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What Is A Power Meter?

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How To Improve Speed & Endurance

Power meter [ pou-er mee-ter] n: a device on a bicycle that measures the power output of the rider. A power meter will relay information on power output to a cycling computer or phone app using ANT+ and Bluetooth Low Energy technology.

This definition doesn’t go very far in answering the question: what does a power meter help with, why do people spend time training and racing with a power meter, and what makes them a must have cycling accessory?

What Is Power?

To fully understand what a power meter does and how it helps improve cycling technique, we are going to take a quick trip back to high school physics and talk briefly about power and watts. 

Power is measured in watts. A watt is a basic unit of power equal to 1 joule per second. It is a common unit used to express effort exerted. A power meter measures power by tracking the amount of torque produced by your pedaling and multiplying that number by cadence, or how fast you’re pedaling. So for a moving bicycle, Power = Torque x Cadence.

What is a power meter? Formula for power is cadence x torque = power. This helps us to understand how to train with a power meter, what is a power meter, how to improve cycling speed and endurance, improving cycling technique and understand why a power meter is a must have cycling accessory.

Why Should I Be Training & Racing With A Power Meter?

Understanding how a power meter works is a great starting point, but what will a power meter help with? Why should people train with power meters? How do power meters help improve cycling speed & endurance? Why are power meters a must have cycling accessory? What do power meters have to do with your cycling technique?

When you train with a power meter, you are able to measure your power output, which in turn enables you to make data-backed decisions that prevent burnout and injuries that come from over-exertion. A power meter provides you with the information needed to get stronger legs for cycling and improve your overall cycling technique. Basically, when power is measured, your training becomes more effective because you are measuring your intensity and work. Incorporating this into your training routine allows you to find the balance between over-working and under-working. You gain a better understanding of:

  • Your baseline fitness
  • Your fitness gains, no matter how small
  • Your energy usage and how you can adjust your nutritional plan
  • The intensity, duration, and frequency of your ride

This information allows you to properly pace yourself, prevent overtraining, and improve faster.

How Do I Start Training With A Power Meter?

Here is the fun part – how to train with a power meter. It’s time to practically apply this knowledge and go for a ride. The first thing you need to do is establish your fitness baseline. For the first week, go about your normal training routine using the power meter. Put the data to the back of your mind; your only job at this point is to collect the numbers. Make some quick notes about how you felt during and after your workout so you can later compare that to the data.

The next step is to complete a quick 20-minute Functional Threshold Power (FTP) test. This will establish the highest average power that you can maintain in a quasi-steady state before fatigue. To do this test, you are going to want to find a spot that you will be able to ride non-stop for the full 20 minutes of all out effort. When going through the warm-up and testing phases, it is important to hit “lap” on your bike computer to mark where your effort is starting and stopping. Before hitting it hard, you will want to start with a 15-minute warm-up and gradually move into endurance. During the warm-up, complete 3 one-minute intervals of fast pedaling where your cadence is at 110 RPM or higher. After your warm-up, you are ready for the 20-minute all out test. Mark the lap button before you start and then go hard, being cautious to not go too hard too fast. The first two to three minutes should be a build up period. In the final two minutes of the test, ramp the power up 10 watts at a time and push as hard as you can. Finish strong. Let the test run five seconds longer than your pedaling to ensure you capture the full test. Once complete, take 15 minutes of gentle spinning to cool down.

How do I start training with a power meter? Get quarq PowerTap p2 pedals and install them on your bike to improve cycling technique, improve cycling speed and endurance, and get stronger legs for cycling. A power meter is a must have cycling accessory.

After you complete the FTP test, you are going to take 95% of the power output value and plug it into your training app, such as the SRAM AXS app. This number is going to give you an established baseline for where your power output should be in order to meet your training goals. 

Congratulations! You are now ready to start training with a power meter. You are well on the way to improving your cycling technique, getting stronger legs, and improving cycling speed and endurance.

Ready to upgrade your bike to power? The PowerTap P2 Tech Page to learn more about easy power upgrades for your bike.

The Functional Threshold Power test was established by Dr. Andrew Coggan, Ph.D. Learn more about the FTP test and Dr. Coggan here.

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SRAM Tandem Team Powers Their Way To Course Record At Leadville 100

SRAM Tandem team Strictly Business took first place and set a course record at the Leadville 100 with a bike outfitted with SRAM bike components and Quarq power meters

SRAM team James Meyer and Nate Keck broke the Leadville tandem course record this weekend, setting a new mark at 7:46:04 and knocking 28 minutes off the 8:14:11 ride set by Roca Roja Rollers in 2018.

Breaking records and tackling 103 miles on a bicycle built for two requires strategy, communication, and a bike that is up to the task. Meyer and Keck chose Ventana’s El Conquistador de Montañas to power through the grueling climbs as they raced to the finish line.

Scroll through the gallery below for equipment breakdown and ride analysis.

SRAM Quarq cycling power meters placed on a tandem bike,  SRAM XX1 Quarq power meter configured with a connect iQ to allow for bicycle power monitoring, SRAM XX1 Quarq power meter configured with a connect iQ to allow for bicycle power monitoring
Top: Ventana El Conquistador de Montañas: a fitting name for a Leadville machine. Empty weight: 44lb 3oz
Bottom Left: Captain crank is a bone stock SRAM XX1 Quarq power meter. The Garmin computers were configured with a Connect iQ datafield to allow both power meters to be monitored by both Captain and Stoker. No slacking off!
Bottom Right: The drive-side timing chain allows for the use of standard SRAM Eagle carbon cranks. The Quarq power meter is custom machined to mount two chainrings. The Captain’s drive power flows from the timing chain and chainring to the 32T drive ring, isolating the captain power output. This allows the stoker power meter to measure the stoker power only.
Left: SRAM Eagle AXS rear derailleur handles the shifting. GX cassette for extra durability with double the normal power. The Leadville course demanded 1858 shifts on race day. 
Center:  Integrated TyreWiz monitored the nominal 27psi front and rear in the 2.8” Specialized Fastrack GRID tires. Gauge tire pressure increased by 2.5 psi on top of Columbine due to the reduced air pressure at 12,400 ft and a bit of warm sunshine.
Right: The team rolled on a stock Zipp Moto wheelset. Tandems are not nimble machines, making descending a pick-a-line and hang-on sort of operation. Tires, wheels and suspension take a serious pounding. 

Top Left: RockShox Lyrik fork shorted to 120mm for proper frame geometry and more front-end stiffness. 200psi and zero tokens.
Bottom Left: SRAM Code RSC calipers with 200mm rotors handle the stopping. Brake discs started the day silver but ended the day ‘rainbow.’
Right: Somebody get these guys a ShockWiz, stat!   RockShox Monarch plus RC3 at 270psi
Left: Another SRAM Code RSC calipers with 200mm rotors in the rear.   Gold Jagwire hose rounds out the package.
Top Right: SRAM AXS controllers configured for roadie style ‘eTap’ shifting logic. Bar ends and Togs provide climbing and semi-aero positions for the 103 miles of Leadville terrain.
Bottom Right: Stoker gets the road drop bars treatment. Keep it narrow for better aero and reduce leverage. Stokers should pedal, not steer.
Left: Stoker gets assigned pacing duties. He can check in on progress every hour or two.
Right Top: A rare flat stretch on Columbine
Right Bottom: The 2019 Tandem Podium 1st Place: SRAM’s Strictly Business at 7:46:04 (course record) 2nd Place: QD Racing at 8:19:53 (third fastest tandem time ever) 3rd Place: Team Doza at 9:55:04 (Leadville PR for Captain and Stoker)

Gearing chart made through SRAM AXS app connected to Quarq power meter
Gearing was a 32T front ring pair with the GX Eagle 10-50T cassette. The 10T cog got the most raw ride time with nearly 1hr 40m of use. The 36 minutes in the 50T was key in the highest effort sections & allowed the team to clean the ultra-steep Powerline climb and ultra-high altitude Columbine goat trail. (The only dab of the day was on the short ‘Brutal Bill’ pitch. The Stoker contends this was due to Captain error.)

The team averaged a combined 380 watts for the day. Leadville has 5 major climbs. Keeping the effort even for the full day was key. Average power on the climbs: -St. Kevins: 586 -Sugarloaf: 519 -Columbine: 464 -Powerline: 435 -Carter Summit: 482 Final effort was Captain at 77kg, 230 NP, 3.0 W/kg and Stoker at 68kg, 210 NP, 3.1 W/kg.

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Quarq Introduces the Automatic Calibration Tool MagicZero

Quarq's MagicZero automatic calibration on the new SRAM AXS app for use with DUB power meters

How Does MagicZero Work?

MagicZero is a new algorithm from Quarq that automatically sets the zero-offset of your power meter as you ride. The goal of MagicZero is to let the riders forget that power meter Zero-offsets even exist. Zero-offset management by the user is an unneeded complexity that can be solved with thoughtful engineering.

MagicZero: Learning As You Ride

MagicZero works by continuously monitoring the torque signals from the strain gages as you ride. When the torque signals meet specific criteria for a period of time, a torque snapshot is recorded. Over time, these snapshots accumulate. When enough snapshots within a given tolerance are collected, then a new Zero-offset is computed and set in the power meter.

MagicZero allows the Zero-offset to be automatically managed by the power meter without any specific user actions. Typically, the MagicZero measurements occur when the bike is stationary, coasting, or slowly backpedaling. But as noted above, the criteria is designed to reject snapshots incongruent with recent observations. The MagicZero algorithm is intended to be continuously operating and reaching stable convergence on the correct Zero-offset. If at any point a misleading Zero-offset is applied, the algorithm is designed to self-correct without user intervention.

Powering Rides For Any Condition

MagicZero was developed over thousands of riding miles, in all kinds of disciplines; from Road to Gravel to Mountain Bike to Fat Bikes, going from 70°F houses to -4° South Dakota winters. We are not aware of any specific environments where MagicZero is inappropriate for use. However, it is still possible to turn off MagicZero and only use Manual Zero from the head unit. To do this, turn off AutoZero on your power meter from the SRAM AXS App.

MagicZero is a feature of Firmware 10 and is available via the SRAM AXS App for all AXS and DZero power meters.

Have feedback? Our riders are our best teachers! Please email us at thinkfast@quarq.com.

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King of Kona’s Power Meter Count

The number of power meters used by athletes at the IRONMAN triathlon in Kona has now reached 59% of the field. These athletes know the training and devotion needed to prepare for this race and the races leading to Kona. To be their top power meter choice for 6 years running is a great honor. We strive to do our part with continuous improvements of the products and providing the service these athletes deserve.

Continue reading King of Kona’s Power Meter Count