Clunking feel between 1:00 and 2:00 under load

[Veloo]

A friend was just inquiring about a clunking feel on the non-drive side crank "area" that suddenly started happening on Wednesday.
He can feel it when under load - up a climb or accelerating but not so much when pedalling lightly.
He said it's more of a feel than a noise thing.
It happens when the drive side is between 1:00 and 2:00 and the feeling is on the non drive side.
It's a Wllier GTR carbon frame with 6800 standard group.

I've never had this myself so I gave him the usual clean out the BB, check for bad bearings, check for cracks anywhere and even check the pedals.

Anyone have similar incidents?

[Tickdoc]

I had this once and it was the chain...I'd measure the chain.

[Peter P.]

Bent chainring tooth? See if it happens on both chainrings.

[echelon_john]

What kind of pedals/shoes?

[FlashUNC]

My initial gut is bearings, but if they shake out, some of the suggestions here too.

[alexstar]

Loose pedal? I had this happen, swore the pedals were tight. Turned out it was juuuust a tiny bit loose.

[rustychisel]

isolate through repetition.

Is it: once per wheel revolution? Check wheels, other fixings to the frame, like seatpost and bolt. And rear cassette wear.

Is it: once per crank revolution? Check BB bearings, pedals, chainring teeth.

Is it: once every 2 1/2 crank revolutions? Chain.

[echelon_john]

My bet is left pedal/shoe/cleat, but my wildcard is compromised/broken nds saddle rail/shell.

[Veloo]

Think he's working away on it tonight so I can get some more info tomorrow.

[bewheels]

To pile on questions... does it happen in all gears? Big ring, little ring? All ring and cog combo, just certain ring and cog combos?
Will it happen if you ride it?

[oldpotatoe]

A friend was just inquiring about a clunking feel on the non-drive side crank "area" that suddenly started happening on Wednesday.
He can feel it when under load - up a climb or accelerating but not so much when pedalling lightly.
He said it's more of a feel than a noise thing.
It happens when the drive side is between 1:00 and 2:00 and the feeling is on the non drive side.
It's a Wllier GTR carbon frame with 6800 standard group.

I've never had this myself so I gave him the usual clean out the BB, check for bad bearings, check for cracks anywhere and even check the pedals.

Anyone have similar incidents?

What rear wheel/hub? If a Mavic wheel..may need a new FH body or at least a clean and lube.

[Veloo]

He cleaned the crank this morning and still clunking.
It's the latest 105 pedals and wheels are Campy Shamal Ultras 2016. Clunk happens across all gears - big and small ring and all cogs.

He's gonna look at the rear end and I may head over tomorrow to have a look if it persists.

[wildboar]

Loose pedal? I had this happen, swore the pedals were tight. Turned out it was juuuust a tiny bit loose.

I just noticed this odd feeling happening to me this week. Looked at the thread here and the above post, and decided to check if a pedal was loose, yup. Just barely loose, tightened it up and all better. New dura ace 9000, too. Though I would add, my pedal that felt like it was clunking at 1-2 o'clock was the loose one. So maybe different than description by original poster.

[CiclistiCliff]

Swap out rear wheels if possible to rule out the hub/freehub.

[David Kirk]

I'd check to be sure that the BB cups are tight.

dave