Tips to loosen a seized cog?
 

Greetings everyone. Last time I had a problem with removing a lockring which was taken care easily with a better tool. This time I'm having a cog removal problem on a different wheel. This is a Weinmann SP17 w/ formula hub and a unbranded cog which looks very much like the cogs that come with stock Kilo TT bikes. I've removed the lockring after some effort but now the cog is pretty much 'glued' to the hub. There seems to be some sort of lube the previous owner applied on the threading before screwing on the cog (I found lube all over the lockring and on the lockring threading after I finally got it off and believe me this substance honestly felt like a weak form of glue.) I've also considered if the threading might have stripped but I would highly doubt it as this wheel is still relatively new. I've tried using a blow dryer and perhaps try to 'melt' the lube a bit before attempting to remove it but it didnt really work. Any good tips to remove this cog from the wheel? Thanks in advance.

spray some wd40 or other solvent/anti-seize and let it sit a few minutes.

google rotafix method

i took off a loctite'd on suicide hub'd cog with ease using rotafix

i free-drilled some holes in a couple blocks of wood that mate with the cog teeth and i clamp the now wood padded cog in my bench vice. then i can use both arms and significant leverage from the wheel diameter. works great. super easy.

if you dont care about destroying the cog, and you happen to have a very large pipe wrench (i found one in the maintenance room of my old apartment building), clamp that on the cog and use some leverage. It will come right off. Or use a bench vice if you have one of those and turn the wheel around it.

Wrap it with a chain whip, give the handle a few tap with a mallet.

This + put it against the wall or something to stop the wheel from spinning when using the mallet. It worked for me easy.

Was the "glue" red, white, blue or green?

Try this before using any of the methods that will destroy your cog. It's easy and painless, and it really works. It gives you the leverage of the entire wheel. If you can't get it off by reverse rotafixing, I don't think you'll get it off any other way.

Instructions: http://204.73.203.34/fisso/eng/schpignone.htm (make sure you do it the opposite way!)

- I've also tried spraying wd40 and it didnt help.
- As for the color glue-like lube substance, it has a very slightly yellow translucent color.
- This bike is running on 3/32 width drivetrain. I'm afraid the weak chain will just get stretched up with no success in removal using rotafix.

I don't think you'll have a problem with Rotafix. Whoever gave you the idea that a 3/32 chain width is so dainty and fragile it needs to be handled with kid gloves gave ya the wrong idear

there is always heat....I've always been a fan of using a torch to make metal move

http://www.bikeexchange.com.au/dbima...popup/REX3.jpg
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http://online.wsj.com/media/norris_E_20090310161115.jpg
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http://prollyisnotprobably.com/asset...0x333-4956.jpg

Only way i know of that consistently works.

WD-40 pretty much fails at making things easier to turn. Use PB Blaster instead,

If you want to go stronger than that, CRC Freeze-Off will get the parts really cold, essentially doing the same thing as heat. Use PB, let it soak for a bit (you can actually watch it pour through crevasses), then give it a 10-15 sec spray with the Freeze-Off.

^^ Gee, I don't think I want to invest in those chemicals just for a cheap cog. I'm just going to play around with the rotafix method for a bit. Hopefully with each yank overtime, I will progress.

I've never used CRC Freeze-Off, but PB Blaster is great stuff. A can will only set you back a few bucks and will come in handy every single time you need to remove a stuck/rusted bolt. Definitely worth it.

Just rotafix the heck out of it until it comes loose. As avner pointed out, you can't "stretch" your chain doing this. Chain stretch occurs due to wear over time, not actual stretching of the metal. It is possible to break a chain this way, but at that point you also run the risk of stripping the threads off your hub. This requires a lot of force and I don't expect you'll run into these problems (unless the cog was JB welded on, or something to that effect.)

i got my brothers shop to machine a pipe tool.

i use only 17 so far so i had him machine a negitive of the 17 weld that on a pipe, with a 19mm nut on the end.

gave me lots of torque.

or just vice.

(if you dont care for cog.)

Cog vise:
http://www.os2.dhs.org/~john/cog-vise2.jpg

http://www.os2.dhs.org/~john/cog-vise4.jpg

Freeze-Off is supposed to be a penetrating fluid, but doesn't work well in that respect. However, it is very useful for getting parts to shrink a bit so they're easier to take off. Basically, you're doing this unevenly so the cog and hub are slightly different sizes as you would when applying heat.

easiest and most effective way (in my experience):

1. after your lock ring is off, put the wheel back in the bike, and put the chain back on
2. sit on the bike and pedal backwards
3. if that doesn't work, stomp on the pedal in order to turn the chain.

this has worked for me when everything else has failed.

edit: and if that fails, go for a ride without your lockring, and try to skid (with brakes I hope)

Finally. After endless attempts with the rotafix method, I finally got the cog off. Thank you all for the help along the way. I'm glad I didn't have to resort to any fancy chemicals. Now I no longer have to drag a B43 along on my rear. Success.

So wait...Chuck Norris shooting uzis at a cheap rear wheel will turn it into a Phil Wood cog?

Rotafix the mother*****
 

And if that doesn't work then use heat and rotafix again.

And if even THAT doesn't work then dremel a crack 99% of the way through the cog (or as far as you can without hitting the hub itself) and then fit a cold chisel into the slot and bop it with your hammer until it cracks all the way through the cog. At that point it'll, "give it up, baby!" Nothing can stay tight once you put a crack in it. Even if some fool put it on with Locktight Red (or god forbid Black Max) it'll come off once you crack the cog.

You can take any cog off no matter how seized if you crack it first -but of course you'll be needing a new cog.

Good that it didn't actually come down to that.

http://www.infobarrel.com/media/image/175.jpg
mad skidzzz w/o lockring hahahaha

BP Blaster is not a harsh or expensive chemical. Just a good cleaner, penetrant, and degreaser. Every one who works on bikes should have some. I prefer Kroil, but it stinks, so using it in the house gets me in hot water with the wife.

I would be careful where you spray penetrants as it can creep into areas that you do not want it, like bearings.


Tom