Roll Model Posted October 27, 2016 Share Posted October 27, 2016 20 hours ago, HunkaHunkaBurningLove said: If we were in the vacuum of space with no gravity on a frictionless flat surface, the same motor with a small wheel versus a large wheel would expend a little more energy to start spinning the bigger one, but once rotating it would expend the same amount of energy per rotation. In this imaginary world "size" means nothing. It is the weight (mass) of the wheel that makes it hard to get turning and again, hard to stop. BUT, there is a thing called 'Angular Momentum' which in general terms is what makes a flywheel relevant. If the larger wheel weighed 10 pounds and the small wheel was 100 pounds...You see? Or if you had two 30" wheels each weighing 100 pounds BUT one wheel had a 99 pound hub and a 1 pound wheel and the other had a 1 pound hub and a 99 pound wheel...You see how different those two problems would be? One would accelerate very easily and the other would be very tough to get spinning. The one with the weight at its outside edge would be very difficult to stop once it did get going, but the heavy centered wheel would be easy to stop. To keep these two 100 pound wheels moving at a constant rate (ignoring the acceleration phase)...I'm not quite sure of (if you could remove the air drag "in a vacuum...') because the one with all the weight outboard has more momentum and so need little to keep it going (it is better at "conserving" the energy it absorbs) when you shut them both off the one with the weight outboard would spin much, much longer (further) than the one with the heavy center... If part of the task was accelerating the wheels, the one with the heavy center would accelerate much easier and much more rapidly - So again, the mix of ridding could begin to be the dominate factor (hilly course, traffic lights, more hot dog ridding technique...) So the problem is not how you have conceived it. Link to comment Share on other sites More sharing options...
Roll Model Posted October 27, 2016 Share Posted October 27, 2016 30 minutes ago, Roll Model said: Rolling resistance has more to do with internal friction in the tire and contact patch than it does with the tires outer diameter. That's why you need to put TALCUM powder between the tube and the tire and the rim and NOT USE green Gunk inside your tubes if you wanted to maximize performance. Put the Talcum powder inside the tire casing and it makes a HUGE reduction in the internal friction that makes up rolling resistance. Try it - You'll like it! Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted October 27, 2016 Share Posted October 27, 2016 Damn I think I just brought a stick to a gunfight with a bunch of angular momentum space time physicists or something. Ima gonna go back to tending my grill... Link to comment Share on other sites More sharing options...
Roll Model Posted October 27, 2016 Share Posted October 27, 2016 37 minutes ago, Roll Model said: Rolling resistance is about the same for all rolling speeds - So roll fast, roll slow and the wasted energy (of rolling) is pretty much "the same". Rolling resistance is no more when going uphill than it is going down hill - So you can see how small a factor in your ride rolling resistance is? At 10mph rolling resistance is the same for all conditions but the load on your batteries can very dramatically at 10mph... Link to comment Share on other sites More sharing options...
Mono Posted October 27, 2016 Share Posted October 27, 2016 1 hour ago, Roll Model said: Funny conversation... I'll add only two points. Rolling resistance is about the same for all rolling speeds - So roll fast, roll slow and the wasted energy (of rolling) is pretty much "the same". Wind resistance is not like that, if you go from 10 to 20 mph you have not simply doubled your wind resistance (it goes up exponentially). So the energy needed to go from 50mph to 51mph is MUCH, MUCH greater than the energy needed to go from 10mph to 11mph...) Wind (ambient air movement) will almost always increase your wasted energy, as only wind coming directly from behind will boost you. Wind coming from a few degrees off your butt will add to the drag and not be of any help. But all that wind, all that increase in speed doesn't affect 'rolling resistance' it is pretty stable. Load becomes a factor primarily when you accelerate (or go up hill, which is the same as constant acceleration) or when the load has a larger frontal surface. If you put a 100 pound back pack on a 100 pound rider he'd get further than a 200 pound rider simply because of the smaller frontal surface. If you double the load, you don't double the rolling resistance (it remains almost unchanged) where as if you double the frontal surface you will MORE than double the wind resistance (assuming the aerodynamics are roughly equal). A wider tire will present more wind resistance at every speed (above 0). Increase the speed and the (air) drag will go up at the square of the speed, which is NOT TRUE for the wheel's rolling resistance. Tire construction would contribute more to rolling dynamics especially how the wider tire (or the tires "profile") deals with different loads (and inflation values). So unless you are comparing tires of the same width, with the same basic construction, there is no real way to simply compare "Tire Size" and get much valuable 'seat of the pants' data from it... Perhaps some one will inflate the tires and roll through a puddle or two to compare the CONTACT PATCH size of the 18" wheel versus the 16" wheel...? Rolling resistance has more to do with internal friction in the tire and contact patch than it does with the tires outer diameter. @Roll Model, true (most of it^1), thats why for low speed a large wheel with a wide tire maximizes range by minimizing tire deformation and for high speed a small wheel with a thin tire maximizes range by minimizing drag. It is not so clear though at which speed wheel drag starts to dominated rolling resistance. Any idea?^2 ^1 "Wind resistance is not like that, if you go from 10 to 20 mph you have not simply doubled your wind resistance (it goes up exponentially)." No, wind resistance goes up quadratically, not exponentially. Doubling the speed increases wind resistance by a factor of four (two squared). It should also be mentioned that the rolling friction energy per km is a constant, however the rolling friction force increases linearly with speed, right? Analogously, air drag energy per km increases only linearly with speed, whereas air drag force is quadratic in speed. Hence air drag is under both view points proportional to friction times speed. ^2 Trying Google, drag and rolling force become equal somewhere at 5-10km/h for a bicycle or wheel chair. The drag of only the small tire of an EUC is still much smaller. Link to comment Share on other sites More sharing options...
Roll Model Posted October 27, 2016 Share Posted October 27, 2016 42 minutes ago, MoNo said: @Roll Model, true (most of it^1), thats why for low speed a large wheel with a wide tire maximizes range by minimizing tire deformation and for high speed a small wheel with a thin tire maximizes range by minimizing drag. It is not so clear though at which speed wheel drag starts to dominated rolling resistance. Any idea?^2 ^1 "Wind resistance is not like that, if you go from 10 to 20 mph you have not simply doubled your wind resistance (it goes up exponentially)." No, wind resistance goes up quadratically, not exponentially. Doubling the speed increases wind resistance by a factor of four (two squared). ^2 Trying Google, drag and rolling force become equal somewhere at 5-10km/h for a bicycle or wheel chair. The drag of only the small tire of an EUC is still much smaller. This makes no sense: "thats why for low speed a large wheel with a wide tire maximizes range by minimizing tire deformation and for high speed a small wheel with a thin tire maximizes range by minimizing drag." Tire deformation is not a correlate of size. Link to comment Share on other sites More sharing options...
Mono Posted October 27, 2016 Share Posted October 27, 2016 1 hour ago, Roll Model said: Tire deformation is not a correlate of size. It is Think about a 1-D model, a small and a large circle. For given weight and pressure, the deformation angle at the border of the contact patch is the smaller the larger the circle is. As a quantitative result, I found "For example an 8.3% increase in tyre outer radius from 60 cm to 65 cm, the proposed model predicts a reduction of 4.8% in tyre rolling resistance coefficient compared to 5% suggested by experimental data."^1 ^1 http://publications.lib.chalmers.se/records/fulltext/200040/200040.pdf Link to comment Share on other sites More sharing options...
Roll Model Posted October 28, 2016 Share Posted October 28, 2016 5 hours ago, MoNo said: It is Think about a 1-D model, a small and a large circle. For given weight and pressure, the deformation angle at the border of the contact patch is the smaller the larger the circle is. As a quantitative result, I found "For example an 8.3% increase in tyre outer radius from 60 cm to 65 cm, the proposed model predicts a reduction of 4.8% in tyre rolling resistance coefficient compared to 5% suggested by experimental data."^1 ^1 http://publications.lib.chalmers.se/records/fulltext/200040/200040.pdf I'm still thinking other factors make this "proposed model" less reliable - Less contact patch will yield lower friction. I'm wondering about steel tires that do not deform or cases where the 1-D model you suggest have a size so large that it becomes almost a flat plane of contact due to the super large arc of the wheel, certainly that flat surface would have a maximum contact patch and more friction that a little wheel. Deformation of the wheel is dependent on many factors and I'm just not sure size is the determinate factor and wondering still more how deformation fits into the dynamic of energy waste. On soft surfaces your wheels would not deform as much and the resistance would change, at some point the size gain would outweigh what ever gain your model predicts, no? I think deformation is more a factor of materials and methods used to construct the tire - Later I'll look at your pdf... It's an interesting point, perhaps too theoretical to of any account. Link to comment Share on other sites More sharing options...
Peter Brierley Posted October 28, 2016 Share Posted October 28, 2016 If you want a cruising wheel, larger is better. i have a brand new KS18 and have ridden it a total of 5 metres in 2 months because I very much prefer riding my 26" wheel. 26" beats 18" in every other aspect, EXCEPT for extreme hills, both climbing and braking. So, larger wheels are far from being a lesser model, in my opinion Link to comment Share on other sites More sharing options...
MaxLinux Posted October 28, 2016 Share Posted October 28, 2016 30 minutes ago, Peter Brierley said: i have a brand new KS18 and have ridden it a total of 5 metres in 2 months because I very much prefer riding my 26" wheel. 26" beats 18" in every other aspect, EXCEPT for extreme hills, both climbing and braking. What is this 26" wheel? Could you give more details about it? Could you post a photo or video of your 26" wheel? Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted October 28, 2016 Share Posted October 28, 2016 Link to comment Share on other sites More sharing options...
16bitSprite Posted October 28, 2016 Share Posted October 28, 2016 14 hours ago, Roll Model said: Rolling resistance is about the same for all rolling speeds - So roll fast, roll slow and the wasted energy (of rolling) is pretty much "the same". Wind resistance is not like that, if you go from 10 to 20 mph you have not simply doubled your wind resistance (it goes up exponentially). So the energy needed to go from 50mph to 51mph is MUCH, MUCH greater than the energy needed to go from 10mph to 11mph...) Wind (ambient air movement) will almost always increase your wasted energy, as only wind coming directly from behind will boost you. Wind coming from a few degrees off your butt will add to the drag and not be of any help. How much help will air coming out of my butt be? Link to comment Share on other sites More sharing options...
Flash Posted October 28, 2016 Share Posted October 28, 2016 1 hour ago, 16bitSprite said: How much help will air coming out of my butt be? About 200% if you put it on fire wonderful wheel 26" but there should be something preventing hands and feets coming in between the spokes and it's not for short people , maybe 22" is the ultimate choice Link to comment Share on other sites More sharing options...
Mono Posted October 28, 2016 Share Posted October 28, 2016 On 10/28/2016 at 6:40 AM, Roll Model said: I'm still thinking other factors make this "proposed model" less reliable - Less contact patch will yield lower friction. I'm wondering about steel tires that do not deform or cases where the 1-D model you suggest have a size so large that it becomes almost a flat plane of contact due to the super large arc of the wheel, certainly that flat surface would have a maximum contact patch and more friction that a little wheel. Deformation of the wheel is dependent on many factors and I'm just not sure size is the determinate factor and wondering still more how deformation fits into the dynamic of energy waste. On soft surfaces your wheels would not deform as much and the resistance would change, at some point the size gain would outweigh what ever gain your model predicts, no? I think deformation is more a factor of materials and methods used to construct the tire - Later I'll look at your pdf... It's an interesting point, perhaps too theoretical to of any account. It seems that most of your questions are addressed in the reference. On soft surfaces large wheels are particularly advantageous because the don't sink it as much (which is quite intuitive and the reason why mountain bikes have wide tires). Wikipedia claims that for solid wheels the friction is proportional to const / sqrt(diameter), but the proportionality const could be very small for rigid surfaces.^1 On 10/28/2016 at 8:01 AM, Peter Brierley said: 26" beats 18" in every other aspect, EXCEPT for extreme hills, both climbing and braking. I am a fan of 26", yet I think they are also inferior in the categories compact size, weight (probably minor), and (I assume) manoeuverability like negotiating tight turns at low speed (looks actually quite difficult in the vid). ^1 https://en.wikipedia.org/wiki/Rolling_resistance#Physical_formulas Link to comment Share on other sites More sharing options...
Peter Brierley Posted October 28, 2016 Share Posted October 28, 2016 13 hours ago, HunkaHunkaBurningLove said: Will have to do another video, that is an older version. My new machine totally changed, casing sits 150mm lower over the wheel. This transformed the handling totally. Here's a stationary pic, note how casing mounted lower to position the rider same as on standard KS18. Link to comment Share on other sites More sharing options...
SuperSport Posted October 28, 2016 Share Posted October 28, 2016 4 minutes ago, Peter Brierley said: Looks nice! Clean job. Link to comment Share on other sites More sharing options...
Peter Brierley Posted October 28, 2016 Share Posted October 28, 2016 While we are discussing rolling resistance, grip and handling, another advantage of the 26" rim is the availability of performance tyres. Unlike when looking at tyres for 18" wheels, there is a huge selection available. I'm using a single compound silica based Maxxis tyre (hookworm) which has low rolling resistance and good traction for urban riding. Can be inflated to 65 psi and has a performance profile. With so many different performance tyres available in this size, you can improve the ride quality of your wheel to suit the style you're looking for. Link to comment Share on other sites More sharing options...
Mono Posted October 28, 2016 Share Posted October 28, 2016 28 minutes ago, Peter Brierley said: While we are discussing rolling resistance, grip and handling, another advantage of the 26" rim is the availability of performance tyres. Unlike when looking at tyres for 18" wheels, there is a huge selection available. Definitely an advantage. 28 minutes ago, Peter Brierley said: I'm using a single compound silica based Maxxis tyre (hookworm) which has low rolling resistance and good traction for urban riding. Can be inflated to 65 psi and has a performance profile. With so many different performance tyres available in this size, you can improve the ride quality of your wheel to suit the style you're looking for. What is the allowed max load for that tire? Link to comment Share on other sites More sharing options...
Rehab1 Posted October 28, 2016 Share Posted October 28, 2016 On 10/27/2016 at 4:24 PM, HunkaHunkaBurningLove said: Damn I think I just brought a stick to a gunfight with a bunch of angular momentum space time physicists or something. Ima gonna go back to tending my grill... My exceptionally large expanse of highly integrated cortex diminished at tad today.? BBQ Guru..Please extend me an invitation to your cookout! Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted October 28, 2016 Share Posted October 28, 2016 Have no fear, A&W is near! ...Except apparently in the US! Jeepers why do you guys have to drive hours to get to a local A&W? They are all over the place in Canada here. I think their new motto should be A&W - All Canadian Food pretty soon! Link to comment Share on other sites More sharing options...
steve454 Posted October 28, 2016 Share Posted October 28, 2016 @HunkaHunkaBurningLove Sir, you have derailed this thread, this belongs on the food thread Link to comment Share on other sites More sharing options...
Cloud Posted October 29, 2016 Share Posted October 29, 2016 19 minutes ago, steve454 said: @HunkaHunkaBurningLove Sir, you have derailed this thread, this belongs on the food thread Lol. Hunka, we believe you that you are a professional thread derailer, you dont have ti prove it to us every time Link to comment Share on other sites More sharing options...
steve454 Posted October 29, 2016 Share Posted October 29, 2016 23 minutes ago, Cloud said: Hunka, that's it. Just go by Hunka. No No No Cloud did not say that I said that. What happened here? @steve454 said that in reply to you're other thread about your profile name not fitting the format. @HunkaHunkaBurningLove Sir, you have derailed this thread, this belongs on the food thread Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted October 29, 2016 Share Posted October 29, 2016 Whoops! Sorry! My bad. My bad. That MSuper food processor thread got me all confused. . Now I associate MSuper with Msuper Dee Duper Food Processor with 19 settings. Link to comment Share on other sites More sharing options...
MaxLinux Posted October 29, 2016 Share Posted October 29, 2016 4 hours ago, Peter Brierley said: My new machine totally changed, casing sits 150mm lower over the wheel. This transformed the handling totally. Here's a stationary pic, note how casing mounted lower to position the rider same as on standard KS18. So you did not purchase this 26-inch wheel, but created it from a KS18? Link to comment Share on other sites More sharing options...
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