cid499

I am new to fixed riding, and have a question about cog slip. I really have read through many threads about cog slip/stripping/etc, so please don't just link me to the search page.

Initially, I had my LBS put on my cog and lockring. This is a Formula hub with whatever generic cog and lockring come normally on a Fuji Track Pro.

I was practicing skidding the other day and seemed to have it down alright on a dusty section of road. So I decided to move onto regular pavement, and I could get some little skids down. Cool. I kept going and after a few skids, I felt an ever-so-slight slip of the cog. At that point, I got off the bike and went for some tools. I took off the lockring and cog, and it looked like the threads were still OK. I guess the cog had just unthreaded itself a little bit.

This time I put the cog back on myself. I cleaned the threads, greased the threads, and rotafixed the cog on there nice and tight. Put the lockring on with a proper lockring tool. Next, I went for some sprints around the block, using only my front brake to slow down. Then, I was able to tighten down the lockring some more.

I figured everything would be cool. So I rode around for a few days, but after skidding around some more, the cog slipped again about 1/16th of a turn. I haven't taken everything off to see what it looks like, but I fear the worst, considering how tightly I had screwed on the cog and lockring.

Luckily the hub is fixed/fixed, so I have a second chance. But this time, I REALLY do not want this cog to slip. Is there anything wrong with the way I installed the cog? Do I need to buy a $$ cog? Is the hub a piece?

Offhoff

Your problem is using whatever generic cog and lockring come with a fuji track pro. Get a dura-ace, surly, EAI or phil wood install it properly and that should fix your problem.

mander

Intertesting. It sounds like you did (almost) everything right, and the cog still failed. A bfssfg member was arguing a month or so ago that poor installation is usually to blame for cog stripping mishaps. Well they may have been partially right but you sure don't regularly hear about people stripping threads with DA/ Surly/ Phil/ EAI/ etc cogs.

chase.

If the cog and lockring on the track pro are the same as they are on the regular Track, then it could be the cog's fault. I didn't really inspect it since it was hanging at my LBS, but the 06 Track's cog looked stamped. Of course, that doesn't mean that they hadn't changed it for 07, or that the Pro doesn't have a real cog.

crater

Its the cog! it happened to me too

cid499

Lucky me, the on-campus bike shop was having an "everything 30% off day" today. I picked up a DA cog and lockring. I'll see how it goes and post back if there are any more problems.

Cheers

Gyeswho

what exactly is a stamped cog or lockring? i hear the term but not sure exactly what is means.

lyledriver

Try putting a spacer behind the cog. The problem could be that your cog is too narrow, and when you are tightening the lock ring on, you're really just tightening it up to the step in threads on the hub.

danv

Using loctite instead of greasing the cog threads will also help.

kludge

no dude, its grease on the cog threads and then you put loctite on the lockring!

danv

My bad.

Why is this the case? Both the cog and lockring may be unthreaded in the future, and neither one is supposed to move when installed. Why grease one and use loctite on the other?

heliumb

Stamped means the cog is punched out of a piece of a sheet of metal like a cookie cutter.
Good cogs will have barely noticable grooves (like a vinyl record) from the milling machine.

get_nuts

Are you sure it was the cog slipping that you felt? Maybe you pulled the wheel forward in the dropouts a little (axle nuts loose?). Was the chain a little more slack afterwards?

I pulled my wheel a bit forward in the dropouts today and I thought the cog had slipped.

blickblocks

That would be me...we concluded that a cheap cog or improper installation could cause stripping. Best bet is to get a good cog and have an experienced mech install it for you.

I'm actually running a stamped cog atm and I don't know really if I ought to have it switched out for a Dura-Ace. I haven't had any slip problems yet but I'd like to keep these track wheels for a few years.

cid499

So I felt the cog slip again, just a few hours after installing the new DA cog and Formula lockring. I was applying some pretty severe backpressure (skidding), and I felt the cog slip backwards just a little bit, until I heard it SQUEAK. After the squeak, it seemed as if the cog wasn't going to move anymore. I picked up the bike and brought it inside.

This is really beginning to get on my nerves. I followed the same installation procedure as before. Any other ideas?

whiney

Have a look at the lockring's threads (the ones near the cog).

It seems to me that they are worn. I had a similar problem a couple of months ago.
Loctite did not help. Unscrew your lockring and see if small aluminium parts come with it.
Sorry, but your hub is probably fixed/free now.

mascher

Can someone please explain to me why cheap cogs are blamed for stripping hubs? Assuming installation is correct, and the cog threads on happily and easily, why would a cheaply made cog be more likely to strip any hub? The hub threads are still soft aluminum, and the cog threads will still be steel, so the battle ought to be the same.

I stripped a hub myself (I didn't hear a squeak, I just felt it move, and when I removed it nearly all of the hub threads were sheared clean off), and it was my own poor installation from before I learned the way of the rotafix. Since then I've used Dura Ace, Phil and several Soma cogs on Miche, IRO and Kogswell hubs, and haven't felt a slip since in years on different bikes with different ratios.

mander

That's a good question ieatrats. Off the top of my head I guess that not-very-hard stampin' steel, ****ty tolerances for thread cutting, and lower overall threaded surface area are to blame, but maybe someone else knows for sure.

Blickblocks I totally got away with a bad installation on my Surly hub with Surly lockring and cog. I suspect but cannot prove that with a cheaper combo i would have joined the ranks of the fg noobs with ruined cogs/ hubs.

mascher

I can't remember my hardness tables from chemistry class, but any steel at all has to be harder than aluminum, and if it was softer, you'd strip the cog threads, not the ones on the hub.

Phil cogs definitely are impressive in their machining, beautiful even, and the threads "look" thick, but any cog that you easily screwed on and doesn't have any side to side play while it's on has to have enough threaded surface to engage the hub threads. Tolerances on machined, forged, or stamped parts will be to the hundredth or thousandth of an inch, and we're talking about something that should never move at all if it's installed correctly.

I'm just throwing that out there, I'm not a machinist or anything, and I certainly won't say that cheaper stuff is as good as more expensive and better made stuff, but this is one of the most popularly repeated things in this forum, that cheap cogs kill hubs, and I just don't get it. I've never used one, but my Somas were accused of being crummy on this forum, and they're infinitely better made than the generics I've seen in shops, but functionally they don't look so different.

mander

Very interesting points ieatrats, i will be watching this thread to see if someone has more input.

kemmer

I'm not sure I buy all this cheap cog business either, but I've heard it enough to make me want to buy a new cog/lockring. I'm using whatever came stock on a specialized langster and I haven't had any trouble, but still...

clayborne

ruined my second iro hub today. The only common demoninator is cheap german cogs (less then 14$). Just finished my wheels myself too. On even the slightest chance it had to do with the cog, i am going all out from now on. PS the hubs were a stock bianchi and an iro hub. Is a nicer hub worth it? In nicer i mean better then iro or surley. Miche hubs look cool but i think i am forever dedicated to fixed/fixed incase the problem repeats. Dura ace? Relacing wheels sucks.

ECDkeys

Okay, this thread has got me a little worried. I've just become adequately comfortable riding fixed, and I want to do my first fixed conversion (an early 80s Bianchi frame). I'm looking to buy a ready assembled wheelset, but I'm beginning to wonder now how common it is to strip that lockring thread. On a similar note, I may have to replace the lockring on my current bike soon, as I've ruined all but one of the notches on this ring tightening it down.

Other than just "be very careful", what do you do to ensure you don't ruin the threading?

heliumb

My theory is that the more likely someone is to buy a cheap cog, the more likely they are to be new & unfamiliar with installing it. So it seems like the cogs fault, when it's actually due to inexperience.

jk610

I had a serious bout of cog slipping with my last conversion and it resulted in 1 toasted hub. After getting a brand new wheelset and lockring I STILL had a couple incidents and finally took it to my LBS and physically watched them tighten everything down as hard as possible. But now Im on a brand new Pista and had a little cog slipping with that on my first ride. Took it back to the LBS and in the nicest way possible told them if this ever slips again and I end up crashing Im going to throwthis bike through your store window. Havent had any problems since then. I have to tackle some pretty tough hills in my daily adventures and the last thing I need is the lockring slipping off on a decline. So Ive invested in a handydandy LR tool and chainwhip.