Removing a Cog
 

I bought a new wheel with a 1/8 chainring already on it. My setup is 3/32, so I got a 3/32 cog and borrowed the tool to get the lock ring off. However, now I need to take off the 1/8 cog, which, I hear, is usually done by pedaling backwards with the lock ring removed. Obviously I can't do that with my 3/32 chain, and I don't have access to a bike with a 1/8 setup. Is there any other way to remove the 1/8 cog short of stopping people in the street and asking to borrow their 1/8 setup?

Not by pedaling backwards, but rather by doing a reverse rotafix.

The following is the rotafix procedure, used to fasten the cog to the hub - you must do the opposite to remove the cog.

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With the rear wheel firmly secured to the frame, slowly wrap the chain around the sprocket in such a way as to trap it inside the chain itself.


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Keep wrapping the chain around the sprocket until it is taut, on one side tightly wrapped around the sprocket and on the other around the bottom bracket shell.


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Grip the rim of the wheel firmly and rotate in an anti-clockwise direction (avoid applying excessive force as this may damage the threads of the hub). With this technique it is possible to apply a tightening torque much greater than that available using a chain whip: the force is applied at a distance which coincides with the radius of the wheel instead of the much smaller radius of the sprocket, greatly increasing the leverage.The lock ring is now unnecessary.

Possibly you could put some wood blocks in a vice and have the cog dig its teeth in, but that seems more of a hassle than having a shop do it for you with a chainwhip.

Go to a bike shop with the proper tools, borrow a 1/8 chain whip, or wrap a scrap piece of 1/8 chain around the cog and put it in a vice, twist with care. I guess the last option depends on how nice your hub is! It does work, my friend does it all the time, never had a problem.

I used a 3/32 chain whip for several years before buying an 1/8 one. Have you tried it with an 3/32 yet? It just may give you the grip you need. I only bought the 1/8 one because the 3/32 whip tore off the handle. I knew it wasn't the right size, but it worked for me a least 5 or 6 times (tight or loose)

Rotofix idea sounds good. I looked at the link and can't say I was smart enough to get it but I guess it would make more sense with a bike in hand....

Thanks for the info, but it doesn't seem like I could rotafix it without a 1/8 chain, but that is useful to know for the future. The vise is an interesting idea. If it doesn't work out i'll take it to the shop, I'm just trying to learn more about my bike, and I don't have much else to do tonight.

I tried it with my 3/32 chain, and the guy at the local roadie shop tried his 3/32 chainwhip, which didn't fit (he didn't have a 1/8...not sure why...). I'll give it another shot though, it may give just enough tension.

Your cog is 1/8", right? You need a 1/8" chain to remove it, whichever method you use.

The vice does work. I've even seen a few guys do it at a bike shop for cogs that were too tight to get off with the chain whip. Just be careful, don't over tighten it. I'm telling you for real that you can get pretty decent grip for removal (NOT RIDING) with the 3/32 chain on the 1/8 cog.

Or take it to a shop

Let me just say that I don't advocate using the wrong sizing and tools for working on your bike but.... If your dying to remove the cog, you can always try to grip it with 3/32. If you want to keep the 1/8 cog mint, then do it the right way with the right tools and size...

Maybe nows the time to switch to 1/8...... Buy the 1/8 chain now and swap the chain ring later.....

word! once you go 1/8 you never go back...

I was thinking about doing this. I know there have been numerous threads here about the pros and cons, and as far as I can tell the difference isn't that big. Since I don't really have a preference, and to tell the truth my 1/8 cog is nicer (Phil Wood vs EAI), is it possible to use the 3/32 chainring with the 1/8 chain?

If you really read those threads, at least you would have learned that you can use a 3/32" chainring with a 1/8" chain no problem.

Also, the difference is not insignificant when it comes to chainring lifespan. Because of the shape of the teeth on a 3/32" chainring, it will last much less than a 1/8" chainring. While at the base the 3/32" teeth are only 1/4 narrower than 1/8" teeth, their tips are thinned down into a point, and will therefore deform easily. If you use a steel 3/32" chainring, that will, of course, last much much longer than an aluminum one, but the difference in teeth shape remains.

The big difference is once you switch to 1/8 and realize how much louder it is compared to 3/32, you'll immediately switch back. People who don't care about noises on their bike excluded.

I know everyone has their opinion but for me, I love 1/8 chain. I ride daily, year round and am over 200 lbs with a heavy bag as well. It makes me feel better and safer stopping on city streets. I keep my chain well lubed and cleaned so I find it to be pretty quite. I would agree, 3/32 is a bit quiter from what I remember. Its been a while.

Well, to be fair, 3/32" chains in theory should be just as strong as 1/8" - the chain's strength (i.e. resistance to snapping) should mostly depend on the thickness of the plates and construction/shape of the plates and pins - both of these factors in theory are identical between 1/8" and 3/32" chains.
Where you might feel safer is the chainring robustness - it very seldom happens, but it happens, that the chainring is folded from the strong force exerted by the chain. This is less likely with 1/8" chainrings.