Snapping or crack sound once per crank evolution
#1
Snapping or crack sound once per crank evolution
As the title says, there is a snapping or cracking sound, kind of like a pop, in the same spot once per revolution of the cranks. I hear it when turning the cranks by either crank arm or by either pedal. It's only heard when rotated forwards not backwards. The faster I spin the cranks, the softer the sound gets. The problem is with a Cannondale road bike with FSA Gossamer cranks and MegaExo BB.
I tightened the chainring bolts and the pedals. I took off the nds crank arm, greased the pinch bolts and reattached it. I would've pulled the drive side and removed the external BB cups and reinstalled them except that I couldn't find my bb wrench (probably is in storage).
I looked all over to see if something was hitting something else but couldn't find any parts making contact that would account for the noise.
Should I remove and reinstall the bb? Any other suggestions?
I tightened the chainring bolts and the pedals. I took off the nds crank arm, greased the pinch bolts and reattached it. I would've pulled the drive side and removed the external BB cups and reinstalled them except that I couldn't find my bb wrench (probably is in storage).
I looked all over to see if something was hitting something else but couldn't find any parts making contact that would account for the noise.
Should I remove and reinstall the bb? Any other suggestions?
#2
Full Member
Joined: Apr 2014
Posts: 457
Likes: 10
From: Central Oregon
Bikes: Redline Conquest Pro, Kona Cinder Cone, Trek Fuel EX8(RIP) Pivot Mach 5 frankenbike
I'd pull the cranks and spin the bearings with my fingertips to check for any crunchiness. This could be debris or damage in one of the bearings. The Gossamer MegaExo bearings aren't very well sealed and tend to get crunchy easily, at least on CX bikes. On the family fleet I use a Raceface bearing press to pop the old ones out of the cups and replace them with Enduro bearings which have held up much better.
#3
Senior Member


Joined: Feb 2004
Posts: 30,225
Likes: 649
From: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Try to relate the position of the crankarms to the sound. I once had a similar noise that was driving me crazy. It turned out to be the front derailleur cable rubbing the right crankarm.
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#5
The bb cups came loose with minimal pressure on the wrench, so I think the sound was from them being loose. The bearings were still very smooth, so I just cleaned and re-greased everything. The drive train sounds silky smooth now!
Thanks all for the help!
Thanks all for the help!
#6
Senior Member
Joined: Dec 2010
Posts: 6,682
Likes: 4
From: Above ground, Walnut Creek, Ca
Bikes: 8 ss bikes, 1 5-speed touring bike
As the title says, there is a snapping or cracking sound, kind of like a pop, in the same spot once per revolution of the cranks. I hear it when turning the cranks by either crank arm or by either pedal. It's only heard when rotated forwards not backwards. The faster I spin the cranks, the softer the sound gets. The problem is with a Cannondale road bike with FSA Gossamer cranks and MegaExo BB.
I tightened the chainring bolts and the pedals. I took off the nds crank arm, greased the pinch bolts and reattached it. I would've pulled the drive side and removed the external BB cups and reinstalled them except that I couldn't find my bb wrench (probably is in storage).
I looked all over to see if something was hitting something else but couldn't find any parts making contact that would account for the noise.
Should I remove and reinstall the bb? Any other suggestions?
I tightened the chainring bolts and the pedals. I took off the nds crank arm, greased the pinch bolts and reattached it. I would've pulled the drive side and removed the external BB cups and reinstalled them except that I couldn't find my bb wrench (probably is in storage).
I looked all over to see if something was hitting something else but couldn't find any parts making contact that would account for the noise.
Should I remove and reinstall the bb? Any other suggestions?
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bryanfellenbaum
Bicycle Mechanics
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07-08-15 04:57 PM





