If you are a cycling hypochondriac then every strange noise signals a potentially fatal crack in the frame or in your most expensive components. Of course, if you’re a cycling hypochondriac you probably shouldn’t be on this site. Some real causes of noises are listed below. It’s still worth checking for frame cracks though!
For each nasty noise you hear, listen to the frequency – is it every pedal revolution, every chain revolution, every wheel revolution? Does it stop or get worse when you stand on the pedals? Does it only happen on rough terrain, or all the time? Only when the drive train is in motion, or only when it isn’t?
Pedals, cranks, pulley wheels and wheels all turn at different rates. Matching the frequency of the noise to the speed of rotation helps you narrow down the likely place on the bike.
Clicks and clunks which occur with every pedal revolution normally come from the pedal, bottom bracket, or something rubbing against the cranks.
Start by oiling/regreasing your pedals, and then spin the cranks backwards to see if they hit on anything like the front derailleur or your cadence sensor magnet. Check that the front derailleur cable end isn’t loose and touching the cranks each revolution.
Clicks that occur once per wheel revolution are normally in the axle bearings, a loose piece of grit in the brake pad, or something as simple as your speed sensor and magnet being too close to each other.
If the click isn’t rhythmical, check your stem and bar bolts are greased, and that the stem/bar interface is clean. Clicks that happen over rough ground may well be suspension pivot points. Don’t lubricate these unless your bike manual tells you to.
If the noise only happens under pressure, it could be the bottom bracket or cranks flexing enough that the chain rubs briefly against the front derailleur cage.
It could also be a loose headset, which can be diagnosed by turning the front wheel to point left or right, holding the front brake on, and then rocking the bike backwards and forwards. Hold your fingers between the steerer tube/stem and the frame. Any movement indicates that you need to tighten the headset.
If the click stops when you stand up, check the seat post binder bolt is greased, and that metal seat posts are greased in the seat tube (carbon ones should not be greased, and tend to click or creak when they are). If that doesn’t cure it, try a very fine coat of grease on the saddle rails.
Creaks tend to happen where two parts that are supposed to be clamped together rub against one another. These areas are the saddle against its rails (spray lube where the rails join the plastic part of the seat), the bottom bracket cups (should you have greased them before insertion, or used PTFE tape?), clipless pedals against the cleats, or even the straps on your shoes.
Spokes can sometimes also creak – either if they are working loose, or where they rub against each other. Check that the wheel is true, and if necessary put a tiny drop of lube at each spoke cross.
Rattles tend to mean that something isn’t tightened down well enough.
Cassette cogs can rattle on the freehub when the lock ring isn’t tightened down sufficiently. Water bottle cages rattle if the bolts are loose. Disk brake pads can rattle in the caliper if the retaining spring breaks, and the whole caliper will rattle if it isn’t tightened down properly. Cable housing or runs of bare cable can rattle against the frame. Accessories such as lights can rattle against their mountings, and the batteries inside them can rattle too.
My most annoying rattle ever turned out to be a loose Presta valve nut which allowed the valve to knock against the rim. A touch of PTFE tape on the threads stopped that. We once found a rogue headset bearing rolling loose inside the top tube of a friend’s bike – it was driving him mad at the start of every climb and descent.
Grinding noises are especially bad, because it means that one component is rubbing against another in a way that is likely to cause damage.
Typically, grinds come from the chain rubbing against the front derailleur or the chain rings –adjust the derailleur and don’t ride cross-chained (big to big, small to small gears). Derailleur pulley wheels can grind if they are being pulled too far to one side by a badly adjusted rear derailleur or if the top pulley is too close to the cassette.
Check also the end of the front derailleur cable against your rear wheel, your tire against a fender or the frame, your front wheel against the front disk brake cable housing/hose or against front rim brake pads, arms or straddle wire.
Squeaks emanating from disk or rim brakes are easy to diagnose, and to fix.
Any part which should be oiled or greased but hasn’t been will squeak – the chain, derailleur pulley wheels (modern pulley wheels typically don’t need lube), or any other really dry bearing – did you wash your bike with a hose, or ride it through deep water recently?
Tip: Check any parts before you just clamp them tighter to get rid of a noise. The noise may be the beginnings of a stress crack caused by over enthusiastic tightening. My handlebars once sheared off at the stem for this reason.