Weird noise from down below.

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slowmotion

Quite dreadful
Location
lost somewhere
I wonder if anybody can help. I was out riding my daily lockdown ten miles this evening when a noise developed somewhere near the pedals. It doesn't have anything to do with the front derailleur because it only occurs once per revolution of the cranks and gear shifting doesn't alter it in any way. It sounds like a slight "graunching" noise for about 45 degrees per revolution and it happens at the same position in each revolution. If I unclip my right foot and only pedal with my left, it stays the same, but only pedalling with my right foot makes the noise go away. I would be very grateful for your awesome advice.

Thank you.
 

I like Skol

A Minging Manc...
Try oiling your left knee?
 
OP
OP
slowmotion

slowmotion

Quite dreadful
Location
lost somewhere
On a serious note.....
What pedals and what bottom bracket?
Hollow tech II tends to eat through LH bearings in my experience. Any play detectable if you waggle the cranks sideways?
The bike's a Specialized Secteur Elite (2010) with triple Shimano 105 gearing. It's been pretty lightly used because I've ridden another bike as well since then, and I'm a pretty crap cyclist anyway. The cranks are Shimano. The pedals are Shimano A520s. There's no slack if I put a lateral force on the pedal end of the cranks, and there's no lateral side-to-side movement. It feels pretty good whichever way I tug or push.
Odd business.

BTW, the bottom bracket has BC1.37 x 24 Road written on the housing on left and right sides. It's the non-drive side that seems to make a noise.
514696
 
Last edited:

I like Skol

A Minging Manc...
Yep, Hollowtech.

My guess will be the left cup has got some moisture in and killed the bearing. They are not very waterproof and I think the RH one is more protected because the chainring spider covers it so it outlasts the left. I have a drawer full of good used RH cups, kept just in case a freak reversal of reality occurs and I find a left one out-survives the right!
Distance covered won't be a major factor in the lifespan of these bearings as it is the moisture ingress that kills them prematurely. Washing a bike then putting it away is not good for them either..... I don't wash my bikes for this very reason :whistle:
 
Location
Loch side.
Why take off the cranks? I can take the chain off the drive side, spin the axle and listen without faffing about with the cranks.
Do exactly that. Use a stick as a stethoscope. A good bearing whooshes. A bad bearing rumbles.
 
Location
Loch side.
Yep, Hollowtech.

My guess will be the left cup has got some moisture in and killed the bearing. They are not very waterproof and I think the RH one is more protected because the chainring spider covers it so it outlasts the left. I have a drawer full of good used RH cups, kept just in case a freak reversal of reality occurs and I find a left one out-survives the right!
Distance covered won't be a major factor in the lifespan of these bearings as it is the moisture ingress that kills them prematurely. Washing a bike then putting it away is not good for them either..... I don't wash my bikes for this very reason :whistle:
Drill a hole in your BB at the lowest point, to drain water. It really extends BB life. Further, Shimano does provide individual left or right side cups. Not many shops like to sell only one cup though. In our shop we sold about double left to right.
 
OP
OP
slowmotion

slowmotion

Quite dreadful
Location
lost somewhere
Due to impressive sloth, I didn't quite get round to investigating the problem further. I took the bike out as usual at 7:45pm and the graunching noise had mysteriously gone. Very odd. I'm sure it will return, at which point I'll take your kind advice. Thank you.
 
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