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Thread: power meters

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    power meters

    i've been reading a lot of the threads on here about training. and i'm thinking that a power meter should be my next investment.

    i'm curious, will the price on power meters such as Powertaps ever come down to a reasonable price?

    Didn't HRM's start off really expensive (relatively)?

    I'm going to start saving up for a PM.
    “(Training) doesn't get easier; you just get faster”
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    I have given it serious thought as well. I doubt we will see traditional powermeters coming down in price like HRM's. The main difference is that HRM's are purely electronics. Electronics can drop in price as the technology matures.

    Traditional Powermeters are a mix of electronics and physical sensors. You need a fairly sensitive strain guage, built to withstand high RPM's. Then in addition they need to be light weight. Factor in that people buying these aren't interested in a low end hub/bottom bracket, and you don't have a good mixture for a low cost device.

    If devices like the ibike take off, then potentially power can come to the masses.

    -D

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    I think prices will eventually come down. With iBike and MicroTech coming into the picture, competition is heating up. I'm sure more devices are in the works, as well. I think there is a huge untapped market out there of "recreational" riders who are starting to understand the benefits of training with power, but maybe don't quite want to spend over $1,000 just yet. Whichever company can reach those people the best is going to make a lot of money.

    And, as you were hinting, the technology is relatively new. Each company will find ways to make their power meters more accurate, more reliable, and eventually more affordable. How many years will that take? I'm not sure. What price do you consider reasonable?

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    i'd say reasonable would be around 400-500$ or so for something like the powertap built up with a box rim.

    training with the HRM is a little bit hard for me. it sometimes takes so long to get the HR up, so I keep pushing harder and harder and then realize I'm way over the zone I'm suppose to be working in. then going down hills and uphills affect my HR a lot.

    people have been using hrms successfully for years, so i'll keep working at it.
    “(Training) doesn't get easier; you just get faster”
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    Quote Originally Posted by dentalman
    i'd say reasonable would be around 400-500$ or so for something like the powertap built up with a box rim.

    training with the HRM is a little bit hard for me. it sometimes takes so long to get the HR up, so I keep pushing harder and harder and then realize I'm way over the zone I'm suppose to be working in. then going down hills and uphills affect my HR a lot.

    people have been using hrms successfully for years, so i'll keep working at it.
    Actually, what you described is a common problem with HR data. There's a lag between upping the intensity and an actual physiological increase in HR.

    Have you heard of the MicroSport Tech power meter coming out? Here's a link: http://www.microsporttech.com/index.php And here's some information you can't find on their website.

    It's going to be cheaper than the PowerTap, but not quite in your budget. It actually takes a direct measure, unlike the iBike. It's not out yet, but it's coming in "early 2007". Something to keep an eye on. I'm going to be a guinea pig for it, so I might be posting some reviews later on in the year.

    If it ends up being more accurate and/or easier to use than the iBike or the Polar unit, then I could see it putting some pressure on the folks at PowerTap and SRM. Then again, it's brand new, so you never know.

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    Interesting. So the sensor is in the shoe and just measures the force exerted on the pedal? That reads out to a handlebar mounted display? The most amazing thing about the website is the vastus medialis and lateralis development on the guy in the middle of the picture. Herschell Walker?
    You're not lost if you don't care where you are.

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    that is the coolest thing ever. i wonder if it affects comfort in anyway, when you're replacing the insoles, it must feel kind of bulky?

    it's awesome that it'll work on any bike. it's also cool that it'll measure your speed and everything. it's definitely something I'll look into getting.
    “(Training) doesn't get easier; you just get faster”
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    Isaias NoRacer's Avatar
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    The thing I don't like about MicroTech's PM is that it assumes everyone mashes the pedals. They come right out and say that they do not believe that cyclists pull up on the pedals throughout a pedal cycle. IMHO, they're wrong and this will be a source of error for their device.

    Quote Originally Posted by http://www.microsporttech.com/faq.php
    It's actually quite simple. In the cycling literature, a 'clock diagram' is a common tool to display the geometric representation of the pedal, crank arm & force vectors. A 'clock diagram' for normal cadence seated cycling is shown:

    And that's probably exactly what you were expecting. Near the top of the crank arm's rotation we start to push on the pedals. The peak force occurs near 90°, and then it diminishes near the bottom.

    But the force doesn't go to zero on the upstroke; and it certainly doesn't go negative. In other words, and despite what your training buddies might tell you, you don't pull-up on the pedals. But that never made much sense anyways, did it, and we at Micro Sport are glad to clear up this common misconception.
    Last edited by NoRacer; 02-26-07 at 07:56 PM.
    2009 mileage = 14,738 miles; 2010 mileage = 15,234 miles; 2011 mileage = 17,344 miles; 2012 mileage = 11,414 miles; 2013 = 12,169

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    Quote Originally Posted by dentalman
    i've been reading a lot of the threads on here about training. and i'm thinking that a power meter should be my next investment.

    i'm curious, will the price on power meters such as Powertaps ever come down to a reasonable price?

    Didn't HRM's start off really expensive (relatively)?

    I'm going to start saving up for a PM.
    I would expect that power meters will continue to drop in price, as they become more common. Having said that, they're fairly finickly devices, and require some good electronic design for the sensor.

    I've seen some of the new ones - the iBike, and the Microtek one, and the polar one - but I'm not sure if it's worth it to get a power meter that's mostly right.

    I do think people will start to buy them more often, with how much people are willing to pay for carbon frames these days.
    Eric

    2005 Trek 5.2 Madone, Red with Yellow Flames (Beauty)
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    Read my cycling blog at http://riderx.info/blogs/riderx
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    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    Quote Originally Posted by derath
    I have given it serious thought as well. I doubt we will see traditional powermeters coming down in price like HRM's. The main difference is that HRM's are purely electronics. Electronics can drop in price as the technology matures.

    Traditional Powermeters are a mix of electronics and physical sensors. You need a fairly sensitive strain guage, built to withstand high RPM's. Then in addition they need to be light weight. Factor in that people buying these aren't interested in a low end hub/bottom bracket, and you don't have a good mixture for a low cost device.

    If devices like the ibike take off, then potentially power can come to the masses.

    -D
    Supply vs. demand. I set up a materials testing lab and we had a rr moore rotating beam tester that was capable of testing at 10,000 rpm. No problems sampling data through a couple of graphite rings with a two dollar multiaxial strain gage. Its just glued onto the piece. I don't know about you but if cheap dollar store "krazy glue" can hold a strain gage in place at 10000rpm, the 100 or so rpm's a cyclist puts out is no problem. The expensive part was all in the electronics. So as electronic bridges, amplifiers, filters, and whatnot advances and miniaturizes, prices will drop.

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    Abby Normal I am The Edge's Avatar
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    Quote Originally Posted by NoRacer
    The thing I don't like about MicroTech's PM is that it assumes everyone mashes the pedals. They come right out and say that they do not believe that cyclists pull up on the pedals throughout a pedal cycle. IMHO, they're wrong and this will be a source of error for their device.

    +1 gazillion

    i was making a conscious effort to pull up on the pedals during my 35 mile climbing ride today. i think the microsport will fail miserably.
    Wow.

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    Personally, I don't see the prices coming down any time soon. Fact is that they are still in high demand with low supply. The "wannabe" power guessers like iBike and Microtech's, and maybe Minoura's will continue to flounder because people are so critical of them. Polar has enough people to say "it's close" to prevent it from complete failure, but from what I'm hearing - Polar's PM is nothing more than an entry drug to the real deal. The fact that Powertap is pulling their lowest cost standard model off the market means they know people are going to continue to be willing to pay the higher cost.

    Saris, SRM, and Ergomo are going to keep making their money as long as the rest of us will keep paying them
    Envision, Energize, Enable

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    Quote Originally Posted by NomadVW
    Saris, SRM, and Ergomo are going to keep making their money as long as the rest of us will keep paying them
    That's the thing. Many of us ARE NOT willing to pay that much and would rather use a cheap "power guesser"--for now. Get enough of us diverting our money to the "power guesser" camp, maybe the big-3 will take notice.
    2009 mileage = 14,738 miles; 2010 mileage = 15,234 miles; 2011 mileage = 17,344 miles; 2012 mileage = 11,414 miles; 2013 = 12,169

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    So, being new to this, the Saris Power Tap is the real deal? The gold standard of power meters?
    You're not lost if you don't care where you are.

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    The cheaper method is to find a long and fairly steep hill. It has to be steep enough to bring down speeds far enough to simplify aerodynamic considerations, but long enough to allow your HR and speed to stabilise early on during the climb.
    Get on your lowest geared bike, strap on your HRM and ride up the hill at different speeds and record your average HR for each ride. Repeat several times for each speed.

    Then measure the distance of the climb, and use a spirit level and a ruler to measure the grade of the hill. The total weight of yourself and the bike (including clothes, shoes, water bottle(s) and so on) and a certain amount of air resistance determines the power exerted during the climb at any given speed. The calculations aren't very complicated, but I won't go into it in this post.

    Anyway, once the power has been determined for each climbing speed, it's possible to correlate each power level to an average HR. With enough data points, a HR vs power curve can be created.

    If this has been done once, the relevant stuff can be entered into an Excel spreadsheet. If a new power/HR curve needs to be created, you'd only have to repeat the climbs and enter the new data into the sheet.

    It all sounds tedious and like it's a lot of work, but it doesn't have to take more than a couple of hours the first time, and maybe half an hour for each subsequent test.

    The whole point is to find how power relates to HR for an individual. This will change over time, and from day to day to some extent, but it provides a good indication of power levels during any ride.

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    Isaias NoRacer's Avatar
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    Quote Originally Posted by wolfgang
    So, being new to this, the Saris Power Tap is the real deal? The gold standard of power meters?
    No. The SRM Science is the "gold standard", but no racer, let alone a word class racer, would even dream of using one of those in everyday training or races at over $5,000US a pop.
    Last edited by NoRacer; 02-27-07 at 06:58 AM.
    2009 mileage = 14,738 miles; 2010 mileage = 15,234 miles; 2011 mileage = 17,344 miles; 2012 mileage = 11,414 miles; 2013 = 12,169

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    Isaias NoRacer's Avatar
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    Quote Originally Posted by CdCf
    The cheaper method is to find a long and fairly steep hill. It has to be steep enough to bring down speeds far enough to simplify aerodynamic considerations, but long enough to allow your HR and speed to stabilise early on during the climb.
    Get on your lowest geared bike, strap on your HRM and ride up the hill at different speeds and record your average HR for each ride. Repeat several times for each speed.

    Then measure the distance of the climb, and use a spirit level and a ruler to measure the grade of the hill. The total weight of yourself and the bike (including clothes, shoes, water bottle(s) and so on) and a certain amount of air resistance determines the power exerted during the climb at any given speed. The calculations aren't very complicated, but I won't go into it in this post.

    Anyway, once the power has been determined for each climbing speed, it's possible to correlate each power level to an average HR. With enough data points, a HR vs power curve can be created.

    If this has been done once, the relevant stuff can be entered into an Excel spreadsheet. If a new power/HR curve needs to be created, you'd only have to repeat the climbs and enter the new data into the sheet.

    It all sounds tedious and like it's a lot of work, but it doesn't have to take more than a couple of hours the first time, and maybe half an hour for each subsequent test.

    The whole point is to find how power relates to HR for an individual. This will change over time, and from day to day to some extent, but it provides a good indication of power levels during any ride.
    Or, you could add a third dimension--blood lactate using a Lactate Pro meter or the equivalent.
    2009 mileage = 14,738 miles; 2010 mileage = 15,234 miles; 2011 mileage = 17,344 miles; 2012 mileage = 11,414 miles; 2013 = 12,169

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    Quote Originally Posted by slvoid
    Supply vs. demand. I set up a materials testing lab and we had a rr moore rotating beam tester that was capable of testing at 10,000 rpm. No problems sampling data through a couple of graphite rings with a two dollar multiaxial strain gage. Its just glued onto the piece. I don't know about you but if cheap dollar store "krazy glue" can hold a strain gage in place at 10000rpm, the 100 or so rpm's a cyclist puts out is no problem. The expensive part was all in the electronics. So as electronic bridges, amplifiers, filters, and whatnot advances and miniaturizes, prices will drop.

    I don't fully agree. There is one key difference with the traditional power meters that will likely keep their prices higher. While the electronics will go down in price, these devices are built into Hubs and Bottom brackets.

    take Powertap. They need to make their hub as light as possible and a race worthy component. How likely is it then that powertap would, at least in the short term, make a "sora" level powertap instead?

    Maybe if the competition starts to show that there is indeed interest in a recreational power meter we will see the "big three" come out with a more affordable device. Until then I don't see their prices coming down.

    -D

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    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    They have a sora level power tap, its only like 600 bucks.

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    A couple of comments on some of the posts as someone who has been training with power for roughly 7 months now.

    In response to the quote, "but I'm not sure if it's worth it to get a power meter that's mostly right", all these devices are "mostly right" for various reaons. They all have their quirks, and use some kind of interpretation to assess power, including the SRM (the supposed gold standard).

    The key is "mostly right" CAN work, as long you have a consistent baseline to start with, and that's what this generation of power meters provides. You may have a flawed baseline (+/- a much as 10% of "real" power), but as long as it's consistent you can measure progress.

    In response to the person who called the iBike a "wannabe power guesser", I'd love to see the data you've gathered where you've benchmarked the iBike vs. the PT, Polar, or SRM. In side-by-side comparisons the variance in power measurement (NP and AP) between the iBike and other PMs is small (+/- 5%). But again it doesn't matter. Why? Because the key is the consistent baseline to start from and measure against over time.

    I also think that comparing the iBike to products that aren't even released is unfair. You should read the the iBike thread on Topica about various users' experiences before making claims that the company/product is "floundering". Maybe you should talk to a Polar user or two as well before you trash that product too. It certainly is finicky, and not for the mechanically inept, but if you are patient, and have mechanical ability, it can work, and work well.

    These products are all first generation and all have their pluses and minuses. I hope prices come down, but if they don't I would hope that at a minimum these devices become more reliable; smaller; and more functional. Even if there is little innovation in the category moving forward, I'm sold on training with power and feel the current gen of devices are good enough, and certainly are an improvement over training w a heat rate monitor or training exclusively by "feel".

    gene r

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    Quote Originally Posted by slvoid
    They have a sora level power tap, its only like 600 bucks.

    Hehe, just looked at their site. I stand corrected.

    -D

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    So the Saris 300 PT stationary trainer with power tap is as sweet as I think it is or no? If I didn't have a foot injury all winter I would probably have bought one because it's a nice indoor trainer, very adjustable for fit and has the power meter.
    You're not lost if you don't care where you are.

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    Quote Originally Posted by NoRacer
    That's the thing. Many of us ARE NOT willing to pay that much and would rather use a cheap "power guesser"--for now. Get enough of us diverting our money to the "power guesser" camp, maybe the big-3 will take notice.
    Probably not. There are enough people willing to shell out the $600-3000 it takes for a reliable power meter.

    Likely, prices will not come down either. These are high end devices. I would expect the features to get better, and the electronics more reliable, rather than see a significant price drop.

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    Dude who rides bike BikeInMN's Avatar
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    Quote Originally Posted by NoRacer
    No. The SRM Science is the "gold standard", but no racer, let alone a word class racer, would even dream of using one of those in everyday training or races at over $5,000US a pop.
    The Science is also much heavier and is not waterproof so my guess is that they're only used for indoor testing.

    From what I've read the Hollowgram SI SRM is the most accurate model they've made to date for everyday use. Too bad it only works on bikes with the over-sized SI bottom bracket.

    Compared to when the SRM was first introduced the prices have come down substantially. Back when Lemond first used them the cost was around 10k.

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    Quote Originally Posted by I am The Edge
    +1 gazillion

    i was making a conscious effort to pull up on the pedals during my 35 mile climbing ride today. i think the microsport will fail miserably.
    That remains to be seen. It will be interesting to see some head-to-head comparisons when their product does come out.

    It will only be a huge problem if the percentage of power you get out of the upstroke is different in different situations. For example, if you get more power on the upstroke during climbing than during sprinting, then that's a big problem, assuming that the power you produce on your downstrokes doesn't completely dwarf what you produce on the upstroke.

    If this doesn't work out, then they should put a sensor in the pedal spindle. Somebody get to work on that. Hey, slvoid, this is your chance to get rich.
    Last edited by CoachAdam; 02-28-07 at 04:33 PM.

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