ISO-Bolt on Cogs FTW!

Wouldn't a properly installed and sufficiently tightened cog and lockring combination prevent any slippage?

If this is not the case, then how often do you all check how secure your cog and lockring are?

I never ever check, I don't even check to see if I can get my lockring on any further from time to time as is often suggested here, and I've never had a slip. I checked after I had my lbs replace spokes on the fly and they had to remove the cog - took them 10 minutes. I didn't have faith in them and missed them putting the cog on, but I saw the size of their chainwhip, and the lockring wrench the kid had in his hand was a foot and a half long. It hasn't budged.

On Zinn's scale of gaging tightness without a torque wrench, he recommends crank bolts as "vein popping tight", and that's the highest he goes. I think cogs need to get even more force than that, which is impossible without shop size tools, a cheater bar, or the rotafix.

As someone else said, stripping hubs seems to be the kind of thing that you do with your first bike/build, and you don't do it again. These shops that are sending people away with slipping cogs probably a) hire unskilled seasonal workers, as most shops do or b) have no familiarity with fixed bikes, as most shops don't, even if they sell them. I go to a shop that has like 6 mechanics on staff in the winter, but I wouldn't go to them if I needed something more esoteric or unmodern, like a 3 speed hub or a fixed cog. It's easy, but if you're not familiar with it, you couldn't know. I'd guess you could even have this problem if you went to a shop near a track (well, a couple years anyway), since they don't stop anyway, and many racers race multiple events with different ratios on the same bike.

I guess the moral of the story is it's worth it to take your bike to a mechanic experienced in cog/lockring combinations and have him check it over and tighten as necessary. I thought I got the cog on to "vein popping" tightness with the rotafix and the lockring on tight enough as well, but several weeks later I felt that confounded slip on a skid. I just hope I haven't trashed the threading.

So, I wanted to replace the lockring that has chipped notches where the wrench engages. I took off the old lockring, rotafixed the cog once again (if this isn't tight all the way, I don't know what is), and then carefully, very carefully, tried to screw on the new lockring. No matter how many times I tried (in the course of fifteen minutes), it would only go a couple rotations before I couldn't finger tighten anymore. Not wanting to risk stripping using the wrench, I simply put the old lockring back on, and I was able to finger tighten all the way to the cog surface.

Is it possible that the threading has been "influenced" by the old lockring, making the new lockring more difficult to screw on? Have any of you experienced difficult switching lockrings on one hub?

I was riding around the other day with my new rear wheel, and felt a slip on forward pressure, and not on skidding or back pressure? It happened twice in a row on starting from a stop.

What should I do? The wheel was built, and components were installed by a pro. The cog/lockring are dura ace.

Hi Eldave
On a new install, the standard advice is :
1 ride it up a hill to tighten the cog and then
2 take the spanner and tighten the lockring a little more.
So you should probably do step 2.
Not too big a deal if you use a brake to slow down and stop.

More likely you got an italian threaded lockring, EAI, Miche or Campy are threaded different than Formula, Surly, DA, etc.

My theory about why stamped cogs might be more prone to slipping is that they are not as thick as the machined ones so they have fewer threads to engage, but more importantly they may not hang off the cog threads enough for the lockring to but tightly against the cog. Instead the lockring bottoms on the step, and doesn't push hard against the cog. This could alow a little movement, and as the cog works back and forth, it will wear the threads until the movement is noticeable. At the point where you feel the movement it may be too late, the threads may already be compromised. I haven't measured a stamped cog, but if there is any truth to the idea that stamped cogs slip, i'd bet money this is the reason.

Someone mentioned using a spacer behind the cog. That might help, but given the cost of rebuilding a wheel I'd just spring for a decent cog in the first place.

Personally, I've had a cog slip on my first conversion, but that was on a Quando hub. As the bike was stolen soon after, I wasn't too worried about the hub. Got a Paddy wagon with the Formula hubs and had a bit of a slip once. Tightened everything down good and tight and threw some blue loctite on the lockring for good measure. Haven't had any problems since. My current conversion with a "sucide" hub has red loctite on the cog and BB lockring and to be honest I trust this combo more than the Formulas on my Paddy. The conversion sees more backpressure than the Paddywagon does since it has some ****ty braking due to steel rims. The Paddy has excellent brakes front and back and they get used all the time.

Thanks for your help, this sounds right.

Because grease lets you tighten the cog much tighter than if you had dry metal to metal contact in the threads. I think the idea is that regular pedaling force will tighten the cog, but the lockring could get unscrewed by that motion? Also, if the lockring stays put, the cog does, too. I didn't do it this way, though.

I didn't use loctite on my lockring, just grease. My cog did some slipping in the first day after I put it on, but once I cranked down tighter on the greased cog and lockring, they stayed put. This was about 6 months ago. I just checked it yesterday with my chainwhip and lockring tool and couldn't get it any tighter.

I would say that grease is more legit than loctite, especially if you've been stripping threads trying to get your cog/lockring tight enough.