pedaling efficiency of clipless vs platform tested
01-09-15 | 02:22 PM
#126
In the wind
Joined: Aug 2006
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From: Calgary AB
Bikes: Giant TCR Advanced Team, Lemond Buenos Aires, Giant TCX, Miyata 1000LT
You mean, partially quoting from the abstract. I explicitly stated that this study showed an increase in watts -- but no changes in velocity. The very next line reads:
"In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." (Emphasis added)
Again, I haven't read the article, so I cannot clarify this apparent conflict.
"In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." (Emphasis added)
Again, I haven't read the article, so I cannot clarify this apparent conflict.
I haven't read the article either but the abstract seems pretty clear and without conflict. Briefly:
a) it doesn't matter how you pedal or if you have foot retention, once you reach your maximum velocity, you are at the maximum. Clips won't help you go faster than flats.
but
b) clips allow you to exert more force on the cranks before reaching maximum velocity. This implies greater acceleration, meaning clips allow you to reach your maximum velocity faster.
For anyone that is racing, or climbing hills, that second point would favor foot retention. If you are just riding along, it probably doesn't matter that much since the limit of your speed is not related to what type of pedals you have.
01-25-15 | 04:09 PM
#127
Cathedral City, CA
Joined: Oct 2004
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From: Cathedral City, CA
Bikes: 2016 RITCHEY BreakAway (full Chorus 11), 2005 Ritchey BreakAway (full Chorus 11, STOLEN), 2001 Gary Fisher Tassajara mountain bike (sold), 2004 Giant TRC 2 road bike (sold)
01-25-15 | 04:54 PM
#128
Old Fart
Joined: Dec 2014
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From: Bumpkinsville
Bikes: '97 Klein Quantum '16 Gravity Knockout
You mean, partially quoting from the abstract. I explicitly stated that this study showed an increase in watts -- but no changes in velocity. The very next line reads:
"In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." (Emphasis added)
Again, I haven't read the article, so I cannot clarify this apparent conflict.
"In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." (Emphasis added)
Again, I haven't read the article, so I cannot clarify this apparent conflict.
01-25-15 | 06:52 PM
#129
Senior Member
Joined: Nov 2014
Posts: 27,576
Likes: 5,454
From: Eugene, Oregon, USA
Like walking and chewing gum at the same time. One can't possibly get the full effect of mastication while walking.
01-25-15 | 08:12 PM
#130
Senior Member
Joined: Nov 2014
Posts: 27,576
Likes: 5,454
From: Eugene, Oregon, USA
Here are some quotes from:
Science of Cycling, Edmund Burke, 1986
Chapter 5, The Biomechanics of Cycling: Studies of the Pedaling Mechanics of Elite Pursuit Riders, Peter Cavanagh, David Sanderson, P. 117-119
What is obvious is that many of the studies are ignoring climbing, as well as short hill climbs and short sprints. Steady state cycling in a laboratory is not representative of non steady state riding in the field.
Unloading of the pedals, of course, is not without benefit as it reduces the pedaling forces of the opposite leg.
In this low inertial test which may approach a hill climb, the amateur riders are, in fact, pulling up. 15 lbs may not be considered a lot, but when added to the unloading, it isn't insignificant either.
I certainly don't pull up all of the time, but I do some of the time, and maybe not with a great force, but every little bit helps. Greatest during hard hill climbs, but also at least weakly during seated or standing acceleration phases.
Science of Cycling, Edmund Burke, 1986
Chapter 5, The Biomechanics of Cycling: Studies of the Pedaling Mechanics of Elite Pursuit Riders, Peter Cavanagh, David Sanderson, P. 117-119
Forces During the Recovery Phase - Pulling Up
The experiments described indicate that the energetics of cycling are affected by the mechanics of the recovery phase. This leads to a second issue, that is, whether cyclists pull up during this phase. When asked, most cyclists' response to a question regarding the direction of force application during the recovery phase is usually unequivocal. They say they definitely pull up. This seems contrary to most of the data reported in the literature and general response of the elite riders whose data we have seen so far. The force-measuring pedal shown earlier (see Figure 5 [photo of a lab pedal with toeclips and some kind of a strain gauge]) is obviously ideal to investigate this question....
When our measurements determine that the pedal is unloaded, the riders are actually pulling up to some degree. To unload the pedal during the recovery phase, they must overcome two forces, the first is the weight of the leg that gravity is pulling down against the pedal. The second is a force resulting from inertial effects - the tendency of the limb mass to resist the motion of the pedal. This second force would be present even in the absence of gravity. Our definition of pulling up is when the rider overcomes both of these forces and then applies more force so that an upward force is actually acting on the pedal.
In all of our studies of steady-state riding of the elite 4,000-m pursuit team and of recreational riders, we found only a few examples of pulling up. Some cyclists did exhibit unloading of the pedals during the latter portion of the recovery phase (315° to 360°) but rarely did they pull up. Typically, the pull-up forces, when they existed, were small and applied over a short duration.
These data are certainly contrary to the expressed opinion in a number of magazines [1986] suggesting that pulling up on the pedals could result in a 30% increase of efficiency. If changes in economy of riding were to be that large, surely the elite cyclist woudl pull up. Because no evidence supports the popular claims, we must question whey riders in laboratory experiments do not pull up. The literature on this issue has been specific and reproducible over a number of years and in different laboratories. Hoes, Binkhorst, Smeekes-Kuyl, and Vissers (1968), Gregor (1976), and Lafortune, Cavanagh, Valiant, and Burke (1983) have reported the absence of pull-up forces in the recovery phase. The one condition common to all of these investigations is that the riding is similar to high-speed riding on the level, it does not replicate sprint or climbing hills. The situation regarding pull up will change during these events.
We have conducted one experiment involving low inertial load. In this case, had the cyclist stopped pedaling, the cycle would also have stopped rapidly. As we can see in Figure 16, the subjects (recreational cyclists) did pull up between positions 15 and 20 with forces that reached a maximum of approximately 70N (15 lbs). In fact, they did not exert negative torques, even in positions 10 through 14, where most riders tend to show negative torques (see Figure 4 [Not displayed here])....
The experiments described indicate that the energetics of cycling are affected by the mechanics of the recovery phase. This leads to a second issue, that is, whether cyclists pull up during this phase. When asked, most cyclists' response to a question regarding the direction of force application during the recovery phase is usually unequivocal. They say they definitely pull up. This seems contrary to most of the data reported in the literature and general response of the elite riders whose data we have seen so far. The force-measuring pedal shown earlier (see Figure 5 [photo of a lab pedal with toeclips and some kind of a strain gauge]) is obviously ideal to investigate this question....
When our measurements determine that the pedal is unloaded, the riders are actually pulling up to some degree. To unload the pedal during the recovery phase, they must overcome two forces, the first is the weight of the leg that gravity is pulling down against the pedal. The second is a force resulting from inertial effects - the tendency of the limb mass to resist the motion of the pedal. This second force would be present even in the absence of gravity. Our definition of pulling up is when the rider overcomes both of these forces and then applies more force so that an upward force is actually acting on the pedal.
In all of our studies of steady-state riding of the elite 4,000-m pursuit team and of recreational riders, we found only a few examples of pulling up. Some cyclists did exhibit unloading of the pedals during the latter portion of the recovery phase (315° to 360°) but rarely did they pull up. Typically, the pull-up forces, when they existed, were small and applied over a short duration.
These data are certainly contrary to the expressed opinion in a number of magazines [1986] suggesting that pulling up on the pedals could result in a 30% increase of efficiency. If changes in economy of riding were to be that large, surely the elite cyclist woudl pull up. Because no evidence supports the popular claims, we must question whey riders in laboratory experiments do not pull up. The literature on this issue has been specific and reproducible over a number of years and in different laboratories. Hoes, Binkhorst, Smeekes-Kuyl, and Vissers (1968), Gregor (1976), and Lafortune, Cavanagh, Valiant, and Burke (1983) have reported the absence of pull-up forces in the recovery phase. The one condition common to all of these investigations is that the riding is similar to high-speed riding on the level, it does not replicate sprint or climbing hills. The situation regarding pull up will change during these events.
We have conducted one experiment involving low inertial load. In this case, had the cyclist stopped pedaling, the cycle would also have stopped rapidly. As we can see in Figure 16, the subjects (recreational cyclists) did pull up between positions 15 and 20 with forces that reached a maximum of approximately 70N (15 lbs). In fact, they did not exert negative torques, even in positions 10 through 14, where most riders tend to show negative torques (see Figure 4 [Not displayed here])....
Unloading of the pedals, of course, is not without benefit as it reduces the pedaling forces of the opposite leg.
In this low inertial test which may approach a hill climb, the amateur riders are, in fact, pulling up. 15 lbs may not be considered a lot, but when added to the unloading, it isn't insignificant either.
I certainly don't pull up all of the time, but I do some of the time, and maybe not with a great force, but every little bit helps. Greatest during hard hill climbs, but also at least weakly during seated or standing acceleration phases.
Last edited by CliffordK; 01-25-15 at 08:19 PM.
01-25-15 | 10:02 PM
#131
Old Fart
Joined: Dec 2014
Posts: 3,348
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From: Bumpkinsville
Bikes: '97 Klein Quantum '16 Gravity Knockout
Last edited by Stucky; 01-25-15 at 10:53 PM.
