Stubborn Track Cog
 

I've got a 1/8" track cog I'm trying to get lose. I've removed the lockring and put the wheel back on the bike. I've then tried to hold the bike in place while pushing all my weight on on of the pedals in the backward direction. It won't seem to budge. I sprayed with some liquid wrench--gonna let it sit for a bit. Any other ideas?

You actually get very little torque your way. Take the wheel off and try using a chain whip. BTW, you may not have a 1/8" chain whip. I took one of my 3/32 whips and replaced the 3/32 chain pieces with a 1/8" chain pieces using a chain tool; a very easy modification and necessary with 1/8" cogs.

Yeah, you're right...pedals weren't giving much torque. I decided to flip the bike upside down, put a ratcher through the crankset to hold it in place, and then grab the wheel and twist. It took some scary force and I thought the wheel might break, but the cog snapped loose in a loud bang.

Next time use reverse Rotafix. Just Google Rotafix. From what I remember there is a helpful Wikipedia page about it. I'm fairly certain it's the most leverage you could possibly get on a cog.

Hey, good call. The important thing is it worked!

Found out what you were talking about. It's interesting, but with the probability of scratching the paint and/or denting the BB shell, I think I stick with a chain whip or x201's Ratchetfix..:thumb: (or maybe not the Ratchetfix either) :p

Or try putting the chain around the BB spindle rather than the shell, which is what I did last time I was faced with installing a track sprocket. Alternatively, use a rag to avoid scratching the paint, and if you have a bottom bracket installed, I'd say that denting the BB shell is very unlikely.

That said, a chain whip is a perfectly adequate way of fitting track sprockets, I only rotafixed that one because I was at the co-op rather than at home, and we only have a 3/32" chainwhip at the co-op.

I looked up that rotafix method--interesting. A chain whip would have been ideal, but I've only got a 3/32 whip. A lot of these sites say, "Oh, just take a 1/8 chain and you can..." ...as if we all have 1/8 chains just laying around :D Maybe some people do...

God I hate to agree with this as I normally use a chainwhip for either installing or removing a cog, but I must admit that the Rotafix method applies more force than a standard chainwhip. If this method doesn't work you will need to resort to cooling the hub in the freezer and then heating the cog with a torch.


Just wrap a shoprag around the BB shell under the chain. You will not deform the shell.

BTW: You can build a chainwhip with just a couple of short pieces of old chain and a $2 piece of flat stock from Lowe's. If you are going to ride FG you will need one.

Have you made one of these and used it to remove fixed cogs that have been ridden?

Unless you take an actual production approach with the requisite tools you have two problems that prevent this from working for most people.

1.) Drilling holes in hardened steel is not cheap or easy.
2.) Cheap, soft steel that is easy and cheap to drill holes in will not hold up as a chainwhip for fixed cogs.

Now if one were so inclined they could buy soft steel stock, drill the holes and then perform some backyard annealing. This approach requires tools, times and a bit of knowledge for it to work.

So in essence, I see people recommend this approach a lot but for most people it's just a better idea to spend the $18 on the Park SR18.

You'll break the chain or strip the threads on the hub before you dent the BB shell, which also goes to show how much force you can put on a cog with this method.

As mentioned, a rag around the BB shell will prevent it from getting scratched. Or if you just rode s----- old bikes like me you wouldn't have to worry about such things :P

I did not mean bending or deforming the BB shell, I meant the chain links would pit the outside of the BB shell (if not protected properly). And while a rag would probably do just fine, knowing me I would not get the chain coiled correctly and it would slip, pulling off the rag and chainsawing the BB shell.:cry:

Thanks for all the replies.

hahahaha

Yes, as a matter of fact I have made at least a dozen for friends over the past 25 years or so years and they seem to work quite well for them, and that including the ones that I just gave away that are based on a pair of alloy motorcycle tire irons. First of all, a $2-3 piece of 12" long piece of flat stock from Lowe's is not hardened in any substantial way, and a cheap cordless drill with a sharp bit will easily drill the three holes you need, and if you use 1 1/2" wide or more piece of flat stock the tool will be plenty stiff enough. Second, even hardened CrMo steel is very easily drilled by even a cheap electric hand drill and a sharp bit. Having been a machinist and certified welder for over 35 years I will use my own experience and judgement at having actually built these tools, rather than to accept the opinion of someone who obviously does not have either the experience or judgement to know how easily this can be done. Thank you though.

It seems there are others who also find that making their own chainwhips is preferred to buying them. These where posted a few months ago by another BF member, but I am sorry I don't remember who. Perhaps he will chime in.....
http://i221.photobucket.com/albums/d...hain_whips.jpg