The Reverse-Threaded Pedals

Cyclists who work on their bikes will eventually notice that removing both pedals is frustrating and weird. It turns out the left pedal on a bicycle has a reverse (left-hand) thread. This means you have to screw it “backwards”. WTF, WHY? Turns out, the pedals are designed to stay tight because of a phenomenon called mechanical precession.

Why One Pedal is Reverse-Threaded (Mechanical Precession)

Mechanical precession is the effect that keeps your pedals secured. In simple terms, when a round object (like a pedal spindle) is forced against the threads in a rotating manner, it will tend to slowly roll around in the opposite direction of that rotation. This means that even though the left pedal rotates forward (which would normally unscrew a right-hand thread), the precession effect makes it tighten instead. In fact, the torque from mechanical precession is much greater than any loosening force from the pedal’s bearings. In nearly all bikes since the 1930s, manufacturers solved loose pedals by using a left-hand thread on the left side.

The Hidden Music in Your Bicycle Wheels

Your bicycle is hiding a secret. Every time you ride, you’re carrying a finely-tuned musical instrument that most cyclists never discover. Professional wheel builders have been quietly using this secret for decades, and it might change how you think about your bike forever.

Here’s something that will blow your mind: bicycle spokes can be tuned like guitar strings. When you pluck a properly tensioned spoke, it rings with a clear musical note. Master wheel builders use this phenomenon to build wheels that are stronger, more durable, and perfectly balanced - all by ear.