Well, track is the one place where narrow hard tires still rule. Not many suspension losses on a velodrome.foo on patrol wrote: I'm using Robino Pro's and they corner better than GP4000s and were only $23 each. Never been a fan of wide tyres, even when I was in the State Squad for the Track as a young bloke. Train on heavy, race on light.
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23mm 100psi faster on short climbs?
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Re: 23mm 100psi faster on short climbs?
Postby madmacca » Thu Nov 29, 2018 4:26 pm
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Re: 23mm 100psi faster on short climbs?
Postby foo on patrol » Fri Nov 30, 2018 8:43 pm
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Re: 23mm 100psi faster on short climbs?
Postby kenwstr » Fri Dec 14, 2018 2:39 pm
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Re: 23mm 100psi faster on short climbs?
Postby HausFinch » Tue Jan 01, 2019 9:01 am
https://www.google.com/url?sa=i&source= ... 8611547146
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Re: 23mm 100psi faster on short climbs?
Postby g-boaf » Tue Jan 01, 2019 9:34 am
Who needs a hidden motor, everyone will just be riding spaghetti bike frames. I'm not buying it.HausFinch wrote:Jan Heine believes some bike frames (thinner walled, more flexible tubes) take and return rider energy in a manner that increases power output compared to very stiff ones. This is most noticeable on climbs. Bicycle Quarterly ran an interesting test of this theory using four identical bikes that only varied in the flex character. More flexible frames averaged 12% higher power output by the test riders, and two of three testers we're 100% accurate in identifying what tubeset they were on.
https://www.google.com/url?sa=i&source= ... 8611547146
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Re: 23mm 100psi faster on short climbs?
Postby HausFinch » Tue Jan 01, 2019 11:40 am
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Re: 23mm 100psi faster on short climbs?
Postby g-boaf » Tue Jan 01, 2019 11:56 am
Sounds like John Howard's core and non-core promises. No, I don't believe a word of it.HausFinch wrote:He makes no blanket claim about more flex being unequivocally better.
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Re: 23mm 100psi faster on short climbs?
Postby foo on patrol » Tue Jan 01, 2019 3:07 pm
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Re: 23mm 100psi faster on short climbs?
Postby mikesbytes » Tue Jan 01, 2019 7:26 pm
While there is plenty of data out there on rolling resistance and aero, I have pondered what difference (if any) there is in power loss resulting from a softer inflated wider tyre over a narrower harder inflated tyreAlex Simmons/RST wrote:Show me the data.
==================
In regards to the frame flex, I suspect the flex is more about how the energy is distributed from the bottom bracket/chainring to the rear axel/cassette. If the rear of the frame is too stiff it causes the rear tyre to 'skip' with each pedal stroke
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Re: 23mm 100psi faster on short climbs?
Postby singlespeedscott » Tue Jan 01, 2019 9:25 pm
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Re: 23mm 100psi faster on short climbs?
Postby Alex Simmons/RST » Thu Jan 03, 2019 7:46 pm
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Re: 23mm 100psi faster on short climbs?
Postby Thoglette » Thu Jan 03, 2019 8:26 pm
Cite please?Alex Simmons/RST wrote:When testers were blinded to the bikes they were riding (supposed “compliant” and “stiff” frames that had frames covered), they were no better than random chance at picking the frame type when tyre pressures were controlled. The primary correlation for what frame type they thought they were riding was all down to the experimenter changing tyre pressure, not the frame.
The following article had two of three testers able to tell the difference in a double blind test.
Myth 4: Stiffer Frames Are Faster
The results confirmed our previous impressions: Two of our three testers could identify which frame they were riding with 100% accuracy, just based on how the frames performed under hard pedaling.
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Re: 23mm 100psi faster on short climbs?
Postby uart » Fri Jan 04, 2019 4:48 pm
Hi g-boaf. It's not really a matter of you missing out on some kind of magical extra power if you have a stiffer frame, quite the reverse actually. The argument is simply that the power "lost" due to frame flex is not necessarily lost in reality, and in some cases much of it may be returned at a different part of the pedalling cycle.g-boaf wrote:So how powerful in watts must one be to benefit from this spring effect, and based on that, work out what this 12% works out to be in watts (and tell me that number) and finally then tell me if you really, truly believe that.
Sounds like John Howard's core and non-core promises. No, I don't believe a word of it.HausFinch wrote:He makes no blanket claim about more flex being unequivocally better.
When a frame flexes under pedalling pressure, some of the power delivered to the pedal during that time is not transferred to the drive train - it instead goes into flexing the frame. The amount of energy that gets "diverted" into flexing the frame is proportional to the product of the pedal force and the frame displacement, so for any given pedaling force this flex energy is directly proportional to the amount of frame flex.
The traditional view was that this energy is largely lost, and hence the desire for stiffer frames as they would lose less energy. The above research doesn't actually suggest that there is true energy boost to having a flexible frame, it instead only suggests that much of the "flex energy" may not actually be lost, and that the previously perceived disadvantage of frame flex may not be as much as thought.
Given this view of flex energy possibly being returned, they postulated that the amount of frame flex desired might be more a matter of what suits a particular rider's style (or even just what they are accustomed to) rather than some kind of "hard and fast" rule that stiffer is always better.
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Re: 23mm 100psi faster on short climbs?
Postby uart » Fri Jan 04, 2019 4:54 pm
One issue that I have with any research that shows riders unable to detect differences in frame flex when tyre pressures were "blindly" altered by the researches, is that it would only prove (if true) that tyre pressures have a stronger influence on the ride feel and performance compared to frame flex.Thoglette wrote:Cite please?Alex Simmons/RST wrote:When testers were blinded to the bikes they were riding (supposed “compliant” and “stiff” frames that had frames covered), they were no better than random chance at picking the frame type when tyre pressures were controlled. The primary correlation for what frame type they thought they were riding was all down to the experimenter changing tyre pressure, not the frame.
The following article had two of three testers able to tell the difference in a double blind test.
Myth 4: Stiffer Frames Are FasterThe results confirmed our previous impressions: Two of our three testers could identify which frame they were riding with 100% accuracy, just based on how the frames performed under hard pedaling.
It wouldn't actually prove that frame flex had no effect or that it was truly undetectable. It would only prove that the confounding variable (in this case tyre pressure) had a stronger effect.
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Re: 23mm 100psi faster on short climbs?
Postby mikesbytes » Sat Jan 05, 2019 12:12 am
That's how I understand it. I was wondering if there were any articles that explain how much of the flex energy gets transferred into forward motionuart wrote:.....
When a frame flexes under pedalling pressure, some of the power delivered to the pedal during that time is not transferred to the drive train - it instead goes into flexing the frame. The amount of energy that gets "diverted" into flexing the frame is proportional to the product of the pedal force and the frame displacement, so for any given pedaling force this flex energy is directly proportional to the amount of frame flex.
The traditional view was that this energy is largely lost, and hence the desire for stiffer frames as they would lose less energy. The above research doesn't actually suggest that there is true energy boost to having a flexible frame, it instead only suggests that much of the "flex energy" may not actually be lost, and that the previously perceived disadvantage of frame flex may not be as much as thought.
Given this view of flex energy possibly being returned, they postulated that the amount of frame flex desired might be more a matter of what suits a particular rider's style (or even just what they are accustomed to) rather than some kind of "hard and fast" rule that stiffer is always better.
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Re: 23mm 100psi faster on short climbs?
Postby Thoglette » Sun Jan 06, 2019 10:35 pm
Not that I know of: there's some armchair theorising in the article I linked earlier.mikesbytes wrote: That's how I understand it. I was wondering if there were any articles that explain how much of the flex energy gets transferred into forward motion
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