Commuting - rear rack attachment

All,

I am becoming a new commuter here in West Tennessee. I have borrowed a rear rack from a friend and he told me that my bike (1990 Trek 1000 aluminum frame) should have the bolts in the frame to attach the rack. I have the threaded holes but the bolt are not there. What size bolts are these? Or where can I get new ones?

The screws/bolts should come with the rack. You might be able to pawn some off at your lbs.

Those should be M5. The next most likely size would be M6. Just about any bike shop should have some. You may also be able to use the water bottle screws off of another frame.

If you have to mail order you can get them from Loose Screws or McMaster.

http://www.thethirdhand.com/index.cgi?c=Fasteners&sc=Screws&id=900400120258

The best type are M5 allen bolts but you can use std hex bolts or slotted machine screws. They come in different lengths; you need them long enough to go through the metal with a couple of threads clear at the other end. Use a washer under the bolt head for security. To prevent rust and seizing, smear the bolt threads with a light coating of grease.

5mm has become the standard size bolt.

If worst comes to worst, take it to a local hardware store (not Home Depot) and experiment. It will take a little longer to find the right ones. But at least you'll have them!

If worst comes to worst, take it to a local hardware store (not Home Depot) and experiment. It will take a little longer to find the right ones. But at least you'll have them!

Thats what I do. If your bottle bolt will fit, take it to the hardware store and match it up. Make sure you buy a stainless steel bolt.

LBS will sometimes give them away; if not, then sell them to you very cheap.

I needed longer rack mount bolts to fit fender stays and my rack in one set of brazes, and the "extra long" bolts were $0.25/ea at my LBS.

Personally I would recommend looking for a bolt made from stainless steel--it will cost substantially more, but with only needing two of them I still think you'd pay more for shipping. A washer is always a good idea, so I second that.

Look for a bolt with a shank (non-threaded part) about as long as the thickness of the rack attachment, it will provide better strength.

Thanks to everyone for replying. I got two bolts from my LBS for the bottom two mounts.
For the upper mounts (by the seat post), I don't have any brase-on or threaded holes. I racked my brain (pun intended) to find a solution. I finally came up with using zip-ties. I tried them on this morning's commute and everything is looking good thus far.

Heavy duty zip ties, I hope? You can also get clamps that replicate the mounting point. It's a good idea to put some rubber underneath it to give it better grip for less pressure.