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Gearless Magnet Bike
- Published on Mar 23, 2023 veröffentlicht
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- Science & Technology
Comments • 6 647
Hey that's pretty neat to learn about the alternating polarity creating a greater resistance. I didn't think of that. You could print a little cube grid that holds multiple magnets with opposing fields and probably get a much more impressive slow down when dropping it down a pipe.
Seeing your comments across a few different channels at the moment. Dont you have videos to make!!😊
@Rob have and owe are two different words as per the dictionary.
If you thought about it for a minute, you would know this. Here's an important thought experiment: what if you replaced the ring of alternating magnets with an actual machined ring neodymium magnet concentric with the axle? How much torque would be transferred?
Zero. The answer is zero. It would spin freely.
Eddy currents form when there's a *change* in magnetic field, not just whenever there's a magnetic field. So the more changes there are, the more eddy currents form. The only limiting factor is when the magnets get so small that the changes in magnetic field don't bridge the gap from the magnets to the conductor.
Maybe the printable magnet company featured on SmarterEveryDay could create a tiny alternating pattern clip-share.net/video/IANBoybVApQ/video.html
@Vin Taylor You people do understand that the efficiency asymptote this thing is approaching with more effective magnetic fields is identical to just gluing the two plates together, correct? There is literally zero benefit to this clutch? I feel like everyone is missing this fundamental concept.
Your projects are always better than most peer reviewed articles
What a fascinating concept and so well executed! Great job on this mate!
Your meticulous research and trials of materials and forces is truly impressive. Then to advise us that it didn't work as you had hoped shows your humility. Thanks for sharing this whole story.
The answer is seen in electromobile vehicles- Alternating current (in motor wire-windings) is far more efficient than permanent magnets only (which are also present in many EV motors). Also stopping power in EV regenerative/recuperative braking had same weakness as described in this video. But - with alternating current oposing the magnet rotation, it can be managed to fullstop in most current EV vehicles.
Which translate to even not using normal friction brakes/pads at all = rusting.
So this research is not completely wasted- it just needs to simulate EV motor = induce some current in copper disc (made from thousands of copper wires, insulated of course). And electronics with variable frequency of alternating current, made by using Gate-transistors.
Of course it is not needed as you can buy such a bicycle now, but- exactly the same proces they do in Tesla, Mercedes factories/labs.
I actually think this project is really interesting. Unfortunately the transfer of torque will always be determined by the change in magnetic flux. Meaning that you will have to pedal faster to get it going and keep it going.
Or induce another magnetic flux which alternates faster as wheelspin. It is called electric synchron motor, and found in most current EV vehicles 😀
You have to admire Tom's enthusiasm, he had an idea and he set about trying to bring it to fruition. Not all experiments work , but I am sure this attempt has brought him some useful insights of what he might try next.
I guess the next step is to build a superconductor clutch to avoid the heat issues. That'll totally work.
A boring fixed gear can do that, too
Nah, he should just invent a room temperature superconductor instead. Seems simpler.
A supercunductor plate would cause it to be locked together lol. It would be almost impossible to slip it. That's essentially how magnetic levitation works.
@Rubiconnn but then it could be controlled. Connecting a grounded resistor to the superconducting plate would disturb the eddy currents, and provide momentary 100% slip. You could switch it on and off PWM style to tightly control slip.
Now we just need room temeprature supeconductor. :(
Yeah that would induce instantaneous eddy currents of such proportion to effectively bolt it together, it would be an expensive, weighty and very cold cog.
I think if you invert the configuration (magnets on the wheel and copper on the sprocket) you don't have to worry about them sticking to the spokes (they are moving at the same rate) and you can have them further away from the chain (maybe you can try an aluminium chain as well). Having electromagnets to turn the friction on and off may be interesting as well, though I am not sure how to wire them in moving parts
............MAYBE JUST USE *BELT DRIVE* ,NO????
Drive chains are made out of Steel because it's tensile strength, stiffness, hardness, fatigue strength, and importantly wear resistance. An Aluminium chain would need to be much h bigger to have the strength making it bulky. Then still it is too soft, even an alloy. So it would just wear out fast. Maybe get hot and seize up.
Electro magnets similarly are too bulky.
I am so amazed by the proffesinal skills of this man, who was recommended by youtube. Wish you progress in that direction, because we live in time when everything possible and I hope we will use antigravity someday...
Amazing, even the absolute terrible failures are still amazing and entertaining to watch, I don't think you need to rushing to the patent office with this one.
Maybe think of adding something to the centre near pedals to allow the copper plate to continue spinning. Similar to a ratchet mechanism but with a silent mechanism. That way you would not loose power when you stop pedalling. Maybe even a round plate of aluminum on the spokes to give more magnetic pull. Otherwise looks really good!
Thanks for an incredibly good vid! When creating resistance with copper and magnets, is there a current created at any point? Or what happens with the energy transformed?
I'm a physics professor and this whole project is incredible! That's one whole chapter of the textbook in a single short video!
That's why I regularly substitute lectures with Clip-Share videos - sometimes there is incredible stuff to find, that saves the student (me) hours of agony and self hatred. Hehe.
Idk what these people do differently, maybe it's because they're closer to the point where they didn't understand it themselves than most professors are, but they sometimes have an incredible efficient way of teaching. (Helped me most with theoretical physics stuff)
@Brain Decay Personally I suspect it's just numbers. If there's hundreds of youtube videos explaining an idea, you're only likely to see the best ones, and the many many terrible videos just drop into obscurity.
Whereas with your actual college course it's unlikely you have all the best professors for every subject.
Although that does create an interesting idea. Imagine if you had access to lectures from hundreds of professors worldwide and your tuition went to the ones you watched the most.
Well I don't think most physics teachers have a small team, a budget that allows for cnc machining and 3d printing custom parts, and weeks/months to dedicate to creating a single 30 minute lesson (when would they do their marking?)
Absolutely Brilliant idea! I’ve struggled thinking of a solution for an inertia clutch used on 7.5 gauge train. This hand powered train is operated by a small child using a vertical push and pull lever method, however operated by only one person.
Once under motion stopping is near impossible as the inertia transfers back to the hands. One way clutch sprockets make start off difficult without starting assist (a push) to get the offset crank under motion.
This combined with a radial ball bearing shift cvt (drives the SIDE of the chain) may be the “magnetic clutch” needed to start off easily with faster easier hand movements shifting the cvt quicker , then stopping when hand motion ends without a sprag style lockup forcing movement of the handles causing the child to let go.
You could significantly reduce the slip rate by increasing the magnet ring to the wheel rim diameter, only problem would be needing to completely re engineer the bike frame to mount the giant disks
The function has two effects: once as a magnetic drive clutch, but also as a magnetic brake clutch. If you do not pedal, the magnetic disc should decouple. Otherwise it acts as a brake.
I would recommend not using a disc of copper, but an annulus. You could have "gearings" by having several nested annuli with notched / cutout bracing supporting them, and different gears would correspond to different magnet arrays for each radii associated with each annulus, where the field strength would differ for each array. But either way, this was a very cool (warm?) experiment!
Bloody smart Aleck, do it yourself and the go to the trouble to put it on u tube!
@Stephen Cummins Thanks for your kind words! I was only spelling out an idea. Not diminishing what was done and obviously he put a lot of effort into this. I apologize for not having a Clip-Share channel and extra money to build projects to have a moral equity in commenting here. I know that everyone has the degrees of freedom in their life to do that and I'm sure you've gonna ahead and pointed out all of the other commenters' lack of platform content when they've made suggestions or had opinions. I will refrain from putting my musings and ill-considered ideas online in the future so as to not offend anyone's delicate sensibilities. Thank you for correcting me. I will say being facetious was not my intent, but I nonetheless deserve the insult for my failures.
@Proton Electron The important thing here is that you learned a valuable lesson in Clip-Share etiquette.
Good luck with your sponsorships, future earnings and endeavors. 😆
@Whatsit 2ya And yours!
Put the copper disk into a stater pattern and leds on with a switch for close to open and the resistance will increase a lot when the leds are on. You can also cook on the disk when riding😊
The side by side comparisons are astonishing, it’s amazing to visualise the different behaviours induced by different configurations of magnets and weights
True. I just wished he had filmed them with his infrared camera, so that we also see the amount of heat loss
@MrGustave1er yeah true
@MrGustave1erYeah that would probably be really interesting, but I still think it’s good as it is of course
Tom is brilliant, I wouldn't be surprised at all if the heat generation turns out to be a huge positive for future project potential, surely this magnetic contactless set up could harness all sorts of free incidental energy
He could've used an off the shelf thread on 6 bolt brake adaptor for $10 instead of printing such a disc
First, congratulations on the great and successful project. At 7'41" of the video. Increasing the number of magnets actually DID reduce the RPM, proportionally, considering how many magnets you've added compared to the count of the magnets already there. In order to achieve the linear response, it takes the proportion to stay constant. If that is, say, 2, then it takes adding 2,4,8,16,32,... magnets in order to keep the response linear.
Making the copper plate thicker would reduce the number of magnets needed by decreasing the resistance for the eddy currents. And as other people have commented mounting the magnets in a steel mount would also improve the performance by helping to concentrate the flux. Similar just for kicks project would be to try to convert this into a homopolar motor regenerative braking setup with some big capacitors.
Having an inverted centrifugal governor that varies the magnet force distance from the hub, you'll end up with a torque/rpm self-regulating system.
Having a twist grip increase or decrease the radius would let you "select" how much power you want to put into the pedals.
Between that and a reduced airgap (cubic law being the cruel mistress that it is), I think a V2 would actually be almost viable.
Love this stuff. Kathy's next video is about magnetism. Kathy loves physics. Belt drive would eliminate the magnets on the chain.
A very interesting project! As I saw the resistance tests, I instantly thought about an "electrical brake" using an electric spool with a variable resistance in a brake lever. A contactless electrical brake (I know, it´s not new, trucks brake that way..) Very neat!
The positioning of the weights at 7:44 is such a pleasing real-world representation of a log graph, I love it
might be a hyperbola
i tought the same !!! cool
@canteatpi or a root of some power. I think it's more likely to be a square root graph, due to the powers in the formulas for kinetic energy
@Михаил Долгополов ты говоришь по русски? я учус, но это очень трудный язык :)
Absolutely fascinating, great effort and presentation. It reminds me of a Kickstarter I backed in 2012 that used this force to spin a dynamo.
I'd love to see the copper painted in matt black, so you could see the temperature variations with a thermal camera when say, "breaking" downhill.
A stellar example of how to test a hypothesis. It's a failure - but what a success for experimentation and engineering! Hats off!
Every project you bring to Clip-Share is amazing man, keep on the good work!
I’ve thought about this exact idea for years. Glad to see someone put it to the test!
You had to overcome many obstacles to make that work. Well done! I could think of many uses for something like that. Maybe the bicycle is not the best use though LOL
As a bicycle mechanic over in Germany I gotta say, I really love your bike related videos. They give me great aspiration, sadly I lack the funding to copy your concepts for my own fun. But they make great talk in the break room!
In another life, I was a bike mechanic too. I probably enjoy as much these videos as you. Now that I’m doing more software and hardware, after building a few robots, it tickles me to try and build a braking system idea I had a long time ago!
as a bike mechanic in Germany, do you work on Rohloffs or other internal gearhubs. How do you like them? If this magnetic clutch/gear works, it would be fantastic!
I'm wondering if being able to vary the strength of the magnets (by making them tiny electromagnets) would make it a practical device. Sort of like gearing through magnetism. Probably not, but it's so tantalizingly almost useful.
By having Flux collector on each magnet of Faris metal you could greatly increase the magnetic strength of each magnet in the desired direction. If done correctly it could reduce the attraction to the chain.
Why not start a youtube channel with bike experimentation? It probably will pay for itself if done right... viel Glück!
Just brilliant. This world needs more people like Tom!
We just covered eddy currents in my physics class, and this is such a cool demonstration! Definitely sending to my professor 😁
🔝🎁🔝 ᴍᴇꜱꜱᴀɢᴇ ᴍᴇ ᴡɪᴛʜ ᴛʜᴇ ᴜꜱᴇʀɴᴀᴍᴇ ᴀʙᴏᴠᴇ ᴏɴ ᴛᴇʟᴇɢʀᴀᴍ.❤️
Absolutely beautiful presentation of your methodologies and results; exquisitely explained. Don't stop tinkering!
One factor you seem to have overlooked is that if you want higher braking at low speed you could always just pedal backwards and increase the effective relative speed of the wheel vs the magnets. I do otherwise agree with people's suggestions of reducing the amount of copper used. I'd also suggest, from my limited electrical engineering knowledge, that you cut air gaps between sections of the copper, as that should cause greater eddy currents since the air will act as a dilectric and theoretically cause increased resistance. Will admit I'm unsure if that'd improve the effective coupling overall, but it seems like something that would at least have an impact.
You put sooo much work into this!! Love it!!
Tom again shows us not only how clever and creative he is, but also just how great Clip-Share can be with the right content providers!
Totally agree, Clip-Share at it’s best.
If my damned AWFUL home feed could learn this... I would be sooooo happy.
^^ I made a new account and seeded it with a Playlist of content types that I wanted and now my algorithm is much better than the old account. Probably a good idea to do this every few years to get a fresh look.
@Derrick Bommarito replies are broken
you are very correct
Amazing, it worked, well explained and easy to understand. Reminded me of those drop tower brakes
What happens if you peddle backwards? Maybe you could put a coaster brake on your pedal to minimize the back EMF you get from the copper plate... just a thought
Two things to think about:
1. You can use the wheel itself. It will give you much more torque. It have much begger diameter. And it is aluminiu. Also can save cost !
If you want, you can cut copper plates and mount them to it.
2. You can pedal backward to stop better. I am interested to see how it works.
3. You can store the energy of the eddy current and power some light or motor.
4. You can use a system like automatic car transmission. This basically means that the wheels lock to each other when you get to a certain speed.
More than two, but 🤷😄
I imagine this roughly corresponds to Thomas Edison's first telephone protorype -- two funnels connected by a 10 ft long 1 inch dia. pipe. Proof of concept, perhaps, but a few iterations away from market-ready. This is how great ideas turn into great applications.
This is awesome. As impractical as it may be, you took an idea and made it reality. That's pretty cool!
The alternating magnets for stronger eddy currents was a great idea! You might want to look into the Halbach Array (a specific way of alternating magnets) that makes the field strength even higher. I think it might perform better than only alternating the magnets.
Exactly what I was Thinking.
Also can't he put a steel plate on one side of the array to cancel the magnetic field so he won't have issues with the chain and spokes?
Also it makes magnetic field much stronger on one side (the clutch side) than on the other side (the chain side).
@Darren Bithell If he made the diameter of the disks bigger he could fit more magnets in to give him the torque he needs to go uphill and it would also solve the spoke problem since the spokes are already sloped away from the magnets further out.
Might run into torque issues breaking the disc though.
the steel plate (ie completing the magnetic circuit) is better than a halbach array unless you are extremely concerned with size and weight
@5naxalotl Rotational inertia is certainly important, though I don't know how much.
Respect to a brilliant man with courage and commitment. Those qualities are crucial to success in any field.
Really awesome experiment! More like a fluid coupling than a cvt. Definitely should be used more than it is!
I have a ThornLab compressor. Looks like a fridge compressor and is as quite as a fridge. Not as powerful as a big compressor but still works great.
This style of video should be taught in schools. Short,Very informative and definitely a crowd pleaser. I learned stuff and your descriptive visuals helped me follow along. As another commenter said, It's a whole chapter in the textbook in one video and your videos are several textbooks on different subjects. Carry the torch and light the way for you are appreciated. Thank you
You are one of many recent (maybe since advent of youtube “lecturing”) fascinating examples of upscaling of verbal communication. Initially for maybe three to five years i did not comprehend on par with reading thus preferred reading for comp and speed. Now neither are concerns with as the prof mentioned below, colating of material, and using increased playback speed. Cheers to your work and teaching. And to including thermal imaging, made me think about a viscous coupling transmission which audi and vw used back in 87 of which i had on my vw quantum which dispensed with having the weight of a traditional 4wd.
As a retired engineer who cycles a lot, I enjoyed this immensely!
Finally you can ride with less efficiency !!
@H K And more expense! It could be a government mandate!
What about using the sprocket rotation to create an electromagnet that can be engaged with the handbrake? Perhaps the electromagnet interacting with the copper disk would have an equivalent effect that would be disengaged to minimize difficulty pedaling.
am truly ecstatic at the genuine ability to go to the bottom of one's intuition.
It was exciting to make, and while the result didn't look like you wanted it to, it's still remarkable.
🔝🎁🔝 ᴍᴇꜱꜱᴀɢᴇ ᴍᴇ ᴡɪᴛʜ ᴛʜᴇ ᴜꜱᴇʀɴᴀᴍᴇ ᴀʙᴏᴠᴇ ᴏɴ ᴛᴇʟᴇɢʀᴀᴍ.❤️
Nice project, thanks for a great walk-through. I believe Aluminium has a greater electric density than Copper when measured by weight. However, Copper weighs a lot more by volume, so Copper would come out on top with the same size discs.
Hey there! The rear wheel hub you have with the stacked reverse threads will accommodate the freewheel drive/gear. The advantage is that you have the full threading on the (current) drive-side of the hub that may give you a more consistent plane* & you can still use the current parts/materials available 😁
I bet Professor Lens would have loved it! Top work as always! Fantastic idea and great effort to make such a great prototype.
The checkerboard is only useful if you also want drag in the left-right direction.; generally the magnet diameter should be greater than the gap between facing magnets.
More importantly, please look into "back irons" - these will easily improve the effectiveness by 2x or 3x and shall also eliminate the problem of the chain sticking to the magnets :)
Yes! I think this would probably double the performance at least. Mumetal is ideally suited for the job (which is why they use it in hard drive voice coils)
Would it not work better if there were magnets distributed around the disc ?
(perhaps at pitch centres corresponding to say 9/10ths of the pitch of magnets, to get a sort of vernier effect).
I guess the poles on the frame would want to be opposite polarity to those on the rotating disc. You'd want magnets both sides of the disc, to balance out the axial forces.
@Gottenhimfella Quite a few drawbacks to your scheme - The damping (i.e. conversion of kinetic energy to heat) happens in the conductor, not in the magnet. A magnet shall store energy as potential energy (and then is mire like to demagnetize too, but that is a different story). So, to convert KE to heat, a conductive disc is essential. The added moving magnets shall add inertia to the rotor (non-issue in a bicycle, agreed) Second issue is that of axial (parallel to the axle of the wheel) force - rare-earth magnets of this size pull hard - a symmetric construction with two sets of fixed magnets and one moving conductor has no axial forces, and hence can be thin and slim.. to work-around this, perhaps 8/10th or 7/10th would be better. The third issue is cogging. Even with the Vernier, you would feel some. The advantage in your scheme (if I understand it correctly) is that you eliminate the air-gap on one side of the damper. The disadvantages that you have to pay as a price are, imo, not worthwhile (at least with my understanding of your described concept. Feel free to 3-d print a holder with 7-magnets and 10-magnets arranged in a circle and try twisting them against one another :) (without a conductor, it will feel more like a detent than a damper)
That is an awesome experiment. You mentioned something of expended energy at one point and I wondered if it could be turned into a generator of sorts maybe to power a front wheel motor or something? I likely have no idea what I am talking about but I figured I’d say it anyway and see what happens by it 😅
The first time I have seen your channel, you are a really good engineer and that is coming from someone that was good (in my mind anyway). Well done keep them up
Now you need to swap out the neodymium magnets, for electromagnets, so you can turn off the effect while travelling down hill without peddling. Or, you can create a clutch system that moves the magnets away from the copper flywheel, to reduce the effect for downhill travel.
I once encountered an aggressive dog on the side of a busy road. What I did was exactly what you are suggesting one should never do and I tried to overrun it, facing the danger of getting in the opposite lane and being hit by a car. Fortunately I didn't, this time it worked, but I freaked the hell out and I realised that I was just lucky as the dog apparently was just guarding a narrow space, being not that interested in me. Every time since then, I just slow down and try to keep calm and friendly. Thank you for sharing your experience!
Loved it! I'd love to see more videos like this!
Those calculations with the dropping weight videos were awesome, such an excellent visualization.that section was great!
oh yeah, you can literally see the non linear curve which was beautiful
Reminds me of Galileh!
This is the stuff that science is made of!
It's an interesting concept you have here. The only real application thus far for something like that is the induction motor. Watching your demonstration was like Matthias Wandel's explanation on how electric motors work where he took a forced air furnace fan motor where he added a weight, pulley and a DC power supply up to it showing the resistance when magnetic energy through the stator windings then suddenly disconnecting the supply showing the weight suddenly falling to the floor.
I wonder how a radially-split copper disc would affect the eddy currents. I'd assume the right size of splits would disturb the eddy currents and implement a tighter clutch; of course the wrong splits might do the opposite, rendering the disc nearly as effective as plastic.
I'm just imagining at some point you had currents going fully around the rim of the disc.
Thank you for building this and sharing it with us. I wonder if the copper plate loses some of it's magnetic properties as it warms up. Can you try the experiment with the weights where one of the discs is warmer than the other?
My initial reaction to the title was that you are trying to solve a non-existent problem, given how efficient and user-friendly bicycle transmissions are, but I really liked the way you conducted your experiment, so bravo!
Hey Tom - I watch your videos all the time and love how you chase a design right down to the finality so that it either works...or it doesn't. I've been having a chat with some fellow SF writers in a Facebook group. I came up with the idea of a rocket with a payload that is pulled by a Nose Cone Thruster rather than pushed from the bottom. The thrust of course would have to be managed from the nose cone in an angle away from the payload directly beneath, which consists of a "pod" for the passenger, with the fuel attached below that which is pumped up to the nose cone thruster. Think of a conical arrow head with flanged openings underneath and the arrow "body" consisting of the passenger pod and fuel tank below. Sort of a ....flying mushroom... if you will. They think it wouldn't fly or would be a dangerous design. I think it would. What do you think?
🔝ᴍᴇꜱꜱᴀɢᴇ ᴍᴇ ᴡɪᴛʜ ᴛʜᴇ ᴜꜱᴇʀɴᴀᴍᴇ ᴀʙᴏᴠᴇ ᴏɴ ᴛᴇʟᴇɢʀᴀᴍ
I think you may have missed a trick. Putting an iron backing plate on both back sides of the magnets (ie facing opposite the copper disc) would give you two additional advantages. One being the flux would be more constrained and not grab the chain/spokes and the field facing the copper disc would be more intense. However the heat due to loss will definitely be more severe when the clutch starts slipping and will equally affect the magnets, which in your case, due to their size might have been a bit cooked too, but cooled faster due to less thermal mass. But in theory, the increase in efficiency would mean less slipping.
Another factor is that neodymium magnets permanently lose their magnetism when heated to approximately 85deg C, which is why when these types of clutches are used in industrial applications, there is usually a significant liquid cooling system that either flows through the clutch components, or the clutch is immersed in it.
They are very precise and consistent (repeatable) clutch designs that can absorb massive dynamic changes in force, so they are very useful in other applications, where longevity and smoothness are more important than efficiency in the force transfer. They are also used as brakes and dampers for similar reasons and also have more traditional lockup mechanisms and or clutches for greater efficiency when output (or input in the case of braking) has reached a certain speed.
Obviously these are stupid expensive, mostly due to materials, proper matching of the specifications, and definitely being customised for the application, not to mention bulky, but sometimes they are worth it, to solve particularly difficult problems where traditional force coupling mechanisms don’t work as well. Anyway, sorry for being “that guy” at the party, great video and demonstration of a very useful and niche device!
I think you're the guy we very much needed on this party. Thank you.
Chain sticking is solved by using a rubber belt
Tom, this response is on the money. Ferrous materials will provide a much lower magnetic impedance than air, increasing the magnetic flux density experienced by the copper. So putting some of the outside faces of the magnet groups will improve performance.
Again, on the money; watch out for heating and ideally turn that ferrous material into a heatsink for the magnets.
Finally, milling a shallow pattern into the copper to sort of turn it into a centrifugal fan, (increasing air turbulence and heat transfer) may also extend the operating envelope.
Mind you, it will always be lossy. Maybe it's more of a mobile cardio machine?
@Paul Chandler c'mon peleton!
Electro mechatronics engineer here and were about to write pretty mich the same thing! However I disagree on the heat part... Yes the magnets suffer from higher temperatures but the heat is generated in the disk and not in the magnets. The suggested ferromagnetic parts to close the magnetic flux would alsobserve as additional radiators for the magnets to get rid of heat.
Great work! I think this is essentially an induction motor. What helps the induction motor work more efficiently will help this clutch as well, e.g. adding slots to the disk to limit the directions of Eddy current, adding iron cores into the slots to increase the magnetic flux density (B = muH)
Now I want to see more about 3d printed bike sprockets. That was super cool!
Totally admire your efforts on this project.
I was thinking the same a few years ago, but using the magnets to power the bike using the opposing force of them. Great video
The world needs more people like you!!!!! Cheers.
This channel was new to me. I was blown away by the concept, quality of the build, quality of the experimentation, and the quality of the video production. You, Sir, are really good at this!
He's a mechanical engineer
Completely agreed, very impressive testing and engineering
Check his railgun project
Seems like youtube as a whole is new to you...
Great video. Could be on to something. Belt drive, and carbon bike frame would help avoid accidental magnetic fields. And what happened if you pedaled backwards whilst coasting. Would that slow you down quicker?
Very interesting. I didn’t know about this eddy effect. It was fun watching you take it to it’s full conclusion.
Pure, pure genius project. I like this. Keep up the good work!
Have you thought of setting up a halbach array in a circle as opposed to just checkerboarding the magnets?
Try Halbach array, so one vertical magnet between the horizontal ones. This increases the magnetic field on one side by 150% and the other side by 50%. This arrangement is used on fridge magnets. Halbach arrays also used for braking high speed objects with no contact.
What happens if you pedal backwards? Would that provide more braking force? How would the addition of an electrical current affect the resistance?
Great videos! I really enjoy watching and learning such interesting concepts!
One of his tests demonstrates that the torque generated was proportional to the difference in RPM between the disc and the magnets, so yes, pedaling backward would increase this difference in speeds, and therefore produce more braking torque.
The other question is interesting. The eddy currents that the magnets induce in the copper disc flow in a ring around the magnets, lagging behind the magnets because it takes some time for the current to die off once it's induced into a particular path. This is really how the torque is created - the ring of current induced by the magnets produces an opposite magnetic flux to that of the magnets, that's constantly trying to align itself with the magnets, so any rotation of the disc produces a "back torque" that opposes the motion. If you were to fit carbon brushes either ahead of or behind the magnets, current passed through the disc through these brushes will also produce a torque for similar reasons. You will have created a DC motor, but this would be very inefficient because the current you apply to the brushes would not just flow through the copper directly between the brushes, but also though many other paths that would not produce usable work. This could be improved by cutting slots radially at intervals around the disc, between the brushes, which would reduce the undesired currents without affecting the intended current path, but now you're getting closer to a conventional commutated DC motor. Which sounds like something interesting. However, if you look up radial flux brushless DC motor, you will find that this is very close to what is already being used for low-speed, high torque brushless motors.
Pedaling backwards does increase the braking resistance, because it means the sprocket RPM becomes 'negative' and the net RPM difference becomes larger.
Regarding electrical current, the current in the disc is not DC but it's a localized AC current which moves along with the magnet's rotation. To get the disc to spin using electrical current, you need to apply a rotating magnetic field through a set of coils. In his experiment, the magnets are replacing the pole pairs of a motor.
thats what i was asking myself the whole vid too😭
@BrightBlueJim Thanks for the response. I'm not an engineer and am not up to speed on the theory of DC motors. I know enough about electricity to be dangerous. My crude thought process was that an electrical current might increase the amount of torque that is being applied to the wheel from pedaling and provide a better braking action. Thanks again!
@BrightBlueJim The homopolar generator designed by Michael Faraday was a similar design as well, very cool seeing how this is basically that but with no wires connected to it.
Amazing story. A fantastic combination of physics, engineering and cycling 😁👍🏻
You do cool projects AND valuable research. Bravo.
Very good sequential explanation, very well explained Tom, well done. I've been imagining a magnetic clutch bike gearing with an expandable appateur for about a decade.
Wow! Great! Very interesting project! I applaud the results!👏🏼👏🏼👍🏼
In home exercise bikes, a magnetic brake is sometimes used in the form of a set of fixed permanent magnets (or electric magnets in expensive devices), and a perforated metal disk (similar to an aluminum alloy) that rotates through an upshift pedals. The adjustment of the braking force is regulated by changing the distance of the magnets from the rotating disc. Excess heat is dissipated from the disk into the air by means of a small impeller with blades on the disk shaft. Thus, it turns out to achieve a fairly wide range of loads (from 50 watts to 1.5 kW) with modest dimensions of the device.
It's fine for a brake, where you are trying to convert energy to heat. That's not what you want for a transmission, where you want to waste zero.
Fajny eksperyment 👍
Ever thought of trying out building a coreless axial flux motor for a bike? If you could minimise those eddy losses, you would for once have a motor that does decent freewheeling and regen-braking. An old Bionx D could be useful for that, although it probably won't be able to develop enough torque.
It’s a pity this sort of content isn’t on a tv show, with it showing both the engineering and research side of a prototyping process. A 10-12 year old me would have been glued to the tv if this was on. Great video.
I wonder if this effect would make a better shock absorber than a drive system.
The pieces of a jigsaw that come together with others to make a whole. Inspirational!
You had an idea and you concisely show how you went about implementing it and the methods you use. Thank you Tom for inspiring the younglings, I have no doubt we'll get some amazing innovations in the future, influenced by your ability to educate. Even though I pay little attention to the numbers and equations I still end up feeling slightly smarter from watching your videos.
Remember that the Lord Jesus Christ died on a cross for you because He loves you so much. He then rose up from the dead three days later
The Ten Commandments are called the moral law, (most of us are lying thieving blasphemous adulterer at heart and deserve hell) you and I broke the law, Jesus paid the fine. That’s what happened on that cross.
By believing that Jesus died on the cross and rose up from the dead 3 days later and not just confessing your sin, but also repenting of all sin you have done and putting all your trust in Him in prayer, He will grant you everlasting life as a free Gift
@Dove Bit off topic mate.
@Billybobble1 That bible bashing fool didn't even knock on your door before randomly spouting his completely irrelevant BS at you. Pretty damned rude I'd say.
Completely agree with your assessment and way of seeing this and others of his videos. There's so much I'll never understand but, I still learn from this sort of thing. One question I had he did answer was, whether the resistance was converted to heat or not. If it hadn't, it could have opened up a few more interesting possible uses like speed control of things without wear, obviously but, heat can be a problem too and a non heat generating device could be extremely useful in some situations. Still very interesting stuff though.
@Dove Tell Jesus I'm not interested
From an engineering standpoint, I see two obvious improvements.
Although copper is a better conductor than aluminum, aluminum is stronger and better for transferring work. Use aluminum instead.
For the magnets interfering with the chain, modify the sprocket to cross the whole axle and put the magnets on the other side.
As for coasting, modify the clutch so that the bike rolls freely even if the sprocket and aluminum plate are stopped. I wouldn't even try adding a magnetic braking system to this setup because that would transfer a ton of momentum to a small part (the sprocket area) which would wear out the sprocket very fast.
If you wanted magnetic braking I would suggest a secondary aluminum plate on the chain side of the wheel. Make it fixed so it moves with the wheel at all times. Then have magnets slide in and out from a fixed position on the bike, probably under the seat and well away from the chain.
I know it's a lot of work but increasing the radius of the copper disk would give a more direct drive... rather than adjusting for the slip with a larger front sprocket. I guess you might have thought about this but it would mean re-manufacturing the whole rear magnetic clutch mechanism... which is a waste of time once you locate all that lost energy in the form of heat.
Amazing project. Super well done. Thanks for sharing.
It would be nice if you could figure out a way of moving the disc away from the magnets as you are pedaling, then closer as you stop pedaling. Like how a manual clutch works in a car. You could use a handle bar mounted brake lever to engage and disengage the plate.
Another idea would be to try building something just the opposite of what u did here. Arrange 3 or more plates of alternating magnet discs similar to those so-called free energy motors. So as you are pedaling, you would get a small boost similar to the heavy flywheel experiments you did. It might not be much but it would be interesting to see how much the force would change by adding more discs.
I love how the composite pictures of weights falling literally shows you the linear and non linear relationships.
What could be very cool would be building a ebike where the pedaling go entirely to charge the battery, at an optimized pedaling speed, while riding only with motor. One could concentrate in pedaling in the most efficient way all the time, even when stopped at the traffic lights (e. g. With an automatic deploying bike kickstand) or uphill...
Great vid. I'd be curious to see this with wider diameter disks and increasing rows of magnets.
It's always so mesmerizing to witness eddy currents. I was playing with magnets and a copper pipe a while back and it's so so interesting to see it happen. The clutch idea is interesting, I could see this being useful in some kind of application that may get sudden changes of resistance, and it would save the output shaft of the motor. Rollercoaster brakes also work similarly to this.
Do not forget that Trains are fitted with induction breaks. No wear, and at high speeds to stationairy rails incredibly effective.
Roller coasters use this for emergency brakes.(obviously using a secondary brake so the train comes to a complete stop)
This is one of the best videos you have ever put out, and one of the best videos I have ever watched. Thanks for doing this.
Great video! We had a chuckle when the magnets stuck to the chain...even working with magnets daily, we're surprised when they jump to something steel. I wonder if using shielding material on top of the magnets would decrease the force enough to the chain, rather than having to change the design. Placing a piece of sheet steel over the magnets should redirect most of the flux lines into itself, thus decreasing the force to the chain. Adding this steel could also increase the field strength in the copper. Also wondering how hot that copper gets when you hold the pedals in place.
🔝ᴍᴇꜱꜱᴀɢᴇ ᴍᴇ ᴡɪᴛʜ ᴛʜᴇ ᴜꜱᴇʀɴᴀᴍᴇ ᴀʙᴏᴠᴇ ᴏɴ ᴛᴇʟᴇɢʀᴀᴍ.
I think using this as just a brake with the chain still driving the wheel may be interesting. Going uphill would be much easier, with the direct mechanical link, but being able to shed speed or better manage steep downhills automatically would be a nice feature to have.
🔝ᴍᴇꜱꜱᴀɢᴇ ᴍᴇ ᴡɪᴛʜ ᴛʜᴇ ᴜꜱᴇʀɴᴀᴍᴇ ᴀʙᴏᴠᴇ ᴏɴ ᴛᴇʟᴇɢʀᴀᴍ.
What happens if you are at certain speed and pedals counter? does it breakes better or the force is too great so you cant pedal backwards?