Evolving Lacing Patterns for Bicycle Wheels | Hacker News Reader

Evolving Lacing Patterns for Bicycle Wheels

master.matsemann.com

131 pointsalexggordon19 comments

Wow, cool to see my thesis here! I posted a picture of it [1] to r/bicycling yesterday titled I managed to make my thesis in computer science be about bicycles!, and it got some traction. I answered some questions in the discussion, if anyone is interested.

[1]: https://redd.it/3p8hua

Can I ask a question, please don't take it the wrong way, as I find optimisation a very interesting topic, and in fact it was also the subject of my thesis. However: How is this a computer science thesis, and not a mechanical engineering thesis? I'm just curious how you managed to pass a wheel-design topic through a CompSci program. Did you have a co-supervisor in engineering? Or does your school have a combined CS/engineering program?

It's really a thesis about EMO-algorithms and how to use them to optimize real-life problems. The wheels just happen to be the chosen application of the optimization, if you get what I mean?

Ah ok, I was wondering if that was the case. Wasn't really clear from the way you presented it. Can you summarize your results regarding the algorithms? What worked best, what didn't?

Building bicycle wheels is incredibly satisfying, I built a set a friend used to win the local state cyclocross championship one year. There's a lot of technique in tightening the spokes, when I see the 'bad ride' simulation of the wheel in the video, it occurs to me you get the same types of visible behavoir if the spokes aren't tightened correctly. I wonder how spoke tension is modelled here?

My guess is that it's not.

From earlier discussion on this article, the wheel was modeled as an infinitely stiff rim, rather than the more mechanically accurate beam on an elastic foundation. For a first level linear elastic approximation, the spoke tension doesn't matter. The spoke tension is really going to only be an issue once you get into the non-linear effects associated with rim stability, which is strongly dependent on the rim stiffness.

Neat idea. Did the author read Jobst Brandt's book, "The Art of the Bicycle Wheel"?

Symmetry obviously makes the ride smoother. The real issue is dish and the incredible strain difference between. The drive side and the non-drive side: did the author simulate modern rear wheels?

This is interesting for sure in identifying novel spoke patterns that might result in a stronger/lighter wheel. Since the simulator identifies lots of possibilities it would be useful to have some kind of figure of merit to help with down-selection. It also seems like things like being out-of-dish or out of true are things that could be used to eliminate possibilities without user intervention.

Lastly I wonder if you constrain this enough whether it would spit out "standard" spoke patterns that are used commonly. I'd like to think that spoke patterns that we use now are close to optimal due to a kind of evolution based on lots of trial and error. But maybe that's not the case.

Not exactly what you're asking about. But I talked to a guy who worked on a project using genetic algorithms to optimize motorcycle wheel designs. He said one of the best designs that came out looked pretty much like a traditionally spoked wheel, just a bit more organic in shape.

I assume it wouldn't function well, but I've always wondered about a wheel were some of the spokes do not go to the hub, but are instead connected directly to another spot on the rim.

I was in a research group with Dave Hadka, who wrote MOEAFramework. I'll have to tell him about this! Nice work!

I really liked the framework. Powerful out of the box, and not that hard to modify/add what I needed. Hadka was also very helpful on answering mails with questions about the framework.

Any comment on how much the new boost 148 standard for mountain bikes helps with stiffness and/or strength?

Neat. Can't wait for the follow-up paper which ranks lacing patterns by simulated load profile.

Did any of these get built?

A quick scan of the paper (it's 105 pages) it looks like it was just simulations.

Basically until a simulated of a wheel is actually built, I'd dismiss all this.

I'd disagree strongly. I think the point of the paper was the evolutionary algorithms. Whether or not the wheels could adequately replace a modern bicycle wheel is kind of a side note. The work was entirely about creating a program that would produce better and better results over time, while balancing multiple objectives to meet. As you can see in the videos, (and he even admits in the paper) most of the wheels would not work very well if they were produced.

That said, I think if you're going to be completely dismissive of a thesis that I'm sure represents thousands of hours of work, I might put a sentence or two explaining why you think the algorithm isn't the important part of this.

I agree. It's really cool that he managed to find the standard 3-cross based on a pretty rough model and an optimization step.

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