porqui Posted August 28, 2014 Share Take two wheels with different weights and roll them down a hill at the same time, see which gets to the bottom faster Touche So why did they not do it like that - so I still wonder. Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted August 28, 2014 Share I would like the input of an engineer here.In this experiment the wheels spin around an almost centre point so really spinningThe thing about a wheel that is in contact with the ground is that the tyre is stationary when on the ground but moving at 2X the cycle speed when at the top of the wheel - rolling. It has 0 momentum at the bottom and then momentum increases to a max in 1/2 a circumference. In experiment momentum is almost constant.How would the forces differ. WTF bro? Where did you go to school? Please tell me so I can keep my lightie out of it... Momentum is the same throughout the rotation, regardless of the position of the tire. What you're stating is just straight out impossible from a physics perspective. HOEKVLAG 1 Link to comment Share on other sites More sharing options...
Eldron Posted August 28, 2014 Share The test only shows 26" wheels will accelerate faster than 29" - anyone who didn't already know this is a bit dense. 26" wheels accelerate faster because they're smaller AND lighter. Like someone said earlier - a 10" wheel will accelerate even faster but I'm guessing the multiple OTB moments will discourage most riders from installing 10" wheels... I love pseudo science. Captain Fastbastard Mayhem, Headshot, ThePubSA and 2 others 5 Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted August 28, 2014 Share Touche So why did they not do it like that - so I still wonder. cos they have to stay upright. Doing it like this facilitates the same principles (rolling around a central point - the hub) without having to constantly keep it on track. Link to comment Share on other sites More sharing options...
porqui Posted August 28, 2014 Share Cpt - the part of your wheel/tyre that is in contact with the ground is not moving so it cannot have velocity nor momentum. Capricorn 1 Link to comment Share on other sites More sharing options...
BarHugger Posted August 28, 2014 Share So all this experiment does is show the difference between "apparent" wheelsize and acceleration.......providing all other variables are kept constant...............similar to comparing different wheelsizes with two equally geared SS or fixies. Luckily I have 20 other options to choose from to make me go faster faster........just a pity about the two engines that need to drive those 20 options. Should actually do an experiment where both wheels are let go with similar RPM. Then determine which wheel travels the furthest distance with the available energy (force/momentum) generated. Might possibly be another result....... Edited August 28, 2014 by BarHugger Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted August 28, 2014 Share Cpt - the part of your wheel/tyre that is in contact with the ground is not moving so it cannot have velocity nor momentum. EDIT: Sorry, yes, from a linear perspective (as Cap said) this is true. But - the wheel IS moving, that's for sure. What you may be confused with is the linear momentum and velocity at the contact patch (doesn't move at that point, in relation to the ground) and the angular momentum (the movement of the wheel itself) But by the very nature of its motion, it still has momentum and IS moving, in an angular direction. If it stopped when it made contact with the ground, the entire wheel would stop. You can't have a wheel in motion and at rest at the same time. Edited August 28, 2014 by cpt armpies mayhem Link to comment Share on other sites More sharing options...
MTBeer Posted August 28, 2014 Share Cpt - the part of your wheel/tyre that is in contact with the ground is not moving so it cannot have velocity nor momentum.so the part in contact with the ground has no velocity, but the rest of the wheel does have velocity? so every micro/nanosecond a part of your wheel is coming to a complete stop and then accelerating again at infinite acceleration to its original speed? Link to comment Share on other sites More sharing options...
BarHugger Posted August 28, 2014 Share I love pseudo science. Maybe if a rider wears two of these (on for each wheel) he will be in balance, experience less OTB's and go faster.....the only question is that if you wear two......won't the one cancel the effect of the other? Edited August 28, 2014 by BarHugger ThePubSA and Daniel J Méssem 2 Link to comment Share on other sites More sharing options...
ThePubSA Posted August 28, 2014 Share Old hat new shoes....http://ep1.pinkbike.org/p4pb10776857/p4pb10776857.jpg The data is in. In a straight line, on a smooth surface, in a laboratory environment, 559 is the fastest. Hands down. Link to comment Share on other sites More sharing options...
ThePubSA Posted August 28, 2014 Share If you build three wheels that are 559, 650b, and 29" with exactly the same hubs, spokes, and rims, the 559 EnduRAD wheel will be lighter every time. 559 wheels weigh 4% less than 650b wheels and 10% less than 29" wheels with comparable components. That means 559 can save you up to 200 grams over other, non-Enduro Specific wheel sizes. Lighter means performance. Lighter means power. Lighter means Enduro. Shed the excess weight of standard Enduro wheel sizes. You'll be riding faster tomorrow when 559 EnduRAD technology lightens up your bike today. Can you smell the weight savings? It smells like Enduro. Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted August 28, 2014 Share so the part in contact with the ground has no velocity, but the rest of the wheel does have velocity? so every micro/nanosecond a part of your wheel is coming to a complete stop and then accelerating again at infinite acceleration to its original speed? No. the part in contact with the ground retains angular momentum & velocity. It has to. Otherwise you'd have infinite sessions of acceleration to 30kph (assumed speed) and then in the same instant, instant deceleration. You'd be at rest, effectively. That's the ONLY time at which a wheel doesn't have momentum - when you're stopped. Link to comment Share on other sites More sharing options...
ThePubSA Posted August 28, 2014 Share Stiffness,weight,acceleration,size.. The polls are in. The world's best have tried 559, and they believe the hype. It's time to get off the couch. It's time to stop wasting your rides on a wheelsize that can't handle your Enduroness. http://ep1.pinkbike.org/p4pb10777064/p4pb10777064.jpg http://www.pinkbike.com/news/felt-bicycles-559-endurrad-enduro-specific-wheelsize-2014.html Captain Fastbastard Mayhem 1 Link to comment Share on other sites More sharing options...
ThePubSA Posted August 28, 2014 Share Maybe if a rider wears two of these (on for each wheel) he will be in balance, experience less OTB's and go faster.....the only question is that if you wear two......won't the one cancel the effect of the other? Can you smell the inadequacies in your #endurolives ENDURAD Link to comment Share on other sites More sharing options...
porqui Posted August 28, 2014 Share so the part in contact with the ground has no velocity, but the rest of the wheel does have velocity? so every micro/nanosecond a part of your wheel is coming to a complete stop and then accelerating again at infinite acceleration to its original speed? It accelerates till it reaches the top of the wheel where it will be doing 2x the speed you are doing on the bikethen it starts to decelerate. Imagine a small dot on the outer circumference of your tyre and follow its path as you ride Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted August 28, 2014 Share It accelerates till it reaches the top of the wheel where it will be doing 2x the speed you are doing on the bikethen it starts to decelerate. Imagine a small dot on the outer circumference of your tyre and follow its path as you ride Sorry - I realise this may be harsh, but you're wrong (and right) on a fundamental piece of the puzzle, as Cap says. The singular point of contact with the ground has nothing to do with the wheel's momentum nor velocity. It does, however, have something to do with the wheel's linear momentum in relation to the ground at the point of contact Edited August 28, 2014 by cpt armpies mayhem HOEKVLAG 1 Link to comment Share on other sites More sharing options...
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