High-Pivot Bicycle Tensioner for Virtual Chain Growth
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Solution Overview
Problem
High pivot point rear suspension bicycles experience increased chain growth due to vertical rear wheel travel, which is not adequately addressed by existing tensioners, leading to reduced suspension efficacy and restricted vertical travel.
Innovation Solution
A tensioner device is positioned closer to the high rear suspension axis and idler pulley, incorporating a pivoting member with a pulley and a spring arm to accommodate chain growth by adjusting the driveline angle, allowing for greater vertical rear wheel travel while maintaining belt tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional tensioner is used in a high pivot point rear suspension bicycle, then the structure is simple, but the chain growth caused by vertical rear wheel travel is not adequately addressed, leading to reduced suspension efficacy
Solution Approach 1:
The tensioner device incorporates a pivoting member that can rotate about a pivot point, allowing the tensioner pulley to dynamically adjust its position and orientation in response to chain growth caused by vertical rear wheel travel. This dynamic adjustment enables the tensioner to maintain optimal belt tension throughout the suspension stroke, resolving the contradiction between maintaining simple structure and achieving reliable suspension efficacy.
Solution Approach 2:
The tensioner device changes the geometric parameters of the driveline by adjusting the angle between the upper and lower portions of the belt through pivoting motion. This parameter change allows the system to accommodate virtual chain growth while maintaining consistent belt tension, thereby improving suspension reliability without requiring a completely redesigned tensioner structure.
2Adaptability or versatility
If the tensioner is positioned closer to the high rear suspension axis and idler pulley, then chain growth is better accommodated, but the device complexity increases
Solution Approach 1:
The tensioner device serves multiple functions: it maintains belt tension, accommodates chain growth from vertical rear wheel travel, and adjusts the driveline angle. By integrating these functions into a single pivoting mechanism positioned near the high rear suspension axis and idler pulley, the system achieves better chain growth accommodation without proportionally increasing device complexity.
Solution Approach 2:
The pivoting member acts as an intermediary mechanism between the fixed tensioner mounting and the moving belt path. It translates the geometric changes caused by vertical rear wheel travel into appropriate adjustments of the belt routing angle, enabling the tensioner to adapt to chain growth while maintaining a relatively simple overall structure.
3Length of moving object
If the driveline angle is adjusted to accommodate chain growth, then vertical rear wheel travel is enabled, but belt tension may be compromised
Solution Approach 1:
The pivoting member dynamically adjusts the driveline angle in response to chain growth while simultaneously maintaining optimal belt tension through its spring-loaded mechanism. This dynamic balance allows the system to enable greater vertical rear wheel travel without compromising belt tension, as the pivoting action continuously optimizes the geometric relationship between the belt segments.
Solution Approach 2:
The tensioner device optimizes the driveline angle parameter to accommodate chain growth while maintaining belt tension through spring force. The spring mechanism provides a restoring force that counteracts excessive angle changes, ensuring that the belt remains properly tensioned even as the driveline geometry adapts to vertical rear wheel travel.
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
The solution enables improved suspension performance by accommodating increased chain growth with minimal angle change, enabling more vertical travel and maintaining optimal belt tension, thus enhancing the bicycle's ability to absorb road imperfections.
Implementation Method 1
a spring arm to accommodate chain growth by adjusting the driveline angle
Data Source
AI summary
A rear suspension bicycle having a suspension pivot point sufficiently above a crank axis (front sprocket/chainring) to provide predominantly rearward axle path and require an idler pulley to route a drive belt/chain. A tensioner is located between the idler pulley and the front sprocket/chainring to accommodate virtual chain growth and maintain appropriate tension on drive belt/chain. The tensioner includes a pivoting member with a pulley mounted thereto, a spring arm connected to the pivoting member at a defined angle, and a spring located between the spring arm and a frame. The pivoting member/pulley pivot away from the suspension pivot point to accommodate the virtual chain growth created when vertical rear wheel travel of bicycle increases. The pivoting member/pulley pivot back toward the suspension pivot point to maintain appropriate tension when vertical rear wheel travel decreases. A spring returning to its steady state size (e.g., expanding) is used to maintain tension.