Originally Posted by
Bill Kapaun
I find the range of sizes at my LBS varies noticeably whenever I need to buy them. If they have the size I want, they'll have ungodly long valve stems etc.
Sometimes they have exactly what I want and sometimes I have to "fudge" a bit.
Now, if they have what I want, I buy 2-3 spares. Murphy's Law says IF I have way more than I need, I probably won't need them.
The diversity in sizes is pretty crazy. It's hard for a bike shop to stock everything nowadays. And it's hard for us, as customers, to even know what we need and what substitutes are reasonable.