JWL and Impact Testing Explained

We get a lot of questions about the weight of our wheels and the relevance of weight to performance and to safety.  The weight is important – this is what makes the difference to the unsprung weight.  It also matters where the weight is concentrated or reduced in order to affect the performance – the moment of inertia. Safety is critical and the authorities governing this are the JWL and the TUV.  Your wheel has to pass the impact tests they define.

Impact Testing – Understanding the Loads

In order to pass either the JWL Impact Test or the German TUV Impact tests, the IMPACT requirements are defined and clear, and must be performed on a test rig defined by JWL:

Strike Weight:

Front Wheel must withstand the impact from a weight 2.5 times the published Static Load rating.

 

BST published Static Load rating is 150kg.
Impact weight = 150 x 2.5 = 375kg.  The wheel can withstand an impact of 375kg.

 

Rear Wheel must withstand the impact from a weight 1.5 times the published Static Load rating.

 

BST published Static Load rating is 250kg.
Impact weight = 250 x 1.5 = 375kg.  The wheel can withstand an impact of 375kg.

 

Check The Facts on the Published Static Load:

Published Static Load of 180kg on a Front Wheel: the strike weight must be 450kg (180 x 2.5).

Published Static Load of 280kg on a Rear Wheel: the strike weight must be 420kg (280 x 1.5).

This is all defined in the JSAE JASO T230 (1985) publication:


The highlighted section is definitive.