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#21
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Fat tire riders look like "fat heads."
On 7/5/2020 3:53 PM, Sir Ridesalot wrote:
On Sunday, 5 July 2020 13:10:07 UTC-4, Frank Krygowski wrote: On 7/4/2020 8:21 PM, Rich wrote: On Saturday, 4 July 2020 17:28:28 UTC-4, Andre Jute wrote: On Saturday, July 4, 2020 at 4:21:07 AM UTC+1, Rich wrote: Unless the stupid bike is powered, why endure that ridiculous rolling resistance? You may be inexperienced or a troll, but I've already settled that question, he http://thorncyclesforum.co.uk/index....16360#msg16360 Andre Jute I don't follow the fashion, I create it PS. BTW, you're ill-informed. Low pressure balloons have a lower rolling resistance, so there is no "ridiculous rolling resistance". Where'd you ever pick up that dumb street corner myth? You are complete wrong on this, it's not possible for a tire with a larger contact patch to have lower rolling-resistance than a small, higher inflation tire. Where did you learn physics, grade-school? I know a lot of people on mountain bikes who switched from 2.25" tires to 1.9" to lower rolling resistance. Assertions and "I know a guy" anecdotes without data and links don't get much respect around here. What do you know about mechanical hysteresis? -- - Frank Krygowski Yet a lot of times you use anecdotes about people you know, to try and prove a point. “One must learn the rules so one can break them properly.” ― Adrienne Posey -- - Frank Krygowski |
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#22
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Fat tire riders look like "fat heads."
On Sun, 5 Jul 2020 22:13:14 -0400, Frank Krygowski
wrote: On 7/5/2020 8:06 PM, AMuzi wrote: On 7/5/2020 5:41 PM, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area.* That increases the ground pressure, which causes the rolling resistance to increase.* That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire’s speed. If lower pressures don’t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike’s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice.* A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance.* Granted I’m not a racer trying to milk milliseconds from my times.* But cornering in a tight downhill is something I care about.* My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me.* Comfortable and good handling.** Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. +1 Except rolling resistance is quantifiable, at least to a degree. Handling is a pretty nebulous item. Similarly, I've been skeptical of Jan Heine's testimonies about bikes that "plane" i.e. that have the precise degree of flexibility (not too stiff) that allows the frame to somehow match his pedal strokes and go faster with less effort. like a speedboat that planes over the water. I'm not saying such a thing is impossible; but I'd like some hard evidence "planing" exists other than his rave review. If some bikes "plane" more than others, how can we measure it? Likewise, if one tire "handles" better than others, how can we measure it? Does anyone know if there is an actual metric? Boats "plane" because they rise up out of the water and thus have far less drag. For a bicycle to "plane" it would require the bicycle to somehow decrease it's "drag" in some manner to allow it to increase its speed. Note that this can be accomplished by going from an erect position on the bike to a "head down, over the bars" position and can be easily demonstrated by coasting down a hill and changing one's position and watching the speedometer :-) -- Cheers, John B. |
#23
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Fat tire riders look like "fat heads."
Andre Jute wrote:
On Sunday, July 5, 2020 at 11:41:11 PM UTC+1, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tires speed. If lower pressures dont make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you dont give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bikes rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted Im not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. Yes, that is why my original article at http://thorncyclesforum.co.uk/index....16360#msg16360 considered roadholding (the mannered response of a tyre) and handling (its tolerance for rude inputs) at some length, and then considered comfort ahead of rolling resistance. By comparison, making a mountain out of rolling resistance, as Rich (and of course Franki-boy) try to do, because that is what they feel can understand from the welter of interrelated considerations, is a juvenile descent to triviality. All the same, I clearly put a higher value on comfort than you do, Duane. Anyone for whom 23mm tyres at 90psi are the sweet spot must have an backside of cast iron. Andre Jute Tyres are horses for courses It’s probably more to do with the bike geometry than my cast iron backside but it’s good to have lots of choices. For me, coming from tires narrow enough to get caught in cobblestones running 135psi this IS comfort. And my wheels are 23 mm wide so the 23 mm tire behaves differently than on a standard width rim. Specs on HED wheels are available online. I do see many new road bikes showing up with wide tires and disc brakes now though so I guess it will become the norm. |
#24
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Fat tire riders look like "fat heads."
On Monday, July 6, 2020 at 12:19:42 PM UTC+2, Duane wrote:
Andre Jute wrote: On Sunday, July 5, 2020 at 11:41:11 PM UTC+1, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire s speed. If lower pressures don t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted I m not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. Yes, that is why my original article at http://thorncyclesforum.co.uk/index....16360#msg16360 considered roadholding (the mannered response of a tyre) and handling (its tolerance for rude inputs) at some length, and then considered comfort ahead of rolling resistance. By comparison, making a mountain out of rolling resistance, as Rich (and of course Franki-boy) try to do, because that is what they feel can understand from the welter of interrelated considerations, is a juvenile descent to triviality. All the same, I clearly put a higher value on comfort than you do, Duane. Anyone for whom 23mm tyres at 90psi are the sweet spot must have an backside of cast iron. Andre Jute Tyres are horses for courses It’s probably more to do with the bike geometry than my cast iron backside but it’s good to have lots of choices. For me, coming from tires narrow enough to get caught in cobblestones running 135psi this IS comfort. And my wheels are 23 mm wide so the 23 mm tire behaves differently than on a standard width rim. Specs on HED wheels are available online. I do see many new road bikes showing up with wide tires and disc brakes now though so I guess it will become the norm. The idea that wider tires equals comfort is false IMO. Lower pressure equals comfort. Wider tires gives you the option to run lower pressures without an increased chance of a pinch flat and at that lower pressure a better handling cornering. Lou |
#25
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Fat tire riders look like "fat heads."
On 7/6/2020 2:02 AM, John B. wrote:
On Sun, 5 Jul 2020 22:13:14 -0400, Frank Krygowski wrote: On 7/5/2020 8:06 PM, AMuzi wrote: On 7/5/2020 5:41 PM, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area.* That increases the ground pressure, which causes the rolling resistance to increase.* That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire’s speed. If lower pressures don’t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike’s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice.* A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance.* Granted I’m not a racer trying to milk milliseconds from my times.* But cornering in a tight downhill is something I care about.* My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me.* Comfortable and good handling.** Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. +1 Except rolling resistance is quantifiable, at least to a degree. Handling is a pretty nebulous item. Similarly, I've been skeptical of Jan Heine's testimonies about bikes that "plane" i.e. that have the precise degree of flexibility (not too stiff) that allows the frame to somehow match his pedal strokes and go faster with less effort. like a speedboat that planes over the water. I'm not saying such a thing is impossible; but I'd like some hard evidence "planing" exists other than his rave review. If some bikes "plane" more than others, how can we measure it? Likewise, if one tire "handles" better than others, how can we measure it? Does anyone know if there is an actual metric? Boats "plane" because they rise up out of the water and thus have far less drag. For a bicycle to "plane" it would require the bicycle to somehow decrease it's "drag" in some manner to allow it to increase its speed. Note that this can be accomplished by going from an erect position on the bike to a "head down, over the bars" position and can be easily demonstrated by coasting down a hill and changing one's position and watching the speedometer :-) I agree. Jan Heine doesn't seem to attribute "planing" of a bike to reduced resistance. He seems to believe that a bike frame with just the right flexibility - not too much, not too little - somehow flexes in synchrony with his pedal strokes and allows him to put in more power with less fatigue. Absent measurements and data, I'm very skeptical. -- - Frank Krygowski |
#26
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Fat tire riders look like "fat heads."
On 7/5/2020 3:41 PM, Duane wrote:
Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire’s speed. If lower pressures don’t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike’s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted I’m not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. For a very different perspective, yesterday I took the gravel bike out for a spin. On the gravel bike - on gravel - rolling resistance takes on a much more dominant role. Handling is more of an issue than on pavement. Never mind efficiency, a harder/narrower rear tire gives so much bouncing and skittering side-to-side that /control/ takes a lot more effort - and I'm talking about riding in a straight line! I've found that good side lugs on a tire help with the skittering - feels like the tire stays on top of pieces of gravel rather than riding up and falling off sideways. I've written before that the gravel in my county is pretty rough, though that seems to vary by the week. Sometimes I'll find a nice hard-pack track down the middle of the road, but I think the county just re-spread gravel, 'cause it was all loose stuff yesterday. There's no doubt I'm sinking a lot more energy into rolling resistance than on a road bike. I can even quantify it a bit, being a data junkie and having PowerTap wheels on both road and gravel bikes. On the road, it takes a very brisk ride to burn over about 33-34 kiloJoules per mile. Yesterday on the gravel, at a much lower speed, I averaged 35 kJ/mile. This is for rides that start and end at the same elevation. It's a topic for another post, but I find on the road that energy /per mile/ is surprisingly consistent, ranging from around 27 kJ/mile for a gentle pootle to maybe 35 kJ/mile for a very brisk hilly ride, with most rides in the 30-33 range. Not, of course, on rides that start and end at different elevations. Lower pressure helps handling/skittering with the wider contact patch. But the lower limit of tire pressure to avoid pinch flats seems to vary by the minute; it all depends on what you hit, so there's no rule there even for a given tire/rim/rider. I've only pinch flat once so far in many rides, but I think it was a fluke rock hit. The rims on my bike - Trek Checkpoint SL 5 - are really too narrow for my tastes, but I took too long to figure that out. The bike came with 35mm tires, quickly swapped to 42mm. The tires are so much wider than the rim, and run around 35-37psi, that they /always/ LOOK flat, even when they're fine. Between the bounce of intentionally soft tires and the vertical flex designed into the frame, the tires always /feel/ a bit flat too, enough that I sometimes stop and check. It's a good question what pressure I'd use on a comfort-be-damned go-as-fast-as-possible ride, since I'm doing this for fun and I haven't raced in many years. Mark J. |
#27
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Fat tire riders look like "fat heads."
On Monday, July 6, 2020 at 7:15:32 PM UTC+2, Mark J. wrote:
It's a topic for another post, but I find on the road that energy /per mile/ is surprisingly consistent, ranging from around 27 kJ/mile for a gentle pootle to maybe 35 kJ/mile for a very brisk hilly ride, with most rides in the 30-33 range. Not, of course, on rides that start and end at different elevations. Tell that to the people that say that 10-20 Watt on average is insignificant. Lou |
#28
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Fat tire riders look like "fat heads."
On Monday, 6 July 2020 13:15:32 UTC-4, Mark J. wrote:
On 7/5/2020 3:41 PM, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire’s speed. If lower pressures don’t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike’s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted I’m not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. For a very different perspective, yesterday I took the gravel bike out for a spin. On the gravel bike - on gravel - rolling resistance takes on a much more dominant role. Handling is more of an issue than on pavement. Never mind efficiency, a harder/narrower rear tire gives so much bouncing and skittering side-to-side that /control/ takes a lot more effort - and I'm talking about riding in a straight line! I've found that good side lugs on a tire help with the skittering - feels like the tire stays on top of pieces of gravel rather than riding up and falling off sideways. I've written before that the gravel in my county is pretty rough, though that seems to vary by the week. Sometimes I'll find a nice hard-pack track down the middle of the road, but I think the county just re-spread gravel, 'cause it was all loose stuff yesterday. There's no doubt I'm sinking a lot more energy into rolling resistance than on a road bike. I can even quantify it a bit, being a data junkie and having PowerTap wheels on both road and gravel bikes. On the road, it takes a very brisk ride to burn over about 33-34 kiloJoules per mile. Yesterday on the gravel, at a much lower speed, I averaged 35 kJ/mile. This is for rides that start and end at the same elevation. It's a topic for another post, but I find on the road that energy /per mile/ is surprisingly consistent, ranging from around 27 kJ/mile for a gentle pootle to maybe 35 kJ/mile for a very brisk hilly ride, with most rides in the 30-33 range. Not, of course, on rides that start and end at different elevations. Lower pressure helps handling/skittering with the wider contact patch. But the lower limit of tire pressure to avoid pinch flats seems to vary by the minute; it all depends on what you hit, so there's no rule there even for a given tire/rim/rider. I've only pinch flat once so far in many rides, but I think it was a fluke rock hit. The rims on my bike - Trek Checkpoint SL 5 - are really too narrow for my tastes, but I took too long to figure that out. The bike came with 35mm tires, quickly swapped to 42mm. The tires are so much wider than the rim, and run around 35-37psi, that they /always/ LOOK flat, even when they're fine. Between the bounce of intentionally soft tires and the vertical flex designed into the frame, the tires always /feel/ a bit flat too, enough that I sometimes stop and check. It's a good question what pressure I'd use on a comfort-be-damned go-as-fast-as-possible ride, since I'm doing this for fun and I haven't raced in many years. Mark J. I remember a few years ago a ride on our MTBs when we were coming home along a dirt road. A few kilometers along after turning onto another dirt road we discovered that it had just been freshly graveled. that gravel layer was deep and loose, so much do that it was hard io ride a straight line on my rigid MTB or my friend's front suspension MTB. Both had 26" x 2.125 or 2.25 knobby tires on them. On a skinny tire it'd have been impossible to ride that stretch or road. Cheers |
#29
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Fat tire riders look like "fat heads."
On Monday, July 6, 2020 at 2:08:32 PM UTC+1, Lou Holtman wrote:
On Monday, July 6, 2020 at 12:19:42 PM UTC+2, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 11:41:11 PM UTC+1, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor.. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire s speed. If lower pressures don t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted I m not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. Yes, that is why my original article at http://thorncyclesforum.co.uk/index....16360#msg16360 considered roadholding (the mannered response of a tyre) and handling (its tolerance for rude inputs) at some length, and then considered comfort ahead of rolling resistance. By comparison, making a mountain out of rolling resistance, as Rich (and of course Franki-boy) try to do, because that is what they feel can understand from the welter of interrelated considerations, is a juvenile descent to triviality. All the same, I clearly put a higher value on comfort than you do, Duane. Anyone for whom 23mm tyres at 90psi are the sweet spot must have an backside of cast iron. Andre Jute Tyres are horses for courses It’s probably more to do with the bike geometry than my cast iron backside but it’s good to have lots of choices. For me, coming from tires narrow enough to get caught in cobblestones running 135psi this IS comfort. And my wheels are 23 mm wide so the 23 mm tire behaves differently than on a standard width rim. Specs on HED wheels are available online. I do see many new road bikes showing up with wide tires and disc brakes now though so I guess it will become the norm. The idea that wider tires equals comfort is false IMO. Lower pressure equals comfort. Wider tires gives you the option to run lower pressures without an increased chance of a pinch flat and at that lower pressure a better handling cornering. Lou That's right. The link between wider tires and greater comfort isn't direct but via the possibility of lower pressure. People are always surprised after they ride my bike to discover that the comfort comes despite the reluctance of the stiff rolling surface on my Big apples to flex very much under finger pressure. But the flex is in the air against the soft sidewalls. Andre Jute Nothing in suspensions, automobile or bicycle, is as straightforward as one might expect |
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Fat tire riders look like "fat heads."
Lou Holtman wrote:
On Monday, July 6, 2020 at 12:19:42 PM UTC+2, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 11:41:11 PM UTC+1, Duane wrote: Andre Jute wrote: On Sunday, July 5, 2020 at 5:46:09 PM UTC+1, Jeff Liebermann wrote: On Sat, 04 Jul 2020 19:21:20 -0700, Jeff Liebermann wrote: When you take the same rider and bike, and switch from slicks to knobbies, you reduce the ground patch area. That increases the ground pressure, which causes the rolling resistance to increase. That's one reason why riding knobbies on pavement is like dragging an anchor. I forgot to mumble something about tire pressu "Everything You Think You Know About Bicycle Tire Pressure is Probably Wrong" https://www.roadbikerider.com/the-tire-pressure-revolution-by-jan-heine-d1/ Quoting: Tire pressure has almost no effect on a tire s speed. If lower pressures don t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Conclusion Tire pressure does not significantly affect your bike s rolling resistance, but the casing construction of your tires does. This means that you can ride lower pressures without going slower, and that wide tires are no slower than narrow ones - as long as they have similar casings. The fastest tires have supple casings that consume less energy when they flex, and transmit fewer vibrations, creating a win-win situation. These tires roll super-fast no matter at what pressure you run them. So, you have a choice. A hard stiff narrow tire at high pressure or a soft flexible wide tire at low pressure. I'm not surprised, Jeff. Comparing the standard and the lightweight folding Big Apples, and the thinner T19A tubes with the standard T19 tubes for 60x622 tyres, I found the lightweight versions to be very much more comfortable with no degradation in handling and roadholding at the limit, and not more fragile either on my rough but tarmacced lanes. Handling is what the tyre does that is expected in response to normal inputs up to the margin of error, roadholding is recovery from something extreme stupid the rider does (or the road or environment does to him) beyond the margin of error. It must have been a common experience, because elements of the folding Big Apple, and especially its ultra-flexible sidewall, were then spread throughout the Big Apple range by Schwalbe, so that the folding tyre is no longer a separate line within the brand. Andre Jute A life spent on the response of wheeled vehicles is not wasted. Sometimes I wish I continued as a hot rodder all my life. I tend to notice handling more than slight differences in rolling resistance. Granted I m not a racer trying to milk milliseconds from my times. But cornering in a tight downhill is something I care about. My HED wheels running 23mm conti folding tire at 90 psi are the sweet spot for me. Comfortable and good handling. Just my two cents but I find the discussion on rolling resistance without handling considered to be a bit useless. Yes, that is why my original article at http://thorncyclesforum.co.uk/index....16360#msg16360 considered roadholding (the mannered response of a tyre) and handling (its tolerance for rude inputs) at some length, and then considered comfort ahead of rolling resistance. By comparison, making a mountain out of rolling resistance, as Rich (and of course Franki-boy) try to do, because that is what they feel can understand from the welter of interrelated considerations, is a juvenile descent to triviality. All the same, I clearly put a higher value on comfort than you do, Duane. Anyone for whom 23mm tyres at 90psi are the sweet spot must have an backside of cast iron. Andre Jute Tyres are horses for courses It’s probably more to do with the bike geometry than my cast iron backside but it’s good to have lots of choices. For me, coming from tires narrow enough to get caught in cobblestones running 135psi this IS comfort. And my wheels are 23 mm wide so the 23 mm tire behaves differently than on a standard width rim. Specs on HED wheels are available online. I do see many new road bikes showing up with wide tires and disc brakes now though so I guess it will become the norm. The idea that wider tires equals comfort is false IMO. Lower pressure equals comfort. Wider tires gives you the option to run lower pressures without an increased chance of a pinch flat and at that lower pressure a better handling cornering. Lou Agreed. |
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