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#12
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Randonneur aerodynamics
And when is a handlebar bag a fairing? I'd like to see the wind tunnel experiments on that one. Jan comes up with a whole lot of untested, intuitive truths that conveniently fit his product offerings. 45mm tires are super fast, and 1950s steel frames "plane" and a pre-WW II design crank are the best, particularly when they cost almost $500 in current dollars Okey-dokey. The bag-fairing is $300 f****** bucks. I got a pair of Orlieb panniers on sale at Westernbikeworks for half that. https://www.westernbikeworks.com/pro...ier-set?sg=507 This is bizarre fashion stuff worthy of a Frank Krygowski shout-down.
And those $300 bags are designed to be used with a front rack ($170 to $185) and a separate decaleur (another $180). |
#13
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Randonneur aerodynamics
On Monday, March 15, 2021 at 10:10:06 p.m. UTC-4, Frank Krygowski wrote:
On 3/15/2021 8:39 PM, wrote: On Monday, March 15, 2021 at 11:22:07 AM UTC-5, AMuzi wrote: https://www.renehersecycles.com/journal/ -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 https://www.renehersecycles.com/aero...ando-vs-racer/ Here is the article you are referencing. What he says makes sense. But it is not a surprise or a mystery or unknown by everyone else. Smaller frontal area makes you more aerodynamic. Which makes you faster. Adding a handlebar bag on front acts as a fairing. And despite the un-aero flat face of the bag, it actually makes you overall more aero because it forms a better shape with your body behind it than if the flat fronted bag was not there at all. This is just a detail, but I've never understood why handlebar bags have flat fronts. The ones I've mad do not. I do think the bag aids coasting speed, based on my experience riding with others. -- - Frank Krygowski Coasting speed can be increased too by simply keeping the legs on close to the bicycle frame and the arms tucked in close to the body. A dew years ago on a Tour (not a race) I was out coasting many riders on fancy high end aluminium or carbon fibre bicycles even though my 1980s era Miel had 30mm Schwalbe CX-Pro knobby cyclo-cross tires on it. Or, perhaps those knobby tires didn't bounce as much a s the high-pressure narrow racing tires did? ;) Cheers |
#14
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Randonneur aerodynamics
On Tue, 16 Mar 2021 00:12:52 -0700 (PDT), Sir Ridesalot
wrote: On Monday, March 15, 2021 at 10:10:06 p.m. UTC-4, Frank Krygowski wrote: On 3/15/2021 8:39 PM, wrote: On Monday, March 15, 2021 at 11:22:07 AM UTC-5, AMuzi wrote: https://www.renehersecycles.com/journal/ -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 https://www.renehersecycles.com/aero...ando-vs-racer/ Here is the article you are referencing. What he says makes sense. But it is not a surprise or a mystery or unknown by everyone else. Smaller frontal area makes you more aerodynamic. Which makes you faster. Adding a handlebar bag on front acts as a fairing. And despite the un-aero flat face of the bag, it actually makes you overall more aero because it forms a better shape with your body behind it than if the flat fronted bag was not there at all. This is just a detail, but I've never understood why handlebar bags have flat fronts. The ones I've mad do not. I do think the bag aids coasting speed, based on my experience riding with others. -- - Frank Krygowski Coasting speed can be increased too by simply keeping the legs on close to the bicycle frame and the arms tucked in close to the body. A dew years ago on a Tour (not a race) I was out coasting many riders on fancy high end aluminium or carbon fibre bicycles even though my 1980s era Miel had 30mm Schwalbe CX-Pro knobby cyclo-cross tires on it. Or, perhaps those knobby tires didn't bounce as much a s the high-pressure narrow racing tires did? ;) Cheers When we lived in Phuket I had a "morning ride" that had a long fairly flat "hill" on the way home. Roughly a kilometer of flat, straight, pavement with a very even slope all the way. I used to come over the top of the hill and then coast all the way down. I found that, with drop handle bars, sitting up with my hands on the top of the bars I might coast at say, 30 kph, and simply by moving to the drops and leaning forward a bit, not a real crouch, the speed increased 1 kph. The hill was long enough that I could sit up and slow down and then back on the drops and speed up several times on the same hill and it was a very constant phenomena. A real crouch, chin on the bars, elbows in, both feet together on the top of the BB and knees squeezed together and the speed increased to almost 33 kph :-) -- Cheers, John B. |
#15
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Randonneur aerodynamics
On 3/16/2021 3:12 AM, Sir Ridesalot wrote:
On Monday, March 15, 2021 at 10:10:06 p.m. UTC-4, Frank Krygowski wrote: On 3/15/2021 8:39 PM, wrote: On Monday, March 15, 2021 at 11:22:07 AM UTC-5, AMuzi wrote: https://www.renehersecycles.com/journal/ -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 https://www.renehersecycles.com/aero...ando-vs-racer/ Here is the article you are referencing. What he says makes sense. But it is not a surprise or a mystery or unknown by everyone else. Smaller frontal area makes you more aerodynamic. Which makes you faster. Adding a handlebar bag on front acts as a fairing. And despite the un-aero flat face of the bag, it actually makes you overall more aero because it forms a better shape with your body behind it than if the flat fronted bag was not there at all. This is just a detail, but I've never understood why handlebar bags have flat fronts. The ones I've mad do not. I do think the bag aids coasting speed, based on my experience riding with others. -- - Frank Krygowski Coasting speed can be increased too by simply keeping the legs on close to the bicycle frame and the arms tucked in close to the body. A dew years ago on a Tour (not a race) I was out coasting many riders on fancy high end aluminium or carbon fibre bicycles even though my 1980s era Miel had 30mm Schwalbe CX-Pro knobby cyclo-cross tires on it. Or, perhaps those knobby tires didn't bounce as much a s the high-pressure narrow racing tires did? ;) Our roads tend to be pretty rough due to potholes and patches. I think my coasting is helped by my diligence in choosing the smoothest path, and in taking a bit of my weight off the saddle - i.e. using my legs to provide some suspension. I don't know if others I ride with do that. I also pay attention to keeping elbows and knees tucked in as much as possible. -- - Frank Krygowski |
#16
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Randonneur aerodynamics
On 3/15/2021 10:21 PM, Frank Krygowski wrote:
About the wind tunnel: In one issue long ago, [Jan Heine] did pay for wind tunnel time. I should dig it out (assuming the guy I loaned it to has returned it), but the points I remember are that drag coefficient is barely changeable, so frontal area is the most important thing; and that (surprisingly) fenders don't impose a significant aero penalty. But I remember in that issue he attached a bit of cardboard to the top of a handlebar bag hoping it would send air over the rider in a touring position - which, of course it didn't. I thought the idea was ludicrous, and showed that his aero instincts are not very sharp. However, I agree with Russell that the handlebar bag can be an aid in a full tuck. My homemade bag is larger than most and less boxy. I've long suspected it's part of the reason I outcoast so many of my friends. I recognize that this is in conflict with "drag coefficient barely changes." More on that in another post. OK, I found the old 2007 issue of _Bicycle Quarterly_ with the extensive wind tunnel article. There are lots of measurements to evaluate different sources of drag. I'll concentrate on just one chart. Page 21, chart #6 has drag measurements for 22 mph (= 9.83 m/s = 35.4 kph) with and without a handlebar bag. Drag is in Newtons in the table, but I'll convert to aero drag Watts at 22 mph, since we're more used to thinking in those terms. Rider on hoods, no bag: 256 W with bag: 262 W Rider on drops, no bag: 238 W with bag: 249 W Rider in aero tuck, no bag: 160 W with bag: 163 W (Those Watt figures ignore rolling resistance and climbing power. And of course, a rider can't pedal in an aero tuck. The rider was pedaling in other positions.) The handlebar bag he used is one of the large, sharp-edged boxy ones. I have vaguely similar bags on a couple bikes, but the two bags I made myself are more smooth, curved and tapered at the front. I suspect it produces less drag, perhaps even a net benefit. BTW, I mis-remembered one point: Drag coefficient dropped by 7% in the aero tuck position; I had thought it stayed closer to constant. This is in addition to the major benefit of the tuck, which was the reduction in frontal area. -- - Frank Krygowski |
#17
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Randonneur aerodynamics
On Tuesday, March 16, 2021 at 9:03:17 AM UTC-7, Frank Krygowski wrote:
On 3/15/2021 10:21 PM, Frank Krygowski wrote: About the wind tunnel: In one issue long ago, [Jan Heine] did pay for wind tunnel time. I should dig it out (assuming the guy I loaned it to has returned it), but the points I remember are that drag coefficient is barely changeable, so frontal area is the most important thing; and that (surprisingly) fenders don't impose a significant aero penalty. But I remember in that issue he attached a bit of cardboard to the top of a handlebar bag hoping it would send air over the rider in a touring position - which, of course it didn't. I thought the idea was ludicrous, and showed that his aero instincts are not very sharp. However, I agree with Russell that the handlebar bag can be an aid in a full tuck. My homemade bag is larger than most and less boxy. I've long suspected it's part of the reason I outcoast so many of my friends. I recognize that this is in conflict with "drag coefficient barely changes." More on that in another post. OK, I found the old 2007 issue of _Bicycle Quarterly_ with the extensive wind tunnel article. There are lots of measurements to evaluate different sources of drag. I'll concentrate on just one chart. Page 21, chart #6 has drag measurements for 22 mph (= 9.83 m/s = 35.4 kph) with and without a handlebar bag. Drag is in Newtons in the table, but I'll convert to aero drag Watts at 22 mph, since we're more used to thinking in those terms. Rider on hoods, no bag: 256 W with bag: 262 W Rider on drops, no bag: 238 W with bag: 249 W Rider in aero tuck, no bag: 160 W with bag: 163 W (Those Watt figures ignore rolling resistance and climbing power. And of course, a rider can't pedal in an aero tuck. The rider was pedaling in other positions.) The handlebar bag he used is one of the large, sharp-edged boxy ones. I have vaguely similar bags on a couple bikes, but the two bags I made myself are more smooth, curved and tapered at the front. I suspect it produces less drag, perhaps even a net benefit. BTW, I mis-remembered one point: Drag coefficient dropped by 7% in the aero tuck position; I had thought it stayed closer to constant. This is in addition to the major benefit of the tuck, which was the reduction in frontal area. I don't have much faith in wind tunnel data except for comparison purposes. |
#18
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Randonneur aerodynamics
On Tuesday, March 16, 2021 at 9:03:17 AM UTC-7, Frank Krygowski wrote:
On 3/15/2021 10:21 PM, Frank Krygowski wrote: About the wind tunnel: In one issue long ago, [Jan Heine] did pay for wind tunnel time. I should dig it out (assuming the guy I loaned it to has returned it), but the points I remember are that drag coefficient is barely changeable, so frontal area is the most important thing; and that (surprisingly) fenders don't impose a significant aero penalty. But I remember in that issue he attached a bit of cardboard to the top of a handlebar bag hoping it would send air over the rider in a touring position - which, of course it didn't. I thought the idea was ludicrous, and showed that his aero instincts are not very sharp. However, I agree with Russell that the handlebar bag can be an aid in a full tuck. My homemade bag is larger than most and less boxy. I've long suspected it's part of the reason I outcoast so many of my friends. I recognize that this is in conflict with "drag coefficient barely changes." More on that in another post. OK, I found the old 2007 issue of _Bicycle Quarterly_ with the extensive wind tunnel article. There are lots of measurements to evaluate different sources of drag. I'll concentrate on just one chart. Page 21, chart #6 has drag measurements for 22 mph (= 9.83 m/s = 35.4 kph) with and without a handlebar bag. Drag is in Newtons in the table, but I'll convert to aero drag Watts at 22 mph, since we're more used to thinking in those terms. Rider on hoods, no bag: 256 W with bag: 262 W Rider on drops, no bag: 238 W with bag: 249 W Rider in aero tuck, no bag: 160 W with bag: 163 W (Those Watt figures ignore rolling resistance and climbing power. And of course, a rider can't pedal in an aero tuck. The rider was pedaling in other positions.) The handlebar bag he used is one of the large, sharp-edged boxy ones. I have vaguely similar bags on a couple bikes, but the two bags I made myself are more smooth, curved and tapered at the front. I suspect it produces less drag, perhaps even a net benefit. BTW, I mis-remembered one point: Drag coefficient dropped by 7% in the aero tuck position; I had thought it stayed closer to constant. This is in addition to the major benefit of the tuck, which was the reduction in frontal area. So unless I'm missing something, the testing shows that no bag is more aerodynamic and that there is more drag with a bag, viz., exactly opposite of Jan's claim. I was going to swap my 16lb Emonda for a steel Renee Herse with 45mm tires and bags to see if I could increase my speed. -- Jay Beattie. |
#19
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Randonneur aerodynamics
On Tuesday, March 16, 2021 at 10:17:12 AM UTC-7, jbeattie wrote:
On Tuesday, March 16, 2021 at 9:03:17 AM UTC-7, Frank Krygowski wrote: On 3/15/2021 10:21 PM, Frank Krygowski wrote: About the wind tunnel: In one issue long ago, [Jan Heine] did pay for wind tunnel time. I should dig it out (assuming the guy I loaned it to has returned it), but the points I remember are that drag coefficient is barely changeable, so frontal area is the most important thing; and that (surprisingly) fenders don't impose a significant aero penalty. But I remember in that issue he attached a bit of cardboard to the top of a handlebar bag hoping it would send air over the rider in a touring position - which, of course it didn't. I thought the idea was ludicrous, and showed that his aero instincts are not very sharp. However, I agree with Russell that the handlebar bag can be an aid in a full tuck. My homemade bag is larger than most and less boxy. I've long suspected it's part of the reason I outcoast so many of my friends. I recognize that this is in conflict with "drag coefficient barely changes." More on that in another post. OK, I found the old 2007 issue of _Bicycle Quarterly_ with the extensive wind tunnel article. There are lots of measurements to evaluate different sources of drag. I'll concentrate on just one chart. Page 21, chart #6 has drag measurements for 22 mph (= 9.83 m/s = 35.4 kph) with and without a handlebar bag. Drag is in Newtons in the table, but I'll convert to aero drag Watts at 22 mph, since we're more used to thinking in those terms. Rider on hoods, no bag: 256 W with bag: 262 W Rider on drops, no bag: 238 W with bag: 249 W Rider in aero tuck, no bag: 160 W with bag: 163 W (Those Watt figures ignore rolling resistance and climbing power. And of course, a rider can't pedal in an aero tuck. The rider was pedaling in other positions.) The handlebar bag he used is one of the large, sharp-edged boxy ones. I have vaguely similar bags on a couple bikes, but the two bags I made myself are more smooth, curved and tapered at the front. I suspect it produces less drag, perhaps even a net benefit. BTW, I mis-remembered one point: Drag coefficient dropped by 7% in the aero tuck position; I had thought it stayed closer to constant. This is in addition to the major benefit of the tuck, which was the reduction in frontal area. So unless I'm missing something, the testing shows that no bag is more aerodynamic and that there is more drag with a bag, viz., exactly opposite of Jan's claim. I was going to swap my 16lb Emonda for a steel Renee Herse with 45mm tires and bags to see if I could increase my speed. -- Jay Beattie. Is this one of your "mostly peaceful demonstrations"? |
#20
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Randonneur aerodynamics
On 3/16/2021 12:17 PM, jbeattie wrote:
On Tuesday, March 16, 2021 at 9:03:17 AM UTC-7, Frank Krygowski wrote: On 3/15/2021 10:21 PM, Frank Krygowski wrote: About the wind tunnel: In one issue long ago, [Jan Heine] did pay for wind tunnel time. I should dig it out (assuming the guy I loaned it to has returned it), but the points I remember are that drag coefficient is barely changeable, so frontal area is the most important thing; and that (surprisingly) fenders don't impose a significant aero penalty. But I remember in that issue he attached a bit of cardboard to the top of a handlebar bag hoping it would send air over the rider in a touring position - which, of course it didn't. I thought the idea was ludicrous, and showed that his aero instincts are not very sharp. However, I agree with Russell that the handlebar bag can be an aid in a full tuck. My homemade bag is larger than most and less boxy. I've long suspected it's part of the reason I outcoast so many of my friends. I recognize that this is in conflict with "drag coefficient barely changes." More on that in another post. OK, I found the old 2007 issue of _Bicycle Quarterly_ with the extensive wind tunnel article. There are lots of measurements to evaluate different sources of drag. I'll concentrate on just one chart. Page 21, chart #6 has drag measurements for 22 mph (= 9.83 m/s = 35.4 kph) with and without a handlebar bag. Drag is in Newtons in the table, but I'll convert to aero drag Watts at 22 mph, since we're more used to thinking in those terms. Rider on hoods, no bag: 256 W with bag: 262 W Rider on drops, no bag: 238 W with bag: 249 W Rider in aero tuck, no bag: 160 W with bag: 163 W (Those Watt figures ignore rolling resistance and climbing power. And of course, a rider can't pedal in an aero tuck. The rider was pedaling in other positions.) The handlebar bag he used is one of the large, sharp-edged boxy ones. I have vaguely similar bags on a couple bikes, but the two bags I made myself are more smooth, curved and tapered at the front. I suspect it produces less drag, perhaps even a net benefit. BTW, I mis-remembered one point: Drag coefficient dropped by 7% in the aero tuck position; I had thought it stayed closer to constant. This is in addition to the major benefit of the tuck, which was the reduction in frontal area. So unless I'm missing something, the testing shows that no bag is more aerodynamic and that there is more drag with a bag, viz., exactly opposite of Jan's claim. I was going to swap my 16lb Emonda for a steel Renee Herse with 45mm tires and bags to see if I could increase my speed. -- Jay Beattie. If that doesn't work, try steel pinned cranks with 3 bolts. Because France. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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