Bicycle cadence and speed logger

I just wanted to break down what you might need to think about if someone was to build this device. It might explain why something already out there is so expensive.

That project you reference seems to be based on an electric powered bike, the rear hub is a motor so I think he was getting some data out of it like when a shift gear occurred.

With all that data, you probably need to bone up on the software side to analyze the behaviors, filter out noise and trend your usage to see if it means anything.

An arduino does not have a real-time-clock, which is an optional add on module, you probably want the data timestamped.

There is also heart-rate sensors so you might want to throw that in for full activity metrics. Maybe windspeed indicator too?

There are GPS modules, accelerometer, and compass sensors for the arduino to give you "flight and location" data if needed.

That said, you are looking at building some sort of black box flight recorder for a bicyclist.

So, basic arduino stuff that there are already examples of:

LCD display is warranted - better than a few LEDs blinking to give status or see what kind of data you are logging in real time

Wheel movement captured by magnetic sensors to calculate speed, RPM and distance travelled

Shift gearing captured by switch postions/encoder of some sort

Datalogging - write to SD card to dump the data to PC for analysis

It is a doable project but even basic bike sensors seem to record speed and cadence, maybe just max values, I guess you really want to analyze your ride as a performance athlete.  Good luck.

Hello Vadim,

Why don't you want to use an Arduino? You'll need something as a development platform, if size is the problem you can later make a custom board.

Arduino is not my preference, but the functionality you like can be easily prototyped with mbed (now supports a lot of boards) or Arduino.

The way I read your message is that you want a very simple data logger, that just logs time and / or pulses from pedal and wheel. If you log to SD card you can easily make this based on a few mbed projects.

Hello Vadim,

Welcome to the Community, we hope you are enjoying it. I will move this discussion to the Single-Board Computers area as I think it better fits your question.

Thank you,

Jamie

Hi Vadim,

This could be accomplished with just a CPU, a battery and a couple of reed relays or hall effect switches. The program in the cpu would simply need to count the number of wheel rotations and the number of crank rotations in a 10 second period and store these 2 bytes every 10 seconds. I would mount 4 magnets on the wheel and four on the crank to provide better accuracy. This would tell you how fast you were going every 10 seconds, how far you went each 10 seconds, how many crank rotations you made in the same period and what your crank rate was. The uncertainty due to the magnets being mounted  a quarter turn apart would average out over multiple readings. Just a few lines of code is all it would require. You would get a sequence of 2 byte pairs recorded at 10 second intervals. I would use something like a BasicX module from Netmedia or a ZBasic module from ZBasic as these are self-contained solutions that don't require any other costs to implement - the development systems are free. Arduinos are also feasible, if you can find a small and inexpensive variant. The Hall effect switches or reed relays could be connected directly to the module. If you use reed relays, be sure your software allows the reed switch to bounce for 15 milliseconds when closing or opening without counting extra pulses and set the input pins to have internal pull-up resistors.

Doug