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sciguy said:
for physiological improvements, I don't see how being more accurate would help from existing PMs taking into consideration day to day variations from hydration, glycogen stores, motivation etc etc
- Apr 21, 2009
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function said:
The role of the power meter isn't to measure hydration, glycogen or motivation. It's to measure power. If power is down from day to day then it's an indicator you need to check hydration, glycogen stores or question motivation.
As mentioned one of my guys has done three rides with both Keo/Polar and Quarq power meters and the Keo/Polar data is very inconsistent. Neither accurate or precise. A rider could be patting himself on the back one day and in complete despair the next.
I'm still trying to work out who, aside from sports scientists, would want a crank that measures independent leg power.
What's the benefit or point?
What's the benefit or point?
- Apr 21, 2009
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Tapeworm said:
Be interested to hear if a sport scientist would find it of interest. Performance is usually their main concern.
Well, it could be of benefit to medical rehab specialists in documenting specific weakness and improvement, for one.Tapeworm said:
CoachFergie said:
So you're telling me if your athlete's power is down within the error margins of current power meters (e.g. SRM, you were advocating more accurate than SRM), you would have them check their hydration etc etc.
Personally i would just flag it as being a biological organism instead of a machine.
FrankDay said:
Frank,
How does the data generated by using these match up with your Velotron numbers?
Hugh
It is hard to say. I set the Velotron on ergometer mode (keeps a steady power) and it seemed I was getting about 25 watts higher on these cranks (didn't realize I could smooth that also so it hopped around a bit). I was lucky I could make it work at all as the cranks require magnets on the bike to "wake them up" and the pickup on the drive side is inside the 62 tooth chain ring on the Velotron. Luckily, it seemed to work through the chain ring.sciguy said:
Now, we would expect it to be a little higher because one measures at the crank and the other at the wheel so we are not seeing any bearing or chain losses but I thought it was a little high. Also, even though the Garmin picks up both cranks and gives the total when one pedals with just the left leg it shows zero power, so it was hard for me to test the cranks independently. And, I think there is a calibration issue with one of the cranks as I consistently get a 60-40 left/right balance, which I find it hard to believe that I am that unbalanced.
There are a few other issues I uncovered. One "big" one was I had to cut off the little chain pick-up shaft off the big chain ring because it hit the electronics cover projecting inside the crank arm (and the derailleur if I tried to shift to the big ring). I believe they didn't notice this issue because they have done most of their development on an exercise bike that doesn't use a standard chain ring configuration or deraileur. Until one encounters a problem one usually has trouble envisioning it. This should be an easy fix.
Anyhow, these are minor issues that I think comes with designing any new product such as this. For a first prototype I am pleasantly impressed. What impressed me most is that the Garmin display is ready for two power meters right now, apparently in anticipation of the Vector pedal meters, which may never happen. That was a stroke of luck. It doesn't give much info while riding but as long as it collects it for download and later analysis I think that will satisfy most.
- Jul 17, 2009
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Is there a topic on any forum in the entire cyber universe more redundant than this one? Is there a topic with more ways to say the same thing than this one. Besides the 'should you wear team kits' or vegan threads that is....
it is however quite readable for the entertainment value
it is however quite readable for the entertainment value
crank arm length
Well 158 pages and counting, my favourites were the video with the dog and the post where the guy said "i'm right, you're wrong... etc"
To start this is my first post, but I have been a "lurker" on this subject for a while.
crank arm vs gearing:
The crank arm represents leverage and gearing represents the opposition against leverage, in other words the torque= force times leverage where as gearing represents the amount of torque you would like to apply. so when people say "just change your gearing- you'll get more power" this is akin to saying just change the gear box in your kia and you'll get the same horse power as my saab (1HP= 746 watts) so gearing and crank arm length are independent and in my view opposite. This is represented in some of Martins work i.e. the 4 sec max power study, so the argument that longer cranks present more torque is actually built into some of the studies.
On the new pedal power systems you have to input crank arm length in order to get some what accurate power numbers.
So if torque is higher with longer crank arms then why would shorter cranks be better? Um not sure, perhaps due to metabolic efficiency of spinning a smaller circle but this is off set by the higher rpm at a given torque to produce a given wattage.
So I sought to test this myself, after a fairly large 12 week base phase (april), it was time to get my clients in for some re-testing and see how the program is validated. so after a 20 hour week (mostly base) and a 2:45 longer trail run the night before, the very next day I tested myself at 185 cranks to see what I would produce. I had been using shorter cranks in for 4 weeks in feb but notice that power at certain HR's was too low, so from march to feb I was using 185's
The result was a 69 VO2 at 185 hr with 385 watts at peak, my rpm was low 70's. two days later I tested at 165's and my VO2 was 63 at 194 HR with the same peak wattage and spinning slightly higher at about 85 rpm.
So even though I was well rested on the 165 cranks (I own a velotron with varicrank) my peak power was unaffected but power at sub max load was greatly decreased with the shorter cranks. ER (ratio of fat to carb utilization, or O2 to Co2) was also much more efficient with the longer cranks at sub max HR.
We train for longer IM distance triathlons so I am uncertain as to how crank arm length may affect roadies or track cyclists, but on the surface when we do bike fit based on power and ER at the desired intensities for the event, testing at shorter crank arm lengths produces higher rpm and higher CO2 (higher carb vs fat utilization) at sub max IM pace, say around 83-88% of max HR depending on the athlete, in other words at least from a longer IM type perspective I fail to see how shorter cranks are better at least in terms of the testing we do, not all HR's are created equal at 145 hr energy utilization patterns are very different depending on what size crank you are using (perhaps based on spin which varies ratio of fast/slow twitch utilization, or perhaps based on the lower metabolic load of longer cranks creating a richer O2 environment)
Long cranks create injuries:
Umm, zero evidence on this one. in cycling injuries are based on frequency, duration, fit, intensity etc there is no evidence that I could find that longer cranks cause injuries. Hard to impossible to prove, in fact maybe you could argue that shorter cranks as you have to apply more net torque there would be a likelihood of higher injuries at shorter cranks.
The sample size of riders who are outside the norm is too small to say that injuries happen either way. IMO the greatest chance of injury comes from poor fit or poor training.
seat position and longer cranks:
If you go long you have to move your seat forward (at least in the TT) for IM we really like to open up the hip angle, although for most athletes this is better for power it also facilitates better digestion and higher O2 utilization, at longer triathlons and IM distance events the primary limiter is calories and hydration, so we need to get in as much as we can.
Just my 2c,
Maurice
Well 158 pages and counting, my favourites were the video with the dog and the post where the guy said "i'm right, you're wrong... etc"
To start this is my first post, but I have been a "lurker" on this subject for a while.
crank arm vs gearing:
The crank arm represents leverage and gearing represents the opposition against leverage, in other words the torque= force times leverage where as gearing represents the amount of torque you would like to apply. so when people say "just change your gearing- you'll get more power" this is akin to saying just change the gear box in your kia and you'll get the same horse power as my saab (1HP= 746 watts) so gearing and crank arm length are independent and in my view opposite. This is represented in some of Martins work i.e. the 4 sec max power study, so the argument that longer cranks present more torque is actually built into some of the studies.
On the new pedal power systems you have to input crank arm length in order to get some what accurate power numbers.
So if torque is higher with longer crank arms then why would shorter cranks be better? Um not sure, perhaps due to metabolic efficiency of spinning a smaller circle but this is off set by the higher rpm at a given torque to produce a given wattage.
So I sought to test this myself, after a fairly large 12 week base phase (april), it was time to get my clients in for some re-testing and see how the program is validated. so after a 20 hour week (mostly base) and a 2:45 longer trail run the night before, the very next day I tested myself at 185 cranks to see what I would produce. I had been using shorter cranks in for 4 weeks in feb but notice that power at certain HR's was too low, so from march to feb I was using 185's
The result was a 69 VO2 at 185 hr with 385 watts at peak, my rpm was low 70's. two days later I tested at 165's and my VO2 was 63 at 194 HR with the same peak wattage and spinning slightly higher at about 85 rpm.
So even though I was well rested on the 165 cranks (I own a velotron with varicrank) my peak power was unaffected but power at sub max load was greatly decreased with the shorter cranks. ER (ratio of fat to carb utilization, or O2 to Co2) was also much more efficient with the longer cranks at sub max HR.
We train for longer IM distance triathlons so I am uncertain as to how crank arm length may affect roadies or track cyclists, but on the surface when we do bike fit based on power and ER at the desired intensities for the event, testing at shorter crank arm lengths produces higher rpm and higher CO2 (higher carb vs fat utilization) at sub max IM pace, say around 83-88% of max HR depending on the athlete, in other words at least from a longer IM type perspective I fail to see how shorter cranks are better at least in terms of the testing we do, not all HR's are created equal at 145 hr energy utilization patterns are very different depending on what size crank you are using (perhaps based on spin which varies ratio of fast/slow twitch utilization, or perhaps based on the lower metabolic load of longer cranks creating a richer O2 environment)
Long cranks create injuries:
Umm, zero evidence on this one. in cycling injuries are based on frequency, duration, fit, intensity etc there is no evidence that I could find that longer cranks cause injuries. Hard to impossible to prove, in fact maybe you could argue that shorter cranks as you have to apply more net torque there would be a likelihood of higher injuries at shorter cranks.
The sample size of riders who are outside the norm is too small to say that injuries happen either way. IMO the greatest chance of injury comes from poor fit or poor training.
seat position and longer cranks:
If you go long you have to move your seat forward (at least in the TT) for IM we really like to open up the hip angle, although for most athletes this is better for power it also facilitates better digestion and higher O2 utilization, at longer triathlons and IM distance events the primary limiter is calories and hydration, so we need to get in as much as we can.
Just my 2c,
Maurice
Maurice,maurice said:
Thanks for your input. Your post addressed several issues and I have several thoughts on some of your other comments but I will address specifically your "test". It is not really clear to me what you did nor how you tried to control things. I believe that most people will probably test best on the crank length they are used to so I believe each length should be tested after a period of adaption to the length. So, you had a 12 week base phase, but on what crank length? And, what changes did you make to the bike fit as you changed the crank length, as that could affect your testing if the fit is substantially different?
FrankDay said:
What is your revised estimation of the percentage benefit to be got from the use of PC's, it was 40%, how can you distinguish between the advantage (if any) to be gained from the use of PC's and that from using a shorter PC type crank.
Most new users who use them essentially exclusively for 6 months can still expect 2-3 mph speed improvements over what they can do now (which is about a 40% power improvement for most). Those who do not use them as we recommend (or if they are really really good now) will see smaller improvement than that.coapman said:
It would be difficult to distinguish improvements from shorter cranks compared to PC's in new users because it is really hard to study two variables at the same time. The best way to evaluate this would be to look at the benefits sequentially, first training with the PC's then shortening the cranks compared to an equivalent control group. Good luck with getting that research done.
BTW, I am showing our prototype powerpowercranks at RAGBRAI and receiving very positive response.
The other thing I do is I have two bikes with PC's on them, one at 172.5 mm crank length and the other at 145 mm crank length. I have visitors try both bikes without telling them what the difference is and ask them which one they feel is "easier". About 80% definitely choose the shorter cranks bike. About 10% choose the shorter crank bike but have to think about it. And, about 10% don't see much difference. I don't think anyone has chosen the longer crank length bike as easier.
FrankDay said:
Hey Frank,
Well in a nut shell, our program ranged from 8-20 hours per week mostly long and slow stuff, about 3 swims, 3-5 bikes, 3-4 runs.
On the bike we do one intensity session about 1.5 hours long with some intensity then a bit of drills etc.
The second session is what I call the kitchen sink workout and is primarily longer duration intervals (say 6X15 min) at IM intensity or about 80-85% of Max HR, after that we run between 5-12km at light tempo or about half to full marathon pace.
For our long days in the winter we skate ski and if we do a 4th bike we replace it with a ski as well, not because we think its better but the trails here (kamloops bc) are awesome and I would way rather spend 3-4 hours outside than doing a slightly more specific work out indoors.
Interms of bikes:
My road and mtb both have 175's we have a PC bike set up on a trainer so in classes we have people cycle through for about 15 min at a time. because there are so many people on it we set the cranks for the shortest position at 165, so for our PC stuff it is always short because we have people from 5 foot to 6'8'. Given time constraints I have spent about an hour per week on the PC trainer.
In terms of adaptation I spent about 4 weeks on the short cranks and did not notice much of an increase in power through that adaptation. I need about 230 watts at IM HR (155-160) and I started in Jan at about 180 watts by the end of march I was up to 230 with the longer cranks but this also coincided with our power phase in the weight room where the whole goal is to do strength training in such a way that we build power on the bike.
Once we got outside in early march I was on my road bike which has 175's, sometimes going on my MTB if it was cold or rainy (or even snowing!), still using 165 PC for about an hour a week. I was waiting for my P-effing-5 (****ed off about the delays) before I would get a longer crank.
My road bike is an old cervelo soloist carbon and I get toe rub on the front with 175's so I wasn't about to go longer, and I like the bike so I'll likely just keep it as it is.
We also did a 10 day trip to Maui end of april (this was post test) where I was on 175's for about 32 hours over 6 days. So in terms of specific adaptation, I was all over the map with the only longer crank stuff being done about 2-4 hours a week from mid feb-mid march, the tests were done early april. It wasn't until the beginning of june that I built up a TT bike with 190 carbon lighting SL cranks (whether you are in the short or long camp, this is one of the only companies that make great cranks outside the norm)
I rode it for about 800 km before doing IM couer d'Alene at the end of June.
In terms of fit I am an "extender" so my inseam is 846mm and on my road bike I am at 775mm (.91 of inseam), for the short cranks when I was trying them I had a seat angle of about 80 degrees in the TT, for the 185's I had to move my seat up to 85 degrees. For the 185's I set my seat to 765mm and for the 165's I raised it to 785mm. So although the seat height is raised on the 165's it only translates to about 12 mm because the seat moves so far forward on the 185's. So aero is not an issue, I have a 160mm drop and my hip angle is still OK.
Test protocol was linear, in other words I started at 100 watts and go up by 15 watts per minute until you puke/die/stop etc. Some people advocate a staged protocol in other words you start at about 75-80% and move up in 3 minute stages. This is great for blood lactate testing as you need to stay at a certain level for three min in order for BL levels to normalize. I personally think that VO2 and Bl should be 2 separate tests with the Vo2/co2 data used for zones and energy management protocol and the BL data used more for threshold determination.
- Apr 21, 2009
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FrankDay said:
When you claim independent crank users typically ride 2-3mph faster how did you try to control for wind, temperature, training, road surfaces, riding in a bunch verses riding alone, gradient, motivation, diet and all the other variables that affect speed.
- Mar 10, 2009
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FrankDay said:
So you still claim a 40% improvement in power output is exclusively due to the use of your cranks (compared to say, training on regular cranks)?
Let's put that into perspective for people. That level of improvement would take me from Cat 3 level to dragging Wiggins up the cols in the TdF. In just 6 months! wow. I thought perhaps you'd eased up on your level of self delusion, but I'm clearly mistaken.
Have I ever said that this improvement is due to the exclusive use of the cranks? No, all I say is that this is the improvement that out typical user sees. since most of these people are not TDF capable a certain amount of the improvement is probably due to just more time on the bicycle. Until one does a study comparing two equivalent groups for a period of 6-9 months it would not be possible to separate how much improvement is due to what. I believe at least half of the improvement that people see (and almost all of the running improvement they report) is due to the use of the PC's since even those who have stabilized see improvement, sometime substantial improvement, without any additional training time.Alex Simmons/RST said:
Well, we did that for one rider, in 13 months of exclusive use as he managed to improve his professionally tested VO2 max from 71.2 to 85.5 ml/kg.min, his ramped max power from 405 to 451W, and his FTP from 284 to 394W. (his improvement in 6 months was ONLY to 81.7 and 358 - hardly worth mentioning). His coach told him that he would be able to stay with the best for a single day. What set them apart was their ability to recover and do it day after day. You don't get that while holding a real job and being close to 40. It isn't self delusion. It is what people report seeing if they follow our advice. Of course, the only people who could possibly see such improvement are those who actually try. Few users of course actually bother to get tested in this way so all we have are reports of speed and/or power improvements.
There has to be a reason that we got a phone call from Taylor Phinney last off season that said essentially "Cadel says I need to get on these". Taylor, I guess, felt Cadel's advice (based on about 8 years experience with the product) to him to be of greater importance than yours (based on zero experience) to the world.
So, when you actually have some real experience with the product, using it as we suggest, for a substantial period of time, then come back and talk to me about my "delusions".
I didn't. It is simply what people report to us again and again. Sometimes they see more, sometimes less, but 2-3 is the most frequent number. My presumption is that most riders are smart enough to know when they are faster, even considering all those variables you mentioned, just based upon their experience. Most of them are not stupid even though you seem to think they are.CoachFergie said:
It is my opinion that the main benefit of shorter cranks is not power but what benefits one might achieve in aerodynamics (and, perhaps, endurance). If one is making the determination as to what is better based on power alone I think they are missing the big picture.maurice said:
It sounds like you might be one of the few with an excellent aero position on longer cranks. It may be that there is zero benefit for you. However, for those who do not have an excellent aero position with their current crank length I think it behooves them to experiment with shorter cranks to see if this helps them to achieve a better, faster, position, without any or much loss in power.
Thanks for the feedback.
- Apr 21, 2009
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We have heard these "claims" and "talk" before and none of it matches the documented evidence. Just the same as your claimed "importance" of crank length.
- Mar 10, 2009
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Alex, Fergie, My delusions, it seems, are destined to continue. Vino's win today gives PowerCrankers 4 wins in the last 4 Olympic road races. You snooze you lose. LOLAlex Simmons/RST said:
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