maybe a silly question -- replacement helmet straps?

[Fredwina]

The hard part may be finding some place that stocks Garneau or Uvex to try on. Most LBS will usually only carry Bell/Giro and if they're a dealer, specialized. Although I noticed my LBS is now Stocking LAS helmets

[HillSlugger]

I'd like to point out that the straps on a helmet are designed to some spec based on the force that they need to be able to survive; while I have no idea what that spec might be I don't know if the stuff you'd find at a fabric store would be up to the task. On the other hand, the webbing you can buy for climbing applications would be more than up to the task. REI, Hudson Trail, and similar stores carry the stuff in multiple widths and colors.