I was doing some searches here on Pinside and didn't see an answer to my question so I will ask it here. I found that vid1900 posted several years ago (https://pinside.com/pinball/forum/topic/titans-competition-silicone-rubber-vids-review) a wonderful review that compared the elasticity of Titan bands to others which is helpful to understand the behavior of a passive sling or bumper when fitted with different bands.

That lead me to wonder has anyone tested and quantified the difference in the coefficient of static friction (µ) and the coefficient of restitution (C) between the different types of flipper bands available? I'm thinking about setting up some of my own experiments to test the differences and find out more, and any insight would be helpful.

While I think the effect of the coefficient of restitution is generally well understood, i.e. how much bounce you get on a dead flip or from a post and probably the reason why Titan offers low bounce flipper rings, I don't see anything other than durometer readings available which don't 100% correlate to how much energy is returned in a collision. This would be an easy test to roll a ball down an incline from a fixed height to strike a fixed flipper and measure the resultant bounce height. This is different than vid1900 's test because we want the determine the bounce and not the spring constant. Think dropping a golf ball on asphalt vs dropping it on a pillow to help visualize the difference we want to measure.

Additionally the coefficient of static friction has a large effect on how much spin is imparted on the ball as well as overall ball speed and launch angle. I haven't seen any test data related to that and I was a bit surprised by that. I would think anyone with a spring scale and a small weight with an eyelet could test this by measuring how much force it takes to begin moving/dragging the weight resting on the surface. You could do the same by resting the weight on the surface and adjust the angle until the weight begins to move.

I recently swapped my TMNT over to using Titan bands. After a couple of games, I switched my lower flippers back to the stock black rubber because ball control was an issue. I was getting way too much spin causing the ball to take some unusual paths. I also observed ball speed increased greatly, which lead to some higher scoring on multiball, but also a lot of out of control play. I also found that the Titan band on the upper flipper makes the center ramp shots easier due to the increased friction.