Questions tagged [power]

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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23
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3answers
21k views

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 ...
20
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4answers
5k 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, the ...
16
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4answers
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 ...
14
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6answers
4k 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 ...
12
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7answers
10k 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 ...
12
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4answers
8k 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 ...
11
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6answers
4k 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 ...
11
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3answers
14k views

Understanding e-bike power/torque

In the UK e-bikes are currently limited to a maximum of 250W assistance if you wish to use them on public roads. However, it seems that the motors do vary in terms of the available torque - from ...
10
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5answers
34k 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?
10
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4answers
2k views

Does rocking the bike side to side when e.g. sprinting or climbing help?

Or would more power go through the pedals if the rider held the frame still/upright? Or is there little difference? How would it be measured and what are the forces acting on the bike when rocking ...
9
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7answers
5k views

Is it possible to burn only ~850 cal. on 1.5h / 20 km fast bike ride?

I have just recorded two following activities (I am 42 years old and seriously fat / 108 kg): Hike: 9.04 km / 1h20m / 90 m elev. / 1,220 kcal Bike: 20.26 km / 1h25m / 146 m elev. / 837 kcal Is this ...
9
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3answers
14k 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 ...
8
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5answers
1k views

What use does a Heart Rate Monitor have if you have a Powermeter?

When should you be riding by HR instead of Power and what can you learn from a HRM when you're riding by Power?
8
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3answers
2k views

Power Output at different Air Densities

Factors Influencing Air Density are: Altitude, Air Temperature, Air Humidity and Barometric Pressure. Calculator: http://barani.biz/apps/air-density/ How does riding at different air densities affect ...
7
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3answers
3k 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)....
7
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5answers
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 ...
7
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3answers
1k views

What method or algorithm is used for computing power curve on Strava?

Many cycling analytics apps like Strava, TrainingPeaks or GoldenCheetah are offering the critical power curve chart, computed from the power meter data. I'm familiar with the curve meaning and usage, ...
6
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3answers
2k views

What is the drag / power lost to a safety flag?

I have a recumbent bike that has a safety flag on the top of a thin pole, so it flutters around higher than and after my head. How much power am I losing to this flag that could be used to power my ...
6
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3answers
2k views

Can pedal-based power meters be used as flat pedals?

I would like to collect as much data as possible about my daily road rides so recently I am considering pedal-based power meters such as Faveor Assioma or Garmin Vector 3. However, I don't want to ...
6
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6answers
2k views

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 ...
6
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3answers
316 views

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 ...
5
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2answers
12k 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 ...
5
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3answers
2k views

Changing from Ultegra 6800 crank to r8000 dual power meter

I currently have a shimano ultegra 6800 crank set on my 2014 trek speed concept 7.0. I want to install a dual side power meter and can only find the r8000 dual side power meter setup. Will the r8000 ...
5
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2answers
479 views

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 ...
5
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0answers
162 views

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....
4
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3answers
439 views

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 ...
4
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2answers
616 views

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 ...
4
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2answers
10k 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 ...
4
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2answers
2k 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, ...
4
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1answer
1k 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 ...
4
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2answers
701 views

What is the cheapest and easiest way to add a power meter to my Diamondback Haanjo 4?

What is the cheapest and easiest way to add a power meter to my Diamondback Haanjo 4? It has a Praxis M30 BB and a Praxis Alba crankset. Thanks!
4
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2answers
1k views

Understanding how to calculate critical power curves

Hello fellow cyclists, There are services out there that can calculate power curves based on your bike ride (when training with a power meter). This curve shows the time to exhaustion (t) based on ...
4
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1answer
179 views

What are the values of Average Power Phase in the .FIT file?

I'm trying to understand the Average Power Phase values inside the .fit file. There are four of them, for example avg_left_power_phase: (355.7812555590821, 199.68750312011724, 202.50000316406255, 97....
4
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1answer
68 views

Deore XT Power Crank

I have an Ultegra Crank set. I also have a Deore XT 175mm left side power crank. Can I use this on a road bike?
3
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2answers
158 views

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 ...
3
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4answers
4k 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 ...
3
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1answer
903 views

What's the difference between power meter and bike computer?

I am currently using a IpBike computer app (on Android) with DuoTrap Speed and Cadence sensors on my bike. I was reading about power meters and how they would help in training by assessing the power ...
3
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1answer
102 views

Quarq dfour installation

I'm looking into getting a sram quarq dfour power meter, but I'm a bit confused as to what parts I need. I have a Specialized Diverge 2021, which comes with ultegra RX810. I know I need the spider. Do ...
3
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2answers
300 views

What power meter would work on my bike?

I have a 2015 bike with a Shimano 105 group set the cranks are 172.5mm and behind the crank is says the following. I’m relatively new to cycling and want a power meter please help cheers
3
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1answer
629 views

Can a BB30 Crank Arm (Left) power meter can be used with a BB386EVO Crankset

I have read many websites and articles about the interchangeability of BB30 and BB386EVOsuch as this and this YouTube video. Many say yes and many say no. Yet, I am not sure which Stages FSA power ...
3
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2answers
1k views

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 ...
3
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1answer
184 views

Why are electric bikes ranked on torque ratings?

A major ranking criterion for electric bikes is the torque rating of the motor. Generally speaking, bikes/motors with higher torques are sold at a higher price than bikes/motors with lower torques. As ...
3
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2answers
582 views

App for displaying 30s rolling average power

I use a power meter without a dedicated cycling computer like Garmin or Wahoo, I prefer to ride with my phone on the handlebars. I found a couple of cycle computer apps which can be paired with the ...
3
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2answers
139 views

Power meter upgrade on 2015 Surly Long Haul Trucker

I have a 2015 Surly Long Haul Trucker with a Andel RSC6 crank and Shimano UN-55 bottom bracket. Is there a crankset I could replace that with that would be compatible with a single side power meter?
3
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1answer
161 views

Is there a left-sided powermeter that requires less than 8 millimeters of clearance?

I'm willing to spend some money on a powermeter to train a tad more effectively on my bike. The problem is, that my frame (Trek Checkpoint ALR 4 2018) does not have the required clearance between ...
3
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1answer
7k views

How to calibrate Garmin Vector 2 power meter pedals with a Wahoo Elemnt computer?

I just installed Garmin Vector 2 power meter pedals on my bike along and am using it alongside a Wahoo Elemnt bike computer. I've done a few rides now and my average wattage is reading very high (i.e. ...
3
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2answers
898 views

Quarq Dfour Fit Problem

I recently buy my first Quarq Dfour power meter to replace my crank Shimano Ultegra 6800. but I have the problem that the quarq spindle its too short ( 106 mm quarq vs 109 mm shimano ultra ). I don't ...
3
votes
1answer
122 views

Cockpit tech: ANT+ Power meter → Android phone?

Question Has anybody had any success getting ANT+ only equipment to talk to Android apps? I'm only talking about a situation in which the Android phone specifically has ANT+ capabilities; obviously if ...
3
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2answers
2k 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 ...
2
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4answers
501 views

What is the difference between a speedometer and a power meter in terms of performance measurement? [duplicate]

If I cycle the same route every day, what would be the benefit of having a power meter over a speedometer? Can't I just measure my speed and compare it against my last run and see if I've done better?...