Fixed Gear Conversion, chain pops off. I know, another chain tension question.
 

So I just converted by Raleigh Super Record to Fixed. Just pulled of the cassette and threw on a fixed cog and a lockring and then took off a chainring. My chain keeps popping off, and not off the chainring, always off the cog. I take a few pedal strokes out of my driveway and then I hear a sort of grinding noise, and then 2 seconds later my chain comes off and I'm not moving. I have a decent chainline at 3ish mm, I don't think that's the problem. Could the problem be because I have a super high ratio (52-16)? I also still have a 10 speed chain on (since the chainring is meant for a 3/32 chain). And I'm tensioning my chain pretty tight so it won't fall off. Any suggestions or past experiences would help a lot.

Thanks

You could possibly be using a 3/32 chain on a ⅛ cog.

its a 3/32 rear cog. I read 10 speed chains are 6.2mm wide and ss chains are approx 7.3mm, so i think that's the problem, thanks franswa

That's the overall width, and is irrelevant. The inner width of the inner link is 3/32" (2.4mm) on both chains.

You need to dish the wheel or buy a fixed gear specific wheel
Good luck

If you're using the outer chainring along with a fixed cog where a 5-speed freewheel used to be, there's no way your chainline is as "decent" as you think it is.

It was 5mm and then respaced to about 3mm chainline variation. Ill do some stuff tmrw and hopefully it works, maybe ill try a new chain.
Thx

Don't adjust your chain too tight. This will actually make the problem worse.

My old 10-speed (5-speed cassette) is about 13mm off as standard on the outer ring and 7mm off on the inner ring. Have you tried measuring the chainline or is the 3mm based upon eye-sight?

Are you using Axle nuts or a QR? The only time I've ever thrown a chain is when I was new to fixed gear and under tightened the nuts.

I measured it to be 3mm

When I get home I'll tighten the nuts. I'm convinced it's not chain line or the chain, since it's not stretched and it's a 10 speed chain on a 3/32 cog
Thx Alex

On that note, I remember another dumb noob mistake I made on an early conversion was grabbing the wrong sized axle nuts from my parts drawer. I find that many times when I think that something is a complicated fix, that the solution is beyond simple. Good luck!

My bike works again! Hopefully
The weirdest thing happened, my chain line was near perfect when I respaced, today I un-respaced and I tightened the bolts so hard that I was sweating. My chain wasn't coming off before the respace, and isn't after the un-respace. Lesson learned: don't fix it if it isn't broke.

thx guys