# Tagged Questions

Power meters and all related data analysis. Power meters measure direct force applied to one of the pedals, crankarm, crankset, rear hub, or other methods. They use cadence in conjunction with the force to measure the power or wattage.

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### How do bicycle power meters work?

What exactly are they measuring? How do they measure it? What are the implications of the different approaches on accuracy / speed of getting a good measure? It would be helpful if someone could ...
2k views

### What's the cheapest way to get into training with power?

I used to train with a stopwatch, and later on, heart-rate. Both required relatively inexpensive tools. Now I'm interested in training with power (measuring the watts produced) and I'm finding that ...
2k views

### What is a power meter and why do I need one?

So I've been looking to become a triathlete soon and I'm hearing all this talk about power meters. Now, upon googling I found vague information which is why I came here. Exhibit A. That article gives ...
2k views

### How can one estimate drag for a bicycle?

I am curious how to estimate drag for a bicycle. This has two different framings: Find the amount of power required to ride at a certain speed. That is, when one is traveling at a constant speed, ...
4k views

### Extra power needed uphill for weight increase

How much does weight mean when going uphill? Let's say I'm going up a mountain with 1000 m of elevation and it's quite steep: 10%. Let's also say I can maintain 250 watts. If I add 1 kg of weight to ...
4k views

### Does gear ratio affect Power?

Let me preface by saying that this may not be the right SE. I considered asking on the Physics SE, but I thought I might try here first. If it is wrong, I am not against it being migrated. From basic ...
1k views

### What's the lowest safe cadence on a climb?

I recently installed a power meter and just used it to get up some rather steep 15%+ climbs. At my weight and lowest gearing (34f 30r) at a sustainable power level for my fitness (225w) this ...
2k views

### What are the 'easiest' ways to determine functional threshold power?

I recently picked up a powertap and have done a fair bit of riding around and a few races now with it on, so I've started to get familiar with some of the numbers. I would like to figure out what my ...
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### Power to weight, FTP and Terrain Profile

If two riders of different build rider 1 - shorter, lighter, thinner rider 2 - taller, heavier, stockier Are riding a rolling terrain. No notable climbs. A few short climbs lasting no more than a ...
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### Increasing stamina while in the office

I started to bike again after 3 or more months of hiatus. I'm currently using a XXS Merida Scultura 300 (I previously used a Trinx R300 needed to upgrade because of the wrong geometry). Thing is I ...
3k views

### Combining Shimano RS500 crankset with Stages Shimano 105 5800

I've been thinking about getting a power meter for a while now. I finally decided I would get one, but now I realise that Stages only starts at the Shimano 105 level. I currently have a Shimano RS500 ...
17k views

### How do I calculate the power required to climb a hill at a given cadence?

Suppose I ride at a cadence of 50RPM for 10 minutes with a 39x23 gear ratio on a hill with 10% grade. Is there a simple formula to calculate the power output required?
7k views

### How accurate are the power numbers from a Tacx Flow?

How accurate are the power numbers (watts) from a Tacx Flow? Multiple aspects : Absolute number : can they be compared with numbers from other power meters ? Relative : if ride two times at 200 W for ...
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### How do I calculate calories burnt using my bicycle's weight?

I've just finished a long bicycle tour on a loaded touring bicycle, and I'm interested in calculating the number of calories I must have burnt over the trip. However, all the calorie calculators I ...
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### Calorie Burn Meter Bicycle

Is there any bicycle with calorie burn meter in market? Its not the one on the gym. Normal bicycle for outdoors. Is there any bicycle like that in market? I have a project for my school work. Really ...
2k views

### Analysis of Stages high-speed data

A while ago Stages added a new feature to their power meter: High Speed Data recording added to capture pedaling force (kgf) and torque (Nm) 64 times per second for post ride analysis (.csv format)...
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### Shifting can't keep up with my acceleration

I noticed that when I really give it hell after stopping or riding slow (I do that all the time on commute), I have to shift two gears at a time in the lower gears, to keep up with my acceleration. I ...
1k views

### What is preferred lacing for PowerTap wheel build?

I've done quite a few wheel rebuilds to make them stronger, but haven't built up a wheel around a PowerTap (SL+) yet. This will be for a training set for a fit triathlete. Raw weight is not an issue, ...
3k views

### Solar charger for iPhone whilst on a bike tour - is it worth it? [closed]

Are there any feasible solar chargers for iPhone / or with a usb slot that will work or is a backup battery available. Best value (and something that works) is my priority. I found this brilliant link ...
1k views

### What's best engine to motorize a road bike

I have a road bike I use for commuting and I'm about to move 20km further out, so I'm considering fitting a tiny engine to it to assist my ride to work. However, where I live I have a restriction - ...
7k views

### How accurate are indoor trainer power meters?

I recently got a Tacx Flow trainer, this being the first time using a power meter. For about 10 years, however, I have been doing monthly "uphill time trials," whereby I put the time into that formula ...
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### How many watts is a good push worth?

The other day as I commuted home a stranger gave me a helpful push as I approached the top of a steep hill. It was wonderful, and I immediately wondered if this is what an e-bike boost would be like. ...
261 views

### Will this power2max power meter be compatible with Cannondale Synapse?

I have a 2015 Cannondale Synapse - specifically, this one: http://www.swiftcycles.co.uk/334/products/2015-cannondale-synapse-carbon-105-6-road-bike.aspx. I would like to add a power meter, and ...
749 views

### Allen Coggan power profile table for Cyclo cross riders?

If you were to create a power profile based on those seen in training and racing with a power meter by Hunter Allen and Andrew Coggan. What would it look like a sprinter or an all rounder? To help ...
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### Swain Power-HR relation

I am trying to understand how to use Swain HR to Power equation in my case. Here is a calculator where one can vary the inputs and see the various outputs based based on the equation: http://www....
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### How do I use my power meter file to improve my time up this steep hill climb tt?

The hill is 0.8km long with an average gradient of 13%. My cadence on my 46t-36t 11-25t 9 speed gear ratio starts at 80rpm and rapidly dips to 40 rpm. Is there a way to calculate what gear ratio is ...
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### Is the real world experience of riding a light bike understated by physics-based calculators?

Take the case where you have two identical riders, Joe Slo and Billy Whizz. They both weigh 75kg and have identical aerobic threshold power output. Joe has a 11kg steel audax bike, but Billy likes ...
2k views

### Does Bike or Rider Weight / Groupset affect cruising speed on the flat

I posted this video on Facebook: and someone commented that my power readings were a bit "optimistic" I asked why and he basically thought that if I'm getting 600W I ...
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### Is there any use to motor pacing for people in the cat 4 to cat 2 range actually useful?

In the local cycling club some people are keen on racing but are no higher than cat 3 in the events that they can enter and the power that they produce. The general consensus is that motor pacing ...
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### Is it worth separating your vo2 max wattage's on the flat and hill climbs in order to provide clearer goals during training?

My watts per kg on hill 5 minute hill climbs seems to be 30 to 40 watts higher than what I can achieve on the flat. This is where I get dropped the most often during group rides and races. My ...
4k views

### How can i calculate the power in watts on an indoor trainer

I am trying to calculate the power needed to hold a steady speed on an indoor trainer, so as I can train using power in watts. I set the bike up and put the crank at 90 degrees, then put a weight of 2....
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### Proper Weight input for a indoor power meter

When setting up the power meter on an indoor Elite Digital Mag Trainer should I put in my weight plus the weight of my bike when I input the weight?
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### Resurrecting an old style SRM Amateur power meter? [closed]

I decided to put my old SRM amateur chainset on my indoor trainer bike, then charged the SRM V unit, but its not working after the charge. I've not used it in 3 years so not surprised, and Im guessing ...
645 views

### what power did alex dowsett put out during his hour record?

Alex Dowsett recently set a new world hour record of 52.937 kilometres, how much power did he have to produce for an hour to be able to achieve this feat?
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### Good cycling goals?

Last year I used a power meter, loved the progress and the tool. I am trying to set some power goals for Maximum 5Min and 20Min. What are some good goals to aim? Last year I had 16% increase in ...
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### Which are better for reproducible power output: Mag- or Fluid-trainers?

I'm looking to buy a trainer but my primary concern is being able to consistently improve my power output. To do this I need a way to measure my output consistently - I don't care what the actual ...
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### Speed to power calc on a 'basic' magnetic trainer

I'm a dedicated non-MAMIL, and I enjoy riding indoors on a cheap-and-cheerful 14-speed (max tooth ratio 48->14) attached to a \$70 basic trainer while watching the footy or listening to music. No wind, ...
429 views

### Allen Coggan Table - Formula for a best fit to time frames

I'm sure lots of people are familiar with the Allen Coggan Relative Power table that then relates your 'score' to what category rider you are. My question is that given rides/segments/hill climbs are ...
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### Has anyone ever tried to estimate peter sagans ftp and 5 sprint power, if so what would they look like? [closed]

Does Peter Sagan's FTP and 5 second power differ hugely from someone like Mark Cavendish or is Mark Cavendish close in his FTP power range but not world class like Sagan? As Mark Cavendish is 70kg ...
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### Can I get my sprinting ability back?

At the end of January this year I purchased a power meter in an attempt to improve my training and general speed. I also performed the obligatory barrage of tests for 5 second, 1 minute, 5 minute and ...
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### which power meters will work with a sram cx1 group set and a bb90 bottom bracket?

I am thinking about getting a new bike but would like to keep using a power meter but can seem to figure out which ones are compatible with sram cx1 and x1 groupsets. Its for my cyclocross bike so ...
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### Can I fit a 105 crank arm (stages) to a Claris 2400 crankset?

I currently have a Specialized Secteur with a Shimano Claris 2400 crankset (compact). I'd like to buy a Stages power meter but they do not sell Claris crank arms. Can I simply put a 105 crank arm on ...