I bought a rear wheel to put on a SS build I'm doing for the student intern at work. Got this one with a blue anodized Shimano hub and it came with a sprocket, but I've never seen this contraption before: Seems to use a standard track sprocket, but it's too small (14t) and I'd like to replace it with something like 17t.
What's to use to remove it/ or the sprocket?
Chainwhip and lockring wrench, or a (special Shimano) 2-prong FW tool?
Who made it?
Thanks for any help!

That's a fixed hub, right? If so, the lockring is reverse-threaded and can be removed with a standard lockring tool or a screwdriver and a good whack to the right. The cog is standard-threaded, removable with a chainwhip.

If it's a freewheel, from here it looks like there's still a lockring that needs to come off, but it'd be standard-threaded (same as an English BB lockring, coincidently). Then the freewheel will thread off with the right freewheel tool.

Wait - is that a cassette with a whole load of spacers? Then the lockring comes off with a chainwhip, standard threads, and everything else pulls off straight out.

it's a freewheel, not fixed. I don't think it could be a cassette since there's no bulge in the hub body...but maybe I'm missing something here.

I vaguely recall seeing one of those particular cassette hubs once. Is the cog splined and held on by a normal 3sp circlip that you pop off with a screwdriver?

Nope, it's a home made single speed freewheel using an old freewheel body. I've done this many times myself.

Won't know if the cog is splined until I start attempting a tear-down, and I'd like to know where I'm going first, but there IS something under the larger "lockring" (that one has 3 notches) which may be a snapring or circlip. The rest of it sure doesn't look like a stack of spacers, it appears to be solid and the end with the smaller (2 *shallow* notches) lockring has what seems to be a dust seal and the hub cone is flush with that dust seal (so looks impossible to get a cone wrench on it). The 2-notch ring sure looks like you'd use a FW remover and not a lockring spanner, and it sure doesn't look like a typical Uniglide or Hyperglide diameter cassette.

Ah-HA, that's what I needed, THANKS!

Not so fast: I poked around and discovered a few annoying things.
1. it's not 120 OLN spacing but more like 110, which makes it impossible for me to use. even if I swapped in a longer axle and spacers and re-dished, the sprocket would never line up for a usable chainline...and can't be altered AFAIK.
(screwed! )
2. liffted off the dustcap and the HUB BEARINGS are right under it. They are NOT in the hub body but part of this strange FW/cassette assembly, and very outboard which would be a good thing IF this wheel was usable.
So I'm thinking it's some strange BMX animal which helps explain why I've never seen one...do BMX use a narrow-spaced rear? (narrower than 120?)

Very early Shimano cassette style BMX hub. Like early 80's early. Date code indicates June of 1980.

Here's one from ebay

https://cgi.ebay.com/OLD-SCHOOL-BMX-S...3A1%7C294%3A50


Cog, spacer, lockring:

https://cgi.ebay.com/Old-School-bmx-S...3A1%7C294%3A50

thanks for that info, Jim. I'm hoping the seller will take it back since it looks to be impossible to use with 120 spacing. Given my recent luck, he probably won't...so if anybody wants this hub I may put it up in the 'for sale' section.