I was curious why can‘t they cut the weight and material by just having two wheels. Since I don‘t ride them for years, I forgot what was the benefit of having multiple wheels. Don‘t they produce more friction?
Some of the early versions of Rollerblades had 2 wheels, but Fun Skater's comment pretty much nailed it why they moved to 4 wheels.
There are several reasons and almost all of the previous answers are dead wrong. turning - the additional wheels allow you to shift your weight to the back to allow sharper turning. If you only have two wheels, you will either have a very wide turn or have to do crossovers. roughness of ride - with only two wheels, your skates will rotate as each end hits a bump or drops into a hole. With multiple wheels, the skates will ride over small holes and the effect of bumps are reduced. rolling friction - it is determined by the rebound of the urethane, the diameter of the wheel, and the amount that the wheel flexes as you roll on it. The amount of flex is partially determined by the weight on each wheel. When 80-84mm wheels were the largest, racing skates used 5 wheels for this and for the stability of the longer wheelbase and the additional smoothness of having 5 wheels on the ground. Now that 90, 100, and 110mm wheels are available, the top pros are on 4 wheels. The larger wheels have less friction than the smaller wheels with reduced weight. They are too large to make a five wheel frame practical. Salad's formula is for static friction. It would only apply if the wheels were locked and sliding or for Probably get reported for thiss idea of the push force. The total force via that equation stays the same regardless of the number of wheels. If you double the number of wheels, the friction of each wheel is halved but you now have twice as many. 1/2 x 2 the same force.
