Slider Deceleration Quantified Scientifically
BalancePlus conducted tests on curling shoes and sliders using Doppler radar equipment that records the speed of the curler during the delivery. The computer digitally captures 130 readings per second and plots 30 readings per second in graph form. From this information the rate of deceleration of various curling shoe systems or pairs was calculated.
This is the opposite of the current 1 to 10 system that rated the distance of slides applying the same kick but using different equipment. The old system was not reliable for the following reason. A curler using their maximum strength kick to start a delivery would not slide very far if a rubber anti-slider (pull-on gripper) was covering their slider. If the same kick were applied using equipment with very low friction the curler would have to abort their slide to avoid hitting the boards at the far end. Using a kick requiring the curler to be subjective about the amount of force they used is not accurate enough. If curlers were that good we would not need sweepers.
The average rate of deceleration has been calculated in kilometers per hour per second.
BalancePlus 100 Series with 1/16” Stealth slider 1.002 km/hour/sec
Competitor’s shoes with plain 5/32” slider and toe coating 0.527 km/hour/sec
BalancePlus 200 Series with 5/32” slider, one BalancePlus hole and toe coating 0.432 km/hour/sec
BalancePlus Delux with ¼” slider, 2 BalancePlus holes and toe coating 0.384 km/hour/sec
The lower the number, the farther the curler will slide using the same kick.
These preliminary results are from the first round of tests. Independent tests conducted in another country using similar equipment resulted in very similar results. We will continue testing to determine other factors such as the impact of the weight of the curler, first end ice vs. later in the game. We intend to have an independent test facility conduct tests to establish deceleration rates of curling shoes.
We also tested curling shoes with stainless steel sliders. New stainless has slightly more friction than ¼” BalancePlus. However, used stainless steel produced more friction than 5/32” BalancePlus. Both new and used stainless felt more slippery and were more difficult to control than BalancePlus but created more friction causing a more rapid deceleration.
Many materials have low coefficients of friction when they are new. However, with use as a curling slider they become marked from sliding over the ice and debris on the ice. These marks cause most materials to become abrasive. This abrasiveness increases friction and deceleration. Debris that is scraped off the ice (detrimental to the ice) often becomes trapped in the scratches. This deterioration of the slider is commonly referred to as the slider “getting slower”. The properties of *PTFE make it the best material for curling sliders. It has the lowest coefficient of friction and scratches do not become abrasive because the material is soft enough to allow the edges of the scratch to become smooth again with regular use. In fact *PTFE sliders become faster with normal use. Adding metal to *PTFE will reduce the positive characteristics of *PTFE and increase the negative characteristics that are found in sliders made entirely of metal.
Should you have scientific data on the subject, questions or comments, we would appreciate hearing from you.
*Polytetraflouroethylene (PTFE) commonly known as Teflon® was discovered by Dr. Roy Plunkett in 1938. DuPont is the registered owner of the trademark Teflon®. Other companies now produce the resin from which PTFE is manufactured