I'm trying to remove my headset mounted front reflector because it was snagging my cables

I need a spacer to take up that extra room
where do I get one? what's it called?

1" diameter keyed headset spacer? Not impossible to find. Can use the non-keyed ones too, but keyed ones make adjustment easier.

I'm wondering if my LBS will have it. I'm having a hard time finding them online. I only found this:
https://www.amazon.com/Wheels-Manufac.../dp/B001CJVKMA

Well, on side note, I used to order tons of stuff from BWUSA when I built mostly cruiser bikes. Top notch fast service!,,,,BD

I'm sure I have one. PM me.

Just had to get a couple of these from my LBS, to do the same thing. Asked the kid that waited on me, and he pointed to a threadless headset spacer and said "Like these?". I told him no, this is for a 1" threaded headset. He looked perplexed but went into the back room and emerged with a couple. Surprised me. I had asked him if they had a junk parts drawer or something similar as I would have been happy to dig around for them, but it appears they don't.

I got nice aluminum spacers for 1" steerer tubes from our local PBS (Performance Bike Shop) a couple of years ago. Not sure if they still sell them but you can check. IIRC, they came in a package of 3 spacers of differing thicknesses.

my lbs gives 'em out like business cards.

Yep, I got their aluminum ones, and I also got some carbon fiber ones, from my mis-spent days of putting a carbon fork on a bike with a 1" steer tube. OP, I used one carbon spacer, with a NR headset, and it looks pretty good, contrasting the chrome & polished aluminum. But that's a personal taste thing, you might like the aluminum ones better, that would blend in & become invisible.

Headset spacer. Last ones I bought were from Bike Tools Etc., used them to fill out an order. If you routinely work on vintage bikes, they are pretty handy to have around.

https://www.biketoolsetc.com/index.cg...item_id=BR-HS2

I have used a threadless spacer when I have to make up the difference in stack height, but yes you do need at least one with a key on it.,,,,BD

hmm, I got a 1" keyed spacer and it's too small.
any idea what other size it could be?

Well, it should be a snug fit, work it around a bit. I've also got a couple of 1" spacers.

it's too tight, it would foul the threads if I tried to get it on.

It is a 1" keyed headset spacer you're looking for, as these guys noted. You may have snagged a snug one from some manufacturer, but others will make ones that fit. I've had better luck finding em at my LBS vs. online, but some shop sellers will cock their head like a labrador when you ask for one.

I got it from my LBS. two of them. neither fit. forcing it on would most certainly foul the threads

........if you are completely unfamiliar with these, some do fit pretty tightly, to the point where if they are at all
off level when placed on or taken off, they will jam up. I just stripped a headset off a bike this afternoon that was
a slight problem because of this and the key that was a little jammed in the slot. You can enlarge them a little
on the inside with a curved mill file....try to use something with a curve that approximates the curve of your washers.

when I lay the spacer on top of the current spacer/reflector holder, there's a pretty significant difference. is it possible it's 1 1/8"? Would a JIS headset have a larger spacer? I saw that some late 80s, early 90s Japanese bikes used JIS standard headsets.

Anything is possible.......get yourself a cheap vernier caliper and join the world of precision measurement.

https://www.harborfreight.com/6-inch-...iper-7914.html

I'm gonna bring it by the shop tonight to see if they can help out with the right size.

The answer was: push harder.