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#21
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700/23 vs 700/25 tires ?
Wired on tyres, 25mm+ on rear perhaps 22+on front, anything less is
painful if you're 3+ hours in the saddle. Rider fatigue caused by constant road shock will slow you more over a long ride, than a less than optimum aero tyre/rim combination. If you 'need' narrow tyres, use tubs, a 23mm tub is more comfortable and grips better in the corners(than 25mm wired) due to a longer contact patch at an appropriate riding pressure. Steering response will also become less jittery with a short trail set up. Confidence in cornering over rough surfaces improves reducing rider tension and improves speed through corners. |
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#22
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700/23 vs 700/25 tires ?
On Thu, 29 Jan 2009 18:21:50 GMT, John Forrest Tomlinson
wrote: On Thu, 29 Jan 2009 10:12:44 -0800 (PST), Chalo wrote: The faster you ride, the more you need in terms of rim protection, shock absorption, wear resistance, pinch flat resistance, and traction. So the faster you go, the more you can benefit from a wider tire. I can see that for traction, though very few people go near the limits of traction on moderatley narrow tires. But why do you need more for rim protection when going fast? [snip] Dear John, The faster the hammer hits the nail, the deeper the nail goes into the wood. More rim protection is needed at higher speeds because impact roughly corresponds to kinetic energy, which is half the mass times the square of the velocity--it rises even faster than the speed. At 20 mph, a rider hits a chunk of gravel (oops!) with an impact of 20^2 whomps, or 400 whomps. At 25 mph, the same rider hits the same chunk of gravel at 25^2 whomps, or 625 whomps. At 30 mph, he hits it at 30^2 whomps, or 900 whomps, more than twice as hard. That's why drivers slow down on rough roads and why faster riders get more pinch flats on bicycles. Cheers, Carl Fogel |
#23
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700/23 vs 700/25 tires ?
On Jan 29, 10:21*am, John Forrest Tomlinson
wrote: On Thu, 29 Jan 2009 10:12:44 -0800 (PST), Chalo wrote: The faster you ride, the more you need in terms of rim protection, shock absorption, wear resistance, pinch flat resistance, and traction. *So the faster you go, the more you can benefit from a wider tire. I can see that for traction, though very few people go near the limits of traction on moderatley narrow tires. But why dod you need more for rim protection when going fast? *Or shock absorbtion? *Or wear resistance? And more to the point, do people trying to go fast care about a little extra shock absorbtion? When I'm going fast there's more weight on my legs and less on my hands and butt, so I notice shocks less than when just rolling along slowly. * And Chalo - I have a couple friends who weigh 100-105 lbs. *In your scheme of things, are they allowed to ride 23s or woudl you tell them they'd be better off riding 25s or larger? *Not knowing them or their riding goals. *Well? It's funny. I remember when 23mms were considered fat. We were racing on 19mm and 20mm clinchers or on sewups (my racing weight 187-195). When I switched to 23s, it made a difference, but that was probably because I changed over to team supplied Conti 23s that were probably 25s. They were squishier, and I didn't like them (yah, I know that is impossible if both tires had the same inflation pressure -- but it was squishier). Also, the difference between 23mm and 25mm is sometimes just a label -- being that nominal sizes are often wrong. I have found differences in tires of the same size, though. For example, a 23mm kevlar belted bomb-proof tire like a Bontrager Hardcase will not roll as well as a 23mm ProRace. Whether that affects your result in a race is hard to say. I use big fat tires during winter (28-35mm) because they give me better traction on wet pavement and more float in the post-snow gravel. They do not ride like 23mm ProRaces, and the penalty is significant IMO -- particularly slogging through the hills. I would not ride them in a race except maybe a cross race on packed dirt.- Jay Beattie. |
#24
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700/23 vs 700/25 tires ?
On Wed, 28 Jan 2009 19:38:42 -0800, Chalo wrote:
jeffreybike wrote: Is there any real difference between 23mm and 25mm tires as far as speed. Will 2mm make you that slower or faster? There is no significant difference in speed between those two sizes of tire. Too narrow a tire will slow you down quite a lot when you get a pinch flat and have to stop and repair it. Instrumented tests have shown that for tires of equal construction, wider tires have slightly less rolling resistance at the same pressure. --snip-- According to Sheldon this is rather moot as generally speaking wider tyres at the same pressure are over inflated or narrow tyres at a same pressure to wider ones will be under inflated (and so not being used optimality presumably). As I understand it anyway. Might not be that relevant with the 2mm difference but just throwing out there. Having said that: in reality little difference in speed I suppose. |
#25
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700/23 vs 700/25 tires ?
On Thu, 29 Jan 2009 11:43:01 -0800 (PST), Nick L Plate
wrote: Confidence in cornering over rough surfaces improves reducing rider tension and improves speed through corners. Good point. |
#26
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700/23 vs 700/25 tires ?
On Jan 29, 1:32*pm, Keiron wrote:
On Wed, 28 Jan 2009 19:38:42 -0800, Chalo wrote: jeffreybike wrote: Is there any real difference between 23mm and 25mm tires as far as speed. Will 2mm make you that slower or faster? There is no significant difference in speed between those two sizes of tire. *Too narrow a tire will slow you down quite a lot when you get a pinch flat and have to stop and repair it. Instrumented tests have shown that for tires of equal construction, wider tires have slightly less rolling resistance at the same pressure. --snip-- According to Sheldon this is rather moot as generally speaking wider tyres at the same pressure are over inflated or narrow tyres at a same pressure to wider ones will be under inflated (and so not being used optimality presumably). As I understand it anyway. Might not be that relevant with the 2mm difference but just throwing out there. Additionally, at equal pressures a wider tire will give a _worse_ ride than a narrower tire. (consider how the size and shape of the contact patch varies with the amount of compression) -pm |
#27
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700/23 vs 700/25 tires ?
On Jan 29, 3:48*pm, Jay Beattie wrote:
Also, the difference between 23mm and 25mm is sometimes just a label -- being that nominal sizes are often wrong. *I have found differences in tires of the same size, though. *For example, a 23mm kevlar belted bomb-proof tire like a Bontrager Hardcase will not roll as well as a 23mm ProRace. Whether that affects your result in a race is hard to say. I think it's well documented that Kevlar belts increase rolling resistance significantly. It's something I noticed and disliked. In fact, I gave away a set of belted tires because they felt so dead to me. - Frank Krygowski |
#28
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700/23 vs 700/25 tires ?
John Forrest Tomlinson wrote:
Chalo wrote: The faster you ride, the more you need in terms of rim protection, shock absorption, wear resistance, pinch flat resistance, and traction. So the faster you go, the more you can benefit from a wider tire. I can see that for traction, though very few people go near the limits of traction on moderatley narrow tires. But why dod you need more for rim protection when going fast? Or shock absorbtion? Or wear resistance? Because the energy contained in bumps goes up as the square of the speed. It's four times easier to pinch flat or flat spot a rim at 30mph than at 15mph. And more to the point, do people trying to go fast care about a little extra shock absorbtion? Why wouldn't they? Every watt of muscle power they spend absorbing bumps is a watt that doesn't make them go any faster. http://www.canosoarus.com/08LSRbicycle/LSR%20Bike01.htm http://davesbikeblog.squarespace.com...ge/Speed04.jpg http://www.fredrompelberg.com/upload...cord_fiets.JPG These are bikes which went very fast indeed, for which rolling resistance was a primary limiting factor in the speeds they reached, and which used both fat tires and front suspension even though they rode on one of the smoothest, least blemished surfaces available anywhere. And Chalo - I have a couple friends who weigh 100-105 lbs. In your scheme of things, are they allowed to ride 23s or woudl you tell them they'd be better off riding 25s or larger? Not knowing them or their riding goals. If they ride on the streets I ride on, the smallest I could recommend is 28mm. That's what my wife uses, and she rides about as slowly and sedately as any able-bodied person could. For much smoother and better maintained streets, perhaps a narrower tire would be acceptable. Chalo |
#29
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700/23 vs 700/25 tires ?
On Thu, 29 Jan 2009 17:17:50 -0800 (PST), Chalo
wrote: And Chalo - I have a couple friends who weigh 100-105 lbs. In your scheme of things, are they allowed to ride 23s or woudl you tell them they'd be better off riding 25s or larger? Not knowing them or their riding goals. If they ride on the streets I ride on, the smallest I could recommend is 28mm. That's what my wife uses, and she rides about as slowly and sedately as any able-bodied person could. OK I have to say it - you're a dogmatic idiot on tire size. To make such a suggestion based on your wife, w/o knowing them. The correct answer to my question is some other questions: "What kind of riding are they doing? On what roads? What are their goals." Not some huge boy dogma. Why TF should people who weigh 100 pounds and compete in some of the toughest bike races in the US use 28s? It's absurd. It's saying "I want to do worse than I can." |
#30
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700/23 vs 700/25 tires ?
On Thu, 29 Jan 2009 17:17:50 -0800 (PST), Chalo
wrote: But why dod you need more for rim protection when going fast? Or shock absorbtion? Or wear resistance? Because the energy contained in bumps goes up as the square of the speed. It's four times easier to pinch flat or flat spot a rim at 30mph than at 15mph. Bumps have only a horizontal component? Interesting. |
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