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The importance of crank length to the cyclist.

23 Feb 2013 04:18

FrankDay wrote:Actually, I don't think he would but since he isn't here I don't think either one of us should try to speak for him


Yup people can go to Slowtwitch and look at Jim's disagreement with your opinion if the want to.


Fergie, not sure what constitutes "actual data" in your mind. Just to help you out here in understanding the difference between anecdotal data and scientific data (which is what I think we are talking about) I refer you to this article in Wikipedia Here is a quote from the article


Outstanding, you linked to the same article I linked in my post. And you claim we don't read your posts:cool:

Anecdotal evidence is important when it leads people to investigate new areas and to the discovery of new knowledge. I believe that is what I am trying to foment here, awareness of this possibility that might lead to additional research in this area.


What additional research, it's been done. Dr Martin has nicely summarised it for us. Even done a few studies since. Meaningless stories without evidence to whether crank length actually made a difference or not do not add anything to the debate.
Hamish Ferguson
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23 Feb 2013 04:57

For those who prefer not to determine importance based on anecdotal evidence. First 3 are a cut and paste from a weight weenies post but I have all these full papers.

So it's not like good people haven't tested crank length fully.

Neuromuscular and biomechanical coupling in human cycling: adaptations to changes in crank length. Mileva Katya; Turner Duncan Sport and Exercise Science Research Centre, Faculty of Engineering Science and Technology, South Bank University, 103 Borough Road, London, SE1 0AA, UK. Experimental brain research. Experimentelle Hirnforschung. Experimentation cerebrale (2003 Oct), 152(3), 393-403.

This study exploited the alterations in pedal speed and joints kinematics elicited by changing crank length (CL) to test how altered task mechanics during cycling will modulate the muscle activation characteristics in human rectus femoris (RF), biceps femoris long head (BF), soleus (SOL) and tibialis anterior (TA). Kinetic (torque), kinematic (joint angle) and muscle activity (EMG) data were recorded simultaneously from both legs of 10 healthy adults (aged 20-38 years) during steady-state cycling at 60 rpm and 90-100 W with three symmetrical CLs (155 mm, 175 mm and 195 mm). The CL elongation (DeltaCL) resulted in similar increases in the knee joint angles and angular velocities during extension and flexion, whilst the ankle joint kinematics was significantly influenced only during extension. DeltaCL resulted in significantly reduced amplitude and prolonged duration of BF EMG, increased mean SOL and TA EMG amplitudes, and shortened SOL activity time. RF activation parameters and TA activity duration were not significantly affected by DeltaCL. Thus total SOL and RF EMG activities were similar with different CLs, presumably enabling steady power output during extension. Higher pedal speeds demand an increased total TA EMG activity and decreased total BF activity to propel the leg through flexion into extension with a greater degree of control over joint stability. We concluded that the proprioceptive information about the changes in the cycling kinematics is used by central neural structures to adapt the activation parameters of the individual muscles to the kinetic demands of the ongoing movement, depending on their biomechanical function.

Mechanical efficiency of cycling with a new developed pedal-crank. Zamparo Paola; Minetti Alberto; di Prampero Pietro Dipartimento di Scienze e Tecnologie Biomediche, Universita degli Studi di Udine, Piazzale Kolbe 4, 33100 Udine, Italy. p.zamparo@mmu.ac.uk JOURNAL OF BIOMECHANICS (2002 Oct), 35(10), 1387-98.

The mechanical efficiency of cycling with a new pedal-crank prototype (PP) was investigated during an incremental test on a stationary cycloergometer. The efficiency values were compared with those obtained, in the same experimental conditions and with the same subjects, by using a standard pedal-crank system (SP). The main feature of this prototype is that its pedal-crank length changes as a function of the crank angle being maximal during the pushing phase and minimal during the recovery one. This variability was expected to lead to a decrease in the energy requirement of cycling since, for any given thrust, the torque exerted by the pushing leg is increased while the counter-torque exerted by the contra-lateral one is decreased. Whereas no significant differences were found between the two pedal-cranks at low exercise intensities (w*=50-200 W), at 250-300 W the oxygen uptake (V*O2, W) was found to be significantly lower and the efficiency (eta=w*/V*O2) about 2% larger (p<0.05, Wilcoxon test) in the case of PP. Even if the measured difference in efficiency was rather small, it can be calculated that an athlete riding a bicycle equipped with the patented pedal-crank could improve his 1h record by about 1 km.

Determinants of metabolic cost during submaximal cycling. McDaniel J; Durstine J L; Hand G A; Martin J C Department of Exercise Science, University of South Carolina, Columbia, South Carolina 29208, USA JOURNAL OF APPLIED PHYSIOLOGY (2002 Sep), 93(3), 823-8.

The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost (R(2) = 0.99 +/- 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 +/- 7 metabolic watts and 22.1 +/- 0.3% (145-mm cranks, 40 rpm) to a high of 297 +/- 23 metabolic watts and 26.6 +/- 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.

Determinants of maximal cycling power: crank length, pedaling rate and pedal speed. Martin J C; Spirduso W W University of Utah, Department of Exercise and Sport Science, 250S. 1850E. Rm. 200, Salt Lake City, UT 84112-0920, USA. jim.martin@health.utah.edu Eur J Appl Physiol (2001 May), 84(5), 413-8.

The purpose of this investigation was to determine the effects of cycle crank length on maximum cycling power, optimal pedaling rate, and optimal pedal speed, and to determine the optimal crank length to leg length ratio for maximal power production. Trained cyclists (n = 16) performed maximal inertial load cycle ergometry using crank lengths of 120, 145, 170, 195, and 220 mm. Maximum power ranged from a low of 1149 (20) W for the 220-mm cranks to a high of 1194 (21) W for the 145-mm cranks. Power produced with the 145- and 170-mm cranks was significantly (P < 0.05) greater than that produced with the 120- and 220-mm cranks. The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks. Conversely, optimal pedal speed increased significantly with increasing crank length, from 1.71 m/s for the 120-mm cranks to 2.53 m/s for the 220-mm cranks. The crank length to leg length and crank length to tibia length ratios accounted for 20.5% and 21.1% of the variability in maximum power, respectively. The optimal crank length was 20% of leg length or 41% of tibia length. These data suggest that pedal speed (which constrains muscle shortening velocity) and pedaling rate (which affects muscle excitation state) exert distinct effects that influence muscular power during cycling. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults.

Elite Cycling Aerodynamics: Wind Tunnel Experiments and CFD
M. D. Griffith, T. Crouch, M. C. Thompson, D. Burton and J. Sheridan
Department of Mechanical & Aerospace Engineering, Monash University, Victoria 3800, Australia

18th Australasian Fluid Mechanics Conference
Launceston, Australia
3-7 December 2012

Abstract
An experimental and numerical study of the aerodynamics of a
cyclist in a typical racing position is presented. The study aims
to provide understanding of the fundamental aerodynamic characteristics
which underpin variations of drag with changes to
rider shape and position. Experimentally, for a mannequin (with
static crank/leg position) in a wind tunnel, velocity fields at several
streamwise stations are measured by traversing the plane
with a probe. The structure of the wake depends strongly on
the leg position, is associated with the flow around the hips and
can lead to large variations in the drag. Numerically, the same
mannequin geometry is modeled and the flow simulated using a
commercial fluid flow solver (ANSYS–CFX). Similar variation
with crank angle of drag and flow topology is observed. Transient
flow simulations are found to match better with the mean
velocity experimental measurements. It is found that for some
crank angles, the wake is defined by a relatively strong vortex
pair, and for others the wake is more oscillatory.
Hamish Ferguson
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23 Feb 2013 04:57

Effect of Crank Length on Joint-Specific
Power during Maximal Cycling
PAUL R. BARRATT1,2, THOMAS KORFF1, STEVE J. ELMER3, and JAMES C. MARTIN3
1Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge, UNITED KINGDOM;
2Department of Performance Analysis and Biomechanics, English Institute of Sport, Manchester, UNITED KINGDOM;
and 3Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT
ABSTRACT
BARRATT, P. R., T. KORFF, S. J. ELMER, and J. C. MARTIN. Effect of Crank Length on Joint-Specific Power during Maximal
Cycling. Med. Sci. Sports Exerc., Vol. 43, No. 9, pp. 1689–1697, 2011. Previous investigators have suggested that crank length has little
effect on overall short-term maximal cycling power once the effects of pedal speed and pedaling rate are accounted for. Although overall
maximal power may be unaffected by crank length, it is possible that similar overall power might be produced with different combinations
of joint-specific powers. Knowing the effects of crank length on joint-specific power production during maximal cycling may
have practical implications with respect to avoiding or delaying fatigue during high-intensity exercise. Purpose: The purpose of this
study was to determine the effect of changes in crank length on joint-specific powers during short-term maximal cycling. Methods:
Fifteen trained cyclists performed maximal isokinetic cycling trials using crank lengths of 150, 165, 170, 175, and 190 mm. At each
crank length, participants performed maximal trials at pedaling rates optimized for maximum power and at a constant pedaling rate of
120 rpm. Using pedal forces and limb kinematics, joint-specific powers were calculated via inverse dynamics and normalized to overall
pedal power. Results: ANOVAs revealed that crank length had no significant effect on relative joint-specific powers at the hip, knee, or
ankle joints (P 9 0.05) when pedaling rate was optimized. When pedaling rate was constant, crank length had a small but significant effect
on hip and knee joint power (150 vs 190 mm only) (P G 0.05). Conclusions: These data demonstrate that crank length does not affect
relative joint-specific power once the effects of pedaling rate and pedal speed are accounted for. Our results thereby substantiate previous
findings that crank length per se is not an important determinant of maximum cycling power production. Key Words: BIOMECHANICS,
MUSCLE POWER, SPRINT CYCLING, CYCLING PERFORMANCE

Influence of crank length on cycle ergometry performance
of well-trained female cross-country mountain bike athletes
Paul William Macdermid Æ Andrew M. Edwards

Abstract The aim of this study was to determine the
differential effects of three commonly used crank lengths
(170, 172.5 and 175 mm) on performance measures relevant
to female cross-country mountain bike athletes
(n = 7) of similar stature. All trials were performed in a
single blind and balanced order with a 5- to 7-day period
between trials. Both saddle height and fore-aft position to
pedal axle distance at a crank angle of 90 was controlled
across all trials. The laboratory tests comprised a supramaximal
(peak power-cadence); an isokinetic (50 rpm)
test; and a maximal test of aerobic capacity. The time to
reach supra-maximal peak power was significantly
(P\0.05) shorter in the 170 mm (2.57 ± 0.79 s) condition
compared to 175 mm (3.29 ± 0.76 s). This effect
represented a mean performance advantage of 27.8% for
170 mm compared to 175 mm. There was no further intercondition
differences between performance outcome measurements
derived for the isokinetic (50 rpm) maximum
power output, isokinetic (50 rpm) mean power output or
indices of endurance performance. The decreased time to
peak power with the greater rate of power development in
the 170 mm condition suggests a race advantage may be
achieved using a shorter crank length than commonly
observed. Additionally, there was no impediment to either
power output produced at low cadences or indices of
endurance performance using the shorter crank length and
the advantage of being able to respond quickly to a change
in terrain could be of strategic importance to elite athletes.

Fatigue during Maximal Sprint Cycling: Unique
Role of Cumulative Contraction Cycles
ALEKSANDAR TOMAS1, EMMA Z. ROSS2, and JAMES C. MARTIN1
1Department of Exercise and Sport Science, the University of Utah, Salt Lake City, UT; and 2Sport and Exercise Science,
Chelsea School, University of Brighton, Eastbourne, East Sussex, England, UNITED KINGDOM
ABSTRACT
TOMAS, A., E. Z. ROSS, and J. C. MARTIN. Fatigue during Maximal Sprint Cycling: Unique Role of Cumulative Contraction Cycles.
Med. Sci. Sports Exerc., Vol. 42, No. 7, pp. 1364–1369, 2010. Abstract: Maximal cycling power has been reported to decrease more
rapidly when performed with increased pedaling rates. Increasing pedaling rate imposes two constraints on the neuromuscular system:
1) decreased time for muscle excitation and relaxation and 2) increased muscle shortening velocity. Using two crank lengths allows the
effects of time and shortening velocity to be evaluated separately. Purposes: We conducted this investigation to determine whether the
time available for excitation and relaxation or the muscle shortening velocity was mainly responsible for the increased rate of fatigue
previously observed with increased pedaling rates and to evaluate the influence of other possible fatiguing constraints. Methods: Seven
trained cyclists performed 30-s maximal isokinetic cycling trials using two crank lengths: 120 and 220 mm. Pedaling rate was optimized
for maximum power for each crank length: 135 rpm for the 120-mm cranks (1.7 mIsj1 pedal speed) and 109 rpm for the 220-mm
cranks (2.5 mIsj1 pedal speed). Power was recorded with an SRM power meter. Results: Crank length did not affect peak power: 999 T
276 W for the 120-mm crank versus 1001 T 289 W for the 220-mm crank. Fatigue index was greater (58.6% T 3.7% vs 52.4% T 4.8%,
P G 0.01), and total work was less (20.0 T 1.8 vs 21.4 T 2.0 kJ, P G 0.01) with the higher pedaling rate–shorter crank condition.
Regression analyses indicated that the power for the two conditions was most highly related to cumulative work (r2 = 0.94) and to
cumulative cycles (r2 = 0.99). Conclusions: These results support previous findings and confirm that pedaling rate, rather than
pedal speed, was the main factor influencing fatigue. Our novel result was that power decreased by a similar increment with
each crank revolution for the two conditions, indicating that each maximal muscular contraction induced a similar amount of fatigue.
Key Words: POWER, ERGOMETER, MUSCLE, CALCIUM, FORCE
Hamish Ferguson
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23 Feb 2013 05:00

Eur J Appl Physiol. 2002 Jan;86(3):215-7.
Effects of crank length on maximal cycling power and optimal pedaling rate of boys aged 8-11 years.
Martin JC, Malina RM, Spirduso WW.
Source
Department of Exercise and Sport Science, University of Utah, Salt Lake City 84112-0920, USA. Jim.Martin@health.utah.edu
Abstract
It is generally reported that cycle crank length affects maximal cycling power of adults and that optimal crank length is related to leg length. This suggests that the use of standard length cycle cranks may provide nonoptimal test conditions for children. The purpose of this study was to determine the effects of cycle-crank length on maximal cycling power and optimal pedaling rate of 17 boys aged 8-11 years. The boys performed maximal cycle ergometry with standard (170 mm) cycle cranks and with a crank length that was 20% of estimated leg length (LL20). Power produced when using the 170 mm cranks [mean (SEM)] [364 (18) W] did not differ from that produced with the LL20 cranks [366 (19)]. Optimal pedaling rate was significantly greater for the LL20 cranks [129 (4) rpm] than for the 170 mm cranks [114 (4) rpm]. These data suggest that standard 170 mm cranks do not compromise maximal power measurements in boys aged 8-11 years so that the test apparatus does not bias physiological or developmental inferences made from tests of maximal cycling power.

A governing relationship for repetitive muscular contraction.
Martin JC, Brown NA, Anderson FC, Spirduso WW.
Source
Department of Exercise Science, School of Public Health, The University of South Carolina, Columbia 29208, USA. jcmartin@sph.sc.edu
Abstract
During repetitive contractions, muscular work has been shown to exhibit complex relationships with muscle strain length, cycle frequency, and muscle shortening velocity. Those complex relationships make it difficult to predict muscular performance for any specific set of movement parameters. We hypothesized that the relationship of impulse with cyclic velocity (the product of shortening velocity and cycle frequency) would be independent of strain length and that impulse-cyclic velocity relationships for maximal cycling would be similar to those of in situ muscle performing repetitive contraction. Impulse and power were measured during maximal cycle ergometry with five cycle-crank lengths (120-220mm). Kinematic data were recorded to determine the relationship of pedal speed with joint angular velocity. Previously reported in situ data for rat plantaris were used to calculate values for impulse and cyclic velocity. Kinematic data indicated that pedal speed was highly correlated with joint angular velocity at the hip, knee, and ankle and was, therefore, considered a valid indicator of muscle shortening velocity. Cycling impulse-cyclic velocity relationships for each crank length were closely approximated by a rectangular hyperbola. Data for all crank lengths were also closely approximated by a single hyperbola, however, impulse produced on the 120mm cranks differed significantly from that on all other cranks. In situ impulse-cyclic velocity relationships exhibited similar characteristics to those of cycling. The convergence of the impulse-cyclic velocity relationships from most crank and strain lengths suggests that impulse-cyclic velocity represents a governing relationship for repetitive muscular contraction and thus a single equation can predict muscle performance for a wide range of functional activities. The similarity of characteristics exhibited by cycling and in situ muscle suggests that cycling can serve as a window though which to observe basic muscle function and that investigators can examine similar questions with in vivo and in situ models.
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23 Feb 2013 05:56

Found a few more with Google Scholar. I find it amazing that someone who claims that crank length is so important was so lazy to base his claims (poorly) off one study.

The effect of bicycle crank-length variation upon power performance

OMRI INBAR, RAFFY DOTAN, THOMAS TROSUL & ZEEV DVIR

Abstract
The purpose of the present study was to define the optimal bicycle crank length (CL) for eliciting maximal leg power output during a 30 s power test (Wingate Anaerobic Test). Thirteen male students 22-27 years old served as subjects for this study. In each of the five sessions the test was administered on a mechanically braked cycle-ergometer modified by a crank slider-assembly which permitted continuous crank-length adjustment. Five evenly spaced CLs, centred around the conventional 17.5 cm crank, ranging from 12.5 to 22.5 cm, were used. The measured variables were mean (MP) and peak (PP) power output. A parabola-fitting technique was employed to define the optimal CL from the MP and PP data. The resulting optimal CL was 16.4 and 16.6 cm for MP and PP, respectively. Optimal CL was shown to depend on leg length. However, within a two crank length span (± 5 cm) about the optimal crank length MP and PP did not vary by more than 0.77 and 1.24% respectively. It is suggested that for a homogenous population, such as used in this study, the conventional 17.5 cm crank is close to the calculated optimum for power production. However, a failure to adjust this factor to the anthropometric dimensions of populations, heterogenous in size, may result in a much greater fall-off in cycle short-term power performance.

The effects of bicycle crank arm length on oxygen consumption.
Morris DM, Londeree BR.
Source
PerforMax: Sports Science Training and Consulting, Colorado Springs, CO 80909, USA.
Abstract
The purpose of this investigation was to determine the effects of various crank arm lengths on oxygen consumption for trained cyclists. Secondary purposes were, if optimal crank arm lengths existed, to determine if these lengths could be predicted based on an individual's leg length. Six trained cyclists completed four experimental protocols riding at a workload of approximately 68% of VO2 max using crank arm lengths of 165, 170, and 175 mm. During each protocol, the cadence, oxygen consumption, and distance traveled were determined, and values were combined to give a VO2.m-1.min-1 value. The values then were placed in either a high, medium, or low efficiency category. Significant differences were found among the three protocols. No significant correlations were found between each subject's most efficient crank arm length and leg length. The results of the study suggest that each subject has a most efficient crank arm length, but it does not appear that optimal crank arm length can be predicted by leg length

Bivariate optimization of pedalling rate and crank arm length in cycling
M.L. Hull, H. Gonzalez

Abstract
The contribution of this paper is a bivariate optimization of cycling performance. Relying on a biomechanical model of the lower limb, a cost function derived from the joint moments developed during cycling is computed. At constant average power, both pedalling rate (i.e. rpm) and crank arm length are systematically varied to explore the relation between these variables and the cost function. A crank arm length of 170 mm and pedalling rate of 100 rpm correspond closely to the cost function minimum. In cycling situations where the rpm deviates from 100 rpm, however, crank arms of length other than 170 mm yield minimum cost function values. In addition, the sensitivity of optimization results to both increased power and anthropometric parameter variations is examined. At increased power, the cost function minimum is more strongly related to the pedalling rate, with higher pedalling rates corresponding to the minimum. Anthropometric parameter variations influence the results significantly. In general it is found that the cost function minimum for tall people occurs at longer crank arm lengths and lower pedalling rates than the length and rate for short people.

Short Crank Ergometry
Schwartz RE, Asnis PD, Cavanaugh JT, Asnis SE, Simmons JE, Lasinski PJ

The change in knee angle during cycling was mathematically analyzed. It was determined that if the crank length of the cycle ergometer was shortened, the arc of knee motion necessary to cycle could be reduced. A computer program was written to represent the above mathematical model utilizing a patient's lower limb lengths to generate an individualized, range of motion profile. A custom cycle ergometer was built with interchangeable crank lengths of 80 mm, 110 mm, 140 mm, and 170 mm. This device can be adjusted to achieve a desired range of motion for a specific patient. The above custom cycle ergometer can be used on early postoperative knee patients who are unable to ride a conventional cycle ergometer because of a lack of knee motion or on patients who require a limited arc of motion in their postoperative therapy protocol. J Orthop Sports Phys Ther 1991;13(2):95-100
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23 Feb 2013 07:57

Hey Fergie, thanks for all those studies. I think the crux of all that is my original contention stands. We all agree that crank length over a wide range has only a small impact on power for most individuals when they are in a standard riding position. Of course, my contention is that each individual cannot know if this is true for them without testing. If you only care about power and you believe that the average of the studies applies to every individual then ride whatever you want.

However, if you had been paying attention to this thread, which clearly you haven't, my main contention is that crank length has its major influence on how good of an aerodynamic position most can attain and if there is going to be an affect on power it will be larger when in the aerodynamic position. Not one of those studies refutes that contention. If you think that unimportant so be it. But, some are focused on more than just power and many believe aerodynamics to be equally as important as power as the two major influences on time trial performance.

Oh, and I didn't see a single one of those crank length studies looking at effects of crank length on power being tested in an aerodynamic position. Can you point to where a single one of those studies specified what position the riders were in when tested? Anyhow, when you can find one of those, get back to the group because that is really what I am talking about. So, it is still up in the air as to how much influence crank length has on power when the rider is in the aerodynamic position regardless of how much band width you waste claiming this is all said and done.

My hypothesis is still intact despite all of your efforts. Thanks for trying though. Now that we know that there are still studies to be done maybe someone out there will do them.
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23 Feb 2013 08:36

FrankDay wrote:We all agree that crank length over a wide range has only a small impact on power for most individuals when they are in a standard riding position.


I refer you to your original comment at the start of the thread...

In summary I feel that shorter cranks do several things for the cyclist.

1. Shorter cranks will improve power output for most.


However, if you had been paying attention to this thread, which clearly you haven't, my main contention is that crank length has its major influence on how good of an aerodynamic position most can attain and if there is going to be an affect on power it will be larger when in the aerodynamic position.


Hmmmm, okay I refer you to the full original point...

In summary I feel that shorter cranks do several things for the cyclist.

1. Shorter cranks will improve power output for most.
2. Although this goes completely against the conventional wisdom, shorter cranks can reduce knee stress
3. Shorter cranks allow better aerodynamic positioning without sacrificing power.


Not one of those studies refutes that contention. If you think that unimportant so be it. But, some are focused on more than just power and many believe aerodynamics to be equally as important as power as the two major influences on time trial performance.


That is correct but there is a little more to aerodynamics than adjusting crank length. Watching the World Championships on TV I don't see too many un-aerodynamic positions and watching our local Tuesday night TT's (my rider won BTW poking in an extra 18 watts over the week before) the riders with poor aerodynamics positions were either old, fat or inflexible. The latter two can be fixed and at least with age odds are everyone is in the same boat.

Oh, and I didn't see a single one of those crank length studies looking at effects of crank length on power being tested in an aerodynamic position. Can you point to where a single one of those studies specified what position the riders were in when tested? Anyhow, when you can find one of those, get back to the group because that is really what I am talking about. So, it is still up in the air as to how much influence crank length has on power when the rider is in the aerodynamic position regardless of how much band width you waste claiming this is all said and done.


Your point would only be relevant if changing crank length was the only option to improve aerodynamics.
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23 Feb 2013 15:40

FrankDay wrote:
When I have the ability to measure pedal forces around the circle (hopefully soon) will it be unacceptable to post how pedal forces change as crank length changes?



What changes are you expecting to see and how will they affect performance ?
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23 Feb 2013 18:07

coapman wrote:What changes are you expecting to see and how will they affect performance ?
I expect to see a better distribution of power around the circle with shorter cranks, especially an improvement on the backstroke portion. I think this can explain why power remains essentially unchanged with crank length over a wide range of crank lengths. If not this then I hope to see something to be able to better explain this phenomenon.
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23 Feb 2013 18:14

CoachFergie wrote:That is correct but there is a little more to aerodynamics than adjusting crank length. Watching the World Championships on TV I don't see too many un-aerodynamic positions and watching our local Tuesday night TT's (my rider won BTW poking in an extra 18 watts over the week before) the riders with poor aerodynamics positions were either old, fat or inflexible. The latter two can be fixed and at least with age odds are everyone is in the same boat.
LOL, Perhaps you might want to spend some time watching an the age-groupers in an event like the Ironman and tell me how many un-aerodynamic positions you see. It is my contention that the shorter cranks especially help the inflexible, or those with back issues, of which there are many.



Your point would only be relevant if changing crank length was the only option to improve aerodynamics.
Yes, but how many can get into those great aerodyanmic positions without losing substantial power? Or, maintain that great aerodynamic position for 5 hours or so. That is the point you can't seem to grasp. Where is that study?
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23 Feb 2013 18:17

FrankDay wrote:I expect to see a better distribution of power around the circle with shorter cranks, especially an improvement on the backstroke portion. I think this can explain why power remains essentially unchanged with crank length over a wide range of crank lengths. If not this then I hope to see something to be able to better explain this phenomenon.


Even if this is the case the numerous studies performed have show that the overall power is not significantly higher so any change does not contribute to improved performance.
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23 Feb 2013 18:33

CoachFergie wrote:Even if this is the case the numerous studies performed have show that the overall power is not significantly higher so any change does not contribute to improved performance.
I repeat, no studies have been done with the subjects in the aerodynamic position. So, we don't know this to be a fact but anecdotal evidence suggests that crank length has a much greater impact on power when in the aero position than when riding more upright. Hence, all your numerous studies are worthless for this condition.
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23 Feb 2013 18:48

FrankDay wrote:I repeat, no studies have been done with the subjects in the aerodynamic position. So, we don't know this to be a fact but anecdotal evidence suggests that crank length has a much greater impact on power when in the aero position than when riding more upright. Hence, all your numerous studies are worthless for this condition.


I repeat that if changing crank length was the only way to improve aerodynamics your point would mean something.
Hamish Ferguson
coachfergblog.blogspot.co.nz
User avatar CoachFergie
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24 Feb 2013 00:15

CoachFergie wrote:I repeat that if changing crank length was the only way to improve aerodynamics your point would mean something.


I haven't checked this thread in about three months and this was one of the first things pointed out. Even the assertion that shorter cranks help pedalling fluidity and completeness of power distribution was/is a counter argument to real life. A good cyclist has gearing choices and shifters; they also change their position based on effort if they know what they're doing. When they are strong and the demand is there for maximum output they are going to big gears, period. I have not seen any serious cyclist push a 53X13-11 in a race situation with cranks under 170mm, ever. Having ridden the track with many geeks I can safely say real world research on 165mm to 180mm cranks yields sweet spots for different output demands.
Same tired discussion...
Oldman
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26 Feb 2013 03:48

This thread is now closed. The topic of crank length got hijacked until this thread was ONLY about extremely short cranks, and PowerCranks.

Someone is free to start a thread about the use of extremely short crankarms, but it should be labeled clearly as such. Or, they can use the latest Powercrank thread, unless the discussion of short cranks begins to detract from the discussion of uncoupled crankarm theories.

The new crank length thread will be about generally accepted crankarm length and issues pertaining to that.
It is of great use to the sailor to know the length of his line, though he cannot with it fathom all the depths of the ocean. ~ John Locke
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