Bicycle Chain Physics and Display Problems

Hey, I’m attempting to make accurate physics of a bicycle chain in BGE but there’s a few problems…

(1) The chain is loose at first. I remedied this by putting a constant linear motion on one of the gears to pull the chain tight. It’s sort of a hackish solution. Is there a way to pull the chain tight outside of running the simulation?
(2) The physics run quite slow. 20fps. I’ve attempted to optimize with little success. Am I doing something wrong?
(3) The gears display quite strange. I’m not sure why they look like that. Could someone help?

If you guys have any other tips to make this better, I’d really appreciate it!
Here’s the blend file: Physics Test.blend

Thanks!
P.S. Scaling the chains and gears down to a more appropriate size causes them to asplode.

1: As a guess, the weight of the chain will make it sag (like in real life), have you tried altering the mass of the chain?

2: Due to the number of physics interactions, the sim will be slow- silly question but do you really need a chain simulation? (It may be better to fake it unless you are doing an engineering visualisation or something).

3: set the object shading to smooth.

Also, you can use the forums upload tool for posting .blends- its very reliable and it means if your host goes the file does not!

By the way, your chain exploded on me, so the above is general guesswork.

1: As a guess, the weight of the chain will make it sag (like in real life), have you tried altering the mass of the chain?

Yeah, still sags. Lower mass makes it break easier. Unless I bump up the physics quality.

2: Due to the number of physics interactions, the sim will be slow- silly question but do you really need a chain simulation? (It may be better to fake it unless you are doing an engineering visualisation or something).

I’m trying to make real time accurate physics simulations of objects. This first test is to give me an understanding of how it works. Through making a bicycle. In a future try I want to make an old fashioned pocket watch that uses gears and in real time simulation produces an accurate time display.

3: set the object shading to smooth.

Turns out I needed to uncheck Backface Culling.

Also, you can use the forums upload tool for posting .blends- its very reliable and it means if your host goes the file does not!

Thanks, I’ll do that!

By the way, your chain exploded on me, so the above is general guesswork.

Why would it behave differently on different machines?

I’ve attached the latest physics test. I bumped up the physics quality and now it runs at 2fps. Though it behaves exactly like it should.

Attachments

Physics Test.blend (725 KB)