Bicycle crunches: how to do them, the faults, and two studies that disagree

A bicycle crunch is a crunch with a twist and moving legs. You lie on your back with your hands by your head and your knees up, lift your shoulders, and bring one elbow toward the opposite knee while the other leg straightens out. Then you switch sides, and the legs move like pedals.

A 2001 lab study ranked it first of 13 ab exercises. A later study tested it again and found something different. This page covers the form, the faults, both studies, the easier and harder versions and the sets.

How to do a bicycle crunch

1. Lie on your back with your lower back pressed into the floor and your hands lightly beside your head, elbows wide.
2. Lift your knees so your hips and knees are bent and your feet are off the floor, then curl your head and shoulders up.
3. Turn and reach: bring your left elbow toward your right knee as you pull that knee in and straighten your left leg out, low and long.
4. Switch: turn the other way, right elbow toward left knee, as the legs swap. That's two reps, one a side.
5. Keep it slow and breathe evenly; your shoulders stay off the floor the whole set.

The 2001 study's own instructions are close to these: lower back pressed to the floor, hands beside the head, knees at about 45 degrees, a slow pedalling motion, elbow to the opposite knee and even breathing.¹ The rest of the cues are practical, not study findings.

The common faults, and a fix for each

• Pulling on your head. Your hands only rest by your head. Keep your elbows wide and lift with your trunk.
• Pedalling fast. Speed turns it into a leg swing. Slow down until each turn takes about a second.
• Only the elbow moving. Turn your shoulder and ribcage toward the knee, not just the arm.
• Lower back lifting as the straight leg goes out. Straighten it higher, at an angle, rather than low.

What the studies measured

Every study here measured muscle activity during the exercise (electrical activity in the muscle, not growth), and none trained anyone for weeks. The two that tested the bicycle crunch by name are not peer-reviewed journal papers: the 2001 study was published as a report in a fitness-industry magazine, and the 2013 study is a master's thesis.

• The 2001 study: first of 13. In 30 healthy women and men aged 20 to 45, each doing 10 to 12 reps of 13 ab exercises at a two-second up, two-second down pace, the bicycle crunch had the highest front-ab (rectus abdominis) activity, 248% of a traditional crunch's, and the second-highest oblique activity, 290%. The report counts only exercises at least 25% above the crunch as notably more effective.¹
• The 2013 study: no better than a crunch. In 14 apparently healthy men and women aged 20 to 24, sixteen ab exercises and products, a traditional crunch among them, were compared with that crunch. No exercise, the bicycle crunch included, had significantly higher activity than the crunch in the upper or lower front abs. It was not among the six with significantly higher external-oblique activity than the crunch, and it was one of nine exercises with significantly higher activity in the rectus femoris, a hip flexor on the front of the thigh.² Its version started with straight legs and the feet six inches off the floor.
• A twist on a curl. In a third study, of 25 healthy people, a trunk curl with a twist produced about the same upper front-ab activity as a plain trunk curl.³

Read together: one study put the bicycle crunch at the top and a later, smaller one found it no better than a crunch for the front abs and harder on the hip flexors. Both are small and short, and their versions differed, so the honest summary is that it works the front abs at least as hard as a crunch and brings in the hip flexors more; on the obliques, the 2001 study found far more activity than a crunch and the 2013 study found no significant difference. The 2001 report also suggested most people can't work the upper and lower abs separately, and the 2013 study found no significant difference between the two in any of its 16 exercises.^1,2

Easier bicycle crunches

• Feet down: keep one foot on the floor and bring the other knee in to meet the opposite elbow, then switch. Your lower back has less to hold.
• Higher legs: straighten each leg up at a steep angle instead of out low.
• Standing bicycle crunch: stand with your hands by your head and lift one knee across to meet the opposite elbow, alternating sides. It's a lighter, upright version.

No study comparing these versions with the floor bicycle crunch turned up in a search for this page, so they are practical steps, not measured ones.

Harder bicycle crunches

• Slower: a two-second pause each time elbow and knee meet.
• Lower legs: the straight leg goes out closer to the floor, as long as your lower back stays down.

These are practical, not compared in the studies above.

Bicycle crunches, crunches and the Russian twist

A crunch curls straight forward. The bicycle crunch adds a turn and moving legs. The Russian twist is a turning exercise sitting up, without the curl. If you want the legs to do the moving, the reverse crunch curls the hips up instead, and V-ups fold both ends at once.

Sets, reps and where they go

• Two or three sets of 10 to 20 slow reps a side, each stopped a rep or two before your form breaks, with about 60 seconds of rest.
• At the end of a session, after your main lifts, in the "curl forward" slot of the core workout, in place of the crunch on some days.
• Progress one thing at a time. (Progressive overload covers the options.)

These numbers are practical, not from a study.

Common questions

Are bicycle crunches better than crunches?

One 2001 study ranked them well above a crunch; a 2013 study found no significant difference in the front abs and more hip-flexor work.^1,2 They are at least as hard as a crunch. Use whichever you'll do with good form.

Do bicycle crunches work the obliques?

In the 2001 study they had the second-highest oblique activity of 13 exercises, nearly three times a crunch's.¹ In the 2013 study their external-oblique activity was not significantly higher than a crunch's.² The turn toward each knee is the obliques' job.

What if my neck or back hurts?

If you have pain, an injury or a medical condition, a doctor or a physical therapist should set the limits before you train; this page is general guidance for healthy adults.

If you'd rather have the week planned

Ab exercises are easy to list; fitting the right one into a week that already has squats, presses and pulls is the part a page can't do. Coaching is the version where your workouts live in Trainerize, built around the days and the equipment you actually have, and a weekly call looks at how the week went and sets the next one. Coaching for beginners explains how the first weeks work, and apply is the first step. Otherwise: at the end of your next session, do two slow sets of bicycle crunches and write down the reps.