I'm thinking to switch handlebars on my 2007 Raleigh One-Way. However, I'm unsure of the stem clamp diameter. The stem is threadless and I'm interested in the VO Montmarte handlebars, which have a stem clamp diameter of 25.4mm. Would these handlebars be compatible with my current stem?

Probably not. Your One-Way came with "drop" handlebars, which typically have a clamp diameter of 26.0mm: https://www.bikepedia.com/QuickBike/B...y#.UOuv9az5XEY

You can either use a shim or buy the correct handlebar stem.

I have no idea what kind of bars re on that bike since you didn't mention it. But it's easy enough to figure out the diameter, understanding that downturn bars are almost always 31.8 mm these days, and if not, 26.0. It might even say on the bars under the stem clamp face plate, or on the stem itself. Flat bars are sometimes 31.8, sometimes 25.4.

It's simple to use and very cheap to buy a simple Vernier Caliper at any hardware or big box store for $10-20 which will be accurate enough to tell the difference between these normal sizes. In case it matters for cost, you don't need digital accuracy for these sort of measurements.

Or bring it into any bike store or anyone you know who has a decent set of tools, they should be able to measure it for you.

i have both a $10 plastic dial gauge, and a $25 cheap electronic one. the electronic one does millimeters easily, the dial one, not so easily (since common american tools are all imperialist).

Thanks for the responses yall.

Right, and a simple calculator will let you turn Imperialist measure into Napoleonic measure. The magic number is 25.4.

Shucks! And all along I thought the magic number was "42".

I just use the regular old caliper and can do to 10ths of a mm. But I'm curious how those inexpensive (cheap) lcd ones work?