What’s my mystery spare object?

HG cassette lock ring?

Or tiny alien space ships.

Seems a bit odd to be castellated but could they be fork bushings?

Might explain why you kept them.

edit - or maybe some odd ball bottom bracket lock ring, similar to Shimano octa thingy whatever.

Why not headset spacer? Have you measured to see if they're 1-1/4" or 1.5"?

Though the split does make me wonder if they're bushes.

Either way, measure the inside diameter and it may make more sense.

Headset reducer?

Not a HG lock ring, way too big. It’d be loose on the cassette body.

Don’t think they’re fork bushings. Made of alu.

BB related? Maaybe but don’t think I’ve had anything too odd. Or anything I don’t know all the bits.

Smaller than 1.5, I _did_ have a giant trance frame and giant were into 1 1/4 for a bit, hmmmm could be related to that.

Or some sort of headset part, can’t think what for though. Maybe each 5mm thick?

A part you need to remove from a new part before fitting? Crank related?

Spacers for discs on some fancy wheelset?

Is it not just spacers for 31.8 bells (for 31.8 drop bars) to fit 22.2 section on flat/riser bars?

Not disc spacers, my fancy wheels are all 6 bolt.

Spacers to fit bells or bars - good suggestion but I’ve slid them over some 31.8 bars to see and even closing the gap tight they’re not anywhere near clamping the bar. Maybe about 33/34mm ID closed up? I’ll get some callipers on them tomorrow.

All my headset spares are in a different place.

Also in the box were some old chain devices (not part of them), some deore octalink cranks, some bar tape, flat pedals, couple bash guards, some half dead original generation sram X0 kit, some road bike pads.

Don’t know any of that is a clue or related though. Doing my head in, I’m normally great at identifying random bits!

I recognise them but cannot place them - I share your frustration

Some sort of bearing retainer? The split would allow it to be fitted inside a tube of slightly larger diameter. Normally these would be more of a circlip but this is obviously a lot beefier. Some sort of Bottom Bracket bearing perhaps?

They really remind me of part of a 1" FSA Orbit headset - like this one:

https://www.ebay.co.uk/itm/364289258148

Clues:

ID a bit larger than a cassette body (so don’t think it’s a spacer, not a headset spacer either)
in that box under the bed

2/3rds of an Arab Strap?
His and hers his cock rings?

Do I win them?

That looks spot on hightension on line.

They really remind me of part of a 1″ FSA Orbit headset – like this one:

Must be, they're identical, and same number of square bits(12), also split.

Giant headset shims  ?
they used to come with lots of giant frames so you could fit a normal headset instead of a ZS one ?

Hitension online seems to be the winner! Though I don’t know where they go in the headset.

Though possibly as orangeboy says.

I have owned both Giant frames and FSA headsets (not 1” ones tho)

Can’t find any pics of them in reference to giant though.

FSA headset makes sense but they’ve obviously never been in a bike so some non essential part?

This makes sense however. Presumably came with my Trance.

Anyway, guess I can get rid. Or post them to RustyNissanPrairie, they’re to date unused 😳

So do they go inside the steerer as a reducer then?

Inside the headtube I reckon.

Makes sense I didn’t use them, the frame in question already had a 200mm headtube without making it even taller!