We have a lot of love for quill stems, which we tend to think have the best look for steel framed bikes, and are quite handy and adjustable. We stock stems with 22.2mm quill diameter, in various heights and lengths.

We also sell threadless-headset stems, AKA Aheadset-style for 28,6mm steerers, and the adapters to use them in threaded forks.

Handlebar clamp sizes we stock:

• 25.4mm for city bars and various generic handlebars
• 26.0mm for really classic drop-bars
• 31.8mm for most handlebars meant to be used with Ahead type stems.

Some old French bikes used metric parts, bless 'em, and need a 22.0mm quill, and have a 25.0mm handlebar clamp. We don't know of any stems still available in those sizes.