Competition Suit DIY: Constructing the Top

If you’ve been following along, we’ve SELECTED OUR FABRIC and put an order in for connectors.  Next up, sewing the suit top.

CUTTING THE TRIANGLES

We’re not going to use a pattern today.  Instead, we’re going to use a set of Swim Shapers to model our suit around – even if we’re not going to use them as padding on our suit.  Alternately, you can use a triangle bikini top that fits well with minimal bunching along the bottom {you want the fabric on your competition suit to be pulled tight when complete}.  

Mark the top corner of the swim shaper.  Lay the fabric pattern side down on a flat surface and set the Swim Shaper on top of it.  Without stretching the fabric, pin the shaper to your suit fabric.  If you’re using a geometric pattern, make sure you align the shaper with the print. I prefer abstract patterns because those lines are really hard to match perfectly once you stretch the fabric a little in a later step.  Cut out your fabric with a 1/2″ seam allowance on each side, and a 3/4″ seam allowance on the bottom.  You need more fabric on the bottom to build the casing for the back strap to run through.

Unpin the shaper.  Cut an identical piece of fabric for the other triangle top from your suit fabric and two from your liner fabric.  For ease, we are not adding a pocket for padding.  I will show you later how to “fake” a packet, which is so much easier!  I may update this later to add instructions for adding a real pocket, but in my opinion, you’re the only one who will see the inside of your suit so going through an additional three steps to have a finished pocket is unnecessary. 

SEWING THE TRIANGLES

Pin a liner triangle to a pattern liner, with the pattern facing up.  Flip the pinned triangle over and lay the shaper on top.  Starting on the top left, run a straight stitch along each side of the triangle, leaving a 1/2″ seam allowance – even on the bottom where you have excess fabric {you’ll fix this seam later}.  A walking foot will make sewing with spandex easier but it’s not required.  No need for perfection – you’ll add edging and cut off excess fabric in a few.

ADDING EDGING

Cut two, 1-2″ wide strips of fabric that run the length of one side of the triangles.   Cut two additional 1-2″ wide strips that are the length of one side of the triangles, plus 3″.  For an A/B spacer, this is about 11″.  If you want to edge your suit in a different fabric, like solid black, you would swap in that fabric here.  Cut four pieces of elastic that align to the length of your four fabric strips.

Loosely pin one shorter strip of fabric, print side down, to the print side of one triangle.  Do the same to the opposite side of the other triangles.  These strips of fabric will form your inner edging.

Flip the triangle over.  Take one of the shorter pieces of elastic and lay with the inner edge just inside the stitch you ran earlier.  Pin the elastic at the top corner only.  To make the sewing easier for the outer edge, leave a small gap between the top corner and where the elastic starts.   Run a lock stitch or back stitch the elastic to the fabric along the inside edge of the elastic to hold it in place.  Pull the elastic slightly to add a little tension.  Do not pull it as far as it can go.  You want the completed triangle to arch a little, but not so much that it bunches.  

Trim off the excess seam allowance outside the elastic, and any excess elastic {there should be a bit from where you pulled to add tension}. Flip the triangle so it’s print side up.  Wrap the smaller strap of fabric around to the back, folding over the elastic on the back side and pin in place.  

Now we’re going to cheat a little to get the finish the edging.  Ideally, you’d sew this with a serger that’s capable of two stitches at once, or use a twin needle.  I don’t have the former and failed epically with using the latter.  Instead, I run two separate straight stitches to secure the elastic in place and give the suit the serger look with a regular machine.  To do this, we want to run it through the machine two more times, print side up, with two straight stitches parallel to each other.  I keep this stitch pretty narrow, which will flatten out the edging and make it easier to attach a rhinestone trim, if you want.  I start on the inner stitch, then run the outer.  If you run the outer stitch first, you can get some puffiness in the fabric that you don’t want.  Flip the triangle over to the back and cut off the excess edging fabric.

Repeat on the other triangle.  Part 1 of edging your suit top is done.  Phew.

The outer edging of the suit is similar, with one key difference.  The edging will need to continue into part of the halter strap where you attach the top connectors.  To do this, you’ll want to line up the strips and elastic with the bottom of the side you’re stitching to, and allow the excess to extend beyond the top of the triangle.  The elastic will run right into the gap you left at the top when you added the inner edging elastic – no overlap means easier on your machine.  As you run the first straight stitch to attach the elastic, add a few reverse stitches at the top of the triangle so the attachment is super secure.  Otherwise, continue as you did for the inner edging.  

To finish off the triangles, you’ll need to sew the casing across the bottom for the strap to slide through.  The easiest way to measure this is using a strap you’ve already created or your elastic.  

With the lining facing up, place the strap or elastic along the bottom of the triangle.  Fold the fabric up and over the strap/elastic, and pin in place.  The resulting triangle should not have a flat edge; rather, the bottom should be curved slightly, following your original pattern.  

Slide the strap/elastic out of the casing.  Run a straight stitch along your line of pins, making sure to lock the stitch in over the edging.  Repeat on the other triangle.

CREATING A BACK STRAP

Cut a strip of fabric 1.5″ wide and long enough to wrap around your midsection and tie in a bow.  Longer is better – you can always trim.  

Flip the fabric print side down.  Pin one end of the elastic to the upper corner of the strap, letting the elastic slack fall along the long edge.   No need to cut the elastic to size;  we’ll take care of that at the end.  Lock in the stitch on the elastic, the putting some tension in the elastic, continue to run a straight stitch the length of the elastic.  

Starting at one end of the strap, fold the elastic, sandwiching it between two layers of fabric.  Flip the elastic one more time so it is fully enclosed in the fabric.  You’ll now run two stitches down the elastic, just like you did on the edging.  Lock in your stitch and run a straight stitch down the side closest to your loose fabric.  

As you sew, you may need to tighten the fabric around the elastic.  Make sure your machine is set to leave the needle down when you stop so the fabric doesn’t shift, then tug on the loose side of the fabric to tighten.

Run a second stitch parallel to the first, as you did with the edging.  Lock off the stitch and you’re done with the strap.

PULLING IT TOGETHER

To run the strap through the triangles, attach a safety pin to one end and guide it through the casing you’ve created along the bottom of the triangle.  

If you’re adding a center connector, thread it onto the back strap, as shown in the photo below, then slide each end into the casing. 

So here’s where we are: 

We’ve SELECTED OUR FABRIC, ordered connectors, and sewn our suit top.  Next, we’ll put our rhinestones on order so they’ve arrived by the time we’ve sewn the bottoms and added our connectors (adding connectors requires a different foot on your machine, so I like to do those all at the end).  

Have questions?  Post them in the comments here or email me: fitgirlinflight (at) gmail (dot) com.

View all posts in our Competition Bikini DIY series here, and SUBSCRIBE via the box on the right to receive email alerts when new posts go live!