How can I tell? Tried to measure the stem w/ no bar, but its hard to tell if its 25.4 or 26 because they are very close. I do have a dirty harry lever, and I use the shims, but where the clamp is it's wider.
Heres s ****ty picture, maybe itll help a little.

You need a set of Vernier calipers. A plastic set won't be more than $3 or $5. Through a simple but clever design, they allow you to accurately measure to a tenth of a mm and beyond. This is handy for cyclists as, as you know, lots of components are speced to dimensions that involve tenths of mms.



You use the pointy things on the top to measure the inside dimensions of holes like in your stem clamp. Or you could use the things on the bottom to measure the outside dimension of the middle section of your bars.

Wow - learned something new. I went to Home Depot and spent $20 I think, for a set of dial calipers, that do not have that fine scale. I can not, for example, tell the difference between a 27.2 or 27.0 seatpost.

I'm ordering a set of these. Got a good reasonably priced source? This was what I got from google:
https://www.northerntool.com/webapp/w...3656_200303656

I even found a tutorial on how they work:
https://www.physics.smu.edu/~scalise/apparatus/caliper/

This is great stuff to know!

That set looks good to me. I got a set of six plastic ones for cad $8.50 or so at Lee Valley in Vancouver BC.

https://www.leevalley.com/wood/page.a...513,43546&ap=1

They're not as nice as the stainless ones; but there are six of them. : ) For cycling purposes they're great.

Someone later got me one of the cad $20 stainless Lee Valley sets. They're overkill for me but pretty awesome to have.

https://www.leevalley.com/wood/page.a...513,43546&ap=1

Analog Verier calipers are one of my favourite tools because they achieve such a high degree of measuring precision with so few moving parts.

sigh.. tell me i'm not the only one who stumbled into this thread and ended up picking up a set of calipers off ebay.

^^noope. I'm astonished too. We have a worthy thread!

I really enjoyed the visual presentation, what did you use to make it?

almost 100% sure it's a 25.4... My Schwinn had that stem and i threw some 25.4 risers on it and they fit perfectly so...

That bike have Sakae Custom components, correct?

gis : )

what kind of risers are they....

if those are nitto b201aa then the bars themselves are 25.4

Look around near the clamp area of the bars. Some manufacturers are nice enough to emboss the size right on the bar.

never was a sr custom that was 26.0

Not sure about the bars, bought them from some old man with a garage full of parts galore, liked the color.
The components are not original, not sure what company makes the custom, but I guess its sakae according to arborohs.

Correct me if I'm wrong here, but aren't most 1" quill stems equipped with a 25.4mm clamp? Seems to be the only spec I see for them these days.

Not really. There is a de-facto "Italian" standard for road bikes that is 26mm, then there are the old Cinellis that used a propriety standard of 26.4mm. Mountain bikes used 25.4mm. Nowadays everyone seems to be going to 31.8mm for road and mountain bikes.

I just sold a bike with a sakae custom stem and bars, it was 25.4