Cog Question

I’m getting a new fixed cog wheel built and a problem has come up. One mechanic tells me that the surly cog I have isn’t going to work because it’s too thick. As in, the threaded area is too thick and the lockring only grabs one or two threads. He tells me to try and find a thinner one. At this point I go to the other shop where I buy parts and ask. Mechanic number two tells me that all cogs, both 1/8 and 3/32 of all brands have the same amount of threaded area. It’s an older suzue track hub. What am I to do? Is the above statement about cog thickness correct?

well… is it too thick? is the lockring only grabbing a few threads? look at it!

i too have encountered this problem with a couple of older hubs. You might have to look on ebay for old cogs. Hard to find in any of the higher teeth counts unfortunately.

I have at times just used the wider cog, but I ride with a brake and am conscious not to put the lockring under a ton of pressure unless it’s an emergency.

I am hoping someone chimes in here with information about new cogs that fit, because I’d definitely like to buy one. Anyone?

I haven’t seen it with my own eyes, however the claim is coming from the owner of a shop and a reputible mechanic who has surely installed a few cogs. I was asking about the statement that all cogs are the same thickness.

mabey get a machinist to shave the cog thinner on a lathe?

Cogs are not all the same thickness. I have seen a few shitty ones lately that are just thin enough that you can’t fully tighten the lockring down on them.

Rule of thumb is go for the Shimano for 16 and under. If you need a bigger cog I have had good luck with the newer J&B cogs (the machined ones).

Older Suly cogs were turds but I have installed some of the newer ones on a few different hubs without any weirdness.

Thanks for the input guys.

Both mechanics are full of shit. Which hub is this? FWIW recent Surly cogs are some of the widest and are built to space out the chainline and still give room for the lockring. Probably, you should just mount the things yourself instead of relying on a mechanic who may know fuck all about fixed drivetrains.

If you post up some pics, I bet you will get some good advice.