Bicycle Tire Bead Structure for Lower Rolling Resistance
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Solution Overview
Problem
Conventional two-wheel pneumatic tires, particularly racing bike tires, face issues with high rolling resistance due to frictional forces between carcass inserts and suboptimal airtightness caused by fabric connections between the interior and exterior of the tire.
Innovation Solution
The tire design features two carcass inserts with angled reinforcements and a bead protection band that covers the carcass insert ends, reducing layer thickness and material usage, while a rubberized monofilament bead protection band enhances airtightness by eliminating direct connections between the tire interior and exterior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three layers of carcass ply are stacked radially inside the tread at the tire's zenith (single-ply carcass with overlapping carcass rollover), then puncture protection is improved, but rolling resistance increases due to strong frictional forces between the three stacked carcass plies
Solution Approach 1:
The carcass is divided into two separate carcass plies instead of one thick ply. The first carcass ply extends from the tread through the sidewall to the bead, and the second carcass ply is arranged radially outward from the first ply, creating a segmented structure that reduces friction between layers while maintaining protective coverage.
Solution Approach 2:
The second carcass ply is positioned in a different radial dimension (outward from the first ply) rather than stacking all plies at the same radial position. This dimensional arrangement reduces overlapping friction in the radial direction while maintaining the protective function across the tire structure.
2Stability of the object's composition
If the tire uses a fabric connection between the tire interior and the tire exterior, then structural integrity is maintained, but airtightness deteriorates
Solution Approach 1:
The fabric connection that creates a direct pathway between the interior and exterior is removed. Instead, the carcass plies are arranged and terminated in a manner that maintains structural integrity through their layered construction and bonding, eliminating the fabric's dual role that compromised airtightness.
Solution Approach 2:
The carcass plies themselves serve as the intermediary structure between interior and exterior, replacing the fabric connection. The plies are arranged and bonded to provide both structural integrity and airtightness, with the chafer providing additional protection at the bead region without creating direct fabric pathways.
3Strength
If the sidewall is reinforced by four ply thicknesses of the carcass, then strength is improved, but weight increases and rolling resistance worsens due to increased friction between carcass plies
Solution Approach 1:
The sidewall reinforcement is segmented into two separate carcass plies rather than four stacked layers. The first ply provides baseline strength, and the second ply adds reinforcement at a different radial position, achieving the required strength with fewer overlapping layers and reduced inter-layer friction.
Solution Approach 2:
The reinforcement is achieved by positioning the second carcass ply in a different radial dimension (outward from the first ply) rather than stacking all reinforcement layers at the same radial position. This reduces the number of friction interfaces while maintaining the four-ply-equivalent strength through spatial distribution.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to tyres, in particular bicycle tyres or road bike tyres, comprising a tread (2), a tyre carcass, tyre side walls (3) and two bead regions (4) each with a tyre bead with a core (5), wherein the tyre carcass comprises two carcass inlays (6, 6'), wherein both carcass inlays (6, 6') reach from a zenith region (17) of the pneumatic bicycle tyre (1) via the tyre side walls (3) as far as both bead regions (4) and are looped there around the corresponding core (5) from the axially inner side to the axially outer side and end with carcass inlay ends (7, 7'), and wherein the two bead regions (4) each have, as chafing protection, a bead protection strip (8) arranged externally on the carcass; for improved rolling resistance, the turned up carcass insert ends (7') of the radially inner carcass inlay (6') from the corresponding bead protection band (8) are covered from the axially outer side by the bead protection band (8).