It seems needless to say, selvedge jeans should always be tapered from the inseam. However, some people still take jeans to local tailors or dry cleaners, who are not equipped with proper denim sewing machines and expect them to properly taper their jeans.
Tapering jeans with double chain stitched lap seams
This fun photo shows an example of tapering from the inseam in-process. This jean was sewn with a double-needle chain stitched lap seam, so it has to be taken apart at the inseam. With the selvedge outseam shown at center, the inseam is then trimmed to slim the leg down. Slimming is done from the hem, up-to just above the knee, and eases out at the thigh.
A tailor without a lap seam sewing machine will never properly taper a pair of jeans with lap seam construction. Instead, they may use makeshift single needle sewing from the hem to the knee area. Leaving the area around the crotch and thigh with the original sewing, connecting the new sewing into the original.
For more detail how we taper jeans constructed with a lap seam, watch our video: How to professionally taper jeans
How to taper jeans with a single-needle, overlocked inseam
Not all jeans have lap seam construction. Some have a single needle top-stitch with overlock construction. The Levi's jeans below have had the legs slimmed down and the excess fabric can be seen underneath.
Most tailors can handle overlocked jeans much easier than lap seams. Overlock sergers are machines commonly used by tailors. However, similar to how traditional tailors may handle lap seam sewing, they will likely remove the original topstitching to just above where the tapering will end. Then use the serger to sew the new leg shape. Finally, to reach high on the leg, so new topstitching can join with the original, the outseams are opened and subsequently closed after topstitching the inseam.
Depending on the details of the tapering, we first remove the entire original topstitching in order to sew a new unbroken/un-joined line. It doesn't matter if the taper is to the knee, above the knee, or like this jean – high into the thigh.
Jeans are tapered high into the thighs when we get requests to make the thigh smaller. We always advise, very little can be done at the thigh. Explaining, the width of the thigh is in connection to the pattern's shape. The seat, rise, and curve in the crotch (which affects movement) are all connected. Decreasing the thigh means the curve must be shortened and straightened, which will restrict movement. Taking from the curve also lowers the rise.
In other words, the best we suggest is easing the taper from the knee, high into the thigh, clipping a bit of the curve, thus reducing the thigh a maximum close to 1/2-inch. We don't feel comfortable taking much more.
Looking closely, the original overlock stitching can be seen in white thread and the new sewing in tan color. This jean was tapered high, so we went completely around the crotch. We use a "feed off the arm" chain stitch machine, which allows us to completely sew the inseam from hem to hem without opening the outseams.
Using the feed off the arm machine is especially advantageous in washed and faded jeans, which develop aging at the outseams. You don't want to disturb the abrasion marks. Tailors who have to rely on taking apart the outseams and reassembling them, find it's nearly impossible to match the exact sewing lines, which will expose dark areas where the seam was previously closed, or close-up the lighter aged markings.
Process for tapering jeans with overlocked inseams:
- Cut the inseam to the requested inseam length, plus 3/4" to 1" (depending hem height)
- Remove the single stitch on the inseam
- Press the inseam flat & draft the taper lines on each leg
- Trim & sew the new leg shape with the serger
- Press the inseam to remove slack
- Sew a new single needle chain stitch on the inseam
- Chain stitch hem the leg opening