Bicycle Crunch

What is the Bicycle Crunch?

The bicycle crunch is a dynamic bodyweight crunch variation: lying on your back you alternate bringing each knee toward the opposite elbow in a pedaling motion. The alternating twist keeps the rectus abdominis under near-constant tension while adding a rotational element to the standard curl.

Muscles worked

Primary: Abs

The rectus abdominis works throughout, flexing the trunk to curl the shoulders up and holding tension as you alternate sides in a continuous crunch.

Stabilizers

The transverse abdominis braces the trunk as the legs pedal, keeping the lower back from arching off the floor.

How to perform the Bicycle Crunch

1. Lie on your back, hands lightly behind the head, and lift both feet so the knees stack over the hips in a tabletop position.
2. This is a rotational crunch: the obliques both flex the spine and twist it, so the drive comes from the trunk, not the elbows.
3. Crunch up and rotate your torso to bring one shoulder toward the opposite knee while extending the other leg out straight.
4. Turn through the ribcage so the shoulder crosses toward the knee. Do not just yank the elbow while the torso stays flat.
5. Switch sides in a smooth pedaling rhythm, drawing the new knee in as the opposite leg extends and the trunk rotates the other way.
6. Keep the lower back pinned to the floor throughout and control the tempo instead of racing through sloppy half-twists.

Suggested working range: 15–20 reps. Default progression: double progression.

Mechanics

A dynamic, alternating trunk-flexion isolation: you hold a curled-up position and rotate side to side while cycling the legs, so the rectus abdominis stays loaded across every rep rather than resetting to the floor. The knee-to-opposite-elbow pattern adds rotation on top of the basic upward curl.

Form cues

• •Rotate from the trunk to bring shoulder toward the opposite knee. Don’t just swing the elbow across while the torso stays flat.
• •Keep the shoulders off the floor the whole set so the abs never get a rest between reps.
• •Slow the pedal down; a controlled rhythm keeps tension on the abs, whereas fast flailing turns it into momentum.

Common mistakes

• •Yanking the elbow toward the knee while the torso stays flat, so no real rotation happens.
• •Racing through the reps so fast that the trunk never actually flexes or twists.
• •Letting the lower back arch off the floor as the extended leg drops too low.
• •Pulling on the neck to force the elbow across instead of turning through the ribcage.

Variations & alternatives

• •Crunch: the straight-ahead version without the alternating rotation, for isolating trunk flexion alone.
• •Sit-up: a full-range flexion movement when you want more range instead of the pedaling tempo.
• •Hanging knee raise: a bottom-up option that shifts the emphasis toward the lower rectus abdominis.

Crunch

Abs · Bodyweight

Cable Crunch

Abs · Cable

Hanging Leg Raise

Abs · Bodyweight

Machine Crunch

Abs · Machine

Decline Crunch

Abs · Bodyweight

Programming: sets, reps & when to use it

Run bicycle crunches for higher reps, about 15–20 per side, as a tension-focused ab movement or a burnout finisher. Prioritize a controlled tempo over speed: the goal is continuous tension, not how fast you can pedal.

Frequently asked questions