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Presuming you are doing a standing start and coming to a complete stop at the top of the hill. The simple requirement is you need energy to move your from the bottom to the top. Most of the energy required will be to raise potential energy of the payload (you and the bike). Essentially you will be creating kinetic energy (moving the bike) by converting ...

According to the FAQ on their website: Note: PowerTap hubs must be laced with a minimum 2 cross pattern to avoid damage to the hub and maintain the warranty." That suggests that making the non-drive side radial could lead to warranty issues. Radial lacing does stress the flange more than tangential lacing so many hub manufacturers do not allow it. To ...

Your question is simple but a full answer is complex. The simplest answer is to point to Part 2 (especially chapter 4) of Wilson and Papadopoulos (2004), or the recent review by Debraux et al. (2011), or the paper by Martin et al. (1998). However, even these papers do not cover approaches that take better advantage of the data available from modern bicycle ...

You don't quite supply enough information in your specific question (that is, "50RPM for 10 minutes with 39x23 with 10% hill") to provide a full answer in absolute terms but, if we assume you're riding a standard sized 700c bike there's enough information to make a good estimate in relative terms. First I'll give a short answer, then a rule of thumb that's ...

There are some bike hubs containing an electrical motor inside. If you google "bike hub motor" and take a look at the images, you'll get the idea. I think these ones are ideal since they require minimal changes to the overall bike structure, allowing for normal riding if the motor is not working, and they don't burn evil oil: you just plug the bike to the ...

I found this image of the first SRM power meter interesting: The crank is rigged up like a lever (rotating around the spindle) - the more forcefully you push the pedal, the more the strain-guage bends, the output of which is used as part of calculating wattage (as is better described in the other answers!) Many modern power-meters are essentially ...

Fundamentally, power meters all work by measuring force (or torque) and a speed. http://en.wikipedia.org/wiki/Power_(physics)#Mechanical_power P(t) = F(t) * v(t) In other words: Power = Force * velocity A pedal or crank based power meter will be measuring either how much torque is applied to the cranks. That combined with your cadence gives you the ...

The Flow appears to be quite consistent though, depending on the mode in which it is used, it can be quite inaccurate. Below is a plot of reported power for speed on the Flow, with each line representing a different "scale factor." All of these data were collected at a coast down calibration of 0, with the same tire, at the same ambient room temperature; ...

The Tacx Power measurement is accurate in terms of consistency, meaning 200w on Sunday is 200w on Monday, as long as your trainer is set up consistently. It is generally showing a higher number than most other Power meters. My Powertap and my Fortius, when run concurrently differ by about 10%. As for long term accuracy, I've had my Fortius three years. I do ...

If you could find several long hills of different but relatively constant (and not too steep) slope, then determine the slope and your terminal velocity on each hill (assuming that velocity is below some safe speed), you should be able to do the math to determine aerodynamic drag (working on the reasonably valid assumption that rolling resistance is ...

If I on one ride add 1 kg of weight to the bike, how much slower (in time) will I be? Assuming that you and your bike mass 100kg (in round numbers), an extra 1kg causes a 1% increase in weight, i.e. a 1% increase in the potential energy associated with climbing the hill. If your power output is constant, that implies a 1% increase in time. However ...

First, get 'Training and Racing w/ a Power Meter' by Hunter Allen and Andrew Coggan. So incredibly helpful in learning about your device. Second, use WKO+ for analysis. I have been using it for 4 years and it is fantastic. In reference to you question, I typically use the 20 min time trial as a good way of setting my training zones. After a solid warm up ...

I will presume you are asking about the types of trainers that one mounts one's own bike onto, and not a dedicated "bike" trainer such as a Monark ergometer or a CycleOps Indoor Cycle (ergometers such as these are used in exercise physiology laboratories and can be calibrated to be very accurate). Consistency and Accuracy of Speed Measurement Accurate ...

Take a look at TrainerRoad.com to see if your trainer is on their list and you may be able to use a Speed/Cadence sensor with an ANT+ USB stick in your computer to use what they call "Virtual Power". They don't actually measure your power output, but based on known power curves of the trainer at given speed/cadence they run through some formulas to give you ...

Jan Heine & crew at Bicycle Quarterly recently reported the results of their wind tunnel research. A summary is available online, but the full results are only available in the printed journal.

You can use the calculator at http://bikecalculator.com, which will give you a reasonable estimate if you know the average grade of the hill, the day's temperature, and the wind speed/direction (probably not so relevant on a hill). A similar calculator is here so you can compare two methods. The website http://www.cyclingpowermodels.com has a host of ...

Given the same rider, same bike weight, and same climb-time, does your gearing affect power? Also assume that the climb is efficient, no slipping tires, normal pedaling, etc. Well, that depends on which "power" you are measuring :-). Obviously, the power exercised by the bicycle as a whole is the same - if it's moving at the same speed, it's ...

No, gear and gain ratios do not affect power. While you are correct in assuming that it would feel different to the rider, if the other three variables are equal, then the power rate will be the same. In this case, in an "easier" gear ratio, the cadence would require a significant increase to maintain the same climb time (speed) and if the rider is ...

The expense is usually due to the physical hardware needed. Somewhere along the way some device needs to measure the power output. But how? Well inside the hub seems like the most common version. Thus you need a wheel build around a 'heavier' hub to get this to work, and thus is never cheap. Polar had a power sensor I never could figure out how it ...

MY first thought was MTFU and get fitter pedalling further. It might not be as hard as you think once you get used to it. However, for a 20k commute, definitely go with an electric hub motor. Loads available off the shelf. Easy to fit and use, very economical and reliable with low/no maintenance. Also nice and quiet.

They're expensive because they use highly-sensitive strain gauges and require careful calibration. A lot of design has to go into working out how to overcome external factors like temperature changes while at the same time producing a light and weatherproof system. I only have experience with Powertap systems. The cheapest is probably a Powertap Elite+ ...

The older wired Powertap hubs go for pretty cheap on ebay. Here's a listing for $399 for a complete wheel with a Mavic open pro rim: http://cgi.ebay.com/Cycleops-PowerTap-PRO-Rear-Wheel-Mavic-Open-Pro-700c-/310247397790?pt=Cycling_Parts_Accessories&hash=item483c2f999e You'll still need to find a wired Saris head unit though, and it won't work with the ...

Maybe it's the difference between, what do you call it, 'isotonic' versus 'isometric' work? What I mean is that, for example, it takes a human a lot of effort (force, power, or work) to try to move an immovable object: to push against a wall or something. In too high a gear you push and push and go nowhere (lots of power to go nowhere => 0% efficiency). ...

Theoretically, you could only measure power with a specialized instrument, usually an electronic (and expensive) torque meter embedded in a custom crankset or rear hub. For the state-of-the-art about this, take a look at http://www8.garmin.com/train-with-garmin/power-meter.html. It will point you a lot of other links on the subject. If you want, like your ...

A Joule is a Newton-meter and is also a Watt-second. Gravity is about 9.81 Newtons/kilogram. Raising 1 pound 1000 feet would be raising 0.4536kg 304.8 meters. So that would be 9.81 * 0.4536 * 304.8 = 1356 Joules, or 1356 Watt-seconds. Your peak sustained energy output is probably in the general range of 300 watts (and "cruising" would be somewhere ...

I have built a Sheldon Brown POWerwheel to a home-made recumbent I have (photo). Although the idea seems a bit absurd (two leading spokes for each trailing spoke), it worked great for years without any issue, gave a very discrete visual (you only notice it is a powerwheel if you look close), and in the end it is possible that it actually MAKES a difference ...

As others have pointed out, this is unlikely to bear any resemblance to the actual resistance at 80 rpm, but if you wanted to turn your numbers into watts, the formula would be: P[W] = F[N] * l[mm] * w[rpm] * 2 * pi / 60,000 P[W] --> Power [in Watts] F[N] --> Force [in Newtons] l[mm] --> Crank length [in mm] w[rpm] --> Cadence [in rpm] For ...

I find that my 8 minute TT outdoor tests always result in a higher wattage average. Even comparing PowerTap to SRM will result in some differences, but if the trainer gives you repeatable wattage's (as well as always pumping the tire to same psi and set same resistance of trainer to your tire), then you can do your indoor training based on those numbers ...

As already pointed out by the other answers, an additional kilogram is rather negligible when concerning purely the additional potential energy you need. But there are other factors where it may have a more or less larger effect. Firstly that your body does not necessarily respond linearly to higher load. As long as you are in a region where you can do the ...