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Inertia demonstration

Inertia demonstration

28 Comments

  • + 8
 Richard... are you trying to make an argument for 26" wheels?
  • + 1
 The track should have had undulations so we could see the benefit of the second wheel as well. But then, I bet this was a demonstration to sell lighter tires so that would have been counterproductive.
  • + 1
 My favorite observation first noted by MTB mag more than a decade ago. Outer rotational mass is the first place to loose weight. weight centered around the hub is not an issue unless you are obsessed with putting your bike on a scale. Now lets look at the bike as a whole. weight at the outer extremities on a bike are also going to affect how the bike as a whole rides. weight around the BB is not an issue. Now lets look at dropper post. this adds easily half a pound to the highest point on a bike. To keep the weight in the center of my bike I choose 26 inch wheels with 800 to 900 gram tires. A heavy bike with light weight wheels will perform much better than a light weight bike with heavy wheels.
  • + 2
 This has nothing to do with wheel size as it states in the begging. The only thing that proves is that a carbon rim with a heavy hub is faster than an alou rim with a light hub.
  • + 1
 The further from the axle you move the weights the greater the effect seen here. Larger wheels move the weight out further.
  • + 1
 An easy experiment any one can try:
Hold your wheel by the axle and spin the wheel.
Now try tilting the wheel . You can feel the centrifugal force.
Try a wheel with out the tire. Easy to tilt the wheel when its spinning.
Now spin the wheel with a tire on which is about a kilo of extra outer rotational mass.
Much more effort is needed to tilt the wheel when its spinning.
  • + 1
 It's true that the wheel with the centralised mass will and does accelerate faster but the having the rotational mass outer most will roll for further, greater perpetual motion surly that is more beneficial as you can hold more speed for longer with the same calorific input.
  • + 1
 But it takes more energy to change direction, a constant issue on the trail. Bowling balls roll further than kickballs, but then, they need smooth alleys.
  • + 3
 Cool thing to show the rotational movement, but what does it have to prove? a heavier hub would be better? or what? **legit question
  • + 4
 It proves that a wheel with a lighter rim (weight more centered around the hub) will gain speed faster than a light hub with a heavy rim
  • + 1
 ahhh got it kinda figured it out, thank you Marc
  • + 3
 The end was also very interesting, the weights mounted towards the outside spun much longer with similar resistance, thus proving that more weight on the outside carries speed much better once at speed, but get up to speed much slower.
  • + 1
 true the closer to the axle of spin there is less speed, and there is less centrifugal force, contrary to the outside
  • + 4
 @Warburrito Possibly, however the first wheel to hit was hitting a larger point of contact that also seemed to be rubber whereas the second wheel was hitting a very small, very smooth point of contact on the first wheel. With far less friction of course the second wheel is going to spin for longer.
  • + 1
 Warburrito has physics on his side here. It is part of why 29ers roll better.
  • + 1
 I love "Scientific" proof... always. But, the real meaning of the sport is to have fun, isn't it? So, I think we should stop the battle of the wheels (size and weight) and get out and ride with whatever the heck you have. Let the developers for racing run the battle... we are the ones who benefit from their results and experiments.

┬┤nough said... Smile

Cheers.
  • + 2
 This experiment needs a 3rd disc with weights mounted in between the extremes to prove 27.5 really is the truth and the light.
  • + 1
 This is not necessarily about wheel size
  • + 6
 Everything is about wheel size here.
  • + 1
 Yep good point!!!
  • + 1
 Hilarious.
  • + 1
 I wonder if putting weights near the hubs would alter this effect. Or using light hubs and clever positioning of weights somewhere between the spokes.
  • + 3
 Rewob deserves POD for that hamster comment...post of the day.
  • + 2
 : D
  • + 2
 Magnets? Or weights?
  • + 3
 Weights - an equal amount on each disc, but in different locations.
  • + 1
 I figured it's something like that. Awesome display of rotational weight. Would work similar with magnets if I'm not wrong.
  • + 14
 It would work similar with hamsters if you could glue them to the wheels.

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