Hi all my brother has put an old quill stem in his cheap modern commuter and although it's tight (stem turns when fork turns) it wobbles insitu as the diameter is smaller than the opening at top of head set.

He's been riding it like this for ages but I'd like to fix it for him.

Thought about a sleeve but it would have to be deep so it meets the expander if this would work.

Ideally though a stem of the correct diameter would be fitted.

What is the diameter of a modern stem (if there is a standard or are they proprietary.

I'd measure it but he lives across town so want to do some research here about best practice.

Thanks in advance, Matthew

As I understand it, quill stems come in different sizes for the quills.

1 1/8":1: (7/8"):
Bar clamp sizes (road drop bars). See Sheldon Brown for more notes.So, for a non-French, non early American, 1" quill, go with a 22.2 quill size, and either 25.4 or 26.0 bar clamp size.

I used aluminum flashing to shim mine. You can buy a small roll at home improvement stores (roofing/siding materials). Using tin snips, cut a rectangle that's long enough to reach past the wedge on the end of the stem. Wearing gloves, give it a fairly cylindrical shape by pressing it around a broomstick or tool handle. If it's still too loose, fine-tune by adding similar pieces of beer can or soda can.

It sounds like he is simply using a 1" quill stem in a 1 1/8" steerer. I guess if it is tightened down enough it would snug down, however leaving the problem with the headset as you describe.

Smart move to change the stem to the correct dimension one. "past performance is not an indication of future funds". Andy.

Thanks everyone for your input and experiences.
Sounds like he has a 1" in a 1 1/8" steerer.
The flashing is a great idea, if it was my bike I'd do that as I can check it's progress and modify if needed.
I don't see him regularly though and he doesn't service his bike so I need a set and forget solution.
Will hunt around for the correct head stem.

1" in a 1 1/8" steerer would be VERY LOOSE. I suppose it is possible, but I find it doubtful. I will do a few stupid things, but I wouldn't ride a bike like that.

Have your brother snap a few photos. And, it would help to get the brand, model, and year of the bike.

Thanks Clifford

Thanks Clifford.

First thing I noticed with his bike was the loose stem, he'd shimmed it (unsuccessfully) and it's been concerning me since.

Unfortunately I don't have easy access to the bike. It's a 5 year old approx. Chinese-made Giant* commuter with 26" wheels*. He removed the original quill stem because the protrusion was angled up and he wanted a traditional stem with an horizontal protrusion so he took a stem off a road bike from the early 90s and changed the bars at the same time.

*Conjecture