Fork size
 

I measured my forks outer diameter to be 28.5 mm. Forks come in 1 inch (25.4 mm) and 1.125 inch (28.58 mm). Which size is appropriate as a replacement for my current fork?

I assume you are measuring the sterrer tube to determine waht size you have. If that is the case you need a 1" fork

Yeah I was, thanks a bunch!

HUH???!!!

His fork measured 28.5mm which = 1.122", or 1-1/8"

To the OP, Forks are measured by the OD and as you noted, the standards are inch sizes. I don't get you, you measured your fork yourself and came up to 28.5mm or just under 1-1/8" and yet you so readily accept 1" (25.4) as the correct fork. You were better off before you asked.

I hope he hasn't already spent his money on a 1".

That's OK. A few wraps of duct tape...
Purchase a 1" headset and you won't have any difficulty inserting them into the head tube.

Since my current fork is just under 1-1/8, wouldn't exactly 1-1/8 be a touch to large? That was my main concern. It wasn't exactly either of the sizes, but it would make more sense to go with the smaller one, as a larger one potentially wouldn't fit at all. Get me now? I'll measure the inside diameter of the headset and go with that me thinks. Thank you all for confusing me. :p

No, your fork is NOT under 1-1/8", it is 1-1/8". Your measurement is so precise it is misleading. Buy a 1-1/8" fork. Forks and headsets come in two sizes, 1" and 1-1/8", there is no intermediate diameter.

There are nominal sizes, which is what we call things, and there the actual sizes which are close but not always spot on, since nothing is truly perfect. 3/1000ths of an inch is a tiny amount and within the manufacturing tolerance for this kind of stuff. Ot possibly you pressed a bit hard with the caliper and got a low reading.

Don't be confused. For practical purposes 1.122 = 1.125, and you need a 1-1/8" fork. If you buy a 1" fork you'll be off by 122/1000ths of an inch which is in a totally ballpark.

Look at it this way. If you wear size 10m shoes, which would you buy, a slightly oversize size 10, or a size 9?

Alright, thanks. I wasn't sure how precise these things were. I'll go buy the 1-1/8 then. Thanks everyone!