Bicycle Tools and Accessories Flashcards
Power Meter: Hardware
Power meters use strain gauges to measure torque applied to the pedal.
Angular velocity of the wheel is used to calculate power, or torque multiplied by angular velocity.
This type of meter is mounted on the bottom bracket, crankset or inside the rear hub.
The athlete’s power output is calculated by combining gravity, inertia, rolling resistance, wind resistance and velocity.
Power Meter: Rear Wheel Hub
Rear-hub power meters are more affordable than bottom bracket based power meters and some crank based power meters.
Rear-wheel power meters limit wheel and hub choice. Athletes must consider this when choosing training and racing wheels.
The wheel can be moved from one bike to another and rear wheel hub power meters are serviceable, easy to install and easy to use.
Power Meter: Cranks
Crank-based power meters are time-tested, reliable and provide no wheel-choice restrictions.
They measure the power of both legs at the crank.
These meters are more expensive and can only be used on one bike.
Crank-based meters require daily calibration and special cranks.
Power Meter: Pedals/Cleats
Pedal-based power meters allow athletes to switch them between bikes.
Pedals are paired in the factory and can’t be changed or isolated.
Pedal-based meters must be tightened to a specific torque (or rotational force) to obtain accurate data.
Crank arm compatibility, chain clearance and types of pedals are limited with these power meters.
Power Meter: Software
Most power meters measure speed, cadence, distance, time and power.
The information is downloaded to a computer, viewed on a screen and uploaded to websites, which track and analyze the data.
Smartphone apps are also available for transferring and interpreting power meter data.
Cadence Sensors
Cadence sensors measure the number of revolutions of the crank per minute. Cadence sensors are typically multi-functional in that they will also measure speed by allowing the computer to calculate distance based on the diameter of the wheel and the number of revolutions the wheel makes in a training session. Cadence measurement is a feature typically included with a power meter.
Speed Distance Devices & GPS
Global Positioning System (GPS) devices are subsets of speed/distance and altitude computers. They provide immediate information on speed, distance, pacing and elevation. They can either be stand-alone bicycle computers, which use a magnet on the spoke of a wheel and other internal sensors, or GPS units within a smartphone or stand-alone GPS device.
Most can also interface with other cycling equipment, such as power meters, cadence sensors and heart rate monitors from a variety of vendors. This technology is called ANT+.
GPS is especially helpful in foreign cities. However, athletes are at risk of developing a dependence on them and forgetting how to read analog maps.
Heart Rate Monitors
Heart rate monitors measure the heart rate and provide another method of evaluating exercise intensity. Coaches can prescribe the use of heart rate monitors to help beginner athletes evaluate perceived exertion. They can also be used to track an athlete’s sleep/recovery cycle.
It is important to prescribe training sessions without the use of a heart rate monitor to avoid overdependence.
