The importance of crank length to the cyclist.

[FrankDay]

It sounds pretty nifty in theory and I'll admit it may well work. In regards to making it actually work in other than tangential force measurement, it would seem to share many of the same computational complexities as the Garmin Pedal system.

I would love to see the patent drawings from Breakaway Innovations but haven't had any luck yet.

Considered yourself very likely owed a beer but I a call dibs on playing with a set of the stain gauge cranks if you have a set there.

Hugh

I am told I will have a set next week. I also have to get a latest generation Garmin display if I am going to take them out on my bike. (latest generation is apparently necessary to get right/left output - they are apparently getting ready for the Vector pedals) but I am told we can do a computer display real time without the Garmin display. Won't know what I can do or what I need until I have them.

One of the first things I am going to do is put them on the Velotron to compare accuracy (should measure a little higher as measuring before chain losses) and to be able to compare output to spinscan. If things look good I will probably post that data for everyone to see. (If things don't look good I will probably contact the developers with a "these are not ready for prime time yet" message - but I think that unlikely as I know they have been working on this a long time and they think they are close to ready.) (We do have a few customers who have PowerCranks converted to use the SRM powermeter. It would be possible and interesting to compare these two systems at the same time. But, I see that as more of an "interesting thing to do" and not a "necessary thing to do" right now.)

I also want to send them to several of our more experienced PowerCrankers so I can get some feedback from them.

And, if everything looks good I will probably have them with me at any expo I am at, Death Ride is a good possibility for the first public viewing and, perhaps, take preorders. If I can I would like to get a really experienced PowerCranks mountain goat, someone like Drew Peterson, to ride them at Death Ride so we can get that data for later marketing purposes. If these are ready for prime-time my guess is we will also be at Interbike this year.

Anyhow, if you are in the SF area, and want to come by and see them give me a call (or send me a PM) and if they haven't been sent out to someone per above you will be welcome to come by and see them, try them out possibly, and talk.

 

[FrankDay]

Well, I have received the cranks and I have now gone out and got a Display that will show left and right power (Garmin 500 - they are apparently anticipating that the Vector will someday stop being vaporware). Now, I have to see if I can get them to all talk to each other.

What we will be getting at first is very rudimentary, total power and the percentage that is coming from the right crank. The software is not ready yet to analyze the full circle forces, but I am told they are working on it. When I have it on the bike and working I will post a picture.

 

[sciguy]

Well, I have received the cranks and I have now gone out and got a Display that will show left and right power (Garmin 500 - they are apparently anticipating that the Vector will someday stop being vaporware). Now, I have to see if I can get them to all talk to each other.

What we will be getting at first is very rudimentary, total power and the percentage that is coming from the right crank. The software is not ready yet to analyze the full circle forces, but I am told they are working on it. When I have it on the bike and working I will post a picture.

The Garmin 500 already provides a right/left power split for the newest Quarq power meters. Hopefully the fellows you're working with are extremely talented. The Metrogear guys have also been "working on it" for a good number of years at this point and even with the resources available through Garmin it appears to still be unready for prime time.

Hugh

 

[FrankDay]

The Garmin 500 already provides a right/left power split for the newest Quarq power meters. Hopefully the fellows you're working with are extremely talented. The Metrogear guys have also been "working on it" for a good number of years at this point and even with the resources available through Garmin it appears to still be unready for prime time.

Hugh

I have already discovered some issues that make this not quite ready for prime time, although these issues have more to do with mounting on a "real" bike than the reliability issues others seem to be seeing. This iteration was developed primarily to work on an exercise bike. trying to do magnetic pickups on drive side cranks with chain rings in place never, apparently, came up. I can make it work because I have a small chain ring but most of you wouldn't be able to use these as they are currently configured. These fit problems are easily fixable IMHO but, of course, change is change which means delays. But, I will continue to do my own further testing cause I can make it work.

 

[FrankDay]

The Garmin 500 already provides a right/left power split for the newest Quarq power meters. Hopefully the fellows you're working with are extremely talented. The Metrogear guys have also been "working on it" for a good number of years at this point and even with the resources available through Garmin it appears to still be unready for prime time.

Hugh

I believe these R/L split capability in the 500 and 800 has more to do with getting ready for their dual input Vectors than an estimate, which is all that Quark can do. The device is able to get "real" r/l balance from two separate r/l outputs. They didn't include this capability to make the Quark look good. That is what these cranks provide. What we can't get just yet are the subtleties of that balance, just yet.

To me, the technological challenges of putting these strain gauges in the pedal spindle or the pedal itself are substantially more complicated than putting them in the crank arm.

 

[FrankDay]

I got this reply based upon my initial feedback to the developer: "Frank, the system has been under test with professional pro team riders for 18 months or more, but the system was fitted to standard road cranks not the PCs, again all these are prototypes, not production units, the feedback from the riders and their DS's and sports scientists that work with them have been very good, in fact better than good, so we know from the electronics side that they will perform better than either SRM or Quark because the latter two are what their other riders are using, so comparisons have been easy to make."

Once these issues of how to fit it all together with the PC design, which shouldn't be too difficult, I think all of these concerns will soon be forgotten. Stay tuned. Now if I can get them to incorporate crank length less than 145 into the design, although 145 is probably short enough to address the bulk of these crank length debates in professional riders.

 

[CoachFergie]

The issues of crank length, left and right balance and power application through the pedal stroke have all been well studied.

If they can deliver on the promise of a more valid and reliable power meter than a SRM that will be a worth investigating.

 

[FrankDay]

If they can deliver on the promise of a more valid and reliable power meter than a SRM that will be a worth investigating.

How much accuracy do you consider "enough" Fergie? 1%, 0.1%, 0.01%, 0.001%. Where is the evidence that more accuracy (beyond a certain point) is better than less accuracy in determining a better outcome? In fact, where is the scientific evidence than any accuracy as regards using PM in training or racing is better than no accuracy (or no PM) at all? Wait, we have been through this before, there is no scientific evidence to support your argument. On with the crank length discussion.

 

[CoachFergie]

How much accuracy do you consider "enough" Fergie? 1%, 0.1%, 0.01%, 0.001%. Where is the evidence that more accuracy (beyond a certain point) is better than less accuracy in determining a better outcome? In fact, where is the scientific evidence than any accuracy as regards using PM in training or racing is better than no accuracy (or no PM) at all? Wait, we have been through this before, there is no scientific evidence to support your argument. On with the crank length discussion.

Ummmm you're the one saying this new system will be more accurate than an SRM.

The questions on crank length have been studied.

Still see you are confusing something that measures an outcome with something that changes an outcome.

 

[FrankDay]

Ummmm you're the one saying this new system will be more accurate than an SRM.

The questions on crank length have been studied.

Still see you are confusing something that measures an outcome with something that changes an outcome.

Ugh, I am told it will be more accurate than an SRM. While that would impress many (including you, I suppose) I am unaware that increased accuracy will improve outcome. It may, but I am not aware of scientific evidence that supports that conclusion. Increased accuracy could be useful for the purposes of doing studies but whether it is useful to better help the individual athlete is not known.

While you may feel that crank length has been studied (which is has) there are some of us who feel that those studies are incomplete such that discussion on the subject is still reasonable. You, apparently, feel that one study by Martin (which only looked at power and nothing else) is definitive. Cool. We all know where you stand.

 

[CoachFergie]

Ugh, I am told it will be more accurate than an SRM. While that would impress many (including you, I suppose) I am unaware that increased accuracy will improve outcome. It may, but I am not aware of scientific evidence that supports that conclusion. Increased accuracy could be useful for the purposes of doing studies but whether it is useful to better help the individual athlete is not known.

Still confusing the accuracy of a measure with what may or may not have caused the measure to change in the first place.

While you may feel that crank length has been studied (which is has) there are some of us who feel that those studies are incomplete such that discussion on the subject is still reasonable. You, apparently, feel that one study by Martin (which only looked at power and nothing else) is definitive. Cool. We all know where you stand.

Several studies by Martin and others. Considerable evidence to discount any importance of crank length.

 

[sciguy]

Frank do the cranks look a bit like these?

 

[CoachFergie]

Those are Swift Cranks. Note there is some adjustability of crank length. Good for lab testing but not practical for field testing.

 

[sciguy]

Those are Swift Cranks. Note there is some adjustability of crank length. Good for lab testing but not practical for field testing.

I was thinking that they would make the Power Cranks seem a bit less bulky ....oh wait maybe not.


Hugh

 

[CoachFergie]

I was thinking that they would make the Power Cranks seem a bit less bulky ....oh wait maybe not.

True, riders are looking for light and aero. Many riders even consider the weight of a SRM to high a cost to bear.

In terms of data all the riders and sport scientists are concerned with is whether any training, diet, recovery or equipment modification is allowing the rider to deliver more power. My only interest in these cranks are if they can occur greater accuracy than the SRM or a greater sampling rate.

Our local Wingate bike can measure power from the flywheel at .1/sec and the SRM cranks at .5/sec so we get better data from the flywheel (subject to further work to ensure calibration) to test the programme is working and to determine which areas we need to focus on.

The wealth of research on crank length and force application around the pedal stroke has indicated that there is no significant importance in changing the current practice. Funny the only person claiming otherwise markets a product that allows one to change both.

 

[FrankDay]

My only interest in these cranks are if they can occur greater accuracy than the SRM or a greater sampling rate.

Then, I think you will like these. The cranks have four compartments in them. These are designed to optimize the torque curves of the strain gauges for both sensitivity and accuracy - I don't know the specs but I am told they are more accurate than the SRM (of course, they have not specified which SRM model they are more accurate than) which interests you. In the pair I was given only two of the compartments have anything in them, one has a battery and the other the electronics. The other two compartments, I am told, are for things like an extra battery or, possibly, a high speed data acquisition device. Something else that should interest you. Not that I see high speed data acquisition being useful for anyone other than research institutions (and then, mostly, for doing pedaling technique studies - something you consider to be useless). But, since you are interested in high speed data acquisition I am sure it has been proven to be beneficial because, as you have told us many times, you don't do anything that hasn't been scientifically proven. I look forward to your review when you get yours and hearing how this improved accuracy and high speed data acquisition is an improvement over the power meters you use now in your helping your athletes improve.

 

[CoachFergie]

Still confusing something that measures performance with something that changes performance like training, diet, recovery or equipment selection

 

[FrankDay]

Still confusing something that measures performance with something that changes performance like training, diet, recovery or equipment selection

Fergie, I don't believe I am confusing anything. I simply don't understand why increased accuracy (+/- 5 W vs 1 W vs 0.1 W vs 0.01 W) in a PM or increasing the data collection rate (from 1 sec to 0.5 sec to 0.1 sec to 0.01 sec) provides any benefit to the coach or the athlete that would justify the increased cost to the end user for such "improvements". Since you apparently believe this to be true ("My only interest in these cranks are if they can occur greater accuracy than the SRM or a greater sampling rate.") and you don't do anything that hasn't been scientifically proven I look forward to your providing a reference to this proof.

 

[CoachFergie]

Fergie, I don't believe I am confusing anything. I simply don't understand why increased accuracy (+/- 5 W vs 1 W vs 0.1 W vs 0.01 W) in a PM or increasing the data collection rate (from 1 sec to 0.5 sec to 0.1 sec to 0.01 sec) provides any benefit to the coach or the athlete that would justify the increased cost to the end user for such "improvements". Since you apparently believe this to be true ("My only interest in these cranks are if they can occur greater accuracy than the SRM or a greater sampling rate.") and you don't do anything that hasn't been scientifically proven I look forward to your providing a reference to this proof.

Strawman

The improvement in measurement doesn't cause the change in performance. The improvement in measurement tells us if a change has actually taken place. With regards to crank length that change is not statistically significant.

 

[sciguy]

Fergie, I don't believe I am confusing anything. I simply don't understand why increased accuracy (+/- 5 W vs 1 W vs 0.1 W vs 0.01 W) in a PM

Many of the cycling improvements we might wish to quantify such as how aero a particular position is or a particular aero helmet is are incredibly small and difficult to tease out during real world testing unless we have some pretty darn accurate equipment. I'm sure you wouldn't want a pharmacist dispensing potent medicines to use a scale with resolution to the nearest ounce.

If the position derived by a particular triathlete riding 145mm cranks instead of 170mm cranks decreases the power required to pedal at 25mph by 2 watts, the only way we will know is by testing with an accurate enough measuring device. The same holds true for seeing physiological improvements as well.

Hugh

 

[CoachFergie]

Amusing that Frank comes back to this thread touting these cranks and the better accuracy than an SRM and then back pedals against that accuracy.

One of my riders brought a set of Keo/Polar pedals and after a week ended up buying a Quarq. Polar are reluctant to refund his money. We did one ride where the power agreed and the next ride the Keo/Polar read 30 watts lower than the Quarq. If I measured my training programmes based off the Keo/Polar I would probably get the sack if a rider dropped 30 watts for no good reason.

 

[FrankDay]

Many of the cycling improvements we might wish to quantify such as how aero a particular position is or a particular aero helmet is are incredibly small and difficult to tease out during real world testing unless we have some pretty darn accurate equipment. I'm sure you wouldn't want a pharmacist dispensing potent medicines to use a scale with resolution to the nearest ounce.

If the position derived by a particular triathlete riding 145mm cranks instead of 170mm cranks decreases the power required to pedal at 25mph by 2 watts, the only way we will know is by testing with an accurate enough measuring device. The same holds true for seeing physiological improvements as well.

Hugh

There is a substantial difference between accuracy and precision. When determining aerodynamic changes one is looking for precision in a PM (i.e., it is better to be 20 watts off but always within 1 watt than 5 watts off but precision is +- 5 watts. When doing these aerodynamic changes it is not so important what the actual drag number is but, rather, what is better.

Anyhow, the question remains, how much accuracy and how much precision is necessary for any of these issues? There is zero scientific evidence to support any accuracy is necessary for a PM for training purposes since the only studies I am aware of show that using any PM makes no difference in outcome compared to using no PM. If that is the case how can one seriously argue that, for this purpose, more accurate is better, especially when "more accurate" usually involves more cost. Improved accuracy in cycling PM's is a marketing argument but has never been shown to have any athletic outcome benefit. It may be true that it is better, but that has yet to be shown.

More accurate and more precision only can be argued to have real benefit to researchers as this reduces data noise and will improve the statistical analysis, making research easier and more cost effective.

 

[CoachFergie]

There is zero scientific evidence to support any accuracy is necessary for a PM for training purposes since the only studies I am aware of show that using any PM makes no difference in outcome compared to using no PM.

Strawman

Because most people understand we use the power meter to measure the outcome. When people try and lose weight the type of scale used doesn't determine how or if the weight is lost.

Got any more logistical fallacies for us Frank

 

[FrankDay]

When people try and lose weight the type of scale used doesn't determine how or if the weight is lost.

Good analogy Fergie. Does the accuracy or precision of the scale used when measuring weight loss affect the amount of weight lost? Does even using a scale at all when trying to lose weight affect the amount of weight loss? Can one tell if they are losing weight or not without a scale (perhaps by how their clothes fit or where the belt buckles)? Thanks for that.

 

[CoachFergie]

If a tree falls in the woods does anyone hear it?

Any other logistical fallacies for us Frank?