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WHAT IS A BEAD

The tire bead is a critical component that secures the tire to the rim, preventing it from detaching during inflation and protecting the rubber from pressure damage. As such, it requires precise dimensions, flexibility, and strength. The performance of the bead is influenced by the material and layers, which impacts its usage. There are two main types: metal beads and fiber beads (Aramid beads).

Metal Beads: Typically used in lower-cost tires, metal beads are heavier and non-foldable. Once bent, they cannot return to their original shape, making it difficult for the bead to fully conform to the rim, increasing the risk of tire detachment.

Fiber Beads (Aramid Beads): Commonly found in high-end, tubeless tires, fiber beads are made from synthetic fibers or polymers, primarily using Aramid materials. Compared to metal beads, fiber beads are more flexible and provide a better seal to the rim, ensuring a tighter fit and maintaining their conformity even when folded.

 

Foldable bead material

Currently, the strength of foldable tire bead materials exceeds actual usage requirements, and the technology is well developed, making the risk of bead breakage extremely low, almost impossible. The critical factor for keeping the tire securely attached to the rim lies in the bead’s “stretch rate.”

The bead's stretch rate is one of the most essential performance indicators for tires. A lower stretch rate allows the tire to withstand higher pressures and impacts while maintaining its seal. This rate is closely related to the choice of materials, and Mortop’s bead materials include high-strength fibers such as Aramid (Kevlar 49), Zxion, and PBO, as well as hybrid fibers combining these to enhance performance.

 The Mortop laboratory has tested the stretch rates of various materials under forces ranging from 180N to 4000N.

The test specifications include eight laps on a 622mm (700C) rim.

Lower stretch rates indicate the ability to withstand higher tire pressures.

 

Tubeless Tires

Tubeless tires are primarily designed to work with two types of rims: hooked and hookless.

For hooked rims, tire beads don’t need an extremely low stretch rate, as the rim’s hook structure helps hold the tire in place and prevents it from separating under pressure. However, to handle higher pressures, a bead with a lower stretch rate is still needed.

In contrast, hookless rims lack this hook structure, so the tire bead requires greater precision, high strength, and a very low stretch rate to ensure an airtight seal. Therefore, it’s recommended to use beads with a stretch rate lower than that of Kevlar 49 for hookless rim applications.

Materials suitable for tire beads on hooked rims:

1. Kevlar 49
2. Kevlar 49 + Zxion
3. Zxion

Materials suitable for tire beads on hookless rims:

1. Kevlar 49+ PBO
2. PBO

Mortop Foldable Aramid bead

As the preferred choice for high-performance, premium tires, Mortop’s foldable tire beads demonstrate a strong commitment to precision, strength, and low stretch rate, offering cyclists more options and enhanced reliability.

	ETRTO	BIC Size*	Layers
12 inch	203mm	640mm	6, 7, 8
16 inch	305mm	952-955mm	6, 7, 8
16 inch	305mm	960-965mm	6, 7, 8
16 inch	349mm	1095-1098mm	6, 7, 8, 9
20 inch	406mm	1272-1277mm	6, 7, 8, 9
24 inch	507mm	1590-1595mm	6, 7, 8, 9, 10
26 inch	559mm	1750-1755mm	6, 7, 8, 9
27.5 inch	584mm	1829-1835mm	6, 7, 8, 9
700C/29 inch	622mm	1946-1955mm	6, 7, 8, 9, 10

*Bicycle inner circle size