Adjusting the bike speedometer from the wheel diameter

Resetting the ODO (Total Bike Mileage)

Press the RIGHT and LEFT buttons at the same time and hold them for 3 seconds to clear ODO Total mileage and other values.
The wheel size and mileage will be reset, the watch will remain unchanged

This model comes in several modifications.

Installation KM / Ch and M / Ch

Press the RIGHT button to select KM / H or M / H. Press the LEFT button to enter ready mode. Press the LEFT button to cancel and enter CLOCK mode.

The calculation accuracy of the cycling computer depends on:

  • tire type. these are slicks or winter toothed with high spikes
  • type of road surface. always more accurate on asphalt than on soft ground,
  • real tire pressure while driving,
  • air temperature,
  • weight of the cyclist and the cargo carried by him,
  • accuracy of reed switch actuation, etc.

And further. As mentioned in the article on installing the bike computer, the distance on the rear wheel is more accurate than on the front.

Personally, I believe that an error of a few percent is not critical for an ordinary cyclist.

Installing the sensor and magnet

Installation of a magnet and a sensor (reed switch) requires the greatest attention. Maximum accuracy is important here. The entire system should be placed at a distance of 7-12 cm from the wheel axis so that the centrifugal force does not knock the magnet off. The side of the reed switch and magnet is only important when using disc brakes, which should be installed on the side opposite to the disc.

The sensor with suitable wires is installed by means of cords or a metal clamp on the foot of the suspension fork, strictly perpendicular to the plane of rotation of the wheel. Ideally, a reed switch (a sealed contact, closes when the magnet is brought up, on which its operation is based) should be perpendicular to the axis of the magnet at the point closest to it, but this is very difficult to achieve, given the angle of deflection of the spoke.

Next, the magnet is fixed to the spoke. It must be installed after the sensor, precisely checking that the distance between the reed switch and the magnet does not exceed a couple of millimeters at the closest point. The magnet is tightened as tightly as possible, until it stops, since all the vibration of the wheel will act on it.

It is very rare that the sensor and magnet are fitted to the rear wheel. In this case, the fastening is even simpler, the main thing is to correctly adjust the length of the flagella, otherwise, during vibration, the sensor will slide and contact will be lost.

Button assignment

Use RIGHT button to switch between ODO, DST, MXS, AVS, TM, SCAN modes (DST, MXS, AVS, TM and CLOCK).
The LEFT button is only used to switch to the Freeze Frame Memory mode.

Odometer ODO. Total Bike Mileage

In ODO mode, the total distance is displayed on the screen (value from 0.001 to 99999 km)
Press the LEFT button to enter DST mode (Distance, distance traveled in the current trip).

How to install and configure the bike computer correctly

There are several types of devices available on the market. The main classification of computers is by the type of connection to the sensor:

  • Wired. simple, convenient, and cheap. Installation can be a problem, but it’s not particularly difficult.
  • Wireless. Wireless connectivity allows you to install the bike computer anywhere, including releasing it as a watch or even as a smartphone app. The disadvantage of this type will be the need for a separate power supply on the sensor.

Further, the division goes by functionality. For example, in addition to the speedometer, modules for monitoring the training mode, storing service distances, GPS coordinates can appear. Top models of bicycle computers are already closer to PDAs and smartphones, and sometimes the border between them is completely erased. The main choice for functional types. in the cost and design of the device.

Main factors

In the instructions for cycling computers, a classic set of indicators is usually prescribed. There are usually no problems with decryption:

  • SPD or SPEED. Travel speed at the moment, it is possible to measure in miles per hour (Mph) or km / h (Kmh).
  • AVS or AVG. Average speed values ​​calculated since the last data reset.
  • TIME or TM. Duration of movement after reset, during stops on the way, no counting is carried out.
  • DST. Total distance covered by bike.
  • ODO. Mileage for all time, you can also reset it, but only after entering a special command. Reset.
  • Skan. One-by-one demonstration of all parameters on the device screen.
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Thanks to the detailed decoding, even novice users can easily understand the speedometer settings. Over time, you can learn how to quickly set indicators, get the necessary information about training, and also reset the results.

Take the survey

  • Wired. A simple and inexpensive gadget, difficulties can arise only at the installation stage.
  • Wireless. Easy to install, but expensive. The sensor is fixed to the wheel, so a separate power supply is required.

Wired Wireless

Installing a bike computer is a simple procedure that you can easily cope with on your own. The process consists of several stages:

  • Installation of the mounting platform. This element is a small panel equipped with two contacts and a lock for fixing the cycling computer. It is usually placed on the stem, bicycle grips, in the center of the handlebars, or over the shifters. Harnesses are used as fasteners, they will have to be tightened as tightly as possible, you can strengthen with a rubber backing.
  • Installing the sensor and magnet. The system should be placed 7–12 cm from the center of the wheel. The sensor with wires is fixed with a metal clamp or bundles. As a result, the reed switch should be perpendicular to the axis of movement of the magnetic element. The latter is mounted on a spoke.
  • Placement of the wire. This laborious procedure is performed if the bicycle speedometer is of the wired type. Carelessly laid cables will spoil the appearance of the bike, over time, the elements will cling to other mechanisms, interfere with the service and maintenance of the vehicle. Usually, two installation paths are used. along the steering column or brake cable.

Installation of a bicycle computer on a bicycle in the case of a wireless device is made in a simplified version. You only need to lay a wire to the emitter from the reed switch, if both elements are made in separate housings.

In rare cases, the question arises as to how to properly install the sensor and magnet on the rear wheel. The procedure is simple, the main thing is to correctly determine the length of the wires, otherwise the sensor will slip from vibration, which will lead to loss of contact.

How to set up a bike computer

Sometimes novice cyclists boast of high speeds, not suspecting that the whole secret of their championship results is in the wrong setting of the bike computer.

It so happens that a person makes round eyes when he hears that he generally needs to be tuned. like, what’s the difference, a bicycle.

I will not tell you which key you need to press, the more it depends on the specific model. The most important thing is to open the instructions for the cycling computer and study it, as a rule, everything is simple.

Read the full article about a bicycle speedometer, what are the varieties, how the wireless model differs from the wired one, the pros and cons.

Wheel circumference

Setting up the bike computer always starts with entering the wheel circumference of the bike. The accuracy of measurements and calculations of the device will depend on the correctness of this value.

The length of the wheel’s circumference can be measured with a thread wrapped around the wheel, or a tailor’s meter, but this is not the most accurate method, since the camera shrinks when moving, and the effective length becomes slightly smaller.

Bike Speedometer Wheel Size Measurement

The exact circumference for a particular bike and cyclist is measured at full load. To do this, just mark a point on the tire, mark it on the floor or asphalt, drive exactly a turn and measure the distance between the two marked points.

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For quick adjustment, a table of correspondence between wheel sizes and circle lengths is suitable:

Customization and key indicators

Bicycle Speedometer Setting Table

Bike settings

To view or change bike settings, go to SETTINGS Bike settings. bike and select bike. The sensors you have connected to the bike are displayed under the bike name.

BIKE NAME: Bicycle 1. Bicycle 2. Bicycle 3 or Bicycle 4

How To Determine Wheel Size For A Bike Computer BikeBlogger

WHEEL DIAMETER (MM): Set the wheel diameter in millimeters. See Wheel Diameter Measurement for more information.

CONNECTING ROD LENGTH (MM): Set the connecting rod length in millimeters.

SENSORS: View all sensors connected to the bike.

Measuring wheel diameter

Accurate wheel diameter data is a must in order to know your ride. There are two ways to determine the diameter of your bike’s wheels:

Measure the wheels manually for the most accurate result.

Use the valve to determine the point where the wheel touches the ground. Draw a line on the ground to mark this point. Drive your bike forward on level ground until the wheel completes a full circle. The tire should be perpendicular to the ground. When the valve is at its origin, draw another line near it to mark a complete revolution. Measure the distance between two lines.

Subtracting 4mm from this distance to compensate for your pressure on the bike will give you the wheel circumference. Enter this value into your cycling computer.

Find a marking on the wheel indicating the wheel diameter in inches or ETRTO units. Use the table to get the value in millimeters (right).

Wheel size data can also be obtained from the manufacturer.

ETRTO Wheel diameter (inches) Wheel diameter setting (millimeters)
25-55926 x 1.01884
23-571650 x 23C1909
35-55926 x 1.501947
37-622700 x 35C1958
47-55926 x 1.952022
20-622700 x 20C2051
52-55926 x 2.02054
23-622700 x 23C2070
25-622700 x 25C2080
28-622700 x 282101
32-622700 x 32C2126
42-622700 x 40C2189
47-622700 x 47C2220
55-62229 x 2.22282
55-58427.5 x 2.22124
bike, speedometer, wheel, diameter

The table shows only approximate values, as wheel size also depends on wheel type and air pressure. Due to different measurement data, Polar cannot be held responsible for their correctness.

Speedometer: speed control and safety

The car is known to be an object of increased danger. Therefore, speed control is necessary to ensure the safety of his driving. This function in the car is performed by a well-known device. a speedometer.

Purpose and role of the speedometer

In any country, to ensure road safety, traffic rules have been developed (hereinafter referred to as SDA), which, with the help of valid signs, regulate the speed on the roads. Taking this into account, the driver of any vehicle must control and adjust his speed.

In a car, this is done by a device. a speed meter, that is, a speedometer. The obligatory presence of this device is established at the legislative level of Russia, and in case of malfunctioning of the speedometer or its absence in the car at all, fines may be imposed.

In addition to measuring the speed, the speedometer shows the distance traveled by the car. This function is performed by the odometer. Separately, the mileage of the car from the beginning of its operation and the mileage set by the driver to determine the distance traveled are calculated. Read more about the run roll-up here. The speed display provided in some speedometers makes it easier for the driver to control the speed on the road.

Division by classification

Currently, three types of speed measuring devices are used: mechanical, electromechanical, electronic.

They differ from each other in the specificity of measuring the speed and in instruments reflecting its value. The sequence of the appearance of devices took place in this order: mechanical, later electromechanical, and then electronic speedometers. Each of the devices has both disadvantages and advantages, so they are still in demand.

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Description of mechanical speedometer

The simplest mechanism is used to calculate the speed in this device. It is measured using a gear speed sensor.

The device is equipped with four key nodes. the first speed node, it shows the current speed, the second node, in which the vehicle speed sensor (DSA) is triggered through the gear mechanism, the third node, the flexible shaft connecting them, and the fourth, this is the odometer connected to all nodes due to mechanical transmission. He is responsible for converting the number of revolutions to meters and kilometers.

The mechanical speedometer has long enjoyed wide acceptance. It’s all about the simplicity and reliability of its device.

Description of the electromechanical speedometer

This type of device combines mechanical assemblies and some electronic components. This is the use of both a mechanical principle of operation in odometers and sensors, and the use of sensors and display units with electronic elements.

Sensors are classified into four types: gear principle, inductive, impulsive and combined principles.

Despite their widespread use in applications, when equipping in cars, electromechanical devices were supplanted, since their place was taken by electronic devices.

Description of electronic speedometer

The only difference that characterizes this device is the use of an electronic odometer in it. For the control function and DSA, the electronic unit and the sensor are used here, respectively.

This type has several advantages over others. One of them is the impossibility of manual intervention in the winding of the run (“twisting” of the odometer). Equipping the car with an on-board computer complicates this action by its inaccessibility.

Interestingly, cars with such a speedometer show the speed in the digital display. But, for now, a conventional device with a speed indicator is considered to be more convenient in perception and in providing better control of the speed of the car.

As practice has shown, each type of instrument has one negative nuance. the error in instrument readings. over, the error values ​​can be 10 percent or more. This often occurs in mechanical and electromechanical instruments. The error, depending on the speed, may be different, and in some situations the sensor does not work at all.

In front-wheel drive cars, there is a distinctive error arising from the peculiarities of the movement of its wheels, which do not pass an equal path. What may not correspond to the readings of the devices, as well as affect the operation of some units.

In some cases, changing wheels can cause a permanent error, which depends on the diameter of the wheels.

It should be noted that at a speed of up to 70 km / h. modern devices show correct readings. Therefore, in order to reduce the danger, the error that occurs when the speed is increased is already included in the algorithm of the program for the operation of the electronic device. And therefore, its elimination is simply not possible for a non-specialist.

In case of changing the speedometer, as well as when carrying out work on the installation of the tachograph, it is necessary to carefully determine its marking. When buying a new reading device, you need to choose the appropriate type. In this case, the accuracy of the readings will be ensured.

Do not forget that it is necessary to carry out car repairs during car repairs, to ensure constant monitoring of the operation of its important components, and a correct and competent approach to the installation and replacement of devices. Compliance with these recommendations will ensure safe traffic and compliance with traffic rules.