Chain jams
(while
pedaling, the chain stays stuck on chain ring’s underside and either locks up
or jams over top of the chainstay):
Check
chainrings
for wear (should
have perfect semi-circle between symmetrical teeth)
Replace
ring
with widened circle between teeth, low teeth, or “dolphin-fin”
teeth, and
chain
also.
Check
chain
for wear or bent links (12 links = exactly 12 inches).
Remove bad link
.
Is chain rusty or stiff?
Replace
vs. lube-work-and-lube
Is chain cruddy with mud or has dust built up
within excess lube?
If rings and chain seem OK, clean and apply light lube to chain
Sudden
"scrunch" sound and
chain slip
as pedal jerks forward, usually in middle ring while pedaling
hard:
Usually caused by
chain stretch
plus worn
front chainrings
,
even if you think they're not that worn
Check chainrings for wear (widened circle between
teeth, “dolphin-fin” teeth)
Check
chain
for wear or bent links (12 links = exactly 12 inches).
Remove bent link.
Replace
worn chain.
Check cassette (cogs) on rear for wear.
Replace
worn cassette.
If chain/rings/cogs seem fine, remove cassette
and freewheel to check pins, springs, and slots (usually a bike shop job)
Usually means the crank is loose (or worn) where it attaches to bottom bracket – tighten
If cranks tightening fixes things temporarily but problem recurs...
If crank attachment looks worn, replace cranks
Try thread-locker on bolt
Is pedal cage loose or cracked?
Check pedal for stripped threads
Check pedal for worn axle bearings, replace if loose
Skipping around in
gears on rear
(or "clunk" NOT at same spot in pedal stroke):
Quick look for weeds wrapped in cassette, around derailleur, or caught in
cables
Make sure the rear wheel is correctly mounted in the
dropouts! Loosen, re-tighten, and test again!
Check
derailleur hanger
carefully – should be directly vertical
to bike frame, with no twisting
Check cogs of
cassette
for bent teeth (and weeds,
pebbles, or wood chunks between teeth)
Check
chain
for bent links
Check the
derailleur
pulley
wheels. Are they warped? Do they rotate easily?
Check
cable housing
for bends, cracks, or
floppiness where housing joins derailleur, frame ferule, or shifter
Check limit screw settings, then
Tune
rear shifting
carefully.
Replace
rear derailleur if damaged.
If tuning doesn't solve problem,
replace cables
and cable housing.
If supplies not available, try
cleaning.
If it still skips, get help from your local bike
shop
Rear
cassette
won’t go
into biggest cog:
Shift all the way to smallest cog and try
clicking down again. Now, does it shift up 1 cog with one click?
If not, tighten cable until it shifts to 2nd cog with the first click,
then
tune shifting.
Does it shift correctly until you get to the big
cog? Adjust low-gear limit screw until it barely shifts into big cog.
Check derailleur hanger to see if it's bent inward.
Is the cable a little bit loose? Adjust the high-gear limit screw until the pulley falls under the smallest cog.
Is cable quite tight? Loosen the cable and see if will go to smallest cog. After cable loosens, adjust limit screw.
Front won't
shift onto biggest ring:
Does the chain get physically jammed between
derailleur cage and chainring?
The
front derailleur
may have slipped down. Loosen, raise a tad, tighten, and
try again.
Go to tiny ring, click down again to be sure
you're in 1st gear. Does it shift to middle ring with first click?
If not, tighten cable until it shifts to middle ring with the first click,
then
tune the front shifting.
Works correctly in small and middle, won't reach
big ring?
Adjust high-gear limit screw
until big ring takes up chain
while you're turning pedal and pushing on shifter lever.
Brake rub:
Rim brake
Make sure the wheel is correctly mounted in the dropouts! Loosen,
re-tighten, and test again!
Check orientation of
pads.
Adjust pad position
as necessary.
Does the wheel rim wobble side-to-side?
True the rim
Are the pads too close to rim?
Let cable out.
Adjust
lever
to comfort.
Wide
space between rim and opposite pad?
Adjust
brake tension screw (near mount of
one brake arm).
Disc brake
Make sure the wheel is correctly mounted in the dropouts!
Check
position of pads
within disc brake housing
Is
rotor
bent or severely worn? Bent = field-straighten w wrench,
replace ASAP
Cable-activated
brake?
If adjusting knob present on rubbing side, turn to move the pad out.
Center calipers as below
Hydraulic?
Center calipers:
Slightly loosen the 2 upward-facing bolts. Grip brake lever
hard.
Tighten the 2 bolts while holding lever.
Not enough brake:
Lever
hits fingers? Adjust
cable tension
to move pads
inward.
Are the pads worn out?
Replace.
Do
rim-brake pads contact rim correctly?
Adjust.
Oil on pads or rim?
Clean with alcohol.
Cable-pull disc
brake?
Turn barrel
adjuster on lever, or turn adjusting knob to move pad closer to rotor
Cracked cable housing or abnormal motion of housing when lever pulled?
Replace cable and housing
Hydraulic disc?
Clean rotors and sand pads.
May need “bleeding” to remove bubbles from line. Not a field operation!
Rim brake? Clean pads and rim with alcohol, buff with steel wool.
Consider "toe in" of pads.
Are the pads quite old? Replace pads Disc brake? Buff rotor and clean pads. Some brands of replacement pads are less likely to squeal.
Is brake unit HOT? (Hot enough to boil a drop from your water bottle?) Take a break from the downhill.
Before your next trip, consider installing a bigger rotor.
Wheel wobble:
Is the wheel correctly mounted in the
dropouts? Loosen quick-release, re-secure wheel into dropout, test again
Is the
tire correctly seated
within the bead of the rim all the way around?
Look for a broken spoke.
Replace
bent or broken spokes.
Is there a
bulge
or obvious tire
damage? Let air out, see if rim still wobbles.
True rim;
if rim won't stay in true,
replace wheel.
Creaking:
Creaks when pedaling "hands-free"?
Check
crank
attachment and pedals.
Still creaks? Consider teflon tape to
bottom bracket
threads.
With pressure on handlebar? Check
attachment of
steerer
to stem, and
stem
to handlebar.
When "bouncing"
full-suspension bike?
Lube shock
and
shock
attachments to frame.
Plus rumbling when handlebars are
turned?
Service and lube headset,
replace
any headset
with worn bearings!