Building a more efficient bike

Changing the classic bicycle crank pedal design to make them more efficient. Re-engineering a bike power train was something that has been done before but often by overlooking the pedal operation themselves, probably for good reason.

Special thanks to my Dad for letting me modify his first mountain bike.

Software Used:
Solidworks
Photoshop
Blender
DaVinci Resolve

Tools and Hardware:
304 SS
316 SS
a Drill Press
a lathe
a vertical mill
Files
a Vice
some saw dust and super glue

[worksbydesign]

Thank you all for the support and constructive feedback! I'd like to note that as many of you pointed out, I made a few errors in the math at 0:32 . At 45 degrees, the torque should be closer to 71% not 50%. I also made some oversimplifications with the mechanics of pedaling, where the forces applied by your foot are more dynamic than the single downward force of gravity like is shown in the animation. I'm looking to improve my video quality and my math in the future so I do appreciate the corrections!

[jonathanlawley]

As a design and manufacturing engineer, I have immense respect for your ability to conceptualize in 3D space! That is NOT a simple skill to master. I also envy your animation ability

[ARVash]

All that work for 10 seconds of demonstration 😢 it deserves more love, maybe a part 2?

[charlestaylor]

Excellent video, but it seems like it ended too soon. You kind of left us hanging. You didn't tell us how the ride was. Was it hard to pedal, how fast, gearing, efficiency, improvements. It seemed as if you were successful, but it also seemed as if you weren't very happy with it. I have a design and it's similar to yours only in how the power from the legs is delivered, with the straight up and down force, the rest is different. It's not electric and it's all in my head. You've got a totally original proof of concept. Get excited!

[Freakybananayo]

I wish you explored the final product more or did a comparison and test to see if your hypothesis of “is this design more efficient” was true. You should definitely make a part 2 for this, there is a lot more content you can get out of this bike

[e]

Well done, but a bit disappointed that there was no review of the user experience after the build.

[jamesredgrove]

A shout to the Dad who's obviously spent a lifetime assembling a wicked workshop and then teaching his son 💪🏻

[gregoryshoemake]

Probably one of the most impressive and underrated parts of this video is the fact that you manually machined all these parts. Getting the precision, required for builds like this, manually is crazy

[cedrichenryho]

Thing is we don't always just apply the force downwards in reference to the moment arm when we're biking, we adjust our ankle to get a better angle in order to produce the most torque which might be a point to consider.

[MikeDS]

Incredible concept. Buuut... There are two overlapping torque curves, one for each leg, flattening out the total resulting torque curve. (Try pedaling with one leg and see how the analysis of a single crank doesn't work). The natural motion of a leg is not vertical or linear and doesn't result in a constant power output. The chain drive is > 95% efficient, and this is probably < 80%. Just listen to how loud this system is compared to a near silent chain drive. A chain drive is also very light and very robust.

[brookewestonctc]

This channel joins Stuff Made Here in the "came out of nowhere with fully formed, highly entertaining engineering videos" category.

[cally]

My god, finally one of these weird and cool machines that's not made entirely of cheap 3D printed plastic. I love seeing something well made like this.

[JMU]

I’d be so proud if i had a son as studious and productive as you are. Great work brother

[MattGallagherComposer]

As a bike mechanic... look, I respect your enthusiasm and drive to execute what is genuinely a neat foray by an outsider into the world of cycling physics, but in the end it's just that, a foray by an outsider. You might get a longer peak torque from this design, but the big flaw with it (and with every other attempt by a non-cyclist to create a vertical pedaling system) is that, with proper saddle height, your feet never stop moving with a traditional crank setup. This maximizes the length of your power stroke, which in turn accomplishes two things: it minimizes muscle strain, and it ensures that you don't lose momentum, which is what would happen with a) overextended legs on the downstroke and b) pedaling vertically. This is all due to the fact that, the moment your feet stop moving, your power stroke ends and you lose all your acceleration, meaning it takes more energy to resume the stroke with your upper foot.

I realize that this has been a nasty wall of text, and for that I apologize, but ultimately this is just an attempt, albeit a well-meaning one, to fix a problem that simply doesn't exist.

[BrightBlueJim]

Fantastic mechanical engineering project! Shimano got the same result with much less expense and work, by making crank sprockets that varied in radius as a function of crank angle. The beauty of this was that you could get whatever advantage this offers, by changing only one component in your drive system. I remember this from the 1990s, so the fact that they're not used everywhere today implies that these didn't provide any significant improvement in overall efficiency. The consequence of having a circular sprocket, and its sinusoidal torque curve, means that the leg muscles are used in a cyclic way, where their maximum output is used only for short periods, and we learn to apply maximum force only when the crank is close to horizontal. Lengthening these periods may just result in quicker fatigue, since the muscles don't have time to relax between bursts of force. So this is more of a bioengineering problem than a simple mechanical one - keep in mind that in walking or running, which we are optimized for, our muscle output is also cyclic.

[somenygaard]

Technological progress has been amazing to watch for me from the early 70’s to present day. Maker YouTube is full of 1 person doing what often took companies with many dozens employees years to accomplish. I find a new creator, what seems like every day, building amazing new projects.

[jessejames]

That shop is to die for. Your so lucky to have such amazing opportunities for creativity.

[Tyler-mpkh]

Not sure if I’m more impressed by the concise high quality video or the engineering skills. Well done.

[MetalShopBuilds]

Just a little constructive criticism here. At the point 9:04, I noticed that some of the master links were facing the wrong way.
Basically you want the side that clips on, to face the opposite way of travel, if not you risk the link catching on one of the gears, and unclipping. It's also probably better to only use one master link, there for reducing the chance of failure. Overall great work, can't wait to see the next project!!

[stevenwolfe]

I applaud your tenacity and dedication to experimentation! Please do a follow up video. I have my suspicions that this system may introduce a lot of extra friction that will ultimately lead to a slower bike, but there is only one way to prove my hypothesis true or false. Excellent job making the components!