I got tired of my bike's pedals catching my laces, so I decided to ditch my laces and go for something else. I ended up with using inner tubes to turn them into slip-ons. They stretch out to put your foot in, and stretch back tight. Mine are incredibly comfortable and very convenient.
All you need is a pair of shoes (laced), an inner tube, and scissors. Go to your local bike shop and ask for old inner tubes. Explain why you need them and they will most likely always give them to you.
Step 1: Unlace shoes
A very easy part. Take off the shoes' old laces. Keep them around to get a sense of how long the new ones need to be.
Step 2: Cut inner tube
Lay out the inner tube and cut it the same length as the shoe lace. Then take that tube and cut two 1 cm. wide strips from it. Some tubes already have markings around 1cm. like in the third picture. Do not leave any jagged edges as they could get worse and rip when stretched.
(You can use scissors, x-acto knives, or rotary cutters to cut it)
Step 3: Lace the shoes up
Another simple part. You can get all fancy with this if you'd like. Just lace the shoes with inner tube strips you cut.
Step 4: Adjust the laces
Adjust the laces so they are tight, but can still slip off when you want them to. When they are nice and tight, keep the shoe on your foot and do the first step of tying a shoe, like in the picture.
Step 5: Tie the knot
It doesn't really matter what kind of knot you tie. Just tie a tight, small knot and the rubber will keep it tight. Cut off the excess tube hanging off (pic. 2)
Step 6: Lace other shoe
Follow steps 3, 4, and 5 for the other shoe.