I've never really had to mess with my stem much, but I need to get a new one and I have a question: The specs for my bike say the stem's clamp diameter is 26.00 mm. But when I look online, all the stems I see say their clamp diameter is 31.8mm. I saw one at 26, but it was pretty cheap looking. Will 31.8 work, would I need a shim or something, or do I need to find a 26?

You can use a shim to allow a 31.8mm clamp diameter stem to work with 26mm clamp diameter bars. However, in my opinion you'd be better off finding a proper 26mm stem. What website were you looking at? There are some nice 26mm stems here: https://www.universalcycles.com/shopp...p?category=630

As you've found though, 31.8mm is the new standard so all of the newest and more expensive stems will be that diameter. Now might be a good time to swap handlebars too if you'd really like a 31.8mm stem.

If you decided to go with a shim anyway, here's what you need: https://www.universalcycles.com/shopp...0&category=784

No need to get a new 31.8 handle bar (unless you want to). Here's what I use:



https://store.icyclesusa.com/3t-4gxl-...rce=googlebase

It's stiff, relatively light, and cheap. So you can buy two and mess around with your fit if you like.
Ritchey also makes and will continue to make 26.0 stems.

Thanks JoeJack - I guess they are out there, I just need to look a little harder than just Performance and Nashbar. Thanks for the link, I'll look around a little more, I don't want to change the bars out.