From getting started to monitoring bike suspension performance

Projects General Guidance
1

Hi all,

I want to get started with Arduino and I have project in mind.
Of course first I want to play with Arduino, but finally I want to build desired project.
Need advise wether this project is possible and what hardware I need to build it.

Little about me.
I am 10+ experienced developer, but mostly high level programming: C#, Java, C++, SQL, etc.
I don't have much experience in low level programming, but I know C language quite good.

My project.
That idea is to use precise distance sensor attached to both parts of bike's fork to meassure distance between them - which leads to meassuring deflection and compression of the fork.
Additionally I want to attach accelerometer on handlebar to meassure what vibrations affects biker. Finally collected data will be transferred to PC or smartphone to visualize performance.

My biggest concerns are:

  1. Is Arduino good choice?
  2. What hardware I need?
  3. Sensors should be so fast to capture distance eg 100 times per second
  4. Sensors should be so precise to measurre even 1mm changes
  5. Sensors attached to the fork should be quite small and light
  6. Sensors attached to the fork shoul work in extremme conditions: temperature, mud, water, sand, wind
  7. How much it will cost?

Hope will get some advises from practitioners!

Thanks you all!

2
  1. Is Arduino good choice?

Would we say otherwise ? 8)

  1. What hardware I need?

That you can afford? That may be the limiting factor for this project. Cheap ping sensors are not all that accurate.

  1. How much it will cost?

For sensors that meet your requirements? A lot.

3

  • Arduino is good at reading real time sensors.

  • Arduino, storage for to log data like SDcard shield because native memory is very small, and sensors. Accelerometer is easy, measuring fork travel is the challenge and probably requires some invention and fabrication.

  • This shouldn't be an issue if it is simply a matter of polling a few sensors.

  • The big unknown is the fork travel sensor. A couple ideas that come to mind:

  • Some sort of linear optical encoder. This would be a direct sensor that meets your requirement. The problems are that you'd probably have to build something that is non-trivial and that the sense rates are much higher than simply reading a number every 1/100th of a second.

  • Just use accelerometers on the upper and lower fork to infer fork travel.

  • If the forks are pressurized, perhaps a pressure sensor could be used to infer fork travel.

4

I think that instead of directly measuring the distances involved you would be better off measuring forces or pressure like MrMark mentioned. Load cells or strain gauges could be incorporated into the fork to measure the forces applied if the suspension system was not fluid based. You would need to determine the relationship between the separation of the parts of interest, after the measurements are made you could make the transformation between force and distance.

5

$300 for a 75mm travel sensor.
http://www.race-technology.com/linear_sensors_suspension_miniature_3_156.html

You'll probably spend a similar amount on making the mechanical couplings.

6

johnnyno83:
Hi all,

I want to get started with Arduino and I have project in mind.
Of course first I want to play with Arduino, but finally I want to build desired project.
Need advise wether this project is possible and what hardware I need to build it.

Little about me.
I am 10+ experienced developer, but mostly high level programming: C#, Java, C++, SQL, etc.
I don't have much experience in low level programming, but I know C language quite good.

My project.
That idea is to use precise distance sensor attached to both parts of bike's fork to meassure distance between them - which leads to meassuring deflection and compression of the fork.
Additionally I want to attach accelerometer on handlebar to meassure what vibrations affects biker. Finally collected data will be transferred to PC or smartphone to visualize performance.

My biggest concerns are:

  1. Is Arduino good choice?
  2. What hardware I need?
  3. Sensors should be so fast to capture distance eg 100 times per second
  4. Sensors should be so precise to measurre even 1mm changes
  5. Sensors attached to the fork should be quite small and light
  6. Sensors attached to the fork shoul work in extremme conditions: temperature, mud, water, sand, wind
  7. How much it will cost?

Hope will get some advises from practitioners!

Thanks you all!

Hello johnnyno83,

funny, i'm working on a very similar project - measuring vibrations on a bicycle with accelerometers, using an Arduino.
my professional background is car engineering, but this is a private project of mine.

As i'm focussing on road racing bicycles -the differences between bike frames of different material (CFK, aluminum, steel) and shape in terms of ride comfort- the distance measuring does not apply in my case, just the accelerometer part.

As a starting point i plan to use an setup of Arduino, 9V battery, SD card as data logger (.csv-files) and a pretty simple 3-axis accelerometer.

What kind of accelerometer sensor are you planning to use? I ordered a board with an ADXL345 (3 axis, +- 16g) for a first "prototype".

I want to use that to find out:

  • range/resolution of accelerometer good enough?
  • there will be a lot of data in short intervals - could SD card write speed become a limiting factor?
  • how small can i pick the interval between two measurements? is the Arduino fast enough?

I'll continue from there...

I'd be interested in sharing experiences and results with you!

cheers,
Martin (Germany)

7

That idea is to use precise distance sensor attached to both parts of bike's fork to meassure distance between them -

You might consider using a sliding pot setup at the the point where the two fork parts meet.

8

for the distance sensor, you might use a digital caliper for that.

9

zoomkat:
You might consider using a sliding pot setup at the the point where the two fork parts meet.

No good for a dirt bike. It'd get clogged or destroyed too quickly.

strongwalker:
for the distance sensor, you might use a digital caliper for that.

The digital calipers I've used don't like fast movements.

10

No good for a dirt bike. It'd get clogged or destroyed too quickly.

Well, I think that would be based on how the hardware setup is designed. Probably much better setups, but the OP appears to be looking for a starting point for the project. There are other ways to measure mechanical deflection, but $$$ might become an issue.

11

Have you tried using string potentiometers? They wirk even better with an absolute encoder. But they are extremely expensive!

http://www.andymark.com/product-p/am-2618.htm
No housing

With housing

Absoulte encoder