mschwett 

i need to replace the 11t and 12t on my 12 speed cassette. i have the cogs. they have built in spacers. the cassette (literally) falls right off the rear wheel, but i haven't yet gone further than that.

the cassette is a CS-R9200, 11-34. i have the Y0MV11000 and Y0MV1200, the park tool lock-ring socket, which fits, and a cassette wrench/whip, but it's described as "5-11 speed" (venzo VZ-F33-058)

any unpleasant surprises waiting for me here? a) will the cassette wrench working on a 12 speed cassette, and b) will/should the cogs just slide right off the hub?



this certainly sounds like a dumb question, but about half the time i try and do something allegedly easy for the first time, there's a catch!

Bill Kapaun

If the chain whip won't fit between adjacent cogs, it looks like the largest cog may still work.

mschwett 

thank you! it looks like it will.

Barry2 

Gotta ask…. Why do they need replacement?
How many miles do you have on them?

Thanks

Barry

mschwett 

skipping under heavy load with new chain. abated a bit as the chain wore a tiny bit but now back in force. can pretty much make it happen at will by getting out of the saddle in the 11 or 12t.

maybe 300 miles on the current chain. around 3,000 miles on the cassette. not great but a cheap replacement, thankfully.

Barry2 

No way you blew those cogs in 3000 road miles… gravel bike?
or
hanger alignment?

Barry

mschwett 

road bike. hanger is perfect, shifts perfectly, a nearly instant snick-snick, has been in the shop and checked out by people who know more than me (which is, well, almost anyone.)

unfortunately i may have run the first two chains on the bike a bit too long, and while conditions here don’t seem that harsh to me i guess the combination of coastal fog, hills, and regular wind-blown sand makes even my fairly average 200-225w average output wear drivetrains more than i’d hope.

trying to do better with cleaning on the latest chain.

BTinNYC 

Keep track of the spacers, they're different widths.

mschwett 

thanks! they should be built into the little cogs, so i can’t mess it up too badly, i hope!

BTinNYC 

And yes, they just slide off...or obey the laws of gravity and spill themselves randomly without concern about unique spacer sizing. 😉

KerryIrons

Are you one of those people who rides in the small chainring and the smallest cogs on the cassette? If yes, consider using the big ring and larger cogs. Slightly lower chain friction and a big reduction in chain, chain ring, and cassette cog wear.

mschwett 

lol, no, in fact 12 speed di2 doesn’t even allow that. it won’t shift into the 11/12 tooth cogs when it’s on the little ring in the front. i do sometimes end up in big-big for a minute before adjusting, but big little, never.

mschwett 

my 1x bike with GRX had endcaps on the rear wheel which were damn difficult to get off, so imagine my surprise when the cassette on this one just fell off while i was replacing the rotors 😂😂

mschwett 

took about 5 minutes.

chain whip/wrench worked reasonably well. made a slight ticking sound on the first few turns of the crank but seems back to normal now. stood on it a few times on the way to work and it didn’t slip, but i wasn’t clipped in, so we’ll see later today.

a rare repair/maintenance which didn’t present any surprises. fingers crossed.

after



before

jgwilliams

As others have said, you seem to have worn out those two sprockets exceptionally quickly. I should make sure you've got yourself a good chain lube and apply it fairly regularly. I wouldn't have expected to get through a chain in 3,000 miles, let alone a cassette. In fact, if you're careful about maintenance you shouldn't have to replace the cassette at all, unless you're doing mega mileage. I recently had to change one that had done 8,000, and that was only because I got careless with checking the chain wear. I let it get really bad and ended up having to change the small chain ring as well, which had done 14,000 miles.

mschwett 

yes. i was definitely not pleased when the original cassette was skipping on the 11 after +/- 3,000 miles. i blamed that on letting the chain go too long - it was already a bit past .5% when i remembered to check it.

i’m now taking the chain off for a good scrubbing every 500 miles or so (once a month) and using the cyclone every two weeks. after every i long ride i wipe it down, which makes it look shiny but probably does nothing for the rollers and interior plate interfaces. i re-lube every 100 miles with drip wax.

Barry2 

mschwett
congratulations on your journey into more advanced DIY maintenance.

Please do report back if the cog changes have cured your skipping issue.

Thanks and all the best

Barry

mschwett 

not particularly advanced! but it definitely worked, did a reasonably hard ride today with some powered descents in the 52x11 with no skipping.

it IS slightly noisier though, for sure. will give it a clean and lube and see where that goes.

mschwett 

i am somewhat incredulous that the barely visible wear on this cog was causing it to skip. it was definitely skipping - basically any time i put more than 500 or 600 watts into it, and often within one pedal stroke of standing on it. it doesn't skip now.

but here are the two cogs, left is new one, right is old one, middle is old one with profile of new one overlaid. taken with 105mm macro lens and full frame 45mp camera, on tripod. almost exactly 3,000 miles of use. 185lb rider.

Barry2 

Personally, I think you should replace your entire cassette then give me the old “worn” one.
I’m pretty sure I can run it for many more thousands of miles.

Great pictures BTW, but not exactly worn is it.
Sorry to say, but I think you have an issue and it’s not worn cogs.

Have you actually checked hanger alignment with the correct tool?

Barry

mschwett 

you know, that’s exactly what the shop said - “you’re due for a new cassette!”

they also couldn’t get the small cogs individually.

three possibilities at this point i suppose - 1) it was actually worn enough to cause skipping, it’s just not easy to see visually. it is fixed, after all. 2) the problem is totally unrelated and it’s random chance that it hasn’t skipped since changing the cogs. 3) there is/was another problem that was slightly alleviated or modified by taking the wheel off, removing the lockring, taking the two small cogs off, and then putting back together.

i do not have a hanger alignment tool. it certainly looks perfectly aligned but that may not mean much.

Barry2 

I believe the Shimano spec is about 1/8" at the wheel rim.
You can't eyeball that.

Given Di2, skipping and drivetrain noise on such a young cassette, it would be the first thing i'd check.

All it takes to upset alignment is to have your bike topple over on the righthand side.

Barry

maddog34

Get a New Cassette.. wow.

mschwett 

not following … wow, that cassette is dirty or wow, i can’t believe your LBS said you needed a new one?

maddog34

Get a New Cassette.
SEVERAL badly worn teeth can be seen in the pics...a lot of the wear is directly attributable to running worn out chains, IMO.
No, i won't bother pointing out each badly worn tooth.
i hope you didn't waste very much money on the two cogs that show minimal wear..... keep the new cogs as spares in case you break one... 11s are known to break on occasion..