Originally Posted by
FBinNY
You're best option is to find a patch of similar 4-way stretch lycra and have it sewn and/or glued on the inside. This requires the right fabric glue and machine that does stretch stitching. Also, the tear should be closed and lined up as well as possible so it all lays flat. Odds are you'll need to go to a pro, and it'll never look perfect, but can be pretty passable.
If you don't do anything, the hole will continue to grow as the fabric, which is a knit, unravels at the edges.
All true. I didn't mention the lycra patch, because finding a fabric match can be so hard. The adhesive product you need is called "Stitch Witchery" a heat-fusable mesh. You cut it to the shape of the patch, and iron it onto the patch using release paper to keep it from sticking to the iron. Then you iron the patch onto the "wrong" side of the shorts as FB says. That is counterintutitive, but it is essential. It will look much better from behind than in front. And you can often use the adhesive to pull the hole in tight and minimize it.
When all is done, however, I still think the bibs will just be suitable for wearing under tights. Lot's of folks do that sort of thing with old and torn shorts. Oh, and the trainer. Don't forget you can wear them on the trainer.
As FB says, patching them with an adhesive patch is a good idea to keep the hole from getting bigger...even though it may not look good enough to wear in public.