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Testlab

NEWMEN Testlab

... the right way to success.

An in-house test lab is absolutely vital for any company that wants to produce genuinely well-designed parts that stand the test of time. This is especially true when the parts have to be both safe and as light as possible, too. Not only that, we feel that most of the minimum legal standards applicable to manufacturers of bike parts are simply not high enough. That's why we have a fully equipped in-house test lab with our own test rigs. Because we want our component testing to be as rigorous as possible, we also design our own in-house testing standards and build the necessary test rigs if they're not available on the market.

Burst Pressure Test for Rim-Tire Combination

As a result of our recall in 2018, we have been working very intensively on burst pressure testing (tire ejection test). We quickly recognized the need for a test that offers greater safety than the well-known DIN ISO 4210 test. The current DIN ISO 4210 test is as follows:

Maximum permissible tire pressure plus 10%. That is, a tire with a maximum permissible tire pressure of 5.0 bar is tested at 5.5 bar. The tire must withstand this pressure for 5 minutes without coming off the rim. Our road bike rims affected by the recall had successfully passed this requirement! However, based on what we know today, this is clearly insufficient. We have determined that a 5-minute test duration is not long enough for the tire to fully expand under the pressure. This means that even if the tire can withstand the pressure for 5 minutes, it is possible for the tire to detach after a period longer than 5 minutes. Furthermore, the DIN ISO 4210 test provides no specifications regarding the test medium (air or water), nor does it specify how quickly the pressure should, may, or must be built up. However, in our experience, both factors influence the test results. We have therefore developed a test setup with a corresponding test procedure. We chose air as the test medium because we want to test the tire-rim combination under conditions that are as realistic as possible. To do this, it is necessary to test the wheel assembly in a secure burst pressure chamber to prevent flying debris from injuring anyone. Furthermore, unlike when using water as the test medium, hearing protection must always be worn during the test. Incidentally, testing with air also allows us to perform burst pressure tests on tubeless-mounted tires—exactly as they would be in real life… with a tubeless tape and sealant. The sealant inside the tire not only serves as a sealant but also “lubricates” the tire, which can cause it to pop off the rim even faster under certain conditions. To replicate reality as closely as possible, we rotate the wheel inside the burst pressure chamber so that the tubeless sealant inside the tire spreads across the entire inner circumference of the tire, just as it would in real life. Our current testing standard is as follows:

-    The test medium is air
-    The starting pressure is, as in DIN-ISO 4210, the maximum tire pressure plus 10%
-    This pressure must be maintained for 1 hour
-    The pressure is then increased in increments of 10% of the maximum tire pressure, with each pressure level maintained for 1 hour
-    The test is passed when 1.3 times the maximum tire pressure is reached, provided there is  no visible damage to the rim and the tire has not come off the rim

The main differences from the DIN ISO 4210 burst pressure test, using an example tire with a maximum permissible pressure of 5.0 bar:

DIN ISO 4210
Test pressure: 5.5 bar; holding time: 5 minutes plus the time required to build up pressure (approx. 3 minutes)
Test duration: approx. 8 minutes
Maximum pressure: 5.5 bar


NEWMEN Standard
Starting pressure 5.0 bar; the test pressure is increased in 10% increments (0.5 bar), and the pressure is maintained for 1 hour at each level.
Test duration: 180 minutes (3 hours)
Maximum pressure: 6.5 bar

Wheel Fatigue Test

On the drum test stand, wheels are tested for the loads encountered during vehicle operation that result from rolling motion. To do this, depending on the type and intended use, the wheels are not only loaded with different weights, but the obstacle height, speed, and number of impacts are also individually adjusted to suit their respective applications. In this test, we do not use the (sometimes common) method of swinging the wheel.
We replace this force application—which we consider unrealistic—with a lateral force application that, to the best of our knowledge, is significantly more realistic. We apply the lateral forces to the wheel at the point of contact with the road, thereby generating a lateral impulse—exactly as it occurs in reality.

Possible defects:

•    Fracture of the hub flange
•    Fracture of the hub axle
•    Premature spoke and/or nipple breakage
•    Rips in the rim, especially at the nipple holes
•    Cracking of the rim
•    Loosening of the spokes

Brake Fatigue Test

This test machine realistically simulates the braking process of wheels equipped with disc brakes. The brake disc is secured to a fixture; the braking force is transmitted to the wheel via a belt; and the wheel load distribution resulting from the load cycle in real-world conditions is applied to the wheel from below by means of an additional cylinder. This cylinder applies the load to the wheel via a floating base plate at the exact moment the braking load is applied to the wheel.

Possible defects:
 
•    Fracture of the hub flange
•    Premature spoke and/or nipple breakage
•    Rips in the rim, especially at the nipple holes
•    Cracking of the rim
•    Loosening of the spokes

Drive Fatigue Test

This test machine realistically simulates the forces generated by the drive system. The wheel is mounted on the test stand, and the drive forces are transmitted to the wheel via a belt. A lever is mounted on the freewheel body, which supports the drive torque (chain pull). The entire rear wheel hub, the spoke lacing, and the rim are tested here.

Possible defects:
 
•    Fracture of the hub flange
•    Premature spoke and/or nipple breakage
•    Rips in the rim, especially at the nipple holes
•    Cracks in the rim at the nipple holes
•    Loosening of the spokes

Rim Impact Test

We use this testing machine to simulate how the rim or wheel behaves during a puncture. To do this, the rim is secured at a defined distance so that it can deflect downward and to the side. The impact strikes the rim at the following realistic impact angle ranges: -20°, -15°, -10°, -5°, 0°, +5°, +10°, +15°, +20°

Possible defects:

•    Denting of the rim flange
•    Deformation of the rim profile
•    Rim fracture

Spoke Pull Out Test

We use this testing machine to simulate how the rim or wheel behaves during a puncture. To do this, the rim is secured at a defined distance so that it can deflect downward and to the side. The impact strikes the rim at the following realistic impact angle ranges: -20°, -15°, -10°, -5°, 0°, +5°, +10°, +15°, +20°

Possible defects:

• Denting of the rim flange
• Deformation of the rim profile
• Rim fracture

 

Wheel Stiffness Testing

Horizontal Wheel Stiffness:
In this test, we measure the lateral stiffness of wheels. To do this, a wheel is clamped horizontally in a fixture and loaded with increasing force up to a preset value. During the application of force, the deflection is continuously measured and recorded. Here, the effects of spoke tension, number of spokes, spoke dimensions, rim material and cross-section, as well as the lacing pattern and the influence of the hub type on the wheel’s lateral stiffness are transmitted to the (test) table without distortion or interference. The test can be performed both with and without a tire.

Vertical Wheel Stiffness:
In this test, we measure the vertical stiffness of wheels. To do this, a wheel is clamped vertically in a fixture and loaded with gradually increasing force up to a preset value. During the loading process, the deflection is continuously measured and recorded. The test can be performed with or without a tire.

Wheel Overload Test:
This test determines the force at which a wheel collapses (breaks apart). To do this, a wheel is clamped into a fixture and subjected to increasing force until it collapses. In our opinion, this test is absolutely essential—especially for lightweight carbon wheels—to rule out such failure during actual use. The test can be performed with or without tires.

Testlab Handlebars & Stem

Overload Test:
In this test, our handlebars and stems are subjected to a static load at a preset force. This test is particularly important for carbon handlebars because it provides highly reliable information about failure under very high loads.

Possible Defects:

•    Stem breakage
•    Handlebar breakage
•    Screw breakage
•    Handlebar twisting

Fatigue Test:

On this handlebar and stem testing machine, our handlebars and stems are tested according to our in-house handlebar and stem testing standards.

Possible defects:

• Stem fracture
• Handlebar fracture
• Screw breakage
• Stem twisting
• Handlebar twisting

 
Stiffness Test:
In this test, we measure the horizontal stiffness of handlebars. To do this, a handlebar is clamped into a fixture and loaded with increasing force up to a preset value. As force is applied, the deflection is continuously measured and recorded.
This test provides us with information about the comfort of different handlebars.