurate, real-time information that any cyclist or commuter will appreciate.

Features and Construction

The SD-558A packs multiple riding metrics into a compact, weather-resistant body. Its engineering plastic housing keeps weight low while protecting the internal electronics. The LCD screen shows two rows of data with four windows, so you can monitor multiple stats at once without cycling through menus.

28 Major Functions

This code table tracks dynamic mileage, riding time, real-time speed, travel time, current time, and current date. It also lets you query average speed, total driving time, total mileage, and ambient temperature at any moment. A stopwatch function is included for timed rides or games, and a speed comparison indicator shows changes in pace. Metric or imperial units can be selected to suit your preference, along with 12/24 hour time and Celsius or Fahrenheit temperature display.

Blue Luminous Backlight

Between 17:00 and 8:00, pressing any key triggers a blue backlight that stays on for about 4 seconds before automatically extinguishing. This high-brightness cold light source makes the display readable in darkness without draining the battery unnecessarily. The auto-off feature helps extend battery life between changes.

Size and Sensor System

The main unit measures 9 x 4.5 x 1.5 cm, with a display area of 7.3 x 1.7 cm. The cable length is roughly 82 cm, giving enough reach for most handlebar and frame setups. A wireless sensor is not used; the included wired sensor provides stable, accurate speed data across a wide operating temperature range. The sensor uses magnets attached to the wheel spokes for pickup.

Uses and Placement

Whether you commute daily, hit mountain trails, or ride an electric scooter, this speedometer adapts to your vehicle. Its generous wheel-size range (4 to 40 inches) means you can move it between bikes or even install it on a motorcycle. The rainproof design allows use in light showers, and the easy-release bracket makes removal quick when parking.

Bicycle and E-Bike Use

Mount the sensor on the fork and attach the magnet to a spoke. The 82 cm cable reaches typical top-tube or stem-mounted positions without slack or tight bends. Set your wheel circumference in the menu to get accurate speed and distance readings. The speed comparison feature helps you maintain a consistent pace on climbs or flats.

Motorcycle and Scooter Use

For motorcycles with wheels up to 40 inches, the same installation method applies. The vibration-resistant design and rainproof housing handle road conditions. Use the speeding reminder to stay within legal limits during urban or highway riding. The ambient temperature display is a handy bonus for planning gear choices.

Night and Low-Light Riding

The blue backlight activates only between 17:00 and 8:00, which covers typical evening commutes and early morning rides. If you ride in low light outside these hours, the display remains readable due to its high-contrast LCD. The backlight saves battery by turning off after 4 seconds, so you only use power when you need it.

Benefits and Buying Value

This speedometer replaces smartphone apps that drain your phone battery and need mounting. It runs on a single CR2032 battery (included) that lasts many months with normal use. The vehicle service reminder helps you keep track of maintenance intervals, protecting your bike or e-bike from wear.

Battery Life and Replacement

One CR2032 button cell powers the unit. The backlight auto-off and standby function minimise power draw when not in use. To replace the battery, open the back cover, swap the old cell, and reset the settings if needed. No special tools are required.

Safety and Convenience Features

The speeding reminder lets you set a maximum speed threshold; exceeding it triggers a visual or audible alert. The perpetual calendar shows date and time, so you always know the current day. The auto-standby function prevents accidental battery drain if you forget to turn the unit off.

Why Choose the SD-558A

It combines 28 functions in a compact, rain-resistant body that fits almost any two-wheeler. The blue backlight sets it apart from basic wired computers without illumination. With metric/imperial units and multiple temperature scales, it works equally well for UK users and international riders. The included Chinese manual covers installation and operation step by step.