Attaching velcro to a stretchy elastic strap?

Cut two pieces of webbing and/or elastic, one for each strap.

Add hook Velcro to one end of the webbing and loop to the other.

Attach one end of the new strap to the Velcro at the end of your current strap and one end to the Velcro that is further down on you existing strap.

Yeah, just take a seam ripper and remove all the Velcro, re-position the Velcro to desired position and sew using polyester thread (e.g., gutermanns thread). Stitch around the perimeter of the rectangle and then do a crossing X. The stitching will look like a box with an X in it when done. You can take it to any drycleaner type tailor and they can do it quick. I could even do it for you for free ( I live in Brookline) just give me at least a couple of hours. Good luck!

EDIT Rereading your post I think it's easier to add another slab of Velcro then to remove the current one and reposition. It takes more work to remove/reposition/resew. Also I've never encountered Velcro on a garment that was held on by anything other than thread.

Daryl:

That's not crazy. The pro would be that i wouldn't have to modify my bibs at all. The con is that there would be twice the potential fail points and double the stiff velcro patches. One way i might be able to get by easily would be to get two pieces of 6-8" x 1" adhesive velcro patches. I could simply stick two together back to back and that would function as the extension strap.

Konrad:
That's very generous of you, thanks! I'll try to avoid troubling you, though. Heck, if it snows tonight i might "work from home" tomorrow and venture down to the sewing shop. I live in Davis Square and there's one just a block away. Fun little snow day project.

"two pieces of 6-8" x 1" adhesive velcro patches"

That'll work.

You could also buy some One Wrap. It comes with hook on one side and loop on the other.

Ah, One-Wrap is a great idea! I'll get some tonight

Just to follow up, i got aggressive with it and ripped out the velcro stitching. This motivated me to get to stitching! I just hand sewed it with polyester thread. It held up fine on its first outting. If it starts to fall apart, I'll have a local seamstress/tailor do it right.

Most importantly, the bibs can be adjusted to fit perfectly now!