Bicycle Mechanics - Type of bolt used for rear racks?

Hi all, really beginner question. My rear bike rack came without any bolts, so I need to swing by the hardware store and pick them up. What type and how many would I need for a standard rack installation?

Thanks in advance

A typical installation uses 8 M5 bolts and 4 M5 Nylock nuts. The length of the bolt by the drive-side dropout is critical, if its too long it can interfere with the chain and if its too short it won't hold.

Metric bolts, probably size M5, maybe 15mm long, probably four of them, but these things vary a lot depending on the exact frame and rack. Get the more expensive stainless steel bolts if they are available so that they won't corrode. Put something on the threads (just some standard grease if that is all you have) before installing them.

PE, Test with one of the bottle cage screws, if it fits go to the hardware store. Most likely a M5, but test with a nut.

Brad

PandaExpress: I like the looks and ease of use of stainless hex socket head cap (button head as well) screws rather than the more common hex head machine screws. Don't forget to put some stainless flat washers on your list as well as the above-mentioned Nylok nuts , also called elastic stop nuts. The screws typically come in 2mm length increments and you can add an extra washer or two to get the length just right especially on the drive side dropout. Fender washers have a larger ID and can be useful if your rack has oversized holes. My local True Value store has an extensive stock of stainless hardware.