Bicycle Stem Power Meter with Strain Gauge
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Solution Overview
Problem
Conventional bicycle power meters primarily measure power output from the legs, failing to account for whole-body exercise, resulting in incomplete and inaccurate performance monitoring.
Innovation Solution
A bicycle power meter system featuring strain gauges on the stem, connected to a signal processing unit and processor, which calculates and outputs comprehensive power, torque, stress, and strain values, enabling detection of power exerted on the stem and monitoring of stem fatigue and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power meter is installed on the pedal or crank to measure leg power, then the measurement of leg power output is accurate, but the measurement of total body power output is incomplete
Solution Approach 1:
The power meter system is designed to measure power from multiple body parts simultaneously. By installing strain gauges on both the pedal/crank (for leg power) and the stem (for upper body power), the system achieves multi-functionality in power measurement, capturing both lower body and upper body contributions to total power output.
Solution Approach 2:
The power measurement function is segmented into two independent measurement systems: one for leg power (pedal/crank) and one for upper body power (stem). Each segment measures local power independently, and the processor integrates these segmented measurements to provide comprehensive total power output data.
2Adaptability or versatility
If the strain gauge is disposed on the stem to detect upper body power, then the comprehensive power monitoring is improved, but the device complexity increases
Solution Approach 1:
The strain gauge serves as an intermediary element that converts mechanical deformation of the stem into electrical signals. This intermediary mechanism enables indirect measurement of upper body power without requiring direct contact with moving body parts, simplifying the overall system architecture while achieving comprehensive monitoring.
Solution Approach 2:
The patent replaces complex mechanical power measurement mechanisms with electrical strain gauge sensing. Instead of using mechanical linkages or moving parts to measure upper body power, the system uses electrical resistance changes in strain gauges attached to the stem, reducing mechanical complexity while maintaining measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances riding performance by providing comprehensive power monitoring, including contributions from upper body, and allows for estimation of stem fatigue and service life, improving training and maintenance practices.
Implementation Method 1
The at least one strain gauge is disposed on an outer peripheral wall of the stem, on an inner peripheral wall of the stem, or on both the outer peripheral wall and the inner peripheral wall of the stem
Implementation Method 2
the signal processing unit correspondingly outputs an electrical signal based on a deformation of the stem detected by the at least one strain gauge
Data Source
AI summary
A bicycle power meter includes a strain gauge, a signal processing unit, a processor, and a signal transmitter. The strain gauge is disposed on at least one of an outer peripheral wall and an inner peripheral wall of a stem of a bicycle. The signal processing unit connected to the strain gauge by signal correspondingly outputs an electrical signal based on a deformation of the stem detected by the strain gauge. The processor connected to the signal processing unit by signal receives the electrical signal sent by the signal processing unit and calculates a measuring value based on the electrical signal and sends the measuring value in an output signal. The signal transmitter connected to the processor by signal receives the output signal sent by the processor and converts the output signal to a wired or wireless signal and sends the wired or wireless signal to a terminal device.