Cheap Digital speedometer

Fed up with speedos breaking on my Jincheng Monkey replicas I fitted them with pushbike computers. These are cheap and if they're calibrated correctly, extremely accurate.

They also have great functions like a clock, total distance and trip meter, average speed travelled, maximum speed reached, duration of trip, etc. In fact they make a normal speedo look silly. They're waterproof and can be detached from their mounting in a jiffy.

The only difficulty is that the magnet that comes as part of the front wheel mounted sensor is designed to be fitted to a spoke. If you have solid or cast wheels you have to get one of those very small and powerful rare-earth or ferrite magnets and glue them onto the rim.
On some bikes the wheels are steel and these magnets will simply stick themselves on to the rim very firmly.

For the calibration you have to enter the circumference of the wheel in mm. Rather than just trying to measure it with mums cloth tape measure, mark the ground with chalk and the bottom of the front wheel in contact with the ground and align them. Roll the bike a few times forward, the more times the better, in a straight line, measure the total distance and then divide by the number of complete turns achieved. This will give a really accurate circumference.
In theory, as the tyre wears down this should be repeated, to maintain accuracy, but probably not worth it.

OK, I know that there are clever-dick ways of calculating the circumference of a circle using maths and geometry, but if, like me, you spent your time at school smoking in the toilets or feeling girls tits for 5 pesetas a go, you're better off with the aforementioned method.:lol8:

The only disadvantages are the loss of perceived performance, as the MPH is now REAL, not the notoriously inaccurate and optimistic readings we get from normal speedos, the tiny battery last about a year and before you change it you have to make a note of the total distance travelled to enter it once more, as this data is lost when the battery runs down.

http://www.igijon.com/personales/nom...te/speedo3.JPG

Great tip Forch. Just want to add that not all bike speedos will work on motorcycles as some have a limited speed read out that will not go beyond a certain MPH/KPH. The brand pictured is the Sigma cycle computer brand which does not have any such limitations.

Also, since the wiring leads from the pick-up to the computer are designed for bicycle forks, many are too short (esp. for dirt bikes) and may need to be lengthened.

Otherwise, they're a great way to get a second set of info on you bike and a waterproof clock!

Anyone found a back-lit unit for use at night?

CC

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Originally Posted by CrazyCarl

Anyone found a back-lit unit for use at night?
CC

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I knew someone would find the fly in the ointment...:icon10:

Thankfully, since I did that mod there's been lots of improvements to these cyclecomputers. The model in the link below, for example is wireless, having a tiny transmitter in the wheel end, it's backlit and has incredible functions like heart rate, useful to check yourself after a 30-ton truck pulls out in front of you, altimeter for those of you intrepid travellers, etc.

http://www.outdoorgb.com/p/Ciclospor...ycle_Computer/

it's rather pricey though, but I'll bet there are some cheaper ones with backlight around now.

For anyone contemplating this mod, there's a brilliant article here. It's about mounting one on a Lotus 7 type car, but the principles are the same. Well worth reading.

http://www.strangely.org/owned/bikecomp/index.html

very cool stuff. i would not think that a bicycle speedo would work. so i never looked into one.

now i am going to mount one to my xf200 and the new 4wheeler i am planning on getting in the next few months. it also has no speedo/trip/clock.

exciting, very practicle, smart and cost effective. on top of that, no tools are required.

very good work forchetto. thank you.

Just a word of advice. I've been experimenting with one on my Qingqi, have found a couple of problems.
The first is that with upside-down forks there's very little choice of where to fit the sensor. On normal forks it can go in a number of positions on the slider, or static bit of the fork. On USD forks you'll find the stanchion, or moving part, gives very little choice. At the moment I'm fixing it to the plastic stanchion stone guards, but these vibrate and move a bit, so it interferes with the air-gap necessary between the magnet and sensor.

If you go for the wireless models, remember that the sensor needs a battery and it has to be replaced at intervals. This means extra expense and bother. Also, check that the transmitter can cope with at least a metre separation sensor-speedo. Some only go 70 cm and it's not enough for these long forks.
Wireless models are also a lot more expensive.

Hi
I did some digital speedometer mod recently
Here is link
http://www.chinariders.net/modules.p...al+speedometer

I'm currently looking at the Veypor vr2 lcd speedo but im still looking,the wheel base for the Adrenaline 125 is 1405mm.

Quote:

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Originally Posted by forchetto

Fed up with speedos breaking on my Jincheng Monkey replicas I fitted them with pushbike computers. These are cheap and if they're calibrated correctly, extremely accurate.

They also have great functions like a clock, total distance and trip meter, average speed travelled, maximum speed reached, duration of trip, etc. In fact they make a normal speedo look silly. They're waterproof and can be detached from their mounting in a jiffy.

The only difficulty is that the magnet that comes as part of the front wheel mounted sensor is designed to be fitted to a spoke. If you have solid or cast wheels you have to get one of those very small and powerful rare-earth or ferrite magnets and glue them onto the rim.
On some bikes the wheels are steel and these magnets will simply stick themselves on to the rim very firmly.

For the calibration you have to enter the circumference of the wheel in mm. Rather than just trying to measure it with mums cloth tape measure, mark the ground with chalk and the bottom of the front wheel in contact with the ground and align them. Roll the bike a few times forward, the more times the better, in a straight line, measure the total distance and then divide by the number of complete turns achieved. This will give a really accurate circumference.
In theory, as the tyre wears down this should be repeated, to maintain accuracy, but probably not worth it.

OK, I know that there are clever-dick ways of calculating the circumference of a circle using maths and geometry, but if, like me, you spent your time at school smoking in the toilets or feeling girls tits for 5 pesetas a go, you're better off with the aforementioned method.:lol8:

The only disadvantages are the loss of perceived performance, as the MPH is now REAL, not the notoriously inaccurate and optimistic readings we get from normal speedos, the tiny battery last about a year and before you change it you have to make a note of the total distance travelled to enter it once more, as this data is lost when the battery runs down.

http://www.igijon.com/personales/nom...te/speedo3.JPG

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Quote:

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Originally Posted by andy68

I'm currently looking at the Veypor vr2 lcd speedo but im still looking,the wheel base for the Adrenaline 125 is 1405mm.

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It may be but you need to put in the circumference of the tyre for the speedo to calculate the distance travelled by the wheel rotating once and hence your speed . Wheelbase is just the distance between your wheel centres .:icon10: