Stationary Bike Flywheels for Fitness Dummies

Spin bike

When people ask questions on the internet, we suspect they want knowledgeable answers. answers that both make sense and are fairly easy to understand. That's one reason why we make a habit of lambasting freelancers who seem to think that their research skills make them experts on everything: too often, they cheat their readers. Take, for instance, the poor schmuck who wanted to know about "The Differences in Flywheel Weights & Spinning Bikes," which Elizabeth Stewart tackled for SportsRec.com.

When you come right down to it, the OQ's search terms were ambiguous: was someone asking for the range of flywheel weights for spin bikes or asking about the effects of different weights? We don't know, and neither, we suspect, did Stewart; so she seems to have just spitballed. Elizabeth started out by trying to define "flywheel" and "weight"...

"A flywheel is disc-shaped, and its weight controls inertia or resistance on the bike. A heavy flywheel improves traction, produces more power at a steady rate and makes the movement more controlled and less jerky. "

We were sure taken aback by the notion of "improves traction" in spin bikes, but what the heck: Stewart must've extracted that useless factoid from her reference on motorcycle flywheels! Moving right along, Elizabeth attempted to set the scene: "A customary [sic] stationary bike is also called an upright exercise bike. The rider is situated in a more upright position, although some stationary bikes allow the seats [sic] to recline." Here, we think Stewart confused a recumbent stationary bike with a PT Cruiser. It's when she got to spin bikes that Elizabeth really kicked into high gear, with such claims as,

• "A spin bike is made of stronger steel..." – That surely depends on the specs.
• "In high resistance spin cycle mode and a rider can stand up to put more strength on the pedals." – We have no idea...
• "...a spin bike also allows the rider to customize the positions of the seat and handlebar by adjusting it forward, back, up and down to generate more power." – A) Most stationary bikes adjust to the cyclist's leg length and B) the adjustments are to get the size of the bike right for comfort and proper mechanics, not to "generate more power"!
• "Depending on the bike, the flywheel can weigh as much as 20 to 30 lbs. and is connected by a chain to the pedal."

Stewart spent most of her article spreading misinformation about exercise and spin bikes, but she did address flywheel weight in her first paragraph... sort of:

"A heavy flywheel... requires more energy and momentum to get the flywheel in motion; however, once in motion, it allows mechanical energy to be stored so the pedals continue to move even after the pedaling action has ceased. A lighter flywheel uses little pedaling power as it requires minimal momentum to start."

It's pretty obvious that Elizabeth didn't know what momentum is or, for that matter, kinetic energy if she went around writing rubbish like "requires minimal momentum to start"!
But as for that flywheel weight, different manufacturers approach the flywheel in different ways. Not only do spin bike flywheels cover a wide array of weights (from about 9 pounds to almost 60), the technology varies as well. Many spin bikes use the properties of magnets to change the effort needed to accelerate a flywheel.

Stewart, however, knew none of that and as a consequence, neither does anyone who reads her post. Dumbass of the Day? Yep.

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