Wheels - lighter weight vs aero
02-16-23, 02:05 PM
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02-16-23, 02:15 PM
#252
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For giggles, here's the answer from ChatGPT, which must have been reading BF:
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When it comes to choosing between light wheels and aero wheels for climbing on a bicycle, it depends on several factors such as the type of climbing, the rider's ability, and personal preference.
In general, lighter wheels will make the bike feel more responsive and easier to accelerate, which can be an advantage on steep climbs where a rider needs to repeatedly increase and decrease their cadence. However, for longer climbs, where sustained power output is required, aero wheels can offer an advantage by reducing wind resistance and helping a rider maintain a higher average speed over time.
That being said, aero wheels are typically heavier than traditional, shallow-rimmed wheels, so the added weight could offset some of the aerodynamic gains, especially on steeper gradients.
Ultimately, the choice between light wheels and aero wheels for climbing on a bicycle will depend on a rider's individual preferences and goals, as well as the specific demands of the terrain they are riding on. For most riders, a balance between lightness and aerodynamics will be the best choice.
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02-16-23, 03:00 PM
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A triangular shape may be a stronger structure shape for some applications, but it is not the most aerodynamically efficient for the application of a bike wheel, and therefore not a shape that is predominantly used. This has been going on since rim brakes were still the standard for road bikes, and has trended further away from triangular over the years. A rim doesn't need to be as strong as it possibly can be, it just needs to be strong enough to serve the demands of how it's used. It turns out that strong enough, light weight, and improved aero properties are all achievable with modern carbon fiber technology.
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02-16-23, 03:11 PM
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02-16-23, 03:13 PM
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As far as profiles, I thought ogive cross-sections mated in width to the mounted, inflated tire had been shown to be the most aerodynamic?
02-16-23, 03:17 PM
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One does not need to know everything about all rims being produced, or be an engineering expert, to recognize current trends in how wheels are being built, and understand the reasons why. Also, just because something can be made a certain way, doesn't mean that's the way it's being done in the real world.
A triangular shape may be a stronger structure shape for some applications, but it is not the most aerodynamically efficient for the application of a bike wheel, and therefore not a shape that is predominantly used. This has been going on since rim brakes were still the standard for road bikes, and has trended further away from triangular over the years. A rim doesn't need to be as strong as it possibly can be, it just needs to be strong enough to serve the demands of how it's used. It turns out that strong enough, light weight, and improved aero properties are all achievable with modern carbon fiber technology.
A triangular shape may be a stronger structure shape for some applications, but it is not the most aerodynamically efficient for the application of a bike wheel, and therefore not a shape that is predominantly used. This has been going on since rim brakes were still the standard for road bikes, and has trended further away from triangular over the years. A rim doesn't need to be as strong as it possibly can be, it just needs to be strong enough to serve the demands of how it's used. It turns out that strong enough, light weight, and improved aero properties are all achievable with modern carbon fiber technology.
02-16-23, 03:22 PM
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02-16-23, 03:25 PM
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Originally Posted by rydabent
With out the brake area, the profile can be more triangular, and everyone knows a triangle is exceptionally strong.
02-16-23, 03:27 PM
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Compared with tires that are significantly wider than the rim (ice cream cone profile), yes. Matching rim and tires width is more aero. This is a big part of the reason why there has been a trend for wider rim widths.
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02-16-23, 04:14 PM
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02-16-23, 04:17 PM
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For giggles, here's the answer from ChatGPT, which must have been reading BF:
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When it comes to choosing between light wheels and aero wheels for climbing on a bicycle, it depends on several factors such as the type of climbing, the rider's ability, and personal preference.
In general, lighter wheels will make the bike feel more responsive and easier to accelerate, which can be an advantage on steep climbs where a rider needs to repeatedly increase and decrease their cadence. However, for longer climbs, where sustained power output is required, aero wheels can offer an advantage by reducing wind resistance and helping a rider maintain a higher average speed over time.
That being said, aero wheels are typically heavier than traditional, shallow-rimmed wheels, so the added weight could offset some of the aerodynamic gains, especially on steeper gradients.
Ultimately, the choice between light wheels and aero wheels for climbing on a bicycle will depend on a rider's individual preferences and goals, as well as the specific demands of the terrain they are riding on. For most riders, a balance between lightness and aerodynamics will be the best choice.
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02-16-23, 04:24 PM
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Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
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02-16-23, 04:30 PM
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While not a perfect triangle, they are what I was talking about. And notice there is not much metal in the area of the rim hook where the tire bead latches on to the rim.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
These are the new lighter aero rims.
smh
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02-16-23, 04:36 PM
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While not a perfect triangle, they are what I was talking about. And notice there is not much metal in the area of the rim hook where the tire bead latches on to the rim.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
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02-16-23, 04:39 PM
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While not a perfect triangle, they are what I was talking about. And notice there is not much metal in the area of the rim hook where the tire bead latches on to the rim.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
Then----------remember not all rim makers are up to speed on the fact that disc brakes are here to say. They will have to get in new machinery to make the new lighter aero rims.
Which rim makers are denying that disc brakes are here to stay? I'm genuinely curious. It seems to me that rim brake wheel options are getting thinner as time goes on, which reflects the types of bikes being sold.
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02-16-23, 05:31 PM
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02-16-23, 07:04 PM
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I asked an AI bot about aerodynamic versus light weight wheels:
Q: When climbing long grades and then doing long flat roads, which bicycle wheels are more efficient, aerodynamic or light weight?A: When climbing long grades, lightweight wheels are more efficient than aerodynamic wheels, as the reduced weight makes it easier to climb uphill. However, when riding on flat roads, aerodynamic wheels can be more efficient, as the reduced drag can allow you to move faster with less effort. Therefore, depending on the terrain, both aerodynamic and lightweight wheels can be beneficial.
Then I rephrased the question omitting hill climbing.
Q: Which bicycle wheels are more efficient, Aerodynamic or light weight?
A: Generally speaking, aerodynamic wheels are more efficient than lightweight wheels. Aerodynamic wheels are designed to reduce drag and increase the speed at which a cyclist can ride. This is achieved by using a deep profile and a smooth surface that reduces air resistance. Lightweight wheels, on the other hand, reduce weight but do not improve aerodynamic performance as much. That said, the best wheels for cycling are those that are both lightweight and aerodynamic.
Conclusion: when riding on mixed terrain use one of each.
Q: When climbing long grades and then doing long flat roads, which bicycle wheels are more efficient, aerodynamic or light weight?A: When climbing long grades, lightweight wheels are more efficient than aerodynamic wheels, as the reduced weight makes it easier to climb uphill. However, when riding on flat roads, aerodynamic wheels can be more efficient, as the reduced drag can allow you to move faster with less effort. Therefore, depending on the terrain, both aerodynamic and lightweight wheels can be beneficial.
Then I rephrased the question omitting hill climbing.
Q: Which bicycle wheels are more efficient, Aerodynamic or light weight?
A: Generally speaking, aerodynamic wheels are more efficient than lightweight wheels. Aerodynamic wheels are designed to reduce drag and increase the speed at which a cyclist can ride. This is achieved by using a deep profile and a smooth surface that reduces air resistance. Lightweight wheels, on the other hand, reduce weight but do not improve aerodynamic performance as much. That said, the best wheels for cycling are those that are both lightweight and aerodynamic.
Conclusion: when riding on mixed terrain use one of each.
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02-16-23, 07:47 PM
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At least the chat bots are not yet claiming that rotational mass is worth 10x static mass. Maybe they will when they’ve heard it stated enough times on BF.
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02-16-23, 10:47 PM
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02-17-23, 07:04 AM
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Zipp has changed their profile a lot of the years, from pointy triangular-like to bulbous toroidal cross sections with more recent ones less so. All dictated on the marketing. Joking aside, selecting the shape and depth as well as fitting a proper width tire depends on wind conditions, rider weight, rider skill, and rider speed. I have some wheels where the stall characteristic is unpleasant and others where it is much less so.
The new 303 Firecrests are much pointier than obsolete diagrams several posts up. The attached is well worth the read as long as the marketing drivel is ignored. I am very surprised at the claimed Crr benefits for the new 303 Firecrests, I have a set and planned to compare the CdA and Crr to a more narrow 62 mm set of wheels but am awaiting kinder weather.
https://www.sram.com/globalassets/pu...explained2.pdf
The new 303 Firecrests are much pointier than obsolete diagrams several posts up. The attached is well worth the read as long as the marketing drivel is ignored. I am very surprised at the claimed Crr benefits for the new 303 Firecrests, I have a set and planned to compare the CdA and Crr to a more narrow 62 mm set of wheels but am awaiting kinder weather.
https://www.sram.com/globalassets/pu...explained2.pdf
02-17-23, 11:40 AM
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The new 303 Firecrests are much pointier than obsolete diagrams several posts up. The attached is well worth the read as long as the marketing drivel is ignored. I am very surprised at the claimed Crr benefits for the new 303 Firecrests, I have a set and planned to compare the CdA and Crr to a more narrow 62 mm set of wheels but am awaiting kinder weather.
https://www.sram.com/globalassets/pu...explained2.pdf
The acceleration comparison was interesting to show the effect of wheel rotational inertia on power:-
Full bore sprint acceleration from 40 kph at 0.13G requires 1067W for the bike/rider + 9.2W for wheel rotational inertia. Reducing wheelset mass by 300g and wheel inertia by 23.5% gives a reduction in required power of 4W, of which only 0.6W is due to the reduction in rotational inertia. You get that whopping advantage for as long as you can accelerate at 0.13G i.e. a few seconds at most until your speed tops out.
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02-17-23, 12:30 PM
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02-17-23, 09:42 PM
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Interesting read on several counts.
The acceleration comparison was interesting to show the effect of wheel rotational inertia on power:-
Full bore sprint acceleration from 40 kph at 0.13G requires 1067W for the bike/rider + 9.2W for wheel rotational inertia. Reducing wheelset mass by 300g and wheel inertia by 23.5% gives a reduction in required power of 4W, of which only 0.6W is due to the reduction in rotational inertia. You get that whopping advantage for as long as you can accelerate at 0.13G i.e. a few seconds at most until your speed tops out.
The acceleration comparison was interesting to show the effect of wheel rotational inertia on power:-
Full bore sprint acceleration from 40 kph at 0.13G requires 1067W for the bike/rider + 9.2W for wheel rotational inertia. Reducing wheelset mass by 300g and wheel inertia by 23.5% gives a reduction in required power of 4W, of which only 0.6W is due to the reduction in rotational inertia. You get that whopping advantage for as long as you can accelerate at 0.13G i.e. a few seconds at most until your speed tops out.
Thanks for carrying the torch, PeteHski.
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