I’ve some small U groove rollers I’m having made and recently I had a brief chat with the company that casts and bonds them onto the hubs. They told be that the weight capacity of these would be around 25Kg each. This seem very low to me so I’m looking to try and increase how they perform but I can not harden or thicken the PU. How do polyurethane wheels fail under pressure? I cant find much online so I’m going off the presumption that under pressure the PU moves and shears of the bonded surface splinting in the centre at the weakest point as the weight pushes down. Picture A, this is the original wheel, the two haves under pressure would be forced apart and it would fail in the middle so I though of putting support on ether side as in picture B. Picture C, this is B with increased pressure until the same thing happens in the weakest and thinnest part in the middle so I changed the profile of the U groove to have the dip in the centre redirecting the pressure away and into the two corners, against the support and acting on the thickest part of the PU as in picture D. What I’m asking is if there is anyone out there with any experience or opinion on how PU behaves under stress, have I got it right or am I misunderstanding how these wheels fail. This PU on these wheels is quite soft by the way, 82-85A.