Not as Straight Forward as it Seems!
After creating the Rimpact ORIGINAL our design team went back to the drawing board to design a no compromises Insert. This became the Rimpact PRO.
We theorised that upping the density of the material used would yield increased protection in the form of greater energy dissipation. We assumed to see these results in a linear fashion. On the graph we have used the grey bar chart to summarise our assumptions based on logic.
What we found however, when putting this to theory to the test, was that an increase in density did not correlate to increased protection. The orange line shows how there is a point in which the material effectively becomes too dense and begins to transfer force applied to it through to the surface below - your rim.
X axis - Density, Y axis - Force Dissipation
Combination of Strengths
After learning this we realised that we needed a fresh approach. The particular foam we used for Rimpact ORIGINAL already fell at the pinnacle of this performance curve so is single step increase in density added negative performance as well as weight.
We looked at other materials that would provide a better sharp edge impact absorption but all were much heavier that the Rimpact foam already used. These also significantly effected ease of fitting due to their stiffness. We were trying to find a single material with all of the following properties:
More impact absorption
Equal or better vibration damping
Low weight so ride quality isn't negatively affected
Malleable enough to allow for easy installation
After months of trying different materials we eventually had a brain wave. Rather than find that 'Goldilocks' material that probably didn't exist, why not engineer a smart design that utilises strengths whilst cutting out weaknesses. This is how we came up with the Dual Density design of Rimpact PRO.
We searched and eventually found an Energy Sensitive material that remains supple whilst under minor forces like general riding and installation.
However once energy is applied, (think sharp rock), the material stiffens and dissipated force across both its surface and the surface of the Rimpact ORIGINAL foam below. We discovered in testing that using just the right amount of foam - not too thick, not too thin - we were able to maximise the impact force dissipation of the two materials when combined together vs anything that was possible with just a single material.
As weight was an issue using the two materials in conjunction allowed for a significantly lighter design of just 150 grams for a 27.5" wheel as well.
We were also able to retained the superior vibration damping that Rimpact ORIGINAL provides as denser single materials failed to absorb the high frequency trail vibrations that ORIGINAL currently eliminates.