Intermittent noise from bottom bracket area

[flat-pack]

Started a while back sounded just like a crank hitting a cable end, then got louder and louder, can't feel much through the pedals but it clanks on every revolution.

Does not happen under load or when no pressure on pedals only on moderate 'keeping speed' peddling.

Can suddenly just go away for days, thought it was the moody DX pedals I bought so changed them and it went for about a week, but now it is back.

No wear evident in bracket by wriggling cranks.

Anyone know what it might be ?

TIA

 

[Canrider]

Need to know more about the bike, eg is it a sealed-unit BB or loose balls? I once cleaned and repacked a loose-ball BB to find it had about 3 small pebbles inside it!
Intermittent pedaling noise can be tricky to diagnose as there's so many bits involved in a small area: pedals, cranks, shoe cleats, loose change tucked inside your socks...

 

[flat-pack]

It is a sealed BB unit now, was a loose one before

Bike is a Giant Sedona about 4 years old, had new BB and cranks about 18 months ago

Don't use cleats, changed pedals and I only carry paper money

 

[Canrider]

Check everything in and around the BB for cracks?

Since it's sealed, swap in a new BB and see if it stops? Not the cheapest option but...

 

[flat-pack]

Cracks ? Yee gads, that means cleaning the mud off

Will have a look see, it was just the coming and going of the noise that had me stumped

 

[Canrider]

At what particular point in the rotation does it clank?

ISTR someone trying to figure out a similar problem, and it transpired their downtube had separated from the BB shell. Not that I'm claiming that's what's happening here!

 

[flat-pack]

Towards bottom of stroke left hand side, will have alook now we have a hose at work I can use and the sun is shining for a change

 

[flat-pack]

No cracks that I can see, will take to LBS see what they say

 

[compo]

I wish I had a pound for every case I have read of noises from the bottom bracket that have turned out to be the seat post creaking in the seat tube or the saddle bracket. Also worth checking the headset and handlebar fixings. Alternatively your's may be the odd one with a creaky BB!

 

[flat-pack]

LBS took it for a short spin, diagnosed pedal click, used their special pedal spanner to tighten up more than I had, then tightened the part that secures crank to BB and voila