Forgive the newbie question, but I've got some unused mount points on my bike that I'd like to plug up to keep random junk from getting inside the frame. What should I use to close these holes? Is there some kind of plastic insert I can buy? Do I need to get some stubby bolts (if so, what would they be called?)?

Thank you!

Clear ....Polyurethane caulk

Just a dab

figure out the size needed & sift there McMC for the ones you need.

https://www.mcmaster.com/screws/material~plastic/

"In general" unused frame or drop out mounts (bottle cage/rack/etc) are going to be M5 X 0.8 threaded. Go to you local real hardware store (Ace/Tru Value/etc) and get some shorter stainless steel allan or button head bolts and fill them as needed. AT those hardware stores you can usually buy them singly.

https://problemsolversbike.com/produ...s/bubs_-_k5431

You can get rubber and plastic plugs at a good hardware store - not necessarily a big box store, but a regular hardware store that has a wide variety of fasteners and little parts. That's where I got some for my bike. I wasn't exactly sure of the size, but they're so cheap I just bought a variety.

Someone above mentioned McMaster Carr - also a great source, but local hardware stores often have the same sort of stuff. On Mc-C search for "panel plug" panel plugs | McMaster-Carr

second option that is a ymmv, would be a fabric/craft store such as joanns or michaels. Hobby lobby might have it too.

I just saw an ad for Problem Solvers Bubbs frame plugs, a whole bunch for ~$7. Search for that and you'll find many online sources other than Bezos.