Does anyone know where might repair a pair of bibs that have split down a seam st the back?

You might want to try your local dry-cleaners. They often have a link with someone local to undertake repairs and alterations.

Either that or visit a sewing machine shop and ask if you could test drive a few machines, state that they need to cope with lycra, and you’ve brought along your shorts to see if they can handle the repair 😛

Cheers, Rich

Depends where you are, but I have used these people years ago and did it by phone and by post, they did a very good repair on my crash damaged (nearly destroyed) jacket.
MAINTAIN OUTDOOR & LEISURE WEAR REPAIRS & ALTERATIONS,
INDUSTRIAL UNITS, HARKER
CA6 4DS CARLISLE
01228 674410

why not fix it yourself? sewing isn’t a particularly challenging or technical activity.

why not fix it yourself? sewing isn’t a particularly challenging or technical activity

This.

Thanks for all the useful help chaps

FFS, just get a needle and thread and stitch them up. Lycra is very easy to repair as it just stretches to accommodate your uneven stitching. My longs are full of stitched bits around the knees.