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-   -   Shimano Ultegra 6800 Cogs, Float, Loose? (http://www.bikeforums.net/bicycle-mechanics/937352-shimano-ultegra-6800-cogs-float-loose.html)

aubiecat 03-08-14 07:40 PM

Shimano Ultegra 6800 Cogs, Float, Loose?
 
I just made a huge leap from a hybrid to a road bike that has an Ultegra 6800 group.
I am am a bit perplexed because I went out on a check ride today and I have some serious rattling going on at the rear of the bike.
I must add that I have to ride on a lot of chip sill covered roads and when I do something is rattling like crazy!
Are the cogs on the Ultegra 11 speed cassette supposed to float a little bit or be loose?
They seem to be attached in groups of three till you get to the smallest gears but these sets "float" independently. Is this normal?
Anyway something rattles like hell and back when I am on the chip sill (rough) roads and it's a bit disconcerting when it's a brand new bike.

FBinNY 03-08-14 07:48 PM

Yes, and no. The loose small cogs and spacers is normal, but they shouldn't be loose once mounted. Odds are that your lockring is bottoming against the face of the freehub and therefore can't properly compress the cassette. Add a spacer behind the cassette to bring it out beyond the front of the freehub so the lockring compresses the cassette without bottoming against the body.

If you've set up and adjusted a threadless headset, you understand the principle, and it's the same here.

gsa103 03-08-14 07:58 PM

Take the bike back to the shop and have them check it out.

It could be something as stupid as a loose reflector.

Al1943 03-08-14 08:08 PM

There should be NO looseness or noise in or from the cassette. As FB said, you may be missing a spacer needed at the back of the cassette or the lockring was not torqued to specs. Loose cogs may damage the freehub splines, especially true if the freehub is aluminum.

Kimmo 03-08-14 08:15 PM

This a bad sign for the quality of service at your LBS.

I'd bring it to their attention, and if they don't appear ashamed of the blunder and fall over themselves to sort it out on the spot, find someone else to do your wrenching.

Sometimes oversights like this might have half an excuse for happening, but as far as I'm concerned this is one for the red pen. Even if the bike is otherwise perfect, B+ max.

I'd never let a bike leave my hands like that.

aubiecat 03-08-14 08:45 PM

So I took the rear wheel off to further examine the problem. I can bang my hand on the tire and get the same rattling sound I get on the road. It is definitely the rear cog making that rattling noise. They are loose as a goose so it's gotta be a spacer that was left off.
At least I know what it is.
Service call bright and early Monday morning.

Andrew R Stewart 03-08-14 10:09 PM

One can grab the various cassette cogs in your hands and wiggle them to confirm their not being fully tightened. Cogs not tightened will at least cause some noises during shifting and at worst the cog set will come apart and things will likely jam between the frame and freehub body. This is something to take care of ASAP.

I see a loose cassette lock ring and/or a missing cassette spacer (the thin one behind all the cogs) often enough. Most of the time only some index/shifting issues are going on, but...

Don't be too hard on the shop. Most assume that the factory will assemble components well enough and most will never remove the rear wheel to check it's condition. Heck, most won't even adjust the front hub bearings, and that wheel and QR skewer are already off the bike. They do need to make the bike right though. Andy.

aubiecat 03-09-14 06:15 AM

This is what I'm dealing with.

demoncyclist 03-09-14 08:01 AM

Definitely missing a spacer behind the cassette. A shop that let that out the door needs a dope slap.

Al1943 03-09-14 08:27 AM

It could be that the lockring was never tightened, or there is a missing spacer or two, or all of the above. The recommended torque is probably shown on the face of the lockring in neuton meters (nm).
If the Hub is a Mavic it's likely to need two spacers, a 2 mm Mavic spacer and a 1 mm Shimano spacer.

hueyhoolihan 03-09-14 09:04 AM

i'm surprised your rear DR even works with the cassette like that. :)


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