Stuck cog

[Jonah]

I bust the chain whip on my track tool
I tried rota-fix (anyone had success with this?)
MLBS couldn't get it off (and bust their track tool as well)

Pipe on the track tool next...

Anyone else got any suggestions please?

[Deano]

Heat. Where you put it kinda depends on whether you care more for the hub or the cog...

https://yacf.co.uk/forum/index.php?topic=13183.0

[Goldcrank]

Bench vice.

Take the wheel off, wd40 and turn in a vice.

It will trash the cog but it will come off.

[Chris N]

Reverse-rotafix worked for me, every time - I kept bending chainwhips.  Swapped to bolted cogs on the Pomp and splined White Industries on the other fix so no issues now.

[mrcharly-YHT]

Heat. Where you put it kinda depends on whether you care more for the hub or the cog...

https://yacf.co.uk/forum/index.php?topic=13183.0

this

With a decent torch you can direct the heat just where it is needed.

[air dancer]

Chisel and a lump hammer.

Having a first aid kit to hand would be wise.

[Ivan]

Changing your gearing for Bryan Chapman by any chance?

[Jonah]

Changing your gearing for Bryan Chapman by any chance?

On one side at least...

[teethgrinder]

I used to have trouble with sprockets seizing up onto hubs and breaking chain whips.
I made my own monster chain whip with some scrap metal from work. Instead of linking the chain to the lever, I wrap the chain around the sprocket and the chain is wrapped around the lever. The lever is a 2ft or so length of tubing and I thread the chain through a hole in the side of the tubing at one end then wrap it around the sprocket.

I've never had any trouble since I stopped greasing the threads of my sprockets and used Finish Line Assembly Grease(which is just Coppa Slip type stuff)

[trumpet]

a technique I've used is to wrap a section of old chain around the sprocket - ideally just enough to cover all the teeth. Clamp up hard in a ( good ) vice & use the wheel as lever to unscrew the sprocket. Chances are sprocket may get damaged. I usually adopt this method when replacing cog & chain due to wear.

[Jonah]

Thanks chaps - she's still soaking at the moment - lift-off tomorrow in preparation for Chappers

[Jonah]

Stuck

[The Solo Socialist]

Assuming its chemical corrosion eg alloy hub-steel sprocket combo reaction, try soaking thread in vinegar for 24hrs at least, you will need to regrease hub bearings afterwards, then if you access to vice clamp/ grip sprocket in vice and use wheel as turning force! If that doesn't work strip hub and use blowtorch to heat sprocket then proceed as above! After that new wheel and or wheel rebuild with new hub etc!
Fit new sprocket use  above Copper Based Grease to reduce chance of it happening again.
Lastly GOOD LUCK!