Symptoms
- Chain rises and falls slightly once per pedal rotation
- Visible wobble when watching the chainring spin
- Chain occasionally skips or drops near the bent section
- Happened after the bike fell over or hit something
Likely causes
- CommonImpact from a fall or the bike tipping overChainrings are relatively thin and can bend if the bike lands on that side.
- PossibleImpact from a rock or curb while ridingHitting an object with the pedal or chainring area can bend the ring.
- Less commonLoose chainring bolts allowing the ring to shiftVery loose mounting can let the ring sit unevenly, mimicking a bend.
What to do
- Shift to the affected chainring and slowly turn the pedals while watching for the point where the chain visibly rises or the ring wobbles.
- Check chainring bolts are tight, since a loose ring can look bent even if it isn't.
- For a minor bend, an adjustable wrench can sometimes carefully bend the ring back at the affected tooth or section, working slowly and rechecking often.
- Avoid over-correcting, which can create a bend in the opposite direction or crack the ring.
- Test by spinning the pedals again after each small correction.
- If the bend is significant or the ring cracks during attempted correction, it needs full replacement rather than continued bending.
- A bike shop can straighten minor bends with proper tools or replace the chainring if needed.
Tools and parts
- Adjustable wrench
- Allen key set for chainring bolts
Bike chainringSearch: “bicycle chainring replacement correct size”
When to call a pro
A bike shop can straighten a bent chainring with the proper tools or replace it if the damage is too severe to correct.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.