Knowing your power … what’s it worth?

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Home Triathlon Forum Triathlon Discussions Knowing your power … what’s it worth?

This topic contains 18 replies, has 11 voices, and was last updated by Avatar of Pete L. Pete L. 6 years, 9 months ago.

Viewing 15 posts - 1 through 15 (of 19 total)
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  • #4027
    Avatar of burnman
    burnman
    Participant

    As triathletes, many of us feel compelled to sweat the small stuff during training, because – let’s face it – on a long course the small stuff can be the difference between a PR and a DNF for some folks. I’ll freely admit that I’m a numbers nerd. I spend hours analyzing things like my pre- and post-workout calorie intake, and my heart rate profiles from the day’s training. Does this make me a better athlete than any of my peers? Absolutely not. However, it does keep me on track and helps me (at least mentally) improve over time.

    The one elusive factor for me has been quantifying my power profile on the bike. Like many others out there, I don’t feel that I’m competitive enough to lay down thousands of dollars on custom power equipment. However, that’s not to say that obtaining power information would be of no use to myself, or to other AG’ers trying to improve their performance on the bike. Aside from the $$$ issues, there is a substantial amount of effort that goes into installing/tuning/maintaining power-specific equipment. Therefore, I ask the question, “What’s it worth?” What’s the value of that information versus the cost of that information? Call it market research. Call it personal interest. I think it’s a very valid question – especially for people that have an appreciation for the dollars-and-cents price of performance.

    If someone proposed to you a power-sensing device that integrates with your existing setup and a modest cycling computer (<$50), how much would that be worth – the equipment AND the information? Now, can it be done for that amount? More importantly, can it be done EFFECTIVELY for that amount? My goal is to find a solution to the latter question.

    #90283
    Avatar of Sully800
    Sully800
    Participant

    If you want info on the benefits of power data, just search this board. There have been a few useful discussions recently and good info posted mainly from MarkyV.

    As for whether power data can be received effectively for less than $50? Nothing exists right now that can do it. If it could, the $1000 power meters would have no market to sell in. If a new method can be created that would sell for $50 a piece you would make a whole lot of money, and put lots of existing systems out of business!

    #90284
    Avatar of ChunkyB
    ChunkyB
    Participant

    The lowest cost “power meter” that I’ve heard of is the iBike Pro, which is under $500 (maybe around $350), but it isn’t an actual measure of power. It measures your speed, cadence, wind speed and direction, ascent, and I’m sure some other things, and then it uses an algorithm to estimate your power. I don’t think it’s nearly as reliable as a powertap, but it can give some useful training info I’m sure.

    One big plus, as you were asking about, is you don’t have to get a new hub or anything. It pretty much just adds to your existing setup. I don’t know if it works with your existing computer, but you don’t have to buy any new bike parts at least.

    EDIT: another thing I forgot to add is that it might be kind of cool to have wind information on your rides, as well as elevation and stuff. I don’t think the power calculations are as accurate as many others, but it might be fun to have all the other info.

    #90294
    Avatar of burnman
    burnman
    Participant

    Good points. Even the most expensive devices (e.g. powertap) are approximate. They all involve some degree of math logic and uncertainty. You could never quantify all of the external forces that contribute to your overall exertion. As a scientist and engineer, I have conceived of at least 3 effective ways to quantify the rider’s translated power output. By this, I’m suggesting correlation of the input power (at the crank) to output (effective motion of the bike). In doing so, you homogenize all of the external factors such as tire slip, wind resistance, gear slop, etc. Such methods can probably get you to +/-5% accuracy. I guess the question I’m asking is how much $ would you drop to be 90/95/99% accurate?

    #90296
    Avatar of scottbland247
    scottbland247
    Participant

    why don’t we save some time and you tell us how much it costs you to manufacture said item?
    (i’m assuming you already have it by the phrasing of your question)
    ;)
    (tone is happy/sarcastic not angry)

    #90297
    Avatar of kylie
    kylie
    Participant

    I am one of those who thought that I didn’t need a power meter. Sure, it gives more a different type of feedback, but there is a large startup cost. However, I made the change to it this year. Why?

    • change in available training time: I no longer have the same very open training schedule. When I get on the bike, I need to get in a good workout and get off. I can’t spend the hours of miles on it I used to — with power I know the amount of work I’m doing, and thus the stress on my body, and can plan so that each workout has a very specific point, and then I can actually match that as I’m riding.
    • my goal is to be my best. If there is a tool out there to help me do that, and I can, I will train with it. As far as wondering if I’m competitive enough, well, I’ve never used that train of thought. Else I would still be on a borrowed bike and training sporadically. I do this for me and for fun — I got a tri bike because I liked riding it more than the borrowed one that didn’t fit. Same with a power meter — it is not going to make me as fast as some of my competitors, but it will make me faster. Plus, I’m also a numbers and data geek, and they help motivate me. So the PowerTap also is adding to the fun.
    • I had the desire to learn to use it. I wasn’t buying an expensive bike computer, but a tool that I was reading about and working with someone well versed in it to maximize my benefit. This increased my fun level, as this type of learning and understanding is something I enjoy.

    So what is it worth? It’s worth the time I save during the bike workouts, and second guessing if I reached the day’s training session goal. It’s worth the fun of playing with the numbers. It is worth the measurement of truly seeing if I’m getting stronger and faster. I have a PowerTap and even though I’m still in the beginning stages of using it, I don’t ever wonder if it was worth it.

    #90307
    Avatar of Sully800
    Sully800
    Participant
    burnman wrote:
    Good points. Even the most expensive devices (e.g. powertap) are approximate. They all involve some degree of math logic and uncertainty. You could never quantify all of the external forces that contribute to your overall exertion. As a scientist and engineer, I have conceived of at least 3 effective ways to quantify the rider’s translated power output. By this, I’m suggesting correlation of the input power (at the crank) to output (effective motion of the bike). In doing so, you homogenize all of the external factors such as tire slip, wind resistance, gear slop, etc. Such methods can probably get you to +/-5% accuracy. I guess the question I’m asking is how much $ would you drop to be 90/95/99% accurate?

    I might first want to know the accuracy of current power meters.

    Say the best Power tap is 99% accurate and costs $1200. The cheaper model is 95% accurate and costs $900. Then I would probably be interested in a 90% accurate method for $400 or less. (The numbers are all just arbitrary, I didn’t look up the current accuracies or prices).

    EDIT: I felt bad about my lack of research so I looked up the info. The cheapest powertap is $900 new and all models claim to be 98.5% accurate. The more expensive models are lighter weight, wireless etc. so it is just convenience issues and not a matter of accuracy. I’d make my estimate of $300-$400 for 90-95% accuracy. I might be willing to spend $50 on something that is 75% accurate, I’m not sure because you would get pretty inconsistent data.

    #90312
    Avatar of ChunkyB
    ChunkyB
    Participant

    I agree that no power meter can actually measure power. But things like powertaps, or other meters where there is only one variable (strain on the spokes or otherwise) could be more accurate than methods where there are many variables, each with its own inherent error.

    #90316
    Avatar of stewarba
    stewarba
    Participant
    scottbland247 wrote:
    why don’t we save some time and you tell us how much it costs you to manufacture said item?
    (i’m assuming you already have it by the phrasing of your question)
    ;)
    (tone is happy/sarcastic not angry)

    Honestly, would you let that out if it were your product that you just invented? Its all about what you are willing pay. If he can manufacture it for $10 and sell it for $1000 because that is what the market will bare, then more power to him. Once it is known how much it costs, the consumer starts making an assumption on how much they should pay based on that figure.

    I think he is going about it the right way. How much is it worth? If I read what you said properly, it would integrate with my existing equipment somehow. As an engineer myself, that presents some problems in and of itself because you have to deal with other products and more than likely their proprietary information, but lets say that you have that licked by an accuracy of at least 95% (I am using 95% because anything less and why even really bother with power). So let’s use ChunkyB’s $350 cheap power meter. Your product in my mind would have to be no more than half that cost for me to look at it seriously. As a consumer I want a well integrated product so my first impulse would be to skip right over your “add-on” product. That is until the price for your add-on starts getting to a point that I have no choice but to justify to myself why I shouldn’t look into it further.

    Having said all of that, there is still the assumption that this is a new untested and unproven tool to the masses (in this case triathletes and cyclists). If your product is good and has good buzz, I may start looking at it at a higher price point, but not knowing anything about it and it not being used by many in the community, I would need to be enticed by a low price entry point and a pretty good satisfaction guarantee policy.

    This whole scenario reminds me of the MP3 players on the market. Why do most people by an iPod when there are other MP3 players out there for cheaper and some if not most have more features? Because the iPod is highly integrated and I don’t mean from a hardware perspective, it is highly integrated with the iTunes software and for people that don’t want to take the time to figure out how the nuances of the other MP3 players work (my mom, wife, etc…) there is a high value in the ease of use knowing that they can take their iPod out of the box and it works with little to no knowledge of why.

    Sorry for the long post.

    #90319
    Avatar of burnman
    burnman
    Participant

    Just for the record, I don’t have this problem solved in a can – though I wish I did. I’m certainly not a marketing expert. My biggest observation is that most serious tri folks are heavy into performance metrics and training analysis. Power measurement is probably the most universal yet fundamental means of quantifying the cyclist’s effort. So, why should it be reserved for the heavily-sponsored elites and/or the well-funded gear junkies? This is not to imply that such individuals do not work their tails off to get where they are. In fact, I admire anyone that values their performance enough to invest in such a tool.

    I think that a rather modest device that is 90% accurate and only costs a couple hundred bills could help many athletes tune their training and evaluate their progress to become better athletes on the fly. This is good discussion, particularly because most of us are not looking to edge out each other for the podium finish. We just want to help each other become better athletes, and if I can develop equipment to that end then I have given back to all of the good advice I’ve received from the tri community. Just as an aside, you’ll notice that most power equipment is developed by established cycling companies. This is because they have the sustainable product base and can absorb the low volume costs of such products. I can hardly absorb the rising price of gas. Can’t wait for the snow to end – so I can commute on two wheels again.

    #90324
    Avatar of scottbland247
    scottbland247
    Participant

    i agree, i’d buy it……and probably for more than my wife would like ;)

    #90325
    Avatar of Toothless
    Toothless
    Participant

    I understand the basic idea here, but the iBike doesn’t sell well because it isn’t very accurate. I was working a table at the Denver Veloswap where five of them sat on the table and people weren’t even buying them for $200. And if you’re only getting 90% accuracy on the “modest device” mentioned above, an athlete could easily stray out of his zones without the device catching it. 180 watts vs. 200 watts can be a big deal depending on the athlete. For those of us who want the performance metrics/analysis but don’t have a lot of dough sitting around there is the used market for the powertaps, etc., which is what I did – picked up a used one locally. Of course, it doesn’t integrate with my rear race wheel, but that’s another post (wheel covers?).

    #90345
    Avatar of MarkyV
    MarkyV
    Participant

    Everyone here speaks of 90% accuracy… but what 90% accuracy means is this… lack of consistentcy in the numbers… if it’s consistentely inaccurate then yer okay… however that’s not really the case…

    example…

    300 watts one day can be 270 another day or 330 another…. uh… that ain’t gonna fly

    further extreme… 75% accuracy…. 300 or 375 or 225… um… not really.

    #90349
    Avatar of ChunkyB
    ChunkyB
    Participant

    I agree. The problem I have with the idea of the ibike is it seems that you would get inconsistent inaccuracies. Since power taps and other things are just measuring one variable, the absolute value of the numbers might not be right, but it will be just as wrong every time. If you’re using speed, cadence, elevation, temperature, wind speed, gradient, etc. to measure the power, each variable will have its own error, and will therefore (presumably) be inconsistent in its inaccuracy.

    Anyways, I think all the units will give you useful information, and it mostly comes down to how important power is, and how much you can spend. Personally, I have too much information with my Garmin Forerunner 305, so I’m not going with power any time soon.

    #90351
    Avatar of RV
    RV
    Participant

    I have the Garmin 305 – and love it – but not a substitute for power. That is my next big budget item… (Will accept donations to the Power for RV fund!)

    Also the other huge drawback to th iBike is that it does not work on the trainer – so those of us holed up in our basements for the winter – it is useless. Also the weight is important to the calculations. And for a long ride that will change quite a bit as water bottles are emptied and other fluid rotation occurs. All that affects the inconsistent results.

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