Rolling Resistance: Hubs
08-20-23 | 05:00 PM
#26
aged to perfection
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From: PacNW
Bikes: Dinucci Allez 2.0, Richard Sachs, Alex Singer, Serotta, Masi GC, Raleigh Pro Mk.1, Hetchins, etc
Has any matter ever been settled here on BF ?
now there's a topic for discussion.
food for thought and grounds for further research
/markp
Last edited by mpetry912; 08-20-23 at 05:25 PM.
08-20-23 | 05:52 PM
#27
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08-20-23 | 06:34 PM
#28
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Gokiso hubs from Japan claim to be the smoothest, lowest friction hubs on the market. Can anyone speak to how to purchase a set of these outside of Japan?
https://www.gokiso.jp/en/products/hub_06.html
https://www.gokiso.jp/en/products/hub_06.html
08-20-23 | 10:22 PM
#29
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I’m not sure anything is ever “settled” but I recall a test on the WISIL site (recumbents.com) that measured the least bearing “resistance” on a stamped-steel caged-bearing hub. Hurray for Wald!
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06-11-24 | 08:52 PM
#30
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I recently bought a new carbon wheelset and did a free spin test on the front wheel compared to the front stock wheel from my 2016 Trek Domane. The old front wheel free spun for almost 2mins, the new front wheel spun for less than 20 seconds. I checked the brakes several times to make sure there was no interference. There just seems to be a ton of resistance/viscosity in these new hubs.
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
06-11-24 | 09:27 PM
#31
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This is not an apples-to-apples comparison. If you kept the same rim and same spoke, and only changed the hub, then that would be an apples-to-apples comparison where the only variable tested was the hub. In your scenerio- maybe the new rim has a greater moment of inertia which alows it to overcome the hub friction easier.
06-11-24 | 09:58 PM
#32
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From: Mid Willamette Valley, Orygun
Bikes: 87 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds. 2019 Giant Explore E+3
I recently bought a new carbon wheelset and did a free spin test on the front wheel compared to the front stock wheel from my 2016 Trek Domane. The old front wheel free spun for almost 2mins, the new front wheel spun for less than 20 seconds. I checked the brakes several times to make sure there was no interference. There just seems to be a ton of resistance/viscosity in these new hubs.
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
It's like putting on a new pair of of cheap jeans without washing them.
06-11-24 | 10:34 PM
#33
Insane Bicycle Mechanic
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From: other Vancouver
Here’s how you test it: put a power meter on your bike. Ride a time trial course at a sustainable power level. Record your time. Go home, switch wheels, then ride the same course at the same power level. Record your time. Do that 9 more times. Remember to record all the variables: weather, tire pressure, what you ate for lunch, etc.
Now, is one wheelset consistently faster? There’s your answer. Is there no consistency? That’s also an answer.
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06-12-24 | 03:29 AM
#35
If the wheels were identical in every way, including in levels of hub resistance, except that the new rim was substantially lighter than the old rim, the difference in rim weights would explain your results. Less mass means less inertia.
Example: drop a ping pong ball into water. Then drop a steel ball the same size into water. The lower mass of the ping pong ball accounts for the fact that the resistance of the water halts the ping pong ball almost instantly whereas the steel ball is barely slowed.
If the new wheel has a lighter rim, there's less inertia, and so wind resistance becomes a more important factor.
Example: drop a ping pong ball into water. Then drop a steel ball the same size into water. The lower mass of the ping pong ball accounts for the fact that the resistance of the water halts the ping pong ball almost instantly whereas the steel ball is barely slowed.
If the new wheel has a lighter rim, there's less inertia, and so wind resistance becomes a more important factor.
06-12-24 | 03:54 AM
#36
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Bouyancy also plays a role in that example (but is related to mass too - but if you could reduce the volume of a pingpong ball enough to match the density of the steel one, it would sink pretty damn fast even with its much lower mass inertia) but yeah I completely agree a lighter rim will slow more quickly.
Also don’t think this has been mentioned, inertia of the bike and rider is 0 when spinning the wheel but high when rolling along the flat, makes the hub bearing friction even more negligible.
Also don’t think this has been mentioned, inertia of the bike and rider is 0 when spinning the wheel but high when rolling along the flat, makes the hub bearing friction even more negligible.
Last edited by choddo; 06-12-24 at 04:38 AM.
06-12-24 | 04:18 AM
#37
Bouyancy also plays a role in that example (but is related to mass too) but yeah I completely agree a lighter rim will slow more quickly.
Also don’t think this has been mentioned, inertia of the bike and rider is 0 when spinning the wheel but high when rolling along the flat, makes the hub bearing friction even more negligible.
Also don’t think this has been mentioned, inertia of the bike and rider is 0 when spinning the wheel but high when rolling along the flat, makes the hub bearing friction even more negligible.
06-12-24 | 05:11 AM
#39
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06-12-24 | 12:51 PM
#40
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Wheel bearing resistance is a tiny source of power consumption in comparison to both aerodynamic drag and tire rolling resistance.
If you're not already using them, changing to tires with a low rolling resistance is the easiest way to get a significant savings in power consumption while riding. The downside? That type of tire is typically more expensive, easier to puncture, and wears out more quickly than average. Pick your poison.
If you're not already using them, changing to tires with a low rolling resistance is the easiest way to get a significant savings in power consumption while riding. The downside? That type of tire is typically more expensive, easier to puncture, and wears out more quickly than average. Pick your poison.
06-12-24 | 01:12 PM
#42
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If the wheels were identical in every way, including in levels of hub resistance, except that the new rim was substantially lighter than the old rim, the difference in rim weights would explain your results. Less mass means less inertia.
Example: drop a ping pong ball into water. Then drop a steel ball the same size into water. The lower mass of the ping pong ball accounts for the fact that the resistance of the water halts the ping pong ball almost instantly whereas the steel ball is barely slowed.
If the new wheel has a lighter rim, there's less inertia, and so wind resistance becomes a more important factor.
Example: drop a ping pong ball into water. Then drop a steel ball the same size into water. The lower mass of the ping pong ball accounts for the fact that the resistance of the water halts the ping pong ball almost instantly whereas the steel ball is barely slowed.
If the new wheel has a lighter rim, there's less inertia, and so wind resistance becomes a more important factor.
06-12-24 | 02:08 PM
#43
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Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
But it barely matters anyway. When comparing rolling drag it's important to consider the torque rather than just the drag. Because the bearings are so close to the neutral axis, hub drag would have to be staggering to matter. Small differences between various hubs are comparable to worrying about the pennies in a jar when the mortgage payment comes due.
Last edited by FBinNY; 06-12-24 at 03:13 PM.
06-12-24 | 02:20 PM
#44
Ah, no. The steel ball will slow down or come to a stop (or even bounce up) depending on the specifics of it's velocity at impact and the size and shape of the "container". Then it will accelerate downward due to graivity. The ping pong ball will initially do the same, and then be acted upon by the opposing force of bouyancy. And none of this has anything to do with the rotational forces at work ina wheel.
To make it clearer for you:
Drop a solid steel ball the diameter of a ping-pong ball from a height of 12 inches into a bathtub filled with water to a depth of about 10 inches.
Observe the behavior of the steel ball. Does it bounce from the water surface? If not, how rapidly does it descend in the water?
Do the same with a ping-pong ball. Does it descend as rapidly as the steel ball? Why not?
And: why quotation marks for "container"?
Those words are spelled "gravity" and "buoyancy," by the way.
(Not grammar police; spelling police.)
06-12-24 | 04:58 PM
#45
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Others understood the comparison.
To make it clearer for you:
Drop a solid steel ball the diameter of a ping-pong ball from a height of 12 inches into a bathtub filled with water to a depth of about 10 inches.
Observe the behavior of the steel ball. Does it bounce from the water surface? If not, how rapidly does it descend in the water?
Do the same with a ping-pong ball. Does it descend as rapidly as the steel ball? Why not?
And: why quotation marks for "container"?
Those words are spelled "gravity" and "buoyancy," by the way.
(Not grammar police; spelling police.)
To make it clearer for you:
Drop a solid steel ball the diameter of a ping-pong ball from a height of 12 inches into a bathtub filled with water to a depth of about 10 inches.
Observe the behavior of the steel ball. Does it bounce from the water surface? If not, how rapidly does it descend in the water?
Do the same with a ping-pong ball. Does it descend as rapidly as the steel ball? Why not?
And: why quotation marks for "container"?
Those words are spelled "gravity" and "buoyancy," by the way.
(Not grammar police; spelling police.)
06-12-24 | 11:25 PM
#46
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From: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
For those who fret over stuff like hub friction, may I suggest some DIY scientific research.
You'll need a friend who weights 20# or so more or less than you, a hill, and of course, a "slow" wheel, and a nice loose one.
Take the two bikes to the top of the hill, and do a coast race down. To be fair, each do their best aero tuck. Repeat the test switching bikes. Odds are the same person will win. If you have a number of friends you can repeat this until you find two matched closely enough that the bike actually determines the outcome.
Friends and I did this years (decades) ago and managed to find 2 close enough that 10psi tire pressure made the difference, but we never found two close enough for the hubs to determine the winner.
You'll need a friend who weights 20# or so more or less than you, a hill, and of course, a "slow" wheel, and a nice loose one.
Take the two bikes to the top of the hill, and do a coast race down. To be fair, each do their best aero tuck. Repeat the test switching bikes. Odds are the same person will win. If you have a number of friends you can repeat this until you find two matched closely enough that the bike actually determines the outcome.
Friends and I did this years (decades) ago and managed to find 2 close enough that 10psi tire pressure made the difference, but we never found two close enough for the hubs to determine the winner.
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Last edited by FBinNY; 06-12-24 at 11:30 PM.
06-13-24 | 06:11 AM
#47
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From: Appleton WI
Bikes: Several, mostly not name brands.
I recently bought a new carbon wheelset and did a free spin test on the front wheel compared to the front stock wheel from my 2016 Trek Domane. The old front wheel free spun for almost 2mins, the new front wheel spun for less than 20 seconds. I checked the brakes several times to make sure there was no interference. There just seems to be a ton of resistance/viscosity in these new hubs.
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
I realize that all the comments here disagree, but this rolling resistance must add up over time. I can genuinely feel a difference in resistance when spinning the wheel slowly by hand.
Could this all come down to extremely heavy grease being used in the hub? Any other thoughts?
06-14-24 | 06:40 AM
#48
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Quotations for container because the size and shape can vary from a solo cup to an ocean. Spelling police not reqired, reading glasses police required. The coomparison still isn't valid, steel sinks, hollow thin walled plastic balls float, duh!. What does that have to do with spinning wheels?
An object's rotational inertia depends on both the total mass of the object and the distribution of that mass around the axis of rotation. Mass farther away from the axis of rotation contributes far more than mass close to the axis of rotation.
Example: take the case of two wheels, identical except for one having a heavy rim and one having a lighter one. Once spinning at the same rate, all else being equal the wheel with the heavy rim will spin far longer before it comes to a stop - because it stored more energy (as rotational kinetic energy) and had far more rotational inertia than the wheel with the lighter rim. (The "flip side": the wheel with the heavier rim will require more energy input to spin up to the same rate of rotation as the lighter rimmed wheel.)
Calculating either inertia or stored kinetic energy is possible for both translation and rotation. However, calculation is significantly easier for translational inertia (m x v) or translational kinetic energy (1/2 x m x v^2) than either rotational inertia or rotational kinetic energy. In contrast, both rotational cases are dependent on size, shape, and distribution of mass around the chosen axis of rotation.
Last edited by Hondo6; 06-14-24 at 06:44 AM.
06-14-24 | 08:04 AM
#49
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Like a mass moving in a straight line (such as a dropped bearing ball or ping-pong ball), a stationary spinning object (such as a spinning bicycle wheel on a truing stand) also has inertia. The object traveling in a straight line has translational inertia, while the stationary spinning object has rotational inertia. That is the analogy.
An object's rotational inertia depends on both the total mass of the object and the distribution of that mass around the axis of rotation. Mass farther away from the axis of rotation contributes far more than mass close to the axis of rotation.
Example: take the case of two wheels, identical except for one having a heavy rim and one having a lighter one. Once spinning at the same rate, all else being equal the wheel with the heavy rim will spin far longer before it comes to a stop - because it stored more energy (as rotational kinetic energy) and had far more rotational inertia than the wheel with the lighter rim. (The "flip side": the wheel with the heavier rim will require more energy input to spin up to the same rate of rotation as the lighter rimmed wheel.)
I can agree with that, I still don't see what that has to do with splashing a ping pong ball though, I used to be a pretty good ping pong player at one time...
Calculating either inertia or stored kinetic energy is possible for both translation and rotation. However, calculation is significantly easier for translational inertia (m x v) or translational kinetic energy (1/2 x m x v^2) than either rotational inertia or rotational kine
tic energy. In contrast, both rotational cases are dependent on size, shape, and distribution of mass around the chosen axis of rotation.
An object's rotational inertia depends on both the total mass of the object and the distribution of that mass around the axis of rotation. Mass farther away from the axis of rotation contributes far more than mass close to the axis of rotation.
Example: take the case of two wheels, identical except for one having a heavy rim and one having a lighter one. Once spinning at the same rate, all else being equal the wheel with the heavy rim will spin far longer before it comes to a stop - because it stored more energy (as rotational kinetic energy) and had far more rotational inertia than the wheel with the lighter rim. (The "flip side": the wheel with the heavier rim will require more energy input to spin up to the same rate of rotation as the lighter rimmed wheel.)
I can agree with that, I still don't see what that has to do with splashing a ping pong ball though, I used to be a pretty good ping pong player at one time...
Calculating either inertia or stored kinetic energy is possible for both translation and rotation. However, calculation is significantly easier for translational inertia (m x v) or translational kinetic energy (1/2 x m x v^2) than either rotational inertia or rotational kine
tic energy. In contrast, both rotational cases are dependent on size, shape, and distribution of mass around the chosen axis of rotation.
06-14-24 | 12:37 PM
#50
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Joined: Apr 2009
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From: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Others understood the comparison.
To make it clearer for you:
Drop a solid steel ball the diameter of a ping-pong ball from a height of 12 inches into a bathtub filled with water to a depth of about 10 inches.
Observe the behavior of the steel ball. Does it bounce from the water surface? If not, how rapidly does it descend in the water?
Do the same with a ping-pong ball. Does it descend as rapidly as the steel ball? Why not?
To make it clearer for you:
Drop a solid steel ball the diameter of a ping-pong ball from a height of 12 inches into a bathtub filled with water to a depth of about 10 inches.
Observe the behavior of the steel ball. Does it bounce from the water surface? If not, how rapidly does it descend in the water?
Do the same with a ping-pong ball. Does it descend as rapidly as the steel ball? Why not?
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.