DIY bike computer repair

In detail: do-it-yourself bike computer repair from a real master for the site my.housecope.com.

In most cases, the cycling computer can be repaired by yourself. To do this, you need a tester (avometer), which can be bought for less than $ 15, a soldering iron and the ability to use it.

Electronics cannot be repaired on your own, but printed circuit boards and microcircuits of modern bike computer models are very reliable and rarely break. And the most common faults are easy to fix. There are three main reasons for bike computer breakdowns: battery problems, wiring problems, or improper magnet or sensor positioning on the bike computer.

Battery faults are the easiest to identify. If you can see clear black numbers on the screen, then everything is in order with the battery. When the battery runs out, the liquid crystal screen dims, and when it is completely discharged, the screen goes out completely. Open the bike computer, remove the battery, check the terminals for corrosion. Remove plaque with a cotton swab dipped in ammonia. Replace the battery. If the screen is still blank, try rebuilding the terminals with a soldering iron.

Some cycling computers are very sensitive to nutritional quality. Ideally, the battery should have direct, solid contact with its terminal blocks. When the contacts "rattle" due to battery displacements, the bike computer will receive "erroneous" data, confusing it. It can show one eights, or random fragments of numbers, or it can go out altogether. This problem is especially common with Cateye Solar cycling computers, which have very firm elastic contacts and use two small batteries that are quite difficult to replace. Many Cateye Solars bike computers that simply needed to be properly reinstalled have been rejected as defective. Previously sold Cateye batteries came with a special small piece of thin plastic that was used to clean the contacts - it was inserted between the two batteries and then removed.

Video (click to play).

Some cycling computers have a special procedure to “reset” the processor, usually by pressing all buttons at the same time.

Electrical wiring on bicycles is very often damaged and torn, especially if the wire is not properly routed and protected.

Problems usually occur in the area of the steering column, where the wire can become taut when steering. Front-mounted bike computers are more reliable in this regard, because there are no loose areas when the bike computer is installed correctly. The wire rises from the fork blades to the front brake and then goes along the brake cable to the handlebars without any attachment to the frame.

Rear-mounted bike computers require more care because of the loose cord that must not touch the tire, which can quickly wipe it down in just a few kilometers. Also, when installing the bike in the simulators, you can accidentally damage the wire laid under the downstay of the rear triangle. At the same time, it is impossible to install the sensor of the bicycle computer in front, since it will not work!

Wireless bike computers have a second battery in the radio transmitter. When this battery runs out, the speed readings become inaccurate and eventually disappear. To get at least some reading, the bike computer sensor must be moved from the rear wheel to the front wheel.On a bike with small wheels, you can break the rule of placing the magnet close to the hub and place the reed switch with the magnet closer to the bike computer.

You can also try placing the wireless bike computer below the handlebars. On sale are available special mounting brackets for installing bike computers, headlights to go. Tilting the bike computer forward and back with the steering wheel can also prevent it from picking up the sensor signals due to the displacement of its internal antenna. This is especially noticeable on the liguerade.

It is easy to check the wiring using an ohmmeter or a tester, you just need to understand how the sensor of the bike computer works. The "sensor" is actually just a magnetically operated switch (reed switch). When the magnet is close enough, the reed switch closes, making contact between the two wires in the cable. When the magnet is far from the sensor, the reed switch is open and there is no contact between the two wires.

If you remove the bike computer from its position on the handlebar, you can see two metal contacts (three for cadence cycling computers). For trouble-free operation, these contacts and contacts on the bike computer itself must be clean and provide a reliable spring-loaded connection. If cleaning the contacts does not solve the problem, you need to check the wiring and the correct installation of the magnet with an ohmmeter or tester. Hold the tester probes on the two mounting pins on the handlebar. If you have three pins, one is for the wheel sensor, the other is for the cadence sensor, and the third is common to both. To determine where is which contact, you need to try all the combinations one by one.

Turn the wheel so that the magnet moves away from the reed switch. There should be no connection between the two pins. If the device shows a connection, then the wires are short-circuited and you need to change the sensor, wire or block with the sensor. (This method does not apply to Avocet bike computers. See the methodology below for Avocet bike computers.

Then turn the wheel so that the magnet is next to the reed switch. The tester should show that the circuit is closed. You can shake the wire back and forth and make sure that the connection appears and then disappears again when the wire moves. If this does not happen, then the wire is damaged and at best the bike computer will work intermittently. If the bike computer passes this test, then the wires and magnet are installed correctly and are not damaged.

If you cannot close the reed switch with a wheel magnet held close to the reed switch, try using a pocket magnet. Hold it exactly opposite the sensor on the same side it should be on according to the instructions. If the circuit still remains open, the wire is faulty. If the pocket magnet works, but the wheel magnet does not, then you need to try to bring the wheel magnet and the reed switch as close as possible.

Expensive Avocet bike computers work a little differently. The sensor on the Avocet bike computer is not a reed switch, but an inductor. A 20-pole magnetic ring spins past the coils of the sensor, generating a small electrical current that can be measured with an AC voltmeter. When the wheel is rotated by hand, an alternating voltage of approximately 50 millivolts should be generated at the terminals on the handlebars.

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When testing, a tester or ohmmet will show the connection regardless of the position of the magnet. Unlike most bike computers, Avocet bike computers can only replace a wire, without completely replacing the bike computer sensor or handlebar assembly. The Avocet 15 and 25 use a conventional reed switch with one magnet on the spoke.

The magnets used in various brands of cycling computers are very simple and interchangeable. Some are more powerful than others. The sensor will not trigger if it is too far from the magnet - therefore a stronger magnet is easier to install.Replacing a stronger magnet with a weaker magnet can lead to problems.

Incorrect installation of the bike computer magnet can also result in irregular or double readings.

The magnet of the Cateye solar bike computer has two lines printed on it. One of these lines must be located on the same axis with the corresponding line on the reed switch. Cyclists do not install the cateye bike computer according to the instructions, assuming that this line on the sensor should go somewhere between the lines on the magnet. This error results in completely incorrect readings on the bike computer. Each of the lines on the magnet is located in the region of the maximum fields of the magnet, and the middle between these lines is not magnetized.

The Cateye Mate bike computers use 4 magnets mounted on the rim. If the rim is bent, one of the magnets will be farther from the reed switch than the others. This can result in a bike computer reading of 15 mph when you are actually riding 20, and so on. You can check that all the magnets on the rim are close to the reed switch by spinning the wheel a few inches back and forth at low speed to allow the magnet to pass. here and there near the reed switch. A speed reading will appear on the screen, even if it is only 2 or 3 km / h. This test must be repeated for each of the four magnets. You must get speed readings from all four magnets, otherwise the reed switch must be reset.

Isn't it easier to disassemble the bike computer itself?

In this model, there is no such function.

PS In the evening I will arrange ritual dances with a tambourine - after that I will unsubscribe.

The bike computer is new, as you wrote, so it could be exchanged.

In this model - this function is absent
The sensor is filled with banal thermal paste - it's not difficult to restore.

They would ring like this (if there is no multimeter), a battery and a TV (if the reception is on a conventional antenna or cable). We would connect a battery or power supply unit instead of the controller's head and run it with a magnet - small ripples on the TV set showed that the wire with the sensor is working properly, or vice versa.

Do not do this under any circumstances! A surefire way to kill a low current signal reed switch. And maybe, at the same time, the power supply unit, if it does not have short circuit protection.
andrey_9999, refrain from advice on electronics if you don't know a lot about it.

In most cases, you can repair a bicycle computer yourself; you only need a tester (workshop). The electronic part cannot be repaired on your own, but the boards and radio elements of modern bicycle computers are very reliable and fail very rarely.

The most common faults in cycling computers are caused by poor contact or broken wires and are easy to fix. There are three main reasons for bike computer breakdowns:

- problems with wires;
- problems with batteries;
- incorrect location of the sensor of the led computer or magnet.

Wires from a led computer are very often damaged and torn, especially when they are not protected or routed incorrectly.

Most often, problems can arise in the area of the steering column - when you turn the steering wheel, the wire can stretch and break. In this regard, the most reliable bike computers are those that are installed in front - with proper installation, there are no areas with sagging wires. The wire from the fork stays goes up to the front brake, and then goes along the brake cable to the handlebars without attachments to the frame.

When installing the sensor and magnet of the bike computer at the back, you need to be more careful, as the loose section of the wire can be damaged when it touches the tire. When the bike is installed in the simulator, the bike computer will not work when the sensor and magnet are located in the front (the wheel does not spin). And, with the rear position, you can accidentally damage the wire that is laid under the lower rear stays of the frame.

They are the easiest to identify. When the battery is good, the numbers on the screen are clear.When the battery "runs out", the liquid crystal screen starts to dim, and when the battery is completely discharged, it goes out completely. In addition to a dead battery, the problem may be in the contact terminals (corrosion, oxidation, plaque). The plaque is removed with ammonia.

Cycle computer malfunctions - some models are sensitive to power quality. In case of poor contact with the battery, the cycling computer receives erroneous data and gives an incorrect result.

If the sensor on the fork or frame or the magnet on the wheel spoke is not properly installed, the bike computer either does not work at all or malfunctions, giving incorrect readings.

The optimum distance between the sensor and the magnet is approximately 1.5-2 mm. During operation, the magnet attachment may weaken and it will break, the same happens when driving on tall grass or when overcoming obstacles.

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On the modern market, there are a large number of people who produce computers for bicycles. Each model has a different pricing policy and a set of many useful functions, which we will talk about a little below. The cycling computer on our bike plays an important role. For one, it serves just so to speak for beauty.

Well, for more advanced cyclists, it is able to show the necessary parameters we need, such as:

travel speed
average travel speed
total mileage
clock

These are the main functions of the cheapest bike computers, there are also more advanced devices that can have a wider range of functions, these can be:

LCD display backlight
storing data in memory
current travel speed
average speed
maximum speed
travel time
total travel time
air temperature
heart rate monitor
calorie burn rate and other features that are added as you improve.

But everyone is not insured against device failure or breakdown. What to look at if the bike computer does not work?

The most common thing that can happen is a malfunction of the position of the magnet on the spoke. I personally encountered such a problem. It is treated by checking the gap between the magnet and the receiver.
The exact same problem can happen with the magnetic pickup sensor that is attached to the bike fork. Checking the gap.
If the computer on the bike is wired, then the problem may be a bare wire or a fracture. We diagnose the wiring from the base to the magnetic receiver. If a fracture is found, it is necessary to carefully solder and isolate the problem area.
Oxidation of the contacts on the bike computer mount (socket). Solution lies in cleaning the jack contacts and on the device itself.

And the worst thing that can happen is the breakdown of the device itself.Diagnostics of the computer consists in closing the contacts, you can close them with your fingers and rub them, thus closing and opening the contacts on the device, numbers and speed readings will appear. If the numbers appear, it is necessary to diagnose the above points. If the computer does not respond to the closure of the contacts, then you will probably have to contact the electronics engineers for repair, or, if the malfunction has not been eliminated, you will have to purchase a new cycling computer.

What to do if the bike computer stops showing the speed?The most obvious and common malfunction. Most likely the problem can be solved

1. Most likely, the position of the magnet on the spoke is lost relative to the reed switch on the frame. Check clearance.

2. The contact in the I / O mount on the base has disappeared. Remove the I / C, wipe the contacts, insert the I / C into place.

3. We check the w / c. We remove it from the base and simply manually quickly close-open its contacts - for example, with open scissors. The numbers "ran" - it means that the w / c itself is working, the point is in the wiring.

4. Check the wiring - carefully inspect the wire for breaks and damage. If a break is detected, the broken wire must be carefully soldered and insulated.

Hello everyone.
Sigma 800 bike computer
Worked until recently (2nd season) without interruption, but. stopped.Fastening, wiring, battery, everything that can be checked, reset all data a couple of times and reinstalled - everything is fine, but it does not work.The bike computer itself displays the time correctly, responds to all buttons adequately (there are no visible damages or defects) but does not display the speed, distance, etc.After the trips, it displays that a distance of several meters has been covered and that the training time is several seconds. (After I reset all the data, but the next time the story is the same.)Tell me what it could be, or is it just time to change the bike computer? Image - DIY bike computer repair

if so, it is more likely that some wiring is broken .. maybe at the entrance to the mount, maybe at the entrance to the sensor

they can also row under the wires of trolley buses ..

The main differences from conventional cycling computers in the PROFEX-1600 are the absence of wires running from the cycling computer itself to the measuring sensor, the presence of a built-in solar panel (greatly increases the service life of the device), very low power consumption, moisture resistance and a decent set of functions.

The set included all kinds of fasteners with ties, rubber pads, and more. The sensor is installed on the front wheel fork, the magnet is screwed to the spoke, the speedometer itself is attached to the steering wheel.

When turned on, the bike computer asks for the size of the wheel on which the sensor is installed. This is necessary so that the speedometer correctly calculates the speed and other values, otherwise you will not get accurate results from it. The size is indicated on the wheel itself, I have it 26 X 2.00. In my case, the number is 2114. The data for input into the cycling computer was taken from this table:

If the typical wheel size is not indicated on it, then you can measure the value for input yourself:

The first way - multiply the wheel diameter by the number Pi (for km / h) or divide the result by 1.61 (for mph).

Second way - mark the origin and reference point on the wheel on the asphalt, then make a full revolution and measure the distance in millimeters. This will be the same number for the calculation.

Next, the units of measure are set in miles / km, hours.

What does this model measure? Current speed, average and maximum developed; total travel time, separate travel time; the total distance of the run, the distance of the current run (you can reset it or change it); determines the direction - forward and backward. There is also a shutdown function when idle and "scan”, Which automatically switches the display modes. The communication distance is about 2-3 meters, for example, you can freely remove the speedometer from the mount and give it to fellow travelers and the connection will not stop.

How does the cycling computer determine the speed? These are tasks from 3-4 classes. Let's say the size of the length of our wheel is 1954 mm, this is 1.954 meters. When the sensor sends a signal, these same 1.954 meters are counted and the time between signals is determined. If we know 2 quantities, then we can find the third - speed.

There is a radio transmitter and a reed switch inside the sensor. Why a reed switch? Yes, because when the magnet attached to the spoke approached, a click occurred - the reed switch contacts closed, power was supplied to the transmitter. Instead of a reed switch, a Hall sensor could be installed, but it needs power, but the reed switch does not.

The bike computer is powered by a 3 Volt CR2032 lithium battery and a 12 Volt battery 23A... A charge of fairly good batteries lasts for 4 months with daily use, but if not daily, it lasted for a year and a half (!).

I think the only drawback of this model is volatile memory. All data will be erased if the battery is removed or the battery itself loses its charge. Otherwise, everything is fine. Review prepared BFG5000.

Despite the high quality of modern bicycle computers, which are distinguished by their enviable resistance to mechanical stress and water resistance, they sometimes tend to break. Manufacturers usually give some recommendations for device maintenance, which avoids some breakdowns at an early stage. For example, it is necessary to periodically thoroughly wipe all the elements of the device. In addition, it is undesirable to leave it for a long time under the influence of direct sunlight, this can have a very negative effect on the "health" of the display.

There are situations when the readings of the cycling computer become difficult to read in winter. Do not be scared and run to the service center, because this feature of "freezing" is typical for liquid crystals.

But if such a misfortune happened in the warm season, it is warm outside, but the screen still does not show, you need to remove the batteries from the device and insert them back in a few minutes. If this manipulation did not help, then there are two options: either the batteries are discharged and need to be replaced, or the device itself is already faulty. It is quite simple to diagnose and solve the power supply issue on the spot, but it is unlikely that you will be able to cope with a more serious breakdown of the bike computer on your own, so it is better to take it for repair to a certified service center or contact a microelectronics specialist.

Oftentimes, the bike computer refuses to process the signal. There are three possible causes of the problem:

incorrect sensor installation
discharged batteries
break (chafing) of the cable.

In this case, it is necessary to carefully inspect the places of contact of the wire with the cable covers, frame, etc. Very often the insulation remains intact, and the wire itself breaks or frays.

The reason for the sudden “freeze” of the device, when the device simply stops responding to button presses, may be mechanical damage. Try to remember if your bike has experienced serious falls, because a really strong blow can damage the most protected machine. In some cases, an inadequate response of the device or a complete lack of response can be caused by damage to the wire. If the wire breaks, then you can either splic it or completely replace it. In this case, it is necessary to carefully inspect other commutations for integrity and restart the computer.

Sometimes water penetration into the product can cause breakdown. In this case, it is not recommended to turn on the device until it is completely dry.

In more modern models, it is possible to disassemble the computer and the sensor.If you have at least a little soldering skills, then you can make small repairs at home, but only in cases of simple breakdown (for example, a wire break).

Whatever happens on the road with a bike computer, never get lost or upset in advance. It is possible that everything will be resolved after usually replacing the batteries or rebooting the device.

Having bought myself a bicycle, the idea immediately appeared to electrify it. I wanted a size flashlight and a bicycle computer, but the question of power supply and control of all this immediately arises, because each of these devices has its own power source, as well as control in completely different places. This is how the idea of creating a bicycle electrician under the control of a bicycle computer arose.

He will control the size of a stop signal and a headlamp, which are necessary when driving in the dark, it will also not be superfluous to charge a mobile phone when leaving the city or simply when forgetting to charge it at home.

To power all this, a li - ion battery of 18650 size and a capacity of 2800 mAh was chosen, and in my opinion a suitable thing for this was chosen as a dynamo hub.

I will begin the description with a dynamo sleeve and a DC - DC converter that charges the battery,

the characteristics of the 6 V 3 W dynamo sleeve, having played with it, I realized that it is more than 6 V and 500 mA with a load it is unable to give out, without a load the amplitude of the output voltage reaches 50 V.

Somewhere on the Internet I saw the idea of rectifying and converting the voltage from a dynamo sleeve to a lower one using a DC-DC converter.

My choice fell on the proven in many devices LM 2575 HVS - ADJ.

For normal operation of this circuit, there is a circuit of the threshold for turning on the converter D 5 Q 1, when

the charge of the capacitor C1 reaches 12 V, the converter turns on. It is thanks to this circuit that the DC-DC converter has a fairly high efficiency.

This circuit perfectly charges the battery, and the charge current with a discharged battery up to 3 V and a speed of 20 km / h reaches 1 A.

How the bike computer works is shown in the video and I will not describe it, but the diagram requires an explanation, although almost everything is described there.

The heart of the device is an STM 32 F 100 C 8 T 6 microcontroller, a display from a SIEMENS SX 65 cell phone labeled LS 020 is used to display information. for charging mobile phones. U 2 lowering serves to control the headlight. The operational amplifier U 4 generates square-wave pulses from one half-period of the DC-DC converter LM 2575 coming from the diode bridge.

On the diagram, in the area indicated by the dash and dotted line, elements are indicated that are installed in certain places on the bike and have nothing to do with the printed circuit board.

The linear stabilizer LP 3985 IM 5-3.0 U 1 for an output voltage of 3 V has a low voltage drop at such low currents of about 60 mV. The phototransistor Q 1 marked HPTB3B-44D with an angle of 20 degrees probably needs more heat.

Supercapacitor C 8 at 0.47 F is used to operate the clock built into the MC and also to store data in the BKP domain of the microcontroller. The supercapacitor charge is enough for 2 days, so after this time the clock will go off, as well as the odometer, distance traveled, travel time, maximum and average speed.

The microcontroller is programmed in any of two ways through the SWD connector J2, by the STM32 ST-LINK Utility program, or by the bootloader J3 by the Flash Loader Demonstrator program.

A double-sided PCB is made without any problems using a photoresist.

In general, the bike computer is working, unfortunately I do not now have a dynamo sleeve with which I can try it out (I will buy a new one), but with the one that I had I checked the DC-DC converter on the LM 2575 + battery, the operation of the operational amplifier was also tested U 4 and its strapping R 11, R 12, R 13 and R 14. Everything works as it should.

To check the bike computer (until I bought a dynamo sleeve), I temporarily installed a reed switch from an industrial bike company.

Circuits and printed circuit boards are made in PROTEUS v 7.10 for them there are ready-made templates for printing in word with a negative photoresist. Before printing, it will not be superfluous to check the dimensions of the templates with the dimensions specified in PROTEUS.

The casing of a bicycle computer, as in industrial ones, is made removable, for this there is a

connector J 6 ZL320-2X7P type “male”, its counterpart ZL307-2X7 “female” is installed on the “terminal” which is attached to the steering wheel. In general, for a home-builder, the case is a sore subject, I liked this one in terms of size and appearance, so I decided to put it all there at all costs. And I would have to try very hard to place it, but the result pleases me.

When I was making the body, there was nothing to take a picture of the process, and I did not even think that I would write an article since there was no time to completely finish the bike computer, so there are only low-quality and not detailed photos.

The racks are removed from the top cover, because of them the display will not go there, the layout of the display window is calculated in such a way that the upper part of the display rests against the top of the cover, then holes for the buttons are drilled at the bottom of the cover (this is done manually with a drill.

Regular inspection and repair of the bike is a guarantee that the owner of this vehicle will be alive and well, no force majeure will happen to him. Many people prefer to contact professionals for preventive maintenance of the bicycle, but it is quite possible to prepare the vehicle for use with their own hands.

Before starting routine bike repairs, you need to stock up on certain tools. They will come in handy in any case and will last a long time. Basic tools for bicycle maintenance:

hex keys of different sizes - it is advisable to purchase them immediately in a set;
wrenches of different sizes - it is advisable to buy a set;
screwdrivers - you will need both Phillips and slotted;
pliers of different sizes;
tweezers;
mallet;
end nozzles;
scissors;
clamps.

These tools and devices should always be available, because they may be needed at any time. In addition to the above, it is worth purchasing:

bicycle chain brush;
sleeve wrench;
a squeeze for a bicycle chain;
ratchet wrench;
spoke key.

Consumables are also a necessary tool for the repair and maintenance of bicycles - they should not only be always available, but also in sufficient quantities. Consumables in this case include:

brake fluid;
oil for various parts;
Note:you need oil for every part - forks, chains, pedals and so on.
solvents;
cleaners;
hydraulic oil.

All these consumables will help not only to repair the bike in a quality manner, but also to keep your vehicle in almost perfect condition. Particular attention should be paid to lubricants - their choice on the market is simply huge, you can trust the sellers, but with caution. In order not to be mistaken, you should remember the following recommendations of specialists:

Any liquid lubricant (I5A oil, for example) is suitable only for processing the rear bushing drum and chain. Such a lubricant has an individual feature - it is excellent for spot application. But there is also one critical point - if you plan to ride a bicycle in the cold season, then liquid lubricant cannot be used, since at subzero temperatures it quickly hardens and complicates the operation of mechanisms.
If there is no time for full-fledged repair work, but it is urgent to lubricate the chain and cables, then aerosol lubricants can be used. They instantly restore the operation of all hinge joints, they are simple to operate - even a child can handle the job.
For the processing of threads and bearing assemblies, the use of thick grease will be the best option.

In order to properly sort out a bike, you need to know the purpose of each detail and be able to carefully examine them.

The most important thing in caring for a bike frame is keeping it clean.Therefore, before proceeding with the bulkhead of the vehicle, it is necessary to thoroughly clean the frame from dirt, dust and peeling paint so that these particles do not get into the mechanisms and make them unusable. The best way to clean your bike frame is to wash it with a warm soapy solution.

The only way to avoid problems when using a bicycle is to carefully examine the wound for cracks and chips. Experts recommend paying special attention to the upper stays of the rear triangle, the head tube, the rear suspension and the bottom bracket when examining. If, when examining the bike frame, scuffs and paint chips are found, then they must be eliminated - it is advisable to use paint from a spray can for this, having previously cleaned the place from rust, dust and paint residues.

The rules for rebuilding the steering column of a bicycle depend only on its type - if an integrated column is installed, then you only need to lubricate it, but with a semi-integrated steering column with a ball bearing mechanism, it will be necessary to replace not only the lubricant, but also the balls. There is even a direct sign of the need to replace parts - during the operation of the bicycle, the creak of the head tube will clearly be heard and problems with turning the wheel will appear.