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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
3D printing from: www.xometry.com/
Laser cutting from: sendcutsend.com/
Hardware from: www.mcmaster.com/
a Drill Press
a lathe
a vertical mill
Files
a Vice
some saw dust and super glue
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!
NOW do it with peddle boats they ALWAYS sucked
Idk, but pedalspeedboats would be awosome, i also would like to say that im going to share this video in person and online, if that makes any sense, i would just share it but i want to be there for the brain melt, ty for the content!!🙏from🇵🇹
What about using an oval shaped gear on the crank to change the gear ratio throughout the stroke? You could achieve a similar effect with much less weight and complexity.
@@techienate There is actually a biopace (oval-ish gear) on the bike already, definitely an easier and less complex way to achieve something similar, but the shape inherently reduces the gear ratio. So the overall torque torque is more constant but the peak torque is reduced, plus I was having a lot of fun overengineering the problem haha. I found this link that depicts an oval vs a normal crank if you are interested: www.cornant.uk/info/ovals02.html
❤
A shout to the Dad who's obviously spent a lifetime assembling a wicked workshop and then teaching his son 💪🏻
@@InTrancedStategood to know. Thanks for that information.
Just the dad alone won't work, I have a workshop full of electronics parts and test equipment but my son is only interested in playing video games.
@@silverback3633hahaha glad I'm single hopefully I can make a good bet one day
@@silverback3633I was like that. Now I have soldering equipment in my room and watching electrical engineering videos. It wasn't the right time for me
@@PulishYuroit still isn't and never will
This channel joins Stuff Made Here in the "came out of nowhere with fully formed, highly entertaining engineering videos" category.
Just what i was thinking
For sure
I normally hate when someone compares channel, but this is a positive one, and apparently the author appreciates it too, so I'll let this one count~
@@aloysiuskurnia7643 His videos reminds me about Tom Stanton. Im subscribed now,, cant wait to see more on this project
This totally reminded me of SMH. Good stuff
All that work for 10 seconds of demonstration 😢 it deserves more love, maybe a part 2?
I've a feeling it works as a proof of concept but not so much in reality. One of Edison's 50 ways not to build a lightbulb. Great experiment, though. Might have bits that end up in a final result but not one in itself.
@@immortalsofar5314 Thomas Edison wasn't the only one who experimented with how not to build a light bulb. the only thing that sold his design was the screw in base. others used prongs that may or may not result in light bulbs falling randomly when they get warm and loosen up. he's not even the one who conceptualized the light bulb. just the first one to make a marketable product.
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
+1
We all fall down and get hurt emotionally, but only Jesus understands your pain. Follow him and he will fill your heart.awdasdadawdaawsadas
@@enriqueamaya3883go away cultist
That is the only way I can conceptualize things. Numbers and words don't really work in my head but shapes and geometry just makes sense
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.
Adding to that using some form of cleats you get even more of a continuous power curve
@@primeprover I believe GCN (and others) found being able to pull up on the pedal wasn't an efficiency advantage over flats they thought it was. This doesn't include 1200W almost out of control sprints, better bike control or the discomfort of faffing with foot position on centuries!
although you may be right, innovation requires trying new things and usually the first prototypes of those things are way worse than what they are meant to replace. its over time as a concept has been proven where optimization occurs so that the new design can get closer to its potential or give inspiration for more innovation. I would love to replace my bike with this pedal system because of its graceful motion and the amazing engineering design.
Adding the second pedal does not flatten out the torque curve. When one pedal is producing torque, the other is doing nothing as it moves upward. It still means the most torque is produced when the pedals are horizontal and the least when the pedals are vertical. This is true even if you add straps. The false assumption made in the video, though, is that we apply force to the pedals straight down. That's not how human legs work, and we rather push the pedals down and forward, then down and back. I suspect the pedals still do not have a constant torque curve, however, so the premise is solid.
That 95% efficiency you mentioned doesn't take into account the way the legs move. It should be used to compare two different methods
Not sure if I’m more impressed by the concise high quality video or the engineering skills. Well done.
This is not engineering. It is design. If it were engineering, there would not be such gaping holes in understanding the problem being solved.
@@nickluhr381what do you mean?
@@Neoproxy_he means he never solved the problem he made it worse. There was no need to design it because we all know it would be much worse. I mean look at all that friction
@@AlfredCombsbut the problème here was to have a more efficient torque you can work on friction later, i mean engineer never solve all problem at once, you go step by step
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.
I'd be interested in finding these shimano variable radius crank sprockets - do you have a link / name for them?
@@Telekq3 no, I don't. This was a number of years ago, and never really took off. I think they were generically called elliptical cranksets, but don't remember the trade name.
They were called Shimano Biopace. Funnily enough the bike in this video has one!@@Telekq3
There are modern versions of Shimano's Biopace under the Osymetric or Rotor Q-Ring brands.
There’s still plenty of these around and available. Just search for ellipse or oval bike sprockets and they come up. Some people use them in the bmx and hardtail mountain bike scene.
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
It's a ton of extra weight, it's several additional sources of friction, it's a 90 degree crown gear, and it's an extra chain. Pretty sure all this greatly offsets the slightly wider power stroke afforded by this contraption. Which is why in several hundred years of cycling technology we're still sticking to chain drive, only adding a derailer for gearing which doesn't interferes with the chain so there's no drawback to having it.
It wasn't
This channel is gonna be one of the best engineering channels on KZhead
Agreed
Do you have ANY means of thought in your head? Look at the design. It's horrible. Weight. Drag. W T F ?
Just need more polish and + This mk2 will Perfect365
he literally just stole an old patent and claimed it as his own design, and you think this assclown is going anywhere but ass pounding jail?
Really? He struggles to get basic trigonometry right. 45° & 50% torque is wrong and every first semester engineer could've told him that his torque graph is going to represent a sine-wave. If he fails at simple stuff like this, I dont trust him. Plus, he completely ignored biomechanics here. If this worked, every racer in the World would ride oval chainrings, but they never caught on.
Being an avid cyclist and mechanical engineering student, this video is just super fun to watch! I'd love to hear more about the mechanical principles and thoughts behind your idea in another video. Great content man!
I would have expected that someone who is into cycling and engineering just rolls his eyes and walks away 🙂
@@anonemoustroll6008morbid curiosity for me. People don't understand the difference between efficiency and mechanical advantage. This is the same flawed logic as putting a bigger great ratio on a bike to improve the top speed in these other popular videos. The human mind quickly learns how to push a conventional pedal, which muscles to use on which part of the stroke. Maximum vs. continuous torque is not a measurement of how good a drive train is, especially when the inertia of the rider comes into play.
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.
Yeah that shit is why I try but can't like Integza videos at all, nothing the guy builds actually works.
@@marklewis1457 some of the 3d print channels are great tho like Tom Stanton
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.
Came here to say just that. The pedal rotation and rider position allows some, probably pretty limited, forward pressure to be placed on the pedal. I would expect that to be modeled and put into the math. Also, you're using the word "design", but aren't doing any engineering on this. The alternator was a good idea, but a dyno would be better. If you don't have access to one, build it as part of the build. Numbers (dyno readouts) showing how a person performs with the current system and the new (your) system. Show the increased mass of your system. Show how the increased mass can be mitigated by moving to titanium or other materials. Show the increased mass's effects on the bike/human. There's so much potential here, and such a poor execution and a short video.
also more torque does not equal more efficient, more torque doesnt equal more work, either. Also what efficiency is trying to be increased? need to measure the work in and the work at the wheels.
One thing missing: the comparison between both design with the practical/sound experiment
Also this was kind of droped for the weighing operation, but still its a good point it was very visual with the sound profile.
Polly the 3d printed jpart couldn't handle the forces involved...
Very cool project! Can’t wait to see more! Ironically, the bike you are working with has a shimano biopace crankset installed which you can see has non-circular rings. These rings already do essentially what your contraption does (to a more or lesser extent I’m not sure). I would recommend simply installing some circular rings and see if you notice a difference. Also you seem to have a bit of a misconception about torque and efficiency. They are not really related in the way you suggest. Simply increasing your torque does not make you more efficient. If that were true, your contraption is unnecessary because you could otherwise just switch to a lower gear. The small inefficiency that a bicycle drivetrain does have is still present in your design because your power is still transmitted through all the original bicycle components, plus all the components in your contraption. It is impossible that you have improved the mechanical efficiency.
The efficiency of the mechanical system wouldn’t be improved, to your point. More components, more friction, less efficient in the mechanical sense of “what percent of input to this system is yielded as our desired output”. However, this design (in theory) does increase the efficiency of the rider, which is probably the more important factor. The extra torque delivered across each time the rider pedals compared to the ‘standard’ configuration is delivered without increasing the force applied by the rider to the pedals (because the lever arm the force is applied with is longer on average through each rotation). What this means is that the same rider, applying the same force, applies more torque (and thus more work). So technically, it’s the efficiency of the rider that’s improved, but that’s more semantics than anything.
@@blazingangel623 Just to continue being pedantic; that is only true if the area under the 'force vs displacement' curve or the 'torque vs angular displacement' curve has increased. One of two (or a combination of both) things must be occurring. 1. The increase in the peak torque zone is a direct result of increasing the length of the stroke (i.e. similar to installing longer cranks on your bike) meaning that the force is applied over a longer distance. 2. the change in the 'peak torque' zone is accompanied by a lower average torque in the rest of the curve (i.e. similar to installing non-circular rings on your bike) meaning the total average torque remains the same. There is no free lunch. If one of these two are not true, than you better take this video down and patent that sh*t because you just successfully created a perpetual motion machine. EDIT: Missed a word
@@blazingangel623 Indeed! The main source of power losses in that setup is a friction. And the most effective way to retrieve power from our muscles - is in pulsating manner. See, our heart is working in a same manner: quick burst, then rest. And it's capable to do that bursts throughout our whole life, without any significant loss in effectivity
Yeah the friction of the air is the biggest power loss ☺️
@@blazingangel623THWG Go Jackets
This is an awesome example of putting engineering skills into action. I'd love to see this compared to a set of pedals on an elliptical gear.
I hope cam-drive bikes become a thing. I had a similar idea while I was going through a thought exercise for a "100km/h bicycle". My main motivation was to get more reciprocating action rather than circular and getting to use the quadriceps longer for each stroke. A cam drive not too dissimilar to this one came up. I'm glad I found someone who actually built one and test it.
Many bikes are cam-driven, although still powered by a circular crank. It's very nice to seal the cam from the elements, but it is a heavier system
You can use carbon fiber or some other light weight material to build it if money isn't an issue @@1queijocas
100kmh? Velomobile
@@Aka.Aka. Velomobiles are bicycle related, but the only thing they're related by is the cranking/pedalling drive. They are basically human-powered cars. It was a design exercise that I never completed. Conventional bicycles have reached 100km/h but they are either gravity assisted or slipstreaming. I didn't even finish researching the drive train, so the frame was never designed.
Whirlpool made a compact washing machine that used cables and eccentric shafts to do the agitation, instead of their usual gear mechanism. They SUCKED. Cables couldn't take the repetitive stress, and frayed, then broke. I suppose they would be easier to replace on bicycles, but still...
Partner with Q rings by Rotor. They make bike chainrings designed according to your legs’ torque curve so they take an oval shape roughly. When your foot is at the 90* position the rings ovalize so they get bigger so it more efficiently uses your power and when your legs are in the 180* position they flatten out so they get smaller so you can quickly pedal out of the dead zone
His dad's bike already has oval chainrings
@@werewolf1195It is Shimano Biopace - those had the exact opposite effect.
Those are as close to prefabricated chain CVT for bicycles, by the way. Just move the ovals' peaks toward the pedals to shift up, and away from them to shift down.
Bro if ever you decide to create a teachable classroom for your fans. I will be the first one to join. Cheers to your efforts.
This is an outstanding video! We really need a part 2 about what it's like to ride, how fast you can go, how tiring compared to a regular bicycle etc.
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.
So many losses… the rollers, the bearings on the drive cylinder, the sliders, the pinion gears… Alfred Nobel tried up-and-down pedalling in the late 1800-s, albeit a different (and likely less noisy = lossy variety. It was unsuccessful. And people who cycle don’t just pedal applying force along one constant vector. People who ride professionally input power even on the part of the pedal stroke that goes upward. Fun, but useless.
the bicycle chain drive system is already something like 95-98% efficient in terms of transferring power from the pedals to the rear wheel. it would be quite the task to even attempt to get another few percent of efficiency, and at the end of the day it wouldn't make any difference to the average rider do to the negligible gains
Completely agree with this. I think the video is well done, and this is probably a good project for developing engineering skills. However it is solving a problem that doesn't exist. If I pay attention to how I'm pedaling, i apply power to the pedals around most of the rotation. Certainly both the up and down stroke, and if I'm really pushing the I'll think about "chasing the pedal around in a circle". Not sure if that's the correct way to pedal, but the change in power output (using a meter) compared to effort is significant
@@bmxscape That efficiency would be from the front sprocket to the ground, leaving out the "efficiency from the human to the front sprocket (which is what @MattGallagherComposer is talking about). The overall efficiency would be the product of the two efficiencies which are in series in the overall "drive train" from human to ground. So the effort to improve the front half is not misguided or otherwise not needed because of the high efficiency of the back half. But it is subject to the concerns Matt raised.
@@virtuous-sloth my comment is just expanding on @migrantfamily's comment about the efficiency of the system in the video. perhaps another more efficient input to the front sprocket is possible but directly cranking the shaft is the most simple and is very efficient due to the low friction created by the one moving part and the natural accommodation by humans.
Here are some thoughts from a cyclist in the real world. • There’s so much good here!Original thinking, clever graphics, beautiful workshop and fine craftsmanship. Applause! • Biomechanics are super complicated. Consider that conventional bikes can be successfully ridden by humans aged 3 to 123 with all their biomechanical diversity. • Biochemistry is even more complicated and none of us are continuous sources of power. Our various components need cyclic rest (as others have mentioned) • This looks like it would add some weight which is a factor on uphills. For many it’s a critical factor. • Even at scale this would surely add considerable cost. Additionally the materials and energy to manufacture raise the carbon footprint which ideally we would keep as low as possible. • There are many more sources of friction (not least all the sliding) which are also very noisy. Noise is something many (most?) cyclists abhor. • The added fiction would increase spectacularly once this gets dirty which is both inevitable and almost immediate. That leads to two further undesirable outcomes: cleaning and maintenance. • While there are many different genres of cycling and cyclists a very large proportion of journeys are for low cost, low speed, low maintenance and low effort city “commuting” (I use the word loosely). Simplicity is the guiding principle. In slight contradiction to some of the above I have for my bike paid a hefty price for something that adds weight and (slightly) reduces efficiency: a Rohloff internal hub. Now this really is a fine piece of engineering for a specific purpose: it eliminates faffing around with derailleur gears on long distance bike touring. And it’s a utter joy to use. But it’s not a solution to any of the problems facing city cycling which are largely behavioural, social and political. I look forward to your next beautiful out of box thinking project. Keep it up.
Gorgeous work. Please get a director to help you show this off because you have a beautiful mind
The alternator is a great idea to compare the speed of the wheel but replace the light bulb with a multimeter and read the current change to get a really accurate picture!
"The garage" scene was so wonderfully edited, the music, the cuts, it wall made it feel so epic and cool, like the part of the movie where the protagonist finally belives in themselves and starts preparing to face the villain. That was a really enjoyable video, it definetly deserves the button clicks, cant wait for more content.
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
I'm going to rain on your parade a little. I designed a linear crank bike using a skiing exercise machine for the sliders back in 2006 thinking that I could apply 100% of my leg strength through the full stroke. The problem is that the stroke length can only be about 15" or so, whereas the stroke length of your foot through a pedal revolution is actually the circumference of the pedal path. A typical crank length is about 7", so the path of the pedal is 22" which means more mechanical advantage. Your leg is limited by stroke length, BUT the next step I hadn't got to yet was designing a linear engine where the piston stroke could be longer and apply 100% of the combustion energy into rotational force using a rack gear on the piston arm and a pinion freewheel style gear. The best way to take more advantage of your leg strength is to try to design something like might look like drywall stilts that effectively lengthen your femur. Your femur length determines how long your crank arms can be and the longer the crank arm, the more mechanical advantage you have. An interesting experiment might be building a bike where you "pedal" it via a crank arm that you rotate with your arm. Although your legs are much stronger than your arms, you can rotate an enormous crank arm with your arm by reaching down low and up high. Standing on a platform you can easily turn a 40" crank arm which would yield nearly 6 times the mechanical advantage over a 7" crank meaning you could technically go faster with arm power
Although I don’t see much real world use since it would be hard to isolate the cam from the environment, it’s still an insanely cool concept, keep up the awesome work!
Feel like with engineered size changes, you could slap a cover over more or less the whole mechanism. All you really need exposed is the pedal shafts.
You can’t isolate a chain from the environment as well. But with proper maintenance it has proven to be very reliable.
it just concept made fully from A to Z just by 1 person. But what if a group of engineers with a lot of budget?
@@deanf7086 Dutch bicycles beg to differ
@@renosimpson9611*By (not "Buy") one person. Doesn't matter if had others make some parts, the design and the build of the bicycle was still done by one person.
The editing is amazing and the project itself seemed very intuitive! Amazing video, great idea, and I can tell this channel is going to blow up soon! Great work!
Some very interesting ideas here, thinking outside the box. Maybe instead of a fragile protruding cam and rollers it could be a grooved drum with one roller? If the drum rotates around the frame stem the driven shaft could be the original crank shaft, doing away with the extra chain drive. Would love to see this subject investigated further 🙂👏
bump
This is a fantastic exploration. The experiment is really well thought out. Your patience with each process in the production is exemplary. A follow up video about how the experience as a rider is might be worth while. A huge part of the success of the bicycle is the anatomy of the rider. While the mechanisms may be more efficient the vertical up and down action might be more punishing on the knees for example.
I love how this is the same but different from the last video. The production value is super high. It’s all done so perfectly. Cannot wait to see what’s next. This is the best part of all my fav engineering channels like Colin Furze, Tom Stanton, Stuff Made Here etc etc. So so glad you exist!!
Wow thank you!!
Like others have mentioned, this was exactly the issue of evening out, as much as possible, the torque curve that the biopace chain ring was meant to address. Sheldon Brown has a write-up on the biopace design and why it never caught on.
It felt awkward, that's why. It did indeed smooth out the torque curve at the wheel, but at the significant expense of rider comfort and endurance. They didn't even catch on in the velodrome where modern, more subtle ovals have been appearing.
Could you mod the gears to cover more distance
Yep, Sheldon Brown. RIP.
What exactly is the supposed to address? There are no efficiency gains, only losses. In the torque profile, less work is performed for equivalent force when the arms is shorter. So by flattening the torque profile to the max of the sinusoidal profile, it also costs more work/energy. Efficiency stays more or less the same. But then adding weight and many moving parts/sliding contacts absolutely kills efficiency. So it's a less efficient bike, just with a more interesting mechanism for more constant torque delivery.
we need a follow up comparing your heartrate while maintaining 15 mph on a traditional bike vs this bike.
lmao, that swap to the card in the spokes is genius
that machining was impressive, although I would have liked to see more of the finished product. I'd guess that with more torque you'll also need to change the gear ratio to make the bike use all that power
OK, looks like a brilliant idea. I do see a lot of design challenges in dealing with friction losses between the sine curve track & pedals, and in the two extra drive train components though 🥴
You can essentially eliminate the extra drivetrain parts, but it would require new custom gears to still get a usabe ratio for a bike
this is one of the coolest things I have seen in a while. modern day davinci.
If the world ends, it’s guys like you that can start a new civilization. And you even manage to do it in family. If I was your dad I’d be incredibly pro
As far as I'm concerned - he just reinvented the wheel. THAT'S COOL.
im glad that this level of expertise is available for free on youtube. this is a masters class in engineering, great 3d cg
Glad you like it!
Definitely not a masters class. Very basic stuff compared to most machines we actually use.
@@EricPeelMusicusing a machine doesn’t even come close to actually building and actually understanding it. I’m sure most people can use a microwave, but how many can accurately describe how it works, or let alone build one themselves?
@@foximacentauri7891 You missed the point. 🛫🙄🛬
@@EricPeelMusic 3:18 this analogy he is using is as good as your gonna get at any college.
That's a cool project. Another way I work around the nonlinear torque characteristic is to add an entire phase of propulsion to the pedals... at 90°, by using my quads and hamstrings and tilting my feet so that I can push 𝘢𝘯𝘥 pull, fore and aft as well as down, instead of just down. More rounded exercise for the legs too.
Why is this one of the coolest videos ever
You are one hell of an engineer, keep it up. Thanks.
Thank you! I appreciate the support!
Second video! Excited to see this channel's future. I know it'll grow even more soon enough. The animations are very good and the editing is also great.
That is a really nice design, with some polish in the ergonomics and less plastic I think it could be awesome
Thank you!
Incredible Invention and Concept Idea.
Jesus Christ those 3d animations showing exactly how things worked must've taken a hot minute to get done. It's an exceptional visual aid though and really helps follow your thoughts.
Wow!! I was impressed by your CAD work at first, but at 3:10 I really had to pause and admire the model - awesome. Super engaging and a fun idea. I built an electric pedal assist bike a few years ago and it's been so fun to ride but this is way more creative XD
Oval front sets do basically the same thing, but I still love this design! Looks like it should be steam assisted 😁
Exactly what I thought
That's what I was going to say, I think they accomplish a very similar thing.
Yes, the shape was actually determined by measuring the torque.
The mountain bike actually had one too
If you go to 8:58 you can clearly see that the bike he is working on has an oval ring... 😕😄
This is my favourite KZhead channel
I loved the contrast of using photogrammetry and cad, then using cardboard and masking tape in the next shot. 😂
I am still amazed with the unique ideas and the quality of the videos. It feels like this channel is destined for greatness! PS. I was here when this channel had only 23.7k subs. Just for the record when I am going to be surprised how much this channel grew in the furture.
You can tell an engineer is proud of their work when they end the video immediately after finishing the project without showing a single comparisons
Sense of sarcasm in that
Nice job on not only designing and building this, but also your cinematography work. Ty for posting.
Got wonder struck by seeing the ability to visualise, conceptualise and put into practice in such precise manner that even a big automobile company should envy. Hats off to your talent and skill. You will come up with something extraordinary!
This would be very interesting to do in a recumbent. You could do longer pedals, too.
I think recumbent would be ideal for this design.
Yoooooo
I think using a ratcheting drivetrain and maybe some weak return springs would be more efficient so you have pedals that push forwards and pull on a string that unwinds off of a one way freewheeling pulley on the back wheel.
@@TimpBizkit Yup. I've been pondering this build for a long time. I picture a long chain that goes around a jackshaft gear and connected to a cable with a coil spring on the other end.
@@heathroush5343 like a Ski erg but each cable is linked to a foot pedal and the gear ratio is stiffer so instead of loose long tugs it's a smaller more forceful movement. If you had a belt strap (like a car seatbelt) that wrapped around a freewheel on an axle, you could even have different gear ratios if you allowed had a winder drum at the front behind the pedals and you could clamp and move them on the belt, so you could run with a wide diameter belt swiss roll on the back freewheel for a low gear or a narrow diameter for a big gear. Now that I think about it, is this a good transmission for a drag car if you use just enough belt for a quarter of a mile, unwinding a coil driving the back wheels for a greater and greater gear ratio as you go down the track? Here's a bike that may be of interest to you kzhead.info/sun/YLWjlpyKpaBngWw/bejne.html It has two independent freewheels unspooling string on the back wheel. You can change gear by increasing or reducing the leverage on the string pulley in a series of notches, to either pull the string harder on a hill or faster on the flat. On the prototype it's linked to a standard rotating crank set, but if you wanted to try with reciprocating "stepper machine" style pedals.
I'm so impressed with all this talent. Bravo , bro.
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!!
This is my favorite type of content
Amazing videography and (more importantly) engineering. I can appreciate the creativity and experience it takes to create this project. Although, as some comments have pointed out, this bike is actually less efficient than (most) standard bicycles for two reasons inherent to the design. This is considering the true definition of mechanical efficiency, defined by the power output / power input. 1. The primary, obvious reason is due to the abundance of sliding friction. The bearings are a good touch, but considering that all of the parts downstream of the CAM are original, any added friction in your system will reduce the efficiency. You can hear the bearings rolling pretty well, which shows the amount of energy being lost to sliding friction either within the bearing itself or against the track as it rolls. 2. The second, much more important loss of energy that contributes to this devices lower efficiency is in the CAM design itself. Not all of the energy that is transmitted by a vertical step is converted into torque, and this is due to the physical nature of a wedge, or an incline. Work is a change in energy, and Power is the rate of Work over time (change in energy over time). Work can be calculated by multiplying a force by its parallel displacement of an object. For example, if you push against a stationary wall, you have done no work (and therefore transmitted no power) because the displacement is 0 despite the application of a force. If you were to instead push up on a box and lift it into the air, you have done work on the box because you applied a vertical force and it experienced a (parallel) vertical displacement. In the same way, by pushing down on a pedal in a downstroke (starting from a 12 o'clock position and ending in a 6 o'clock position) power is transmitted because the downward force is parallel to the pedals displacement, since the pedal has displaced vertically and not horizontally. The energy is transferred through the torque that the force creates on the pedal, and although the torque does follow the sin shape your graph showed, this does not make it inefficient. All of the energy supplied by the leg (ignoring friction) is transmitted into velocity of the bike. Unfortunately, as beautiful as your design is (especially the JB weld😉), it does not have 100% efficiency (ignoring friction) like a standard bike pedal. To explain why, consider pushing a cart up on an inclined surface, or a ramp. Although it is difficult to fight gravity, you reach the top and you have two things: a cart with more potential energy because it is elevated, and a cart with kinetic energy from its horizontal velocity (congrats!). The potential energy comes from the work done by the vertical component of your force, and the kinetic energy is from the work done by the horizontal component. Because you are in a world where friction doesn't exist, you have been 100% efficient. Now go up the ramp again, but imagine now once the cart reaches the top, it runs into a wall and stops completely. The potential energy is the same, since that is only based off of the height of the cart, meaning that all of the energy transmitted through the vertical component of you pushing the cart is conserved (100% efficient). However, the car has no velocity anymore because it hit the wall and lost its kinetic energy through some process of plastic deformation or transferring the energy into the wall itself. So, whatever energy was spent pushing the cart horizontally is now gone, indicating a drop in efficiency. Remember, in a fully efficient system, the total energy of the cart-earth system after the action is done should equal the total energy before, but as we just showed, it is lower because the cart has no kinetic energy. If the ramp were at a 45 degree angle, the displacement in the horizontal and vertical direction would be equal, and the force applied in the horizontal and vertical directions would be equal, and so it is known that the Kinetic Energy (KE) = Potential Energy (PE) at the top of the ramp. So, when the KE is lost from the cart stopping, this results in a system with only 50% efficiency! Now, how does this relate to your CAM? Let's look at one bearing and examine the forces. Well, when the pedal is pushed down, the bearing transmits a horizontal and vertical force on the CAM track. The horizontal force in this case is what is converted into Torque and therefore rotates the CAM and in consequence the wheel. This is analogous to the vertical force in the ramp example (confusing I know) because as long as you keep rotating in the same direction, or keep pushing the box uphill, the work done will be positive and will not be lost. *However*, if you look at the vertical force that the bearing applies to the CAM track, what do we see as the CAM undergoes 1/2 of a rotation? It starts stationary, then the bearing moves vertically (which can also be considered an opposite vertical motion of the CAM itself) as the pedal is pushed down, until a half rotation occurs, and then the bearing no longer has a vertical velocity! Work had to be applied to the bearing in the vertical direction at some point in the process, otherwise it would have no change in vertical velocity, but as we can see, the beginning and end state of this half rotation results in the same vertical velocity of the bearing. This is the same as in the case with the cart, where the beginning and ending horizontal velocity are 0 because energy was lost during the cart's collision with the wall. Even though the force and displacement are always in the same direction for this half rotation, indicating positive work should be done on the bearings vertical velocity, the bearing ends up with no change in its vertical velocity, and so we can conclude that this energy was lost. And, ladies and gentlemen, what does it mean when energy is lost from a system? It's efficiency goes down! What this means is that if your track were at a 45 degree angle, for example, it would be the same 50% efficiency as seen in the ramp scenario. Of course, yours is much steeper, but the efficiency could still be calculated to be tan(angle). TL;DR, the vertical component of the force applied to the CAM does work to the bearing-CAM system, but this energy is promptly lost, indicating a loss of energy from the system and therefore a loss of efficiency. In comparison, a bicycle's transmission system has 100% efficiency (all of this is ignoring friction effects). Great video and project! Hope to see more soon.
Really enjoyed the video. About what you are engineering: there have been a lot of attempts to optimize efficiency. There are some examples in "bicycling science" by David Borden Wilson. There is a point where the muscles get too little rest while cycling and acid is building up. If you are looking for that the project will be an real life usable improvement would suggest to include human factors in this project.
Interesting points, though I'd add that likely all those examples were judged on their applicability to racing. But if you're after peak efficiency you wouldn't be going anywhere near race pace. The most efficient way of converting food calories into km covered is at a pretty low intensity, and at those lower intensities, I wonder if the lactic acid considerations are relevant anymore. So there's still a chance this actually is a more efficient bike, just not better performing in a competitive race.
Also it's not exactly clear that having more torque available through more of the "cycle" necessarily means it is more efficient. I guess it depends what he means about efficiency, but in the strict sense it is about energy loss. I think the only way one could measure this would be to perform controlled experiments measuring the amount of CO2 which is being breathed out versus the amount of energy which is coming out of the wheel/chain drive...
@daveuk appreciate the point you bring up. It could be the overload of muscles and buildup of lactic acid from the examples in the book where only aplicable in racing. Get the idea that long duration cycling could give the same muscle overload but at a different power output. NASA did some testing on the duration cyclist could perform with what power output with different levels of fitness. Guess the only way to see the optimum user case for the transmission this video covers is to test it. The underlying point of my comment was to include human factors in the next video(s) and perhaps draw inspiration / mental models on the experiments documented by others for doing so because it is an aspect that fascinates me and hopefully others too.
Interesting engineering. Yes that's a great book. As a cyclist I push/pull forward, backward and upwards on pedals as well as down (easy with clipless pedals) so I think the assumption here is a bit simplistic. Still it's a skill. There have been other attempts to modify the torque curve.. Anyone remember Biopace chainrings? This was an asymmetrical chainring. I think I remember one of my racing friends' quotes in the 90's.. 'Biopace was made by Satan'. A human factors problem, the different torque curve messed with his muscle memory.
@@airborne0x0as for biopace: I heard they eat through cyclists knees because of the higher more rapid acceleration at the upper and lower end of the pedal stroke. I suspect something along those lines is happening here. Also it’s debatable what’s more physiologically efficient: pedaling in a curve or in a straight line.
You are multi skilled person and the best part is that you apply your skills to projects !
Innovative mind, tools, resources, everything is amazing. Feeling so jealous.
I've never seen a channel with such elaborate and beautiful projects (yes, I'll take two as a valid sample size for now), so I really hope you get the attention you deserve.
Seasoned cyclist here. This idea is delivering so much more power vs the traditional crank mounted pedals. Would be awesome to see someone manufacture it. Patent it and get in contact with the big boys! It goes without saying, great work!!!
I might be missing something here but to me it seems like torque isn't the only factor. His system has mire friction and more weight and the transfer from the bottom of the wave is steeper so I would believe that averaged out the gain in torque wouldn't be that high so a system that is more complex.
Cool concept! Can't wait to see it's final form!
This channel is only a couple of months old and it's already a super cool must watch channel!
this is a really interesting idea, i wonder how it works out with actual pedaling tho since it seems like you might not be able to engage as many muscle groups which could hurt efficiency on the human side, offsetting the improved mechanical efficiency
Its truly inspiring to see such a new channel with this quality. Keep up the great work!
This guy deserves way more subs
Very cool. Wax the cylinder and slides and see if that helps to reduce the friction.
This concept is amazing. Love the work you did! You didn’t just want to make a thing, but explain and understand why it did what it did
I think it might be made better with the pedals themselves on horizontal bearings, so your legs can make a more natural motion that way
That's exactly what I was thinking! Having the pedals on the horizontal crank they're on on the original bike, but maybe also having a disconnect between the flywheel and the pedals so it could keep spinning and maintain its momentum as you freewheel (or not, for simplicity's sake).
Can’t wait to see this technology getting better thanks to you, someone that starts it. We will see more energy-efficient future eco-friendly.
Big Respect, this is "very" Hard Work 😮
Interesting . This has been addressed before in the form of a wire drive system consisting of an L shaped crank and a wire wrapped around a hub. The pedals move almost vertically up and down and the wire transfers the motion into rotational movement at the wheel. A velomobile is suited to a linear pedal movement using a similar wire system to convert to rotational motion.
Glad I found this channel early with the lock design, this is amazing, great job on the bike and channel
Absolutely amazed by the passionate engineering artistry on display here! The dedication and creativity that go into crafting such intricate designs are truly inspiring. Kudos to these brilliant idea for pushing the boundaries of recent design and bringing inspiring technological solutions to life! 🚀
You guys are efficient with CAD work.
Neat little physics experiment, but more weight and more moving parts probably hurts your efficiency more than helps it. Still a very interesting contraption, however. Thanks for sharing your ideas with us.
You could've just made the pedal sprocket slightly elliptical to improve torque when the pedals are above each other. Your legs can push forward and back, not just up and down. The elliptical sprocket may require new chain guides since it will tend to shake the chain at high speed.
Elliptical sprockets are already a thing
His dad's bike was already equiped with elliptical sprockets
i like this kind of talented and creative university students...🙂
Your music taste for montages is really the best about this videos but of course only if we ignore all that amazing engineering.
Incredible work again! your projects are so unique and cool.
It was exciting to watch your design come together, and I can't wait to see what you build next. We definitely need a comparison video of this design and a traditional crank design! Awesome work!!
Great idea, graphics, build, explanation, everything!!!!
My guy did a KZhead speedrun and got. 1 million views on his second video , good job
The concept here is amazing! If the loss of the cam and moving parts is less than the gains from the system this could honestly be something amazing
There are no gains, only losses. In the torque profile, less work is performed for equivalent force when the arms is shorter. So by flattening the torque profile to the max of the sinusoidal profile, it also costs more work/energy. Efficiency stays more or less the same. But then adding weight and many moving parts/sliding contacts absolutely kills efficiency. So it's a less efficient bike, just with a more interesting mechanism for more constant torque delivery.
Im not well versed in this stuff, but i thought that more parts meant more lost energy. I would have liked to see more testing and more numbers, but i guess the objective was completed already. The design does in fact work and thats really cool.
Man, your dad collected some fine machinery! Amazing design btw ;)
Pure engineering, i wonder how you got on that Idea. Amazing work, that's what we are meant to do (at least some of us) 😅
This really seems like it could go far, this channel and its videos are greatly produced, the explanations are impecably done, and on top of that easy to folow. Great job, this deserves more than a couple thousand views, im a fan
0:32 cos(45°) is not half, its .707 so youre making 71% of the total torque. Half would be at 60°, 30° on your display in the video, you can even see this in the projection you do of the length. Probably just an oversight but might be worth fixing. Good video, always love to see new concepts.
I appreciate the correction! Definitely an oversight
We used a regular crank set up to pedal a 27,500LB. GVW dump truck, and got it to go up to 40MPH back in 2012. Since then, our knowledge on human power has increased dramatically. We're doing a Volvo tractor trailer, and already have most of it ready to go! If you're ever in New Jersey, come see the physical proof. 🍷🍷😎
I love the project! The involvement of theory of operations, data collection, planning, use of various software, trials and prototype builds is what keeps honing your skills and understanding of what works and what doesn't. It should also teach you the difference between making something better (improving), and making it efficient (cost or construction of a technology). We are always faced with the questions: "should we, because we can?" "It works, but can a consumer afford this?" "Is it too complex for its environment?"
Great project! It looks like the bike has an oval chainring (Shimano Biopace). It would be interesting to see whether/how that affects the torque curve of the new system, compared to a normal round chainring.
also compared to a modern oval chainring at if there is one that fits a square bb ^^
Biopace is 90° out of phase, its harder to pedal at bottom dead center. Even the most extreme oval rings are only 6% less effort at bdc
That's quite a marvel of engineering you've designed there. And when you machined those mountings about 6:55, they looked so professionally done, that they remind me of suspension fork mounts for a motorbike. Fair play. I can understand why this likely wouldn't be something mainstream though because of how complex it is. So many intricately machined parts. Brilliant nonetheless, and you proved the title 👍 P.s. that bike's gonna be one harsh ride. Suspension is a wonderful thing 😉😜
The “world saved” at 1:54 made me happy.
Needs a part 2 with durability updates and power benchmark.