how to rig a bicycle chain?

hi, I have a problem with a bicycle chain.
I have to run chain simultaneously with the pedals.
I turn 360 degrees the crown and calculation of how the chain moves along the x axis to get to the starting position.
The result is that the beginning and the end are fine but during the path the chain does not have a constant speed and mechanisms do not fit together
also tried with the constraint transformation but nothing work…I do not understand …maybe the system is all wrong?


nobody help me? … how can I do?

Use a driver.

Bicycle Gear Drivers.blend (1.06 MB)

Delete the location keyframes on the chain, and add a driver of a similar sort to the “chain” I have here. The ratio between your gear’s rotation and your chain’s movement will, of course, be different from 1.04, but the principle is the same.

You can also add a driver to the rotation of the other gear so that you can drive the whole mechanism simply by animating the bigger gear.

I tried following your advice but I did not succeed …
always the same speed problem!! not constant on the chain!
I attach files with a few items you can try …??


biketest.blend (2.16 MB)

You need to right-click on the chain’s x-location, click “add driver,” and then put something similar to what I’ve done (see the center-left screen.)

biketest.blend (2.17 MB)

When the driver is there, the x-location tab will be purple instead of yellow/green. The driver will be accessible under the graph editor panel -> drivers (as opposed to f-curves, which is the default,) and the driver is set up like so:

Driver is of the type: scripted expression.
The expression is: var*3.2
(3.2 seemed to be what would keep the chain following the gear best. Feel free to make it more precise.)
var is a variable of type: transform channel
the object var depends on is “cro,” the transform channel it uses is y-rotation (transform space.) (Using transform space is necessary; using world space can go wrong if you’re animating the entire bike and making it turn so the gear’s local y-axis does not align with the world’s y-axis, and local space doesn’t work at all.)

And now the chain moves with the gear!

thanks …
how to insert the driver had understood but I do not understand how to calculate the expression …
your espression works until the 180 degrees of “cro” and then nothing …
I do not want to disturb too much so I ask if you know an easy guide to understanding these drivers

I was going to go to sleep and I realized that I wrote a stupid huge …
sorry man you wrote everything right … sorry again and thanks

like you said before I can adjust the speed, correct rotation of evry soingle object etc etc in a very fast way…
what a fool I am!!

I have a 'tank Track tutorial on my youtube site that might help… it covers much of the information of what you are doing here…

hello Texan and thanks …
when I find some time I look at him …