Cog or Chain ? What's worth swapping out ?

Alright. Here:



Pretty simple problem. Cog doesn’t fit chain I currently have. However, it’s a flip-fliop hub the chain does fit the SS side.

I’m assuming the chain is 3/32" and the cog is 1/8" from what I can gather.

I just want to know if I should buy a new cog that fits the chain or buy a new chain that fits both cogs. What’s the better approach ? (It’s a POS cog so I’m leaning towards that)



Currently using a 16t freewheel cog. Should I go larger cog or smaller on fixed ?

Really depends what you’re running on the front. I’m sure many people would agree to have the same or larger fixed sprocket though.
Changing sprocket will probably be best because then your whole running gear will be 3/32.
That said, I’ve run 1/8 chain on 3/32 teeth endlessly without any issues.

Just to clarify, I’m not saying it would be better to have 3/32 as opposed to 1/8, I don’t want to start that debate.
I’m saying it may be more desirable to have all 3/32 as opposed to 3/32 chainring and 1/8 chain and sprocket. And changing the sprocket alone will give you a uniform drive train.

By large you mean in size ? So more teeth ?

I’d like to have something different than the 16t freewheel so I have to option to swap. Might go to 18t or 20t.

I have a 39t front ring

I think you want to go the other way, 39/18 is for bike polo!

39/15 or 39/14 would be better depending.

What’s a chain cost? $20…

What’s a new sprocket cost? $20…

Pick one! As others have said, 1/8" chain on 3/32" running gear is no issue.

But it’s nice to have all matchy match so i’d probably swap sprocket. Or chain & chainring.

so I want a higher gear ratio when running fixed?

I figured it would be the other way around cos I didn’t want to struggle if I hit some hills. But thats cool.

Yeah I figured I could go either way. Gonna hit Gear tomorrow and grab a cog. \


As has been said, 39/18 is on the lower end. But it depends on each persons riding style and legs. Best way is to try it out and see for yourself.
If you don’t want to buy a bunch of cogs to try and end up not using them, there are plenty of people here who I’m sure would lend you one for a test.

Aren’t there a million threads covering this? Go read Sheldon…

There are… in fact half of the total internet is taken up by bike forums answering this question.