What biflex is and how to sew a gymnastics or dance leotard

Biflex is the main fabric for rhythmic and artistic gymnastics leotards, dance, figure skating and swimwear. Here is what this fabric is, why it behaves the way it does, how it differs from ordinary jersey, how much you need for a leotard, how to cut it so the garment fits close and does not pull, and how to decorate it.

What biflex is

Biflex is a smooth synthetic knit with a high elastane content that stretches in two directions and springs straight back. It dries quickly, does not fade from sweat or chlorinated water and fits close to the body without restricting movement. That is why everything that works under stretch is made from it: leotards, jumpsuits, leggings, tops.

• Biflex is matte or slightly shiny, the base fabric of a leotard.
• Disco and holographic fabrics have the same stretch knit underneath, with a metallic coating: they are used as inserts or for competition leotards.

Why biflex stretches and keeps its shape

Biflex is made of smooth synthetic yarns with added elastane, a fibre that stretches several times its length and returns to it. The knit structure itself gives the fabric stretch, while elastane makes sure it does not sag after being pulled. Synthetic yarns absorb almost no water, so a leotard dries within minutes after training and does not get heavy with sweat. The smooth surface glides, does not snag or pill, and the dense knit keeps the fabric opaque even when stretched.

Biflex or ordinary cotton-elastane jersey

What biflex is used for

• Rhythmic gymnastics: training and competition leotards, often decorated and with disco or holographic inserts.
• Artistic gymnastics and acrobatics: leotards that do not hinder movement or ride up.
• Dance: bodysuits, tops, training leotards, the base for stage costumes.
• Figure skating: the base of the dress, with a skirt of euro mesh sewn on.
• Swimming and fitness: swimsuits, leggings, tops, shorts.

Colours

We stock biflex in black, grey, red, yellow, lemon yellow, green, blue-green, blue and leopard print. Black and blue are versatile for training, bright colours are more often chosen for performances, and leopard print suits dance costumes and fitness.

How much biflex you need for a leotard

For fabric 150 cm wide, roughly:

Add 0.3-0.5 m for a skirt, briefs under the leotard or a lining. To be exact, lay the pattern out on a table, measure how long it runs and add 10 cm.

Our minimum cut is 1 m, so with a child's leotard you will have fabric left for a skirt, a headband or a second, smaller leotard to change into.

How to cut so the leotard fits

• Greatest stretch around the body. Before cutting, pull the fabric lengthwise and crosswise: where it stretches more, that is where bust, waist and hip go.
• Cut in a single layer on a flat table, without stretching the fabric or letting it hang over the edge, or the piece will distort.
• A leotard pattern is 10-15 % smaller than the body measurements: biflex should fit tight, without wrinkles.
• Hold the pattern down with weights and trace with soap or a marker; pins pull thin knit.

Why around the body? A leotard stretches most across the body when a child bends, folds or does the splits. If the greatest stretch runs lengthwise, the leotard will press on the shoulders and cut into the crotch even though the size seems right.

What to sew it with

A jersey or stretch needle (75-90), polyester thread and a stretch seam: overlock, narrow zigzag or a stretch stitch. Neckline and armholes are finished with a binding from the same biflex or with elastic. We cover seams on a regular machine without an overlocker in a separate article.

Fitting and adjusting

Before the final finishing, baste the leotard with a wide zigzag and try it on. Ask the wearer to move: squat, bend, raise the arms. The leotard should not slip off the shoulders, cut into the crotch or wrinkle on the back. If it pulls at the shoulders, the torso is usually too short: let out the shoulder seams. If wrinkles form, take in the side seams by 0.5-1 cm.

How to decorate a leotard

• Disco or holographic inserts: stripes, geometric shapes, patterns on the bodice.
• Mesh: sheer inserts on the sleeves and back in euro mesh or sports mesh.
• A skirt of mesh sewn at the waistline, for figure skating and dance.
• Rhinestones for competition leotards: glued onto the finished garment with special fabric glue.

Care

Wash at 30 °C by hand or on a delicate cycle, without bleach or softener, dry laid flat away from radiators and sun. Do not iron a disco or holographic leotard on the right side.

Softeners leave a film on synthetics that makes the fabric breathe worse and lose stretch sooner, and the heat of a radiator or direct sun ages elastane so the leotard starts to sag.

Common mistakes

• Cutting with the stretch running lengthwise. The leotard presses on the shoulders and crotch even though the measurements fit.
• Straight stitch on the seams. The thread snaps at the first stretch: biflex needs stretch stitches only.
• An ordinary universal needle. It pierces the knit loops, leaving small holes and skipped stitches.
• A pattern at full body measurements. The leotard wrinkles and shifts as the wearer moves.
• A hot iron. Synthetics melt, and the metallic coating of disco and holographic fabric is ruined.

Frequently asked questions

Can biflex be sewn on an ordinary machine?

Yes: you need a jersey needle and stretch stitches, an overlocker is not required. Before you start, sew a test seam on a scrap and pull it: the thread should not break, and the seam should stretch with the fabric.

How long does a biflex leotard last?

With regular training and proper care, a training leotard keeps its shape for several seasons. Most often a child outgrows it before it wears out. To make it last longer, wash it right after training and do not leave it wet in a bag.

Is biflex see-through?

No, the fabric is dense and stays opaque even when stretched. For light colours, a swimsuit still gets a lining at the bust and briefs.

Where to buy

Biflex at Hop.Shop is cut from 1 m in 0.5 m steps, 150 cm wide; from 10 m of one colour the wholesale price applies. Next to it are all stretch fabrics: disco, holographic, lurex, velvet.