I’m reaching out because I’m slowly losing my sanity. For the past few months, my bike has developed a persistent rhythmic scraping sound, and it’s completely ruining the joy of riding.
Since I know this community is full of cyclists with a “good ear” for mechanical oddities, I thought I’d drop a video for your expert opinions. Any idea where this delightful cacophony of scraping and grinding is coming from? Is my bike just trying to start a garage band without me?
Here is the breakdown of what’s happening:
The sound: It’s a rhythmic scraping noise.
The pattern: It usually doesn't start immediately. It kicks in after about a few minutes of warm-up/pedaling and consistently gets louder as the ride progresses.
It seems to be linked to my pedaling cadence, but I can’t pin it down.
I’ve been quite thorough, but nothing has worked so far:
-Crankset & Bottom Bracket: Completely disassembled, cleaned, and regreased everything.
-Bearings: Replaced the press-fit bearings in the front axle/bottom bracket area.
-Pedals: Swapped them out for a different set to rule them out.
-Seatpost: Pulled it out, cleaned it, and reinstalled it (just in case it was a creak echoing through the frame).
Despite all this, the noise is still there and getting worse. So, my question for you guys:
Since I’ve basically rebuilt the front half of the drivetrain, could this be coming from the rear axle? Maybe something related to the shifting? Has anyone experienced a scraping sound from the rear hub or cassette that only starts after the bike "warms up" for a few minutes?
Any advice or suggestions on what to check next would be greatly appreciated!
Losing my mind over a rhythmic scraping sound
byu/Ontframed inbikewrench
by Ontframed
9 Comments
Did you check your rear derailleur alignment? In every gear? Because it sounds a lot like a chain trying to climb to a higher gear
Not an expert, but could the chain be stretched and jumping links, or could the bottom bracket be creaking, or could the chain have a stiff link?
Does the sound change/stop when you stop pedaling, or select a different gear/cadence while maintaining the same speed?
Try with another rear wheel.
How’s the front derailleur alignment? Your chainrings could be out of true and touching the cage from time to time.
Brakes?
Sounds like the disc is hitting the brake caliper. The sound has something metallic in it. Like the disc is rubbing on the caliper due to a warped disc.
If it takes a little riding before it starts, it is likely your brakes (heat from braking causes expansion) or your freehub (prolonged sheering forces are putting a bearing out of whack and causing interference). Check your rotors are true and aren’t scraping on a pad when the frame flexes under load. Check for play in the freehub by wiggling your cassette, if it moves, replace your feehub.
It doesn’t sound like either of those things to me though. From the video it looks like the plastic spoke protector (dork disc) behind the cassette has been removed, though the sound is very similar to a broken one flopping around the rear hub/coming I to contact with the cassette – if the dork disc is still on, try removing it. Otherwise I’d check for a broken spoke on the drive side of your rear hub; a bent/warped chainring; or your front derailleur rubbing against your chainring/crank arm. Also sounds like a cable end might be catching on something.
Could be spoke tension. Adding torque by pedaling could change tension in the rear wheel and cause that sound. Grab a handful of spokes two at a time and see if any are loose. I bought a used bike and had to retension the wheel after hearing sounds like this.