# Gap between cog and lockring



## pianopiano (Jun 4, 2005)

I'm in the process of building a set of wheels for the track, and I've come across an interesting situation. The hubset that I've purchased came with a Joy Tech cog, and I've purchased a couple more, but there is about a 1-2mm space between the cog and the lockring. I've done a bit of 'Googling', but couldn't find a reasonable answer anywhere as to why this is so, and what to do about it.

I'm assuming that I'll need to find a spacer of some sort, but I can't figure out why they make cogs that aren't wide enough to properly fit the hub? These are pretty standard inexpensive flip-flop track style hubs, like I've seen used on a lot of track and fixie wheelsets.

Any suggestions?


----------



## No Time Toulouse (Sep 7, 2016)

Is that a fixed-gear hub, or just a single-speed hub? I don't see both left and right hand threads, so I assume that you are trying to put a FG cog on a hub meant for a freewheel.

Don't do this, IT IS DANGEROUS. First time you retard your speed with your pedals, the cog and ring are gonna screw themselves off. If you run without calipers, you just became an unstoppable projectile. Even using threadlock isn't safe (and makes it a ****ing pain to remove the cog).

True track hubs have the cog screw in with RH threads, and the lockring screws on LH. Also, if you are planning to actually race on a track, these hubs won't pass inspection.


----------



## bikerjulio (Jan 19, 2010)

This is a flip flop hub. The 2 sides are different.









Left on this image is for the freewheel, Right is for the fixed cog.

As NTTL says,they are different for an important reason. 

If that's the only thread you have on that hub, then it's for a freewheel.


----------



## pianopiano (Jun 4, 2005)

My hub is basically identical to the Novatec hub in your image (a flip-flop hub), and I AM putting the fixed cog and lockring on the proper side, where the cog is screwed on clock-wise and then the lock ring goes on counter-clockwise, and should butt up against the cog.. 
The cogs that I'm using are identical to the one in that image as well, but I'm left with that gap (see my first pic) between the cog and lockring. I do have an older cnc'd cog that I tried and there's NO gap, but why the gap with all of these other cogs, including the one that came with the hubs!? It doesn't make any sense to me.


----------



## bikerjulio (Jan 19, 2010)

do you have the right lockring?

https://www.sheldonbrown.com/fixed-conversion.html


----------



## pianopiano (Jun 4, 2005)

It's the lockring that came with the hubs, and it screws on just fine, so I'm assuming that it's the right one.


----------



## velodog (Sep 26, 2007)

I'm just pulling this out of the air, but could the gap be to allow spacers to be used to adjust the chainline?


----------



## bikerjulio (Jan 19, 2010)

velodog said:


> I'm just pulling this out of the air, but could the gap be to allow spacers to be used to adjust the chainline?


Has the be the only logical explanation.

Sorry OP I didn't fully understand your original post, and the picture of the threads was fuzzy.

So, when you screw the cog fully on, there are 2 mm of threads visible before the shoulder? And the lockring is just then butting up to the shoulder?

It must be a "feature" of the hub/sprocket. Unless it's faulty. It is unusual.

You need a spacer. Should have come with the hub.


----------



## pianopiano (Jun 4, 2005)

Bikerjulio you're correct. When I screw the lockring on fully, there is about 1-2mm of visible threads between the lockring and the cog.

IF the hub was intentionally designed this way, to allow for the use of spacers to obtain an optimal chainline, then it would of been nice to receive some spacers with the hubs, because it's been a big PITA to try to find some here in Toronto. I didn't think that a single speed drivetrain would end up being so complicated.

I'll head over to a shop that sells fixed gear bikes later today, to see if they can help me out. Thanks for the replies!


----------



## bikerjulio (Jan 19, 2010)

Urbane Cyclist on John should have.


----------



## velodog (Sep 26, 2007)

https://www.modernbike.com/product-2126240260


----------



## JCavilia (Sep 12, 2005)

with all due respect, Toulouse, you might have saved yourself the time you wasted in typing irrelevant advice if you had read the original post more closely and looked at the picture. He said, and showed, that the lockring stopped before it met the cog. The only thing that could make it do that is bumping against the shoulder on the stepped thread. If he were using a freewheel hub with a bottom-bracket lockring, it would thread on all the way; there's nothing to stop it until it meets the cog.

With respect to your warning, it's standard advice, but overstated if you know how to use the equipment. I've ridden thousands of miles in traffic with such "suicide hubs" with nary a problem. I have a front brake on all my FG bikes, and I use it for all hard stopping (no skid stops), but I do use back pressure for more moderate speed control, and I've never had a cog move a bit. I use blue Loctite, which makes it take a little muscle to remove a cog, but I certainly wouldn't call it a ***king pain.

I'm not advising anyone to do anything, but if you want to do an inexpensive FG conversion using an old freewheel hub, it can be ridden safely, as long as you understand the limitations.


----------



## pianopiano (Jun 4, 2005)

*Problem solved*

I went up the street to the local bike shop, and asked the mechanic what I should do. She sold me a 2.5mm Wheels Manufacturing bottom bracket spacer, which did the trick. Since the gap that I needed to fill was about 2mm, I've gently filed it down to make it fit perfectly. It wasn't absolutely necessary to do that, but I am a bit of a perfectionist.

Thanks to everyone for taking the time to respond. It's been greatly appreciated.


----------

