I bought my niece a used Trek 1500 which overall is in great condition. However, I noticed on unpacking that the rims were somewhat grooved, and when she rode it today there was a fairly loud rasping noise. It comes with Bontrager Select wheels and unnamed alloy brakes. From what I've read here it sounds like the pads need replacing immediately (probably with Koolstops). You can see the ridges in the pads (and maybe even metal inclusions) in the attached photo. Can I improve the situation by also smoothing the rim? What's the best way to repair it?
These rims have a "wear sensor" but I can't find any info on how to interpret it. Is the rim okay as long as the dot is still visible?
Are there Koolstops that will replace these pads, or do I need to replace the shoes too?