Ok so I already bought a 25.4mm handle bar (bull horn)
https://www.universalcycles.com/shopp...&category=2788.

Does this mean that I should get a 25.4mm stem? I'm confused because on the Soma site it says that 25.4mm stems are for Mountain Bikes while 26.0mm stems are for road.
https://store.somafab.com/stems.html

thanks

25.4 is also a track diameter. If you already own a 26.0 stem you can use this
https://www.benscycle.net/index.php?m...226c7ebc19a05b


If you don't already own a stem then yes get a 25.4

Either a 25.4 or 26 stem will be fine.

If you get a 26, you don't need an expensive shim, you can be like Greg Lemond in the TdF and shim it with a bit of Coke can.

See here.

I'll go with the 26.0mm with the shim but what size should I get? on the Soma site they have 80mm-130mm. What does that size even refer to?

that refers to the length of the stem (how far it sticks out). the size to get will depend on the size of you, the size of your frame, and the type and extension of the bars that you're using.

80mm-130mm refers to the length of the stem itself, i.e how far forward the handlebars will be. long stem for long arms, short stem for short arms.

if you're buying a brand new stem, why not just get the right size 25.4mm stem? the only reason to use a shim is if you already have a stem thats the wrong size. not that it really matters -- im just curious.

I would get 25.4. That size does not really make a stem "mountain" if that's what you're worried about. Lots of road bikes have bars and stems in that dimension.

Yep - until 12 years ago or so, all bars were 25.4. Many still are, including most Nittos. The oversize 26.0 is fairly recent, and Cinellis tend to be a bit bigger yet. Get the right size.

the reason that I want a 26.0mm stem that I can always add a shim to it and make it 25.4mm but a 25.4mm stem won't let me get a 26.0mm handle bar. Is that idea kind of ********?

you can do that, but unless you need one right now, why bother?

and the Soma site says "Request a shim if you need to fit a 1" steerer" but doesn't have that option for the 25.4mm stem.

"Request a shim if you need to fit a 1" steerer" is because I have a 1" headset, right?

Yep. That shim will work in either stem; it sizes the 1 1/8" steerer tube clamp down to 1".

If it makes you feel any better torabora, 26mm is the more oddball bar size in my experience. I have 26mm bars and I could be wrong but it seems like most of the commonly available road stems out there are 25.4. Shopping for a new stem was a bit tough anyhow.

thats not ******** at all -- thats good logic. its interesting that bullhorns almost never come in 25.4mm, so if you ever plan on using bullhorns, your foresight would pay off.

suprisingly the bull horn that I bought is a 25.4mm handle bar

I went to my lbs and they said to fit a 1 - 1/8th stem in a 1" fork I would have to buy and adapter for $27 do I still have to do that if I buy the Soma headset with a shim fit a 1" steerer?

I told them about the 1' steerer and they didn't know what I was talking about.

if you have a 1-1/8" stem and a 1" steerer yes you will need a shim, but no it should not cost thirty bucks. i got mine for about eight. i'm not sure what headset you are referring to, but the headset size you buy should correspond to the size headtube on your frame and has nothing to do with the size of your stem.

This is
making
my head
hurt!

the adapter may be to convert threaded to threadless. that's my guess.

^^ its possible, tora do you have a threaded or threadless headset?

I'm pretty sure I have a threadless, I believe the converter is to fit my 1" steerer

if you have a threadless 1" headset/steerer combo, a 1-1/8" stem this is all you need

Shim

get a 31.8 stem and shim it if you really want a lot of bar options. better get that 6 pack of diet coke.