Watt Matters is a blog about training and racing with power and other related musings.

Aside from writing items here on occasions, I also provide cycling performance improvement services via coaching, aerodynamics testing and host a cycling tour.

If you'd like to ask me a question or suggest a topic you'd like my take on, then just head to Ask Alex and let me know!

All Things in Moderation. Except Science.

All Things in Moderation. Except Science.

This is my eighth year of blogging. It's a personal thing for me. I enjoy writing about training and racing with power. It's just stuff. Pub chat fodder for those four sad guys that talk about power meters in pubs. You know who you are. It's OK to come out and admit it, there's nothing wrong with it.

Occasionally I post an item that seems to be actually helpful to people, such as items on performance testing or indoor training. By posting I learn things and that's enjoyable. Hopefully others learn too. And I make mistakes. It happens.

I think I've held pretty well to the purpose as stated in my very first post.

I also used the blog to help me through difficult times, as longer term followers would be aware through sharing some of my experiences of getting back to racing after my 2007 accident and amputation. Where possible I tied the two themes together.

It's not a commercial blog and the subject matter is reasonably esoteric, and the following is modest with views numbering in the hundreds of thousands, not millions.


I also know that public online interaction forums require moderation. Again it's mostly to keep spammers at bay, but occasionally some stretch the bounds of reasonableness and need to be reeled in or reminded of some basic netiquette. Troll watch duties as well. Sometimes you forget to check the moderation queue for comment that require moderation and they get posted a bit late.

I am a forum moderator myself, at the wattage forum on Google Groups which grew from modest beginnings in 2001 and was originally hosted on Topica. Want to pull apart anything to do with power and cycling? That's the place to do it. The archives are a gold mine of information, and the early days had a high signal to noise ratio. Only very rarely does moderation occur there, it's mostly self policed and the 10,000+ crowd are generally technically or scientifically oriented, so bullshit generally gets called out early and dealt with.

or Censorship?

But what I've never understood is why some forums or blogs dedicated to performance and/or training and racing would want to prevent actual relevant science or scientific discussion from being published/referred to.

I first encountered this a few years ago when I was banned by a triathlon forum owner from posting to the Slowtwitch forum. My crime? I wanted to know why they were persistently censoring the publication of a link to new published scientific research related to pedalling a bike. They didn't like the subject matter, nor my criticism of such censorship, so I was shown the electronic door and all evidence of the matter wiped. I was not offensive, I did not abuse, swear or curse at others, I did not break published forum rules. OK, it's their privately owned business, they can do what they like and they are large so what does it matter?

But it made me think. If you censor science, or discussion of science, is it really a place worth visiting? Well obviously lots think so, because such things are but minor ripples in the ocean of posts about saddle height, cadence, new bike frames, paleo diets, and the inevitable sarcastic pseudonymous responses.


So hooray for science. Perhaps.

Fast forward to a blog followed by many who, like me, enjoy their science in accessible form - the guys at The Science of Sport blog. I've followed it for a number of years, pretty much since it began in 2007. They dissect performance matters from a range of sports, in particular running, and introduce various topics for discussion. All good stuff and I think they do a good job of it.

Eventually they started writing about cycling performance like this one talking about the 2008 TdF and the all pervasive issue of doping. As they began to inform themselves on such issues in the cycling world, they also joined the bandwagon of estimating power from climbing speeds / VAM, and what we can learn from such information. They also began to suggest what is and is not physiologically plausible sans doping.

In the early days of such posts, I helpfully explained to them via the blog comments one of the difficulties in using climbing speed to estimate power, i.e. the large unknown factor of wind, and they got that message loud and clear. They even referenced my comments in subsequent posts. And they have usually referenced the issue of wind confounding such estimates whenever this topic comes up.

In general they have also tried to steer people away from the folly of using individual data points on climbing speed (or power estimations from them) as some means to infer doping status, but rather to consider the longer term trends. All good stuff.


Wham bam, thank you pVAM

Lately though they have been publishing a lot of information derived by the pVAM methodologies, which I am less enamoured with for a couple of reasons.

Firstly, whether intentional or not, it encourages the invalid use of such information as a "dopeometer" and secondly, I'm unconvinced they have sufficiently critically assessed the validity of the pVAM and dpVAM model. I think this is bordering on a desire for publicity than on good science. Not nearly to the extent that Antoine Vayer's occasionally dodgy maths does, but are they pushing the "Publish" button a little too quickly at times?

I get that their blog is designed to provoke discussion about sports science matters, make things accessible and to make people think more critically about stuff, and that's a good thing - but when you represent yourselves as "The Science of Sport" and present methodologies or models under that masthead that have not been peer reviewed or are based on known/published science, or without having done critical assessment against existing models, well I just think more caution is warranted before lending an overweighted amount of credibility to such things. Perhaps greater emphasis is needed on making it clear what is opinion and what is actually science.

I could of course be completely wrong and talking out of my arse. Happy to stand corrected. Most of us out here is the interwebs are not well versed in understanding the credibility differential of such material published by scientists under a heading of "The Science of ...".

It's difficult for me to strongly criticise since I'm not a scientist and not well versed in such peer review, so I just occasionally chip in with my amateur 20 cents worth and hopefully it generates some thoughts, at least in a pub chat kinda way. At the least I have a personal sense of contributing in some way, however insignificant that contribution may actually be. Which is what I did four days ago when I pointed out an error in a statement they made about the pVAM method.

This is what was written on their post:
"The error in the wind component is much larger, which has implications for the assumptions of cdA (drag co-efficients). In the model, however, the relative contribution of the wind during climbing is small, and so the total error is actually not too bad."

I then pointed out the obvious (to me anyway) physics mistake by posting this to the comments:

"The error in CdA isn't the issue, but the wind velocity most definitely is. Ignore that and you may as well throw darts at a W/kg board. That interpretation suggesting the error introduced by wind is, frankly, nonsense.

Even modestly different wind conditions for the same VAM can see estimates of power over a 1W/kg error range. The wind for the Armstrong/Pantani ascent was quite different to this year's ascent."


Perhaps my tone wasn't ideal, but nonsense is nonsense, right? And scientists generally have pretty thick skin.

For anyone wondering what I'm on about, when estimating power from steep climbing speed, if your assumption of the rider's coefficient of drag is (CdA) is wrong, well it doesn't generate a really big error in the estimate of power. It's not "sensitive" to that particular assumption. But it is most definitely sensitive to the wind velocity assumption. Get that wrong and the numbers can easily be wrong, and by a large margin.

Comment MIA

Then yesterday another SoS post about Alpe D'Heuz climbs and the pVAM and dpVAM methods appeared, so I thought I would post a comment with a link to djconnel's cool blog post which introduces a critical appraisal of the pVAM model, from both a physics and physiological basis, by comparing it with actual published and well established science models. I also provided links to a couple of charts about ADH climbing times that were easier to read than the ones they posted up.

As scientists, you think they might be interested in discussing the limitations of a model they are presenting as highly credible, or consider how it might be improved or under what circumstances we need to be very careful in using it.

Well for starters, I suggest using actual physics when estimating power from climbing speed, and also checking how the model stacks up with established physiological models.

Except my comments to them are now being moderated and have not appeared.

As Robert Chung would say, Hmmm.


Which power meter?

Which power meter?

The Elusive Dopeometer

The Elusive Dopeometer