sixty2strat

Im trying to convert the freewheel side of my wheel to fixed cog, how do I go about aligning the cog in the same plane as the freewheel?
Note there is extra thread leftover when tightening down the fixed cog, I cant seem to tighten any further (by hand)- see pic with cog screwed on. Im not sure about jamming down on this to get it flush? seems like I will strip the thread?

acoustophile

You're not going to be able to get it to the same alignment as the freewheel as the freewheel is a wider unit. Clean the hub and cog threads and use a chain whip or rotafix method to make sure the cog in on tightly. Make sure you use a liberal amount of grease before you start threading anything on.

What is your plan for a lock ring to keep the cog from slipping? Or are you running dual brakes and not planning on back pedalling?

sixty2strat

Yes excuse the mess, I forgot to clean before photos.. I guess my main question was why can't I tighten the cog right down by hand? Is it that the cog thread changes at the end so that it is not going to allow the freewheel thread? (can see in pic#3 the gap in the thread). I really don't want to mess the thread up as that will wreck the wheel.. .
Re the lockring, I was planning on running a BB lockring. I plan to use mainly on a track. If on street I will have a brake and don't skid stop.

acoustophile

Those look like standard novatech track hubs, so i would assume the that the cog and freewheel is 1.375 x 24 TPI threading size. As long as the threads are clean and greased, I wouldn't worry too much about adding a bit of force to it. The manufacturing standards on cheaper hubs can lead to imperfect thread cutting but shouldn't be a concern especially if you were able to get the freewheel off.

Rolla

Why not use the fixed side of your hub instead of the freewheel side?

sixty2strat

wanted to run two different cogs to change up gearing.. by the looks of things it ain't gonna work with this hub....

Rolla

Yeah, I'm not a fan of the "suicide" set-up, anyway. I've used a Surly fixed/fixed hub, but of course that would require a wheel re-build. Plus, in order for the chain to work on both cog sizes, they have to be within a couple of teeth of each other, which I found wasn't worth the trouble.

mack_turtle

using the freewheel thread side of a hub for a fixed wheel is called a "suicide hub" for a reason. I tried that: treaded the clean threads with strong thread locker, roto-fixed the cog with all my might, installed the lock ring TIGHT and it still came loose after some miles. having your cog suddenly loosen up while riding is terrifying. add a hill or vehicular traffic and you have a recipe for disaster. I know people are going to do it anyways, because that's what I did. several people told me it would be a bad idea but I had to learn the hard way. fortunately, I was able to finish my ride without injury and saved up for a wheel with a proper track hub after that.

veganbikes

If you are trying to run double fixed, you will want a double fixed hub, The lockring is threaded opposite from the fixed cog helping to keep it on in case of something bad happening without that you could be in a world of trouble. Yes people do use loctite and hope but that isn't safe and just ain't worth it to save a little money.

I honestly don't flip my wheels around much and if I do it is usually at home or at the shop. The only time I might do that is if I was doing some serious mountain riding fixed then I might consider it but honestly I am not doing that ever, I have geared bikes for a reason. I can always bring a cog and something like the EAI/Makino Pro Keirin Tool or Pedro's Trixie and chain whip (if you need larger stuff) If I know I need a change.

rustystrings61 

I can see the value of the double-fixed hub, though, as I used to run 45x17 and 45x19, giving me a pavement gear and a dirt road gear. I would stop to flip the wheel around when I knew I would be on dirt for more than a mile or two, and it was especially useful on the local fire service roads and on the back o' beyond dirt roads down in the southern part of the county. I have run fixed cogs on freewheel threaded hubs, but always with brakes fore and aft. YMMV, though, and given the choice I run double fixed hubs.

Rolla

Also worth noting that a freewheel will thread onto the fixed side with no problem whatsoever; there are plenty of threads to secure it. I've been running a freewheel on a fixed/fixed hub for years now.

rewop12

That's not a good idea, you don't have any threads for a lockring so if you try to back pedal your cog will become loose.

79pmooney

That cog is a Eur-Asian Import cog. I see them at the velodrome. I also use them almost exclusively. Very well made and consistent. Probably right on spec. Lesser hubs are far less so. I've had a few where I had exactly the issue you've got only mine were fixed threading. I just broke out the killer wrench extension, lots of Phil Wood and my biceps. The cog now (years later) still doesn't spin on but it is a lot easier. You have a lot more thread than I had to deal with so you would do well to find some bigger biceps than I could find.

Running a fixed cog on freewheel threads - use a BB lockring. Use brakes, not your legs. It will do just fine. If you spin the cog off, it drops onto the axle. Stop pedaling. The chain will probably stay on. Brake to a stop, Screw the cog back on. (You will probably have to slide the wheel forward to start it back on.) The chain can jam the tire. If that happens, you do a long skid to a stop. The tire will be dead or nearly so. You might damage a chain link or two. You will massacre the chainstay paint and leave some deep scratches. (I don't recommend carbon frames for road fix gears.)

I like the EAI cogs because as you can see, the teeth are cut very square. Lots of material. They wear well. But more important in my book, they are the total antithesis of modern shaped, sexy and quiet cogs. They shift like the antiquities they are shaped like. And you know what? I love fix gear cogs that shift really badly because every shift ends badly. In practice, I can set my chain to more slack in full confidence than I can with any cogs that "rate" for quiet and smoothness. (Very useful if you are running a road crankset with less than velodromve standards of roundness. Also very useful if you flip your wheel often on rides or when you are hammered like at the tops of hills.)

There is a chance that the threads will be ruined. You may be able to find another cog that threads on easier (ie is spec'd a little looser). If you plan on changing cogs often, I'd put the cog you don't plan on changing much or an easier threading non EAI cog on this side.

Edit: I run fix-fix hubs on two of my fix gears, a single fix on my winter/rain/city fix. Never owned a fix-free hub. Started my fix gear riding on a road freewheel hub and BB lockring. Tried to coast at around 20 mph first ride. Crashed spectacularly but the cog stayed on nicely. Never got into brakeless riding so that first ride was probably the biggest test I ever gave a lockring. I have stripped threads on two hub, both lesser quality (and I got them used with no idea of their history.

Ben

sixty2strat

cheers all. I didn't mention but its predominantly for velodrome use as a warmup gear, so the lockring is not a huge deal. I do not do any skid stopping anyway and run a front brake on the street. I probably wont even bother with it due to the chain alignment problem.. I'll look out for a spare track wheel.