Help me understand fixed/freewheel rear hub
 

Building my first singlespeed bike and I am not really understanding fixed/freewheel rear hub. Here is the story:

- got Origin8 fixed/freewheel rear hub wheels
- my crankset 48t 3/32 and so is the chain is 3/32
- want to ride 48x20 freewheel

Having a tough time to find a 20t cog and freewheel with 3/32.

What are my choices?
Would buying a 1/8 20t freewheel cog work with this combo?
Is there a way to get a freewheel "body" and buy a 20t track cog?

thanks in advance.

Here's a link to 3/32 freewheels: https://www.amazon.co.uk/Sturmey-Archer-Single-Speed-Freewheel/dp/B00IWRZPQW/ref=sr_1_1_sspa?crid=1R1AQ2E0MKC0D&keywords=3%2F32+freewheel&qid=1566451069&s=gateway&sprefix=3%2F32 +free%2Caps%2C145&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExMkI4SEhTSlcxQllKJmVuY3J5cHRlZElkPUEwMDUzMTc0M040RTI3NkE wWk85RyZlbmNyeXB0ZWRBZElkPUEwODM2MDA5M0hTNDRHN1RWOTFFQyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWR pcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

If you end up getting a 1/8" cog or freewheel you can still keep your 3/32" chain ring, you just have to run a 1/8" chain on it.

Not sure what you mean by your second question, but if you're thinking about putting the freewheel shell around a fixed gear cog then that won't work. Choose one or the other. I bet your Origin8 hubs probably have the ability to be flipped so you can put a fixed cog (don't forget the lockring too) on one side, and the freewheel on the other if you want to try both.

Freewheels and cogs are two different things.

A freewheel allows you to coast. A track cog is for riding fixed gear.

You need a 3/32 20t freewheel. There are many available.

A decent, removable one which should go nicely with your H+Son wheels is at https://www.modernbike.com/acs-paws-...3-32-gun-metal

Yes. 1/8" chain works fine on 3/32" chainrings and/or single cogs/single freewheels.

Hi, I need help with purchasing a freewheel as well. I'm trying to get a quick engagement in a 3/32 with 14 or 15 teeth if possible. The last freewheel I ordered in a 14 teeth was to small to fit on my rear wheelset. Any suggestions?

Single freewheels for road type and flip/flop hubs are limited to 15T or larger to provide room for the ratchet mechanism.

Single freewheels with 14T or fewer only mount on specific BMX-type hubs.

Thank you. I read piper's question and was wondering what that 14 tooth FW was. A wild rarity like the 41 tooth Campy chainring (yes I know they exist; I even know someone with two but I have never actually seen one) or the 11 tooth track cog? And the question in my mind; how did they get the bearings and ratchet in there. 14 tooth cogs aren't much larger than standard FW or FG hub threads.

So now I know. BMX hubs use smaller diameter threading. Good to know. I'll probably never use one, but who knows? I've done stranger things. (Are they 120 mm dropout spacing?)

Ben

Thank you. I read piper's question and was wondering what that 14 tooth FW was. A wild rarity like the 41 tooth Campy chainring (yes I know they exist; I even know someone with two but I have never actually seen one) or the 11 tooth track cog? And the question in my mind; how did they get the bearings and ratchet in there. 14 tooth cogs aren't much larger than standard FW or FG hub threads.

So now I know. BMX hubs use smaller diameter threading. Good to know. I'll probably never use one, but who knows? I've done stranger things. (Are they 120 mm dropout spacing?)

Ben