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Discussion Starter · #1 ·
I feel and hear a clicking/thumping sound coming through my cranks as I pedal. The sound comes when the left crank is at 9 o'clock and the right is at 3 o'clock. It only happens while pedaling and intensifies with more pressure on the cranks. It cannot be replicated while the bike in the bike stand I think because there's not enough resistance in the drivetrain.

It is a threaded bottom bracket.

It sounds like a bottom bracket problem, but I am having trouble wrapping my mind around that diagnosis because the bike is new and doesn't have enough miles for the bottom bracket to have gone bad.

Does anyone have any theories or ideas for isolating the sound?
 

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If it’s an entry level BB it very well could be. One of my bikes came with one and it was complete garbage. Couldn’t get it off the bike fast enough. Easy/fix conversion (at home) to my goto BB the Shimano MT 800. I’m pretty sure the project was delayed until Amazon delivered something dub specific like an extractor or cap removal tool etc.
 

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So many things could cause a noise like that and it's impossible to say what based on the provided info. I would say that it's extremely unlikely that you have a bad bb, more likely something which may or not be bb related isn't torqued to spec.
 

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So many things could be at fault here. I would not think it was a bottom bracket issue unless you tend to submerge it at creek or river crossings. But anyhow, it is easy enough to pull the crank and check the bearings by hand, making sure they don't have play and roll smoothly. Then, double check the BB torque and the crank bolt torque. As another thing to check, many people get a new bike and bring over a used set of pedals. I chased a noise similar to yours and found it was the pedals in need of a service. Though, it could be pivots if this is a full suspension bike. It could be the seat post or saddle rails. Good luck.
 

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So many things could cause a noise like that and it's impossible to say what based on the provided info. I would say that it's extremely unlikely that you have a bad bb, more likely something which may or not be bb related isn't torqued to spec.
I agree.
There are many possibilities. Chainring, rear hub, the axle, loose cassette, if it's full suspension bike than wrong torqued pivots can couse noises under pedal load, or at worst a crack somewhere in the frame.

My friend and a riding buddy both had terrible noises coming from the bb, only to find out later that the real cause was a crack in the seat stay on the left side. Both frames broke, noise was gone but both frames were toast.
 

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I've experienced this with a few bikes. I never figured it out. To me it always felt like it was my non drive pedal because that's where I would actually feel the click. It's actually an on and off issue for me right now. Last time I felt this issue was around 6 years ago. I've had all sorts of noise issues with race face cinch rings, but the first time I felt this issue I was running 104bcd. I never had a BB crap out or even feel rough when I've experienced this. Fist time I felt the click was with threaded 24mm bb. Currently experience it with 30mm PF. In my case I think I can safely rule out the BB.

I'll add that I've felt this with three different pedals too. One with all bearings, the other two with inboard bushings. Wish I knew the culprit.
 

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Make sure both crank arms are tight on the spindle. I tore apart my crankset and bottom bracket multiple times before I realized the NDS crank arm wasn't properly torqued to the spindle from the factory.
 

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Discussion Starter · #14 ·
In the interest of eliminating the rear wheel, I changed that out. Same noise. I’m gonna try pedals next.

I did remove the cranks and the left side bottom bracket bearing did have some gnarliness to it. But I want to try to eliminate as much as possible before dropping coin on a new bb.
 

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I had pretty much the exact same issue on an Eagle GX with PF92 BB. Annoying as hell riding on the road up to the local trail but I couldn't hear it above the crunch of the rocks when I got to the trail so didn't pursue fixing it right away. Ended up selling that bike after a couple of months so never did figure out what it was. At least BB are pretty cheap so not much risk in swapping it out.
 

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Having an extra BB around will not be a waste of money, as you will need to replace it eventually. I just replaced my DUB BB last week after I heard a some loud crunching going on when applying torque. I had serviced it multiple times to stretch service out of it, but it finally gave up the ghost and now all is quiet. I knew it was going bad because I could feel play in it when I grabbed the crank arms and could feel the play in it some time ago. I always keep a spare on hand due to the conditions I ride in can be quite hard on components.
 

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Are DUB BB's servicable? as in can you drop the BB seal and clean and grease?
Yes they are. You have to gently pry the plastic sleeve out. I use a flat head screwdriver and pry it out. You can feel inside the sleeve or look for the end of the sleeve that goes into the shell. Then use a pick to take off the outside seal and you have access to the bearings. The sleeve can be a bit of a pain to get back in, just be patient, but yes I have serviced mine many times. You do not have to remove the bottom bracket from the bike, just take out the cranks.
 

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Why buy an entirely new BB, why not just buy the bearings?
 
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