Free mtb suspension kinematics app for Macs

Hello World,

After struggling away with virtual machines, I’ve built (by built, I mean, harassed Claude™️ into writing almost ALL the code for) an app to help me design a mono-pivot suspension bike on a Mac, with some idler options.

i’ve never used GitHub before, but I think this file hosting arrangement should work? if it doesnt and you know why, or if you have any important/strong recommendations, maybe DM me? I’ve tried to just upload a zip of the app direct to the forum but no luck, but iin either available download (follow the link) there should be; a) all the source code (i used Xcode, maybe you can too) , b) a licence, and c) an actual copy of the published app that /should/ simply run on a modern Mac, (im on an m3 processor running Tahoe 26.2, and don’t know my way around.)

i’ve built one app before ever (edit, that was a lie, i’ve built three, but never released one,) so this is probably pretty ropey, im trying pretty hard to release this under an AGPL-3.0 licence you can read here. My intent and understanding is that under this licence people can use this to work from and build off it, but they must credit the work done so far, and they must publish it all openly under these same rules.

this licence is pretty language heavy but the intent is for people to feel pretty free to open and mess around with this, and if they develop something, then they share it all too, I guess with notes? i think its good practice to put the notes up the front in each .swift files code, though I might be completely wrong about this.

I guess im sharing this and hoping this is handy for someone else, or even inspires someone to build off it, try adding a feature etc, fix something i’ve missed etc. ideally a bit of input might build this into something pretty useful, but like, Im totally guessing, Claude is hallucinating, and we’re all busy right?

Mono-pivots FTW ( for now at least, I guess).

The code might be pretty bad, but im hoping the app its-self is pretty intuitive to use; its pretty basic. note one thing that may not be immediately clear, is that you can save a design as a pretty basic (JSON) file type and then open it later.

yours in endless frustration,

Pat

NB: edits for clarity.

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if you download the compressed file, and un-compress it (double click), in the folder that subsequently appears, there is an item call “MTBsuspension.app” , which you should be able to simply run like any other program.

if you’re keen to try it out and need help making it work, please each out and ill do my best to get it working for you.

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…it should look something like this…

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It probably works fine, but it’s more normal to upload the actual files, not a zip or a tar.gz. Then people can just browse the source on the website first rather than having to download and unpack it all.

AH,

that seems obvious now you’ve said it; thank you for the tip…

all files are now uploaded directly and browsable,

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@crowe-molybdenum I’m currently working on a browser-based port of this as a project (I’m a software engineer). Would I have your blessing to make it publicly available on the web (given appropriate attribution) once it is working?

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I’d be really happy for you to, given the conditions of the licence are followed; which it sounds like they will be, (share alike etc).

Thanks for the interest, and plausibly for the upcoming work! please reach out with a DM if i can lend any clarity along the way..

pat

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What are the chances! I recently did the same with claude-code. Here it is: https://suspension-sim.onrender.com/

Currently trying to make claude-code do a dynamic sim so I can maybe figure out shim stack and oil viscosity for emulsion type simple shocks - but for that I think I actually need to do coding and understand some fluid dynamics. What an age we live in!

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Some of the functionality is now available in the browser here: https://mtb-suspension-nine.vercel.app/

Source code is here: GitHub - christiaanjs/mtb-suspension: Suspension kinematics web app

The more interesting kinematic calculations (i.e. anti-squat and anti-rise) are implemented (I started from a “one-shot” conversion of the Mac app using a coding agent), but I want to work through them and verify that they are actually doing something vaguely correct.

I’m very happy to take feedback or suggestions for features.
One thing I have implemented so far that I don’t think is in the Mac app is calculating leverage ratio from wheel travel.

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love this!

being able to move the front and rear end independently will be important to how some people think about AS and AR, once those features are added. I know in the eyes of some, looking at them in a fully suspended scenario (as I like to) is very wrong

thanks for the effort!

definitely easier to point someone at a web link than a GitHub list of code eh!?