Slipping Cog

About two weeks ago,I picked up a Mavic Ellipse Track Wheelset.I took the stock cog off my Bianchi Pista and stuck it on,all fine so far.So during the next week of riding I notice my cog slipping every time I skid,not too much,but enough to make me faceplant..Every day after riding I tightened up the Lockring(with a lockring tool) but to no avail.There's no question about tightness of the lockring,I got it as tight as I could.So today,I decided to take the lockring and cog off,clean everything including the threads and stick em back on.When I stuck the lockring on,I tightened it as hard as i could,until the lockring met the bigger threads of the hub(where the threads for the cog start)..I then noticed that there is a gap of about 2 threads thick between the cog and the lockring, even though the lockring was super tight.

Can anyone give me any suggestions?Is it something to do with the fact that im using a bianchi cog meant for a bianchi hub?Are these crappy stock cogs made just for the stock hubs?Thanks for any help!
ps:Sorry if this post seems a tad long-winded,I'm really frustrated!!

Suggest you buy a decent fat cog, then it will have more thread and your lockring will work.
I haven't seen the bianchi cogs, but there is a noticeable difference between a pressed steel 3/32 cog and an EAI 1/8.
I also havent seen the Mavic wheels you speak of, but if they are for use on the track then maybe you need to upgrade everything. Get a new chain too! ;-)

Thanks!I think it's time to bite the bullet and switch from 3/32" to 1/8".

Wally, go into your local bike shop and ask for a cassette spacer, the sort that sit on a freehub body, most mechanics usually have a box of them sitting around - stick this between the cog and the lock ring so that the lock ring is exerting force on the cog (through the spacer) and not simply running out of threads.

They come in various thicknesses - 4mm, 2.5mm, 1mm are pretty common, get one (or a combination) that is just thicker than the area you need to fill.

If they don't give it to you for free (which most do) it should cost you around 50p - £1.

P.S

You can, of course, also put the spacer(s) onto the inside of the sprocket/cog (against the hub) - to give you a little adjustability - if you need to tune your chainline.

Good idea! ^

wallys back not put of by the barrage he received after his first post !! good man

Got two 1mm cassette spacers today from lbs,works a charm.Thanks Tynan,You've saved a poor student.

rota fix that cog on tight too.

+1

when you have the cashwads, Surly cogs are nice and thick, look nice too. won't break the bank

Thought it would be more useful to recycle an existing thread instead of starting a new one but...

I'm confused...

Yesterday I was trackstanding in a queue of traffic, went to pull away (hard) and I had the old slip-KERCHUNK feel of the cog slipping. Didn't think too much of it until I got to the shop, went to skid stop and the whole thing just unwound.

Got the bike home, stripped the cog off and cleaned it up, and there's no sign of any damage. Put it all back together and took it outside - and the same happened. Got pissed off, took hub apart again, thought it could be chainring bolts slipping as well, so took off chainring and tightened everything up.

Got up this morning, rotafixed the cog on, went outside and went to stop/skid and again - slip-KERCHUNK. 'Sod this' I thought and in a fit of pique decided to rip the thread apart by pulling a big bad 'I'll show you who's boss' skid, only to pull a big bad 'I'll show you who's boss' skid, without the cog slipping at all. Did it again, and then another five or six times, and then I stopped because the neighbours were getting funny about the noise...

Wheel seems fine now - it stops, the thread doesn't unwind and it's not 'chunk'-ing back and forwards when I stop and pull off - but I can't relax and am convinced it's going to unwind and rip the thread off when I'm 20 miles from home.

What's happening Uncle FGSS?

^ when similar happened to me I found that my cranks were shagged.

your lockring isn't on tight enough

your cockring isn't on tight enough

fixed

Paid a vist to Charlie the Bikemonger on eBay and finally got myself sorted out with a lockring spanner and a chainring bolt tool. Can't believe I've been bodging everything together for such a long time with screwdrivers and hammers...

advice from here + rotofix + screwdriver and hammer sorted me out good. should probs get the proper tool tho.

p.s. nice name.

p.s. nice name.

Hutch: [pointing at Starsky] I like your style.
Starsky: [pointing at Hutch] I like your moves.

hi, just wanted to bring this thread up again! ha, sorry!

but i have had the same problem on and off for a few weeks now. but didnt have any time to sort it out, so i just rode it... but it got a bit dangerous sometimes.

I did all i could think of, tightened it all up. still did it... so i went to cavendish and they said they thought it could be that the cog wasnt on as far as it could go so when the lock ring went on there was still a tiny bit of room for the cog to slip. so i bought a new cog (surly one), cleaned it all up, put it on as tight as it could go, there is no way it was going any more, and then put the lock ring on with a lock ring tool as far as it goes. tried it out out and the same thing happened. the only 2 things i can think of is; either the bit of threading where the cog goes is slightly bigger than the cog so where the lockring finishes, there is a tiny bit of space where the cog can move. meaning id need a spacer between the hub and the cog? or the threading on the hub is fucked, meaning the cog can move some how?

it only happens when i skid, and then after that itll only happen when i pull away and so on... so i think it could be my first solution...

anyone got any other ideas...

and anyone know where to get some spacers if that is the problem?

thanks in advance!

hope someone can help out

dave

ps. the strangest thing is, that its only started doing it after a year or so... i dont get it

Does it look like there's a gap between cog and lockring?

hmmm, its not a clear gap. i can just get the tip of the corner of a piece of paper down it... but it doesnt look anywhere near as big as the amount the cog slips...

does it matter if the cog hangs slighly over the edge of where the lock ring thread finishes?

is it a double fixed hub?

nope, a flip flop, but i know i am on the right side as the cog and the lock ring threads go opposite ways

No, so long as the lockring is actually threaded on and butts up against the cog it should be fine.
Sounds like there could be something stopping the lockring getting close enough and when you apply reverse pressure you're spinning cog and lockring off a bit.

^ @pavid

sure, just wondered if you had another side to use

You may have mucked-up the threads, maybe skidding with a loose lcokring/sprocket etc.
it may just be time for a new hub, a year isn't that bad