Hi,
Got a slight problem with my 6870 gears clicking. It comes from under load eg accelerating or when going up a hill. It’s definitely coming from the rear mech/cassette area. The mech’s adjustment is dead central to the cassette and the noise has got me stumped on what it could be. Cassette is ultegra along with the chain.

Indexed gears by 5th adjusting until rubs 4th then down shifting 4 presses, and adjusting on the fly so see if noise goes away
Nipped up chainring bolts
Greased pedal threads
Greased bb axle
Swapped qr axle
Replaced mech hanger

Any suggestions?

Chain wear?
Bent tooth on cassette?

It’s only done 600 miles the groupset, so wouldn’t have thought chain would be worn. It does it in a few gears so don’t think it would be a bent tooth.

Stiff link in the chain? Makes a click going through the jockey wheels.

If it’s in more than one gear I’m suspecting a stiff or twisted link in the chain

It does it no matter what position the chain is. It’s less of clicking noise, more like the chain rubs and grinds and clicks on something.

In that case examine the rear mech to see if the side plates have got squashed together or bent at all. Make sure the jockey wheels are running smoothly too – if one is getting stuck and then freeing itself suddenly, that would account for an irregular clicking.

Is you hanger straight?

It only comes from under load. Jockey wheels look free, hanger has been changed so that’s ruled that out.

Only under load?

Cassette locking tight? Not too tight and crushing the spider though?
Freehub problem?
Wheel bearings?
Quick release?

It’s really impossible to diagnose at distance though…. If I had it up on the stand in front of me I’d be in with a chance! 🙂

Is you hanger straight?

🙂

There’s a pun involving Ali G and a stretch of a racing circuit in there somewhere…

🙂

I wouldn’t rule out a new one being bent either! 1st thing I do on every build is check the alignment of the hanger, even new ones.

Me too, about 9 out of 10 new bikes I build have bent hangers to some degree, often quite a lot.

How can I check if the hanger is straight? Compared the new one with original and it looked the same. Wheel are dura ace c24’s, there’s no play in the wheel or if you try and wiggle the cassette it’s rock solid.

Might have to give the bike to a bike shop to have a look at.

too tight and crushing the spider

😯 who makes crushable spiders ?

Mine does/did the same, I put it down to chain alignment on 3rd gear. After adjusting on the move it seemed to go away bike had only done 100 miles so could be a bedding in issue?

Is the chain routed through the rear mech correctly?

Pretty basic question but you wouldn’t be the first.

Dirty dog bet me to it!

To check alignment kinda, eye the mech with the cassette, does both jockey wheels hang plumb or do they sit skew. this checks vertical alignment. Twist is more difficult to spot by eye. I use a Park DAG-1.

Chain is routed correctly. Done that mistake myself, as I was wondering why is was so noisy!

Looks straight to my eye.

I’ve even swapped for a different wheel and a different cassette and it still does it.

It’s definitely coming from the rear mech/cassette area

I know it’s a road bike, but how often have we had this discussion for mtbs and it turns out to be a pedal/bb/chainring bolt/demonic possession/… ?

(not missing a spacer on the freehub or something ? – unlikely if there are 2 wheels involved)

Hard to explain but the noise definitely sounds like chain/cassette.

No spacer needed, 11spd cassette on 11 spd wheel.