Question about something.

[dunedigger]

What is the average screw/bolt size for a bike. I bought a rear rack and it came with neither screws, nor clamps. So now I'm kinda stuck wishing I had bought the seat post rack. So, if anybody could give me a rough estimate I'll try and figure out how to attach this thing to my bike. As it didn't come with instructions either. And I'm hardware challenged. This is gonna be interesting. Late '90s Raliegh MTN Bike is what I have btw. Thank you much!

[John Nelson]

The "average" size is 4.5 mm. You will have no bolts at all of this size, but it's the average between 4 and 5, both of which are very common. If I had to guess, I'd say you probably need an M5.

[Spokey]

Most of mine are M5.  But it probably varies.

Although I like the look of black painted ones, they tend to rust after awhile.  So I bought a bunch of stainless M5 and I'm slowly replacing them.  I did need to get a variety of lengths.  I bought maybe 12, 15, 20, 25 and I think one even longer.  I got mine from Amazon in bags of maybe 100.  A few bucks a bag, but my heirs will get these.

I suggest removing one from a water bottle cage or some other easy bolt.  See if that fits the seat stays, dropouts or where ever you need to attach the rack.  If it does, take that to your LBS.  I'm sure they have some lying around that they can give or sell to you.

Seatpost racks may not  handle the weight you want. 

You say a mountain bike.  I don't know that model but if it has a suspension, make sure the rack doesn't interfere with that.

[scott.laughlin]

What is the average screw/bolt size for a bike. I bought a rear rack and it came with neither screws, nor clamps. So now I'm kinda stuck wishing I had bought the seat post rack. So, if anybody could give me a rough estimate I'll try and figure out how to attach this thing to my bike. As it didn't come with instructions either. And I'm hardware challenged. This is gonna be interesting. Late '90s Raliegh MTN Bike is what I have btw. Thank you much!

If you don't have a LBS nearby you might try Lowe's or Home Depot.  They stock a large assortment of small metric nuts and bolts.  Be sure to take one with you.  The selection is overwheming.

[dunedigger]

Thanks all for the info.

[bogiesan]

If you don't have a LBS nearby you might try Lowe's or Home Depot.  They stock a large assortment of small metric nuts and bolts.  Be sure to take one with you.  The selection is overwheming.

You're looking for those cool drawers of  weird fasteners. Even Ace hardware stores have them. Sometimes the clerk in the hardware dept gets all giddy over searching for this stuff, it can be tons of fun. You may want to include a handfull of split washers, star washers, nuts, and aircraft nuts.

You can also buy a kit of assorted M5s from several online suppliers. Google will return a long list of online fastener and specialty fastener shops. Takes patience.

david boise ID

[velo]

Most eyelets take 5 mm x .8 pitch. These are the two numbers, 5mm refers to the diameter. .8 pitch refers to the pitch of the threads, basically how coarse or fine they are.

You can get bolts in different lengths, don't get then too long or they might run into things before they get tight. Don't get them too short or they won't stay.

6mm x 1.0 pitch is also common, 4mm is around as well.