Variation of Momentum on Big Inline Skate Wheels
This article will help you best understand when a bigger wheel is faster than the smaller wheel.
To begin, logic may be telling you that larger wheels mean a larger circumference and that in turn means fewer turns for a given distance. Translation? A larger wheel will get you there faster. Faster? Who doesn’t want to go faster? Slow down there friend. A larger circumference skate wheel doesn’t take into consideration variation of linear momentum due to resistance, required torque, and other factors impacting the moment of inertia.
The Keys To Speed on Skates
Revolutions Per Minute (RPM)s and inertia are the keys to speed with small and big wheels. One can argue that bigger wheels go faster if the RPMs are equal on both a smaller 72mm wheel and larger 125mm wheel. Still. You have to build those RPMs which requires torque and inertia. We’re talking mass and velocity. Momentum. Spooling up.
Spooling Up
Building your linear momentum is what some speed skaters refer to as spooling up. Spooling up with a small wheel takes less energy despite less resistance from a large wheel depending on your method. Consider these two mechanics in spooling up.
Recreational skaters start off from a standing position. They lean forward slightly to push off. The skate disciplines of hockey, freestyle, urban, aggressive and fitness all achieve momentum over the length of many strides. Those strides require more energy to produce the power or torque to reach an average top speed — spooled up.
Now let’s break down spooling up with a speed skater’s mechanics. Speed skaters are generally in a race to finish fastest. They need to reach maximum speed immediately to win their race. They won’t slowly push off the starting line.
A speed skater launches from a down position. They literally sprint forward and run along their center seams. It takes between four and eight running steps before planting a skate, at which point they begin pushing off from leg to opposing leg.
Deconstructing Speed on Inline Skate Wheels
The diameter of a 125mm wheel is… 125mm — that’s the distance across the wheel, not around it. The resistance factors in a larger wheel result in a higher moment of inertia. Still, the human body generally has more than enough torque to generate the necessary force to quickly spool up. Especially if you use a speed skater’s method of sprinting off your starting mark.
Yet. That same exact level of energy will make a small wheel faster too.
The only way a larger wheel goes faster is by way of equal Revolutions Per Minute (RPM). This means that once you are spooled up, the larger wheel will appear to go faster. What a larger inline skate wheel is doing is providing you improved speed performance.
Inline Skate Wheel Speed Specifics Explained by Size
| TYPE SKATE WHEEL | SKATE WHEEL SIZE | ACCELERATION v SPEED EFFICIENCY | MANEUVERABILITY v DIRECTIONAL STABILITY |
|---|---|---|---|
| Aggressive skates | 55mm - 80mm | High Acceleration. Not efficient. | Max control. Least directional stability. |
| Hockey skates | 65mm - 84mm | Very good acceleration. Not efficient. | Max control. Low directional stability. |
| Freestyle skates | 75mm - 90mm | Adequate acceleration. Semi-efficient. | Balanced control & directional stability. |
| Rec Skates | 82mm - 110mm | Modest acceleration. Improved efficiency. | Balanced control & good directional stability. |
| Speed Skates | 110mm - 125mm | Labored acceleration. High speed efficiency. | Hard control & best directional stability. |
Smaller Wheels: More Contact with the Ground
Smaller wheels provide more contact with the ground. That’s good for control due to friction. Friction negatively affects efficiency in maintaining momentum (or speed). Because small wheels make more contact with the ground, you feel every bump in the road.
In summary — the resulting friction in using small wheels causes you to work harder to maintain momentum and speed.
Larger Wheels: Smoother Ride
To a degree the larger your wheels are, the smoother your ride. The smoother ride does mean less friction — less resistance. That means you can maintain your speed more efficiently. That means faster speed is more possible due to the force transmitted on larger wheels. Fast speed is more easily maintained due to efficiency.
The Secret of Big Wheels
Here’s the take-away. Big 125mm skate wheels won’t go faster than smaller inline skate wheels, they’ll enable you to expend less energy to maintain higher speed. Once you’re spooled up, you’ll work less than had you been on smaller wheels. In some way you could argue an inline skate wheel with a larger circumference is faster than a smaller skate wheel, but only once you have reached your average top speed.
Do you want to work less at high-speed?
What's The Best Wheel Size For Speed?
A fit human can easily produce enough torque to overcome the issue of inertia and spool up quickly. But big wheels don’t make you go faster. Big skate wheels help you maintain a fast speed once you’re spooled up. The question to ask yourself is, Do you want to work less at high-speed? If so, are you willing to give up some maneuverability?
It’s a trade-off that most skaters who enjoy a common inline fitness skate (rec skate), are blissfully unaware they’re in the sweet spot of balance. The manufacturers understand this question more than anyone. It’s why many urban skates are sporting 125mm wheels with short frames for maneuverability. Bottom line, go with what you enjoy. If you want speed, go big. If you want to be nimble, go small. If you want something that does it all, good luck.
