The one end of the loop on my bike shoes came off. I tried taking it to an alterations (sewing) place. He glued it on and it lasted about 5 seconds. That's when it dawned on me to go to a shoe repair shop. For about $20 it is as good as new. So, my recommendation is to try to sew it on, probably best to go to a shoe repair shop, they'll have the equipment, material, and expertise to do this.

They answered this question recently on the TTL podcast. IIRC Paula and Eric use gorilla glue and old shoelaces that they cut to size.

I have always cut them off

Thinking more aero

Maybe I was wrong?

My instinct would be to cut through the top layers of material and loop it through those for a positive engagement. Would take a bit of individualization to make sure it doesn't cause any friction points. There should be an area between the Achilles and tarsals on either side that's relatively open

I sewed on loops to endorphin pro's. It was a nightmare to sew because the back of the shoe is so thick. In the end, it didn't work very well because it would distort the shape of the back of the shoe. If I try it again I would just use a tab instead of a loop. I would definitely take it to a shoe repair place if I try it again.

It is hard to believe that gorilla glue would ever work.