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#11
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(Wheels and) tires are to bicycles what speakers are to hi-fi
On Thu, 30 Jul 2009 16:52:42 -0400, "(PeteCresswell)"
wrote: Per : Any 23-25-28mm tire from any of the manufacturers will ride just about the same. You could not pick them out reliably in a blind test. Any 38-35-32 tire from any of the manufacturers will ride the same. That has not been my experience with MTB tires. Maybe its different with larger tires, but I feel a very large diff in rolling resistance between a low thread count tire and a high tread count tire. Dear Pete, If you put out the same effort into the pedals, you just go very slightly faster with a tire that has lower rolling resistance. Plug 250 watts into both sides of this calculator and change the default rolling resistance on one side from .0050 to .0025, which represents a large difference in rolling resistance for bicycle tires: http://bikecalculator.com/veloMetricNum.html The predicted speed rises from 32.51 km/h to 33.65 km/h (~20 mph). No rider can "feel" the 1.14 km/h (0.7 mph) difference between those two speeds while just riding around. Cheers, Carl Fogel |
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#13
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(Wheels and) tires are to bicycles what speakers are to hi-fi
Per :
If you put out the same effort into the pedals, you just go very slightly faster with a tire that has lower rolling resistance. Plug 250 watts into both sides of this calculator and change the default rolling resistance on one side from .0050 to .0025, which represents a large difference in rolling resistance for bicycle tires: http://bikecalculator.com/veloMetricNum.html The predicted speed rises from 32.51 km/h to 33.65 km/h (~20 mph). No rider can "feel" the 1.14 km/h (0.7 mph) difference between those two speeds while just riding around. That kind of fits bc what I really should have said was that the higher TPI tire rolls better - not that it had less rolling resistance (because I don't have a clue what rolling resistance really is...) But I can say that if I'm on my FS bike on my (rather lumpy) lawn, the thing rolls perceptibly easier and further on the high-count tires of the same size as the el-cheapo low-count tires. OTOH, my car definitely runs better, handles better, and accelerates faster after it's been washed. Even more so after being waxed.... -) But I really do think there's something to the better rolling perception. -- PeteCresswell |
#14
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(Wheels and) tires are to bicycles what speakers are to hi-fi
RonSonic aka Ron Bales wrote:
[...] That max pressure isn't even a recommended pressure maximum. I can't imagine why you'd want over 90 psi in a 37 unless you just really want to get on Mythbusters. "Is it true some moron blew the hell out of himself with a bike tire - we put it to the test." The whole point of running a tire that fat is so you can lower the pressure.[...] I run 110 psi in the 53-406 Maxxis Hookworms on my trike. Rides just fine due to the rear suspension. -- Tom Sherman - 42.435731,-83.985007 Celebrity culture is an opposite of community, informing us that these few nonsense-heads matter but that the rest of us do not. - Jay Griffiths |
#15
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(Wheels and) tires are to bicycles what speakers are to hi-fi
On Fri, 31 Jul 2009 20:11:08 -0400, "(PeteCresswell)"
wrote: Per : If you put out the same effort into the pedals, you just go very slightly faster with a tire that has lower rolling resistance. Plug 250 watts into both sides of this calculator and change the default rolling resistance on one side from .0050 to .0025, which represents a large difference in rolling resistance for bicycle tires: http://bikecalculator.com/veloMetricNum.html The predicted speed rises from 32.51 km/h to 33.65 km/h (~20 mph). No rider can "feel" the 1.14 km/h (0.7 mph) difference between those two speeds while just riding around. That kind of fits bc what I really should have said was that the higher TPI tire rolls better - not that it had less rolling resistance (because I don't have a clue what rolling resistance really is...) But I can say that if I'm on my FS bike on my (rather lumpy) lawn, the thing rolls perceptibly easier and further on the high-count tires of the same size as the el-cheapo low-count tires. OTOH, my car definitely runs better, handles better, and accelerates faster after it's been washed. Even more so after being waxed.... -) But I really do think there's something to the better rolling perception. Dear Pete, If one tire rolls perceptibly easier and further than another tire of the same size on the same surface with the same effort, it has impressively lower rolling resistance. Cheers, Carl Fogel |
#16
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(Wheels and) tires are to bicycles what speakers are to hi-fi
In article ,
"(PeteCresswell)" wrote: Per : If you put out the same effort into the pedals, you just go very slightly faster with a tire that has lower rolling resistance. Plug 250 watts into both sides of this calculator and change the default rolling resistance on one side from .0050 to .0025, which represents a large difference in rolling resistance for bicycle tires: http://bikecalculator.com/veloMetricNum.html The predicted speed rises from 32.51 km/h to 33.65 km/h (~20 mph). No rider can "feel" the 1.14 km/h (0.7 mph) difference between those two speeds while just riding around. That kind of fits bc what I really should have said was that the higher TPI tire rolls better - not that it had less rolling resistance (because I don't have a clue what rolling resistance really is...) Energy loss from flexing the tire where the tire rolls through the contact patch. -- Michael Press |
#17
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(Wheels and) tires are to bicycles what speakers are to hi-fi
In article ,
"(PeteCresswell)" wrote: Per : If you put out the same effort into the pedals, you just go very slightly faster with a tire that has lower rolling resistance. Plug 250 watts into both sides of this calculator and change the default rolling resistance on one side from .0050 to .0025, which represents a large difference in rolling resistance for bicycle tires: http://bikecalculator.com/veloMetricNum.html The predicted speed rises from 32.51 km/h to 33.65 km/h (~20 mph). No rider can "feel" the 1.14 km/h (0.7 mph) difference between those two speeds while just riding around. That kind of fits bc what I really should have said was that the higher TPI tire rolls better - not that it had less rolling resistance (because I don't have a clue what rolling resistance really is...) But I can say that if I'm on my FS bike on my (rather lumpy) lawn, the thing rolls perceptibly easier and further on the high-count tires of the same size as the el-cheapo low-count tires. OTOH, my car definitely runs better, handles better, and accelerates faster after it's been washed. Even more so after being waxed.... -) But I really do think there's something to the better rolling perception. I feel that too. -- Michael Press |
#18
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(Wheels and) tires are to bicycles what speakers are to hi-fi
Michael Press wrote:
*PeteCresswell wrote: OTOH, my car definitely runs better, handles better, and accelerates faster after it's been washed. *Even more so after being waxed.... -) But I really do think there's something to the better rolling perception. I feel that too. It's there, for sure. I believe that it's as conspicuous as it is because the gross amount of drag doesn't vary much with speed. So when you're just taxiing around, rolling resistance represents a large percentage of total drag and it really comes through. When you pick up the pace and there are kgf of thrust at the rear tire to divvy up, the dozens or hundreds of gf attributable to rolling resistance get sort of lost in the noise. But then when you're riding like hell with some other folks to compete against, you get a keener sense of your speed than when riding solo at the same effort, and that lets you observe relatively small effects like rolling resistance. I spend a lot of my time on the bike in the city just coasting down, or idling while looking for an opening in traffic, or cruising alongside my wife. In these circumstances, efficient tires make the difference between low effort and negligible effort at the pedals. That's not important, really, but it is nice. Chalo |
#19
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(Wheels and) tires are to bicycles what speakers are to hi-fi
On Aug 1, 1:11*pm, Chalo wrote:
Michael Press wrote: *PeteCresswell wrote: OTOH, my car definitely runs better, handles better, and accelerates faster after it's been washed. *Even more so after being waxed.... -) But I really do think there's something to the better rolling perception. I feel that too. It's there, for sure. *I believe that it's as conspicuous as it is because the gross amount of drag doesn't vary much with speed. *So when you're just taxiing around, rolling resistance represents a large percentage of total drag and it really comes through. *When you pick up the pace and there are kgf of thrust at the rear tire to divvy up, the dozens or hundreds of gf attributable to rolling resistance get sort of lost in the noise. *But then when you're riding like hell with some other folks to compete against, you get a keener sense of your speed than when riding solo at the same effort, and that lets you observe relatively small effects like rolling resistance. Yep. When I first picked up an MTB I was impressed at how much faster it was when I put slick tires on it. Now that I'm more fit and "ride like hell" I am impressed by how my MTB with knobbies has basically the same top speed as my touring bike with Paselas. The difference in rolling resistance is easily felt when you coast to a stop though. Carl could quantify that by seeing how fast a bike coasts to a stop from 10 mph, or by going to his favorite analytic cycling calculator, plugging in a ground slope of -1% and a rider power of 1 watt and seeing the effect of rolling resistance in that situation. I spend a lot of my time on the bike in the city just coasting down, or idling while looking for an opening in traffic, or cruising alongside my wife. *In these circumstances, efficient tires make the difference between low effort and negligible effort at the pedals. That's not important, really, but it is nice. Chalo |
#20
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(Wheels and) tires are to bicycles what speakers are to hi-fi
Per Chalo:
It's there, for sure. I believe that it's as conspicuous as it is because the gross amount of drag doesn't vary much with speed. So when you're just taxiing around, rolling resistance represents a large percentage of total drag and it really comes through. When you pick up the pace and there are kgf of thrust at the rear tire to divvy up, the dozens or hundreds of gf attributable to rolling resistance get sort of lost in the noise. Bingo! I think that resolves the conflict between my observations (rolling across my lawn at 1.5 mph) Carl's note. -- PeteCresswell |
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