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New rear tire installed...
Wow.
I just got back from my first ride after installing a touring tire on the rear wheel of my bike. (20" rim folder) What a difference! Old ti Innova 54-406 (20"x1.95) knobby (or "semi" at least) New ti Vee-Rubber 47-406 (20"x1.75") tourer I just rode 10km averaging 3km/hr faster than usual - and I don't feel nearly as tired as I did on the old tire! How much of this is just psychological? Surely not all of it... Boy was that fun! HUGE thank you to Sheldon Brown - I was reading either a post or a page from the Harris Cyclery discussing the merits of same/different front/rear tires. I left the semi-knobby on the front wheel for now and I'm loving the handling of the bike. Nice and crisp in corners but so much faster... On the topic of "found while riding" - aside from getting a bit closer to enlightenment, I also found a lone platform pedal on my ride today... Chris |
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#2
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New rear tire installed...
On Tue, 28 Jun 2005 21:19:22 -0400, "C.J.Patten"
wrote: Wow. I just got back from my first ride after installing a touring tire on the rear wheel of my bike. (20" rim folder) What a difference! Old ti Innova 54-406 (20"x1.95) knobby (or "semi" at least) New ti Vee-Rubber 47-406 (20"x1.75") tourer I just rode 10km averaging 3km/hr faster than usual - and I don't feel nearly as tired as I did on the old tire! How much of this is just psychological? Surely not all of it... Boy was that fun! HUGE thank you to Sheldon Brown - I was reading either a post or a page from the Harris Cyclery discussing the merits of same/different front/rear tires. I left the semi-knobby on the front wheel for now and I'm loving the handling of the bike. Nice and crisp in corners but so much faster... On the topic of "found while riding" - aside from getting a bit closer to enlightenment, I also found a lone platform pedal on my ride today... Chris Dear Chris, The psychological improvement (if any) should fade within two weeks, so you can watch your times for that. Meanwhile, you can go here, pick metric units, and fiddle with theoretical recumbent styles and front/rear tire choices: http://www.kreuzotter.de/english/espeed.htm Using the defaults, I picked a short wheelbase equipped for commuting (a middling recumbent), stuck a pair of offroad 1.75" tires (the worst knobbies), and got 28.7 km/h. When I swapped the rear knobby for a wide high pressure slick, the speed improved to 29.6 km/h. Stick a high pressure slick on the front, and the speed improves to 30.8 km/h. Now add a 3.5 km/h headwind, and the speed drops back to the original 28.7 km/h. Very few of us can notice a 2.2 mph headwind change--a very minor wind speed change can blow away a rolling resistance advantage, which is why calculators and wind tunnel tests are used more than attempts at repeated practical runs. One possible fudge factor: the calculator may not address the horrible wind drag of impressive knobs, which may be just as bad as their increased rolling resistance. The FAQ for the page shows that the increased drag of pedal cadence is noted, but I've found nothing about the relative aerodynamic drag of miniature rhino horns versus smooth tread. Carl Fogel |
#3
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New rear tire installed...
On Tue, 28 Jun 2005 21:19:22 -0400, C.J.Patten wrote:
How much of this is just psychological? Surely not all of it... Some new carbon fiber insoles could surely add another 3kph? :P I wouldn't doubt your claims--though new gear does tend to make you happy and thus ride better--rubber is one of those things that does make a difference. No more knobby squirm to waste energy, that's a good thing. |
#4
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New rear tire installed...
OH! Speaking of gear(s) - I was averaging one gear *higher* than I've been
using over the past month. On my ride this morning, I felt like I was struggling in 14th gear - tonight, I was in 15th for most of the ride. The only thing niggling at me now is I have to start looking at buying a larger front chainring! (44 now...maybe a 54 next?) I found the source page I was reading last night: http://www.sheldonbrown.com/tires.html#width I love your term: "squirm" Very fitting... 8D Chris "maxo" wrote in message news On Tue, 28 Jun 2005 21:19:22 -0400, C.J.Patten wrote: How much of this is just psychological? Surely not all of it... Some new carbon fiber insoles could surely add another 3kph? :P I wouldn't doubt your claims--though new gear does tend to make you happy and thus ride better--rubber is one of those things that does make a difference. No more knobby squirm to waste energy, that's a good thing. |
#5
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New rear tire installed...
Very cool Carl. Thanks for the info - and detailed test results!
I'm using a "wedgie" bike - a folding model with 20" wheels - that website is fantastic! I'll bookmark that. One thing on my mind: I'm VERY out of shape. I notice even slight changes during a ride. When I have a headwind (tonight's wind was ~4mph) I experience a noticable drag versus cross or downwind. My route takes me in all directions so I get this from all angles. The switch to the slick seemed just as pronounced a difference as the wind direction. Good suggestion - I'll wait a couple of weeks and see what comes of this. Cheers! Chris p.s. now you got me wanting a WindCheetah recumbant. 8p wrote in message ... Dear Chris, The psychological improvement (if any) should fade within two weeks, so you can watch your times for that. Meanwhile, you can go here, pick metric units, and fiddle with theoretical recumbent styles and front/rear tire choices: http://www.kreuzotter.de/english/espeed.htm Using the defaults, I picked a short wheelbase equipped for commuting (a middling recumbent), stuck a pair of offroad 1.75" tires (the worst knobbies), and got 28.7 km/h. When I swapped the rear knobby for a wide high pressure slick, the speed improved to 29.6 km/h. Stick a high pressure slick on the front, and the speed improves to 30.8 km/h. Now add a 3.5 km/h headwind, and the speed drops back to the original 28.7 km/h. Very few of us can notice a 2.2 mph headwind change--a very minor wind speed change can blow away a rolling resistance advantage, which is why calculators and wind tunnel tests are used more than attempts at repeated practical runs. One possible fudge factor: the calculator may not address the horrible wind drag of impressive knobs, which may be just as bad as their increased rolling resistance. The FAQ for the page shows that the increased drag of pedal cadence is noted, but I've found nothing about the relative aerodynamic drag of miniature rhino horns versus smooth tread. Carl Fogel |
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New rear tire installed...
On Tue, 28 Jun 2005 21:19:22 -0400, "C.J.Patten"
wrote: Wow. I just got back from my first ride after installing a touring tire on the rear wheel of my bike. (20" rim folder) What a difference! Old ti Innova 54-406 (20"x1.95) knobby (or "semi" at least) New ti Vee-Rubber 47-406 (20"x1.75") tourer I just rode 10km averaging 3km/hr faster than usual - and I don't feel nearly as tired as I did on the old tire! How much of this is just psychological? Surely not all of it... Dunno in your case, but swapping from knobbies to slicks on one of the bikes here made a perceptible difference in the coasting range coming off one of the overpasses nearby. That bike doesn't have a comp, so I don't know what the speeds were. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#7
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New rear tire installed...
On Tue, 28 Jun 2005 23:00:14 -0400, "C.J.Patten"
wrote: Very cool Carl. Thanks for the info - and detailed test results! I'm using a "wedgie" bike - a folding model with 20" wheels - that website is fantastic! I'll bookmark that. One thing on my mind: I'm VERY out of shape. I notice even slight changes during a ride. When I have a headwind (tonight's wind was ~4mph) I experience a noticable drag versus cross or downwind. My route takes me in all directions so I get this from all angles. The switch to the slick seemed just as pronounced a difference as the wind direction. Good suggestion - I'll wait a couple of weeks and see what comes of this. Cheers! Chris p.s. now you got me wanting a WindCheetah recumbant. 8p wrote in message .. . Dear Chris, The psychological improvement (if any) should fade within two weeks, so you can watch your times for that. Meanwhile, you can go here, pick metric units, and fiddle with theoretical recumbent styles and front/rear tire choices: http://www.kreuzotter.de/english/espeed.htm Using the defaults, I picked a short wheelbase equipped for commuting (a middling recumbent), stuck a pair of offroad 1.75" tires (the worst knobbies), and got 28.7 km/h. When I swapped the rear knobby for a wide high pressure slick, the speed improved to 29.6 km/h. Stick a high pressure slick on the front, and the speed improves to 30.8 km/h. Now add a 3.5 km/h headwind, and the speed drops back to the original 28.7 km/h. Very few of us can notice a 2.2 mph headwind change--a very minor wind speed change can blow away a rolling resistance advantage, which is why calculators and wind tunnel tests are used more than attempts at repeated practical runs. One possible fudge factor: the calculator may not address the horrible wind drag of impressive knobs, which may be just as bad as their increased rolling resistance. The FAQ for the page shows that the increased drag of pedal cadence is noted, but I've found nothing about the relative aerodynamic drag of miniature rhino horns versus smooth tread. Carl Fogel Dear Chris, It's annoying, but many initial improvements turn out to involve a fair amount of the new-toy syndrome--we pay more attention to what we're doing when we first play with our new toys, and consequently pedal more steadily than we normally do. We often feel a tremendous improvement with a slightly lighter bike and even find our times reflecting some of this sensation--but the physics involved indicates that the actual improvement due to the weight savings is scarcely measurable. Still, there's nothing wrong with trying new toys to keep our interest up and the manufacturers solvent. And your switch to a slick instead of a knobby should indeed improve your time slightly because of reduced rolling resistance, slightly because of reduced wind drag, and slightly because you rode off on your test ride more interested. As for the wind, there's regrettably a good deal of drag in a crosswind. Jobst Brandt's theory and testing suggest that at reasonable biking speeds, a reasonable wind doesn't go neutral until it's around 10 degrees behind the rider: http://www.sheldonbrown.com/brandt/wind.html#milliken For recumbents, here's another speed calculator to play with, which has some tire tables: http://www.recumbents.com/wisil/simul/HPV_Simul.asp There are so many variables and so many assumptions in these calculators that they're unlikely to agree perfectly, but in general they give a fairly good idea of what's going on. Fooling around with different weights, tires, winds, and positions will give a notion of what kind of effects can reasonably be expected, as opposed to what the wicked marketing departments claim and virtuous riders mistakenly think. Carl Fogel |
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