I know this is somewhat of a personal feeling but how much lighter does a wheel have to be to notice it? I dont mean nessiasarily just time but feel too. For instance when my disc wheel goes on I feel sluggish and slow accelerating and coming out of corners where i had to slow down. Once i get going though no problems. Everyone talks about wheel weight but since i only own 1 set of wheels plus a disc I cant really compare weights. How much weight would it take for me to notice a difference in feel or time for wheels setup for different courses.
Go to analyticcycling.com, and plug in any numbers for any course profile and any wheel weights you want. You’ll find that wheel weight is insignificant for “coming out of corners”. If you think you felt a difference, you are probably wrong.
Weight only really matters during acceleration and steep climbing. While you might feel sluggish coming out of a corner, you probably aren’t losing as much time as you think. Personally, I can tell a minor difference between my training wheels (1700g) and my racing wheels (1250g), but only on very hard accelerations. Also, it’s not the wheels, it’s the total vehicle weight. Emptying half a water bottle would do the same thing.
When I say coming out of corners I mean where you have to slow down significantly and then build speed again. What about moderatly hilly courses or bike racing? how much weight would make a difference there. In other words for basically the same type of wheel, how much lighter would it have to be before you can tell that there is some difference?
Fastest 40k TT I ever had (sub 50 min) was with Shamal HPW wheels - in the rain and the wheels had filled with about a pound or two of water each…big flywheels at that point.
A pair of wheels that weigh 1kg more (.5kg each: an extreme case) will have about this effect on coming out of a corner from 6m/sec: At the end of 100m Standard Rider is ahead by 0.04s and 0.41 m.
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I believe it makes a big difference. Although, I do think you are correct that there is more of a difference in acceleration. If you want to see what a difference it makes, buy some hard case tires. They are heavy but will help you not get as many flats. I train with hard case tires and it is a VERY noticeable difference weight wise. I am not as fast even on the top-end and after three to four hours I am more fatigued. They are great for training though because once I switch back to racing tires they feel light as a feather.
This probably has more to do with the difference in rolling resistance than the difference in weight. Vehicle weight is what matters (there’s nothing special about wheel weight), and the difference of even a pound is insignificant. People seem to think that rotational weight really matters. To prove that it doesn’t, do as John Cobb suggested and run up the stairs holding a wheel in your hands. Then do it again but spin the wheel. You won’t notice any difference in how hard it is to run up the stairs - despite the wheel being heavier as a result of rotational weight - because the difference is negligible.
You may be correct. Don’t know about John Cobb or all the scientific data. I just know what I feel from riding experience. When I add the heavier tires it makes a BIG difference.
I have heard this a couple of times as justification that rotational weight doesn’t matter. Its a complete crock.
First the reason that rotational weight matters more that static is because it takes energy to spin the wheel and keep it spinning. Obviously the weight doesn’t increase.
Second, have you actually done this test or are you just assuming the results will be what you expect? A rapidly spinning bicycle wheel has a lot of torque. Trying to run up stairs while holding a spinning bicycle wheel is much harder when holding a non spinning wheel.
Please note that I did not state how much of a difference wheel weight makes or how much difference a spinning wheel makes, just that it weight does make some difference and that rotating weight makes more of a difference.
I never said the difference in weight doesn’t exist. I said that the difference it makes is insignificant.
It should be fairly simple to test. Weigh your bicycle with the rear will spinning and with it still. See which one weighs more. I’ll bet your digital scale can’t tell a difference (mine can’t, and it displays weight in 1/5 lb. increments).
As for the energy required to spin a heavier wheel, run some models on analyticcycling.com and see that the difference there is also insignificant.
Rotational weight is a crock from a real-world cycling perspective.
Actually, here’s the result of a model I just ran comparing a rider with x weight wheels with a rider with x+.5kg wheels (about 1lb heavier per wheel): At the end of 100m Standard Rider is ahead by 0.01s and 0.12 m.
Actually, here’s the result of a model I just ran comparing a rider with x weight wheels with a rider with x+.5kg wheels (about 1lb heavier per wheel): At the end of 100m Standard Rider is ahead by 0.01s and 0.12 m.
Now why didn’t I think of doing that? Wait, I did. Never mind. (By the way, did you change the moment of inertia for the wheels, too?)
First the reason that rotational weight matters more that static is because it takes energy to spin the wheel and keep it spinning.
What energy does it take to keep a spinning wheel spinning? Only the energy required to overcome air resistance and bearing friction, both of which are pretty darned small, and really small compared to the other resistive forces on a bike/rider in motion.
Here’s a really simple experiment you can do in your home with nothing but you and your bike. Put the bike in a stand (or have someone hold it). If you have a rear pickup cyclocomputer, put it in a big gear and give the pedal a turn using one arm. Check the speed. It’ll be about 20mph. That’s using one arm (much weaker than your legs, I’m guessing) for one pedal stroke. Compare the energy and time you used to spin up that wheel to the energy and time required to get you and your bike up to 20mph. That should convince you that wheel weight doesn’t mean spit.
Again, wheel rotating weight only matters when accelerating, and the accelerations on a bicycle are really, really small. So small that they don’t matter for triathletes. Perhaps for track sprinters, but you’ll notice that they all use those big, heavy disk wheels anyway.
I didn’t change the moment of intertia, just the wheel weight. Actually, the more accurate way would be to run the same model but add the extra 1kg to the weight of the rider. That way we’re comparing vehicles that weigh the same, but one carries the extra weight on the wheels. The difference would be even more negligible than what I posted above.
I never said the difference in weight doesn’t exist. I said that the difference it makes is insignificant.
It should be fairly simple to test. Weigh your bicycle with the rear will spinning and with it still. See which one weighs more. I’ll bet your digital scale can’t tell a difference (mine can’t, and it displays weight in 1/5 lb. increments).
Well you should have said the difference doesn’t exit because it doesn’t. Again, the wheel does not get heavier when spinning. It does take energy to spin, to accelerate, and to turn.
As for the energy required to spin a heavier wheel, run some models on analyticcycling.com and see that the difference there is also insignificant.
Rotational weight is a crock from a real-world cycling perspective.
Actually, here’s the result of a model I just ran comparing a rider with x weight wheels with a rider with x+.5kg wheels (about 1lb heavier per wheel): At the end of 100m Standard Rider is ahead by 0.01s and 0.12 m.
Okay so assuming your calc took every thing into account, at the end of a 50 lap 4 corner criterium, you would be 0.12 x 50 x 4 = 24 m behind the winner.
Well, I said I wouldn’t argue about the magnitude just that it exists. I’m not sure your "experiment works, though. Try this put your bike in a stand, grab the pedal and crank by hand to 25 mph. Keep pedaling by hand to keep the wheel spinning at 25 mph for an hour. Still think it takes an insignificant amount of energy?
