BB noise: not a click, not a creak, but a CLANK

[scottyjames]

As in a pretty solid metal-on-metal clank. Bike was just built up by a local shop. Older steel frame, italian thread 105-level octalink BB, no apparent damage to either the BB shell or the BB itself. Took it out for the first ride on Sunday and started getting noise 20 mins in. Noise grew in clankiness the longer I rode, and would clank when both pedaling and coasting, especially when I unweighted the bike to absorb a bump. 95% certain it's coming from BB. But there's always that 5%...

What's going on here? Any help welcome.

[nighthawk]

If you are hearing it while coasting, it's not the bottom bracket, because the axle only spins when you pedal.

Any fenders or racks that may be loose? Is it louder when you pedal vs. coasting? Is it louder over bumps, whether you are sitting or not?

[eddief]

i asked the 8 ball and that's what it said.

[maunahaole]

Re-evaluate that 5% estimate. Often times stuff sounds like it is coming from the BB, but it is really something else. It is infuriating to track down, but you need to check lots of stuff out, think...grease the front skewer, et. al.

There is a good chance that switching to Campy be a huge help with this.

[nighthawk]

maybe your mechanic left a cone wrench in your seat tube... :)

[scottyjames]

No fenders, racks, nothin -- straight-up, stripped-down steel road bike configuration. I can't detect any logic to what triggers the sound as far as being seated, standing, coasting, downstroke, etc. All I know is that it seemed to become more pronounced the longer I went.

Interesting idea with the loose cassette -- could that clank with enough force for me to actually feel the vibrations in my feet, which I can?

Maybe a rogue cone wrench floating around somewhere down there isn't such a crazy idea...

[scottyjames]

would it be noticeable if I tried jiggling it on the wheel? if so, is it likely a spacer issue?

[eddief]

they fixed (broke) it, let them fix it.

[Ralph]

If you hadn't said it did it while coasting......I would have suggested you check to see if crank arm is hitting Front derailleur as it comes around.

[rustychisel]

hairline crack of bottom bracket weld? cracked chainstay? Drive side fixed BB cup overlooked and not tightened to spec by preoccupied shop monkey?

New headset? Not correctly seated? Take off wheels, cleans axle stubs and dropouts, lightly grease and reinstall?

And not to overlook the seatpost and saddle rails...

[zetroc]

Loose or cracked pedal spindle? My brother pulled his older LOOK Delta pedal right off the spindle once while riding. Not something I'd want to have happen.

[David Kirk]

If it does it while coasting you can rule out most of the drivetrain.

Any chance the headset crown-race doesn't fit the fork well? Does it clunk when you hit the front brake?

dave

[neiltron]

Wheel bearings?

[victoryfactory]

raise and drop the front wheel from 10"
then pick up back wheel and drop it from 10"

If you hear it from the front, It could be the headset area per Dave
if you hear it from the rear, it could be the cassette (missing spacer) like eddief said (you will be able to feel the movement in the cassette if you
take the wheel off and
rock it back and forth)
And while you have the wheel off,
if you have mavic clinchers, there is a plate in there that sometimes breaks loose
and makes an awful rattle. near the place where it's welded. hit that area with the
heel of your hand and you will hear it (there is a DIY fix for that)

good luck

VF

[oldpotatoe]

As in a pretty solid metal-on-metal clank. Bike was just built up by a local shop. Older steel frame, italian thread 105-level octalink BB, no apparent damage to either the BB shell or the BB itself. Took it out for the first ride on Sunday and started getting noise 20 mins in. Noise grew in clankiness the longer I rode, and would clank when both pedaling and coasting, especially when I unweighted the bike to absorb a bump. 95% certain it's coming from BB. But there's always that 5%...

What's going on here? Any help welcome.

'Local shop' needs to find it and fix it.

[Bob Loblaw]

There are a few kinds of octalink BB.

One is a cartridge type, one is a threaded cup and spindle type. If yours is a threaded cup and and spindle, it MIGHT be the Italian threaded BB is working itself loose. That will happen from time to time.

Also there are two different types of octalink spline and they are incompatible. If your cranks shift fore/aft, it could be a BB/crank compatability issue. To check, set the bike on level ground and pedals at 3 and 9 o'clock, reach down with a hand on each and push down hard and fast. FLip the cranks 180 degrees and repeat. If you feel a shift, there's your issue.

Other than that it sounds like something is loose. I would start grabbing stuff and shaking it looking for rattles. Crank arms (both sides), rims. Grab the front brake, and rock the bike back and forth and see if the headset rattles. Lift the bike by bars and saddle a few inches and drop it and listen for the clank. See if you can isolate where it's coming from.

Good luck.

BL

[FlashUNC]

FWIW, I once has a creak that I was sure was coming from the BB. 100% positive, no doubt.

Turns out it was some of the non-drive side rear spokes were under tension and creaked intermittently.

So I wouldn't rule out anything just because you're sure its the BB, especially, as others have mentioned, with the coasting bit.

[scottyjames]

In case anyone was holding their breath on the solution to this problem, the answer was a combination of loose BB cups and slightly loose crankarms. Shop made the fix yesterday, and I rode 2+ hours today free of clanking. Silence is good. Thanks to everyone for weighing in on this one.

[eddief]

just wondering.

In case anyone was holding their breath on the solution to this problem, the answer was a combination of loose BB cups and slightly loose crankarms. Shop made the fix yesterday, and I rode 2+ hours today free of clanking. Silence is good. Thanks to everyone for weighing in on this one.