Troubleshooting a Noisy Drivetrain
This article will discuss troubleshooting creaky or noisy drivetrains.
Creaking and squeaking noises are annoying, and can be a sign of more serious problems. Damage to component parts may result if they are left unattended. Creaking is usually caused by two things rubbing together, such as a crankarm rubbing on a spindle. Many of the solutions below rely on adequate torque on the parts. See also an article on Bicycle Torque Specifications. Thread preparation is also critical, see also Basic Fastener Concepts.
Correctly diagnosing the source of the noise can be difficult. It may help to have a friend assist you. Have them flex the parts while you listen and feel for noise. Creaking will often resonate enough to be felt as well as heard.
If during a ride you hear a creak or squeak once per revolution, it is probably located in the crankset and pedal area. If the noise is once every 2 - 3 revolutions, it may be in the chain. There can be several causes of creaking. You may need to proceed through the drive train step by step, part by part to eliminate potential problems. Here are some of the possible sources and remedies for drive train creaking.
The most common cause of creaking is the crank being loose on the spindle. Remove the crank bolts, lubricate the threads and under the bolt head, and reinstall. Tighten the bolts to the manufacturer recommended torque. Use a torque wrench if possible. Typically, 300 inch-pound is considered a minimum torque, which is 50 pounds of effort holding a wrench six inches from the bolt.
For more on crank installation, see How to Remove and Install a Crank.
The chainrings are held to the cranks by chainring bolts. Use a hex key wrench and check each bolt. Hold the back chainring nut from spinning with a chainring nut wrench, such as the Park Tool CNW-2. Again a mild thread locker or grease on the threads is a good idea. Secure steel chainring bolts to about 60 inch-pounds, which is about fifteen pounds of effort holding a wrench four inches from the bolt.
Some cranksets use a chainring mounting arms (spider) that are removable from the crank arm. There is a lockring on the backside of the arm that may need tightening. Remove the crankarm and then remove the snap ring with a screwdriver. Install the BBT-18 lockring tool on the ring, and loosen counter-clockwise. Drip some mild thread locker onto the threads, then tighten the ring to 400 inch-pounds.
If you have riding shoes, the cleats under the shoe can loosen and also cause noise. Use a mild grade of thread locking compound or grease on the bolts, and tighten them fully. Even regular “street shoes” on a platform pedal can cause noise. A shoe lace can tap against a crank arm, and the rubber can move and squeak under the sole.
Tighten pedals into crankarms. The torque typically recommended is 300 inch-pounds, which is about 50 pounds of effort hold a wrench six inches from the pedal. Pedal bearings can also creak. Spin the pedal and listen for noise. Different makes of pedals have different bearing service options. For more detail see Pedal Installation.
The bottom bracket may not be properly secured into the frame. Most bike frames use a threaded bottom bracket shell. If the bearing cups or retaining lockring are not tight, there may be movement between the internal and external threads.
Listen for dry links by spinning the chain in a repair stand. Lubricate as necessary, with a drop of lubricant on each roller and rivet. Look at each and every rivet to check misalignmet in the chain plates. Inspect for twists in side plate, or burrs, cuts or other damage to the side plates. Place chain in a gear combination that relaxes the rear cage, and spin chain backwards. If the chain hops as it passes of the pulley wheels, it may have a tight link.
Derailleur Pulley Wheels
The two pulley wheels of the rear derailleur spin as the chain turns. Use a light lubricant to quiet them.
Wheel and Spokes
Creaking can be the result of loose spokes in the rim. Spoke may be moving in the rim or spokes may rub one another at the spoke interlace. In either case, increase spoke tension, using a spoke tension meter if possible. For more detail see Wheel Truing. Some rims are made with a hollow section, and junk can collect in this hollow area causing a rattling.
Housing End Caps
If there seems to be a creaking when the handlebars are turned, inspect the housing end caps where they enter the frame. These end caps are often metal, and may creak inside the frame fitting as the housing is moved side to side. Lubing is a temporary fix. It is sometimes possible to shim the cap for a tighter fit.
It is possible non-drive train creaks will masquerade as coming from the drive train. After checking other possibilities, check the frame itself for problems. A crack in a weld or a glued joint that is separating can also cause a creaking sound. If you suspect a crack, stop riding the bike and take it to a professional for further evaluation. The images below show a crack above the derailleur mount, a bonded bottom bracket shell separating, and a fork crown cracked. None of these bikes were crashed or wrecked. Once a crack has developed, repair is difficult and is often practically impossible.
The saddle may also be loose on the seat post, causing a creak as the saddle rails move and rock. Check security of the saddle rail binder bolts. The seat post can move slightly in the frame seat tube, especially in the fit inside the frame is marginal. Knurling the post, or even cutting off excess post may help.
The headset connects the main frame to the fork and front wheel. Some headsets rely on a tight pressed fit on parts into the frame or fork. If the fit is not properly tight the parts may move and creak when stressed. In some cases the fit can be improved using a “retaining compound”. It may be best to consult a professional for this repair. For more on headsets see Threadless Headsets or Threaded Headsets
The rear cogs are not a likely source of a creak, but they should be checked in the interest of thoroughness. For cassette cogs, check security of lockring. For more detail see Cog Removal and Installation. Inspect teeth for burrs and wear, which may cause a pop noise rather than a creak.
Stem and Handlebars
A loose stem or bar bolt may also cause a creaking sound. If the bolts threads are dry and without lubrication, they may not secure properly. Remove bolt, grease the threads and under the bolt head, and re-secure. Some handlebars use a center section that is press on, called a sleeve. This sleeve may become loose with use, and may begin to creak. Replacement is the best repair in this case. You may try a penetrating thread locking compounds if you have one, but it is likely to keep creaking. A center sleeve is seen in the left image below. In the right image below, the bar had no center sleeve. However, the bar developed a crack where it was held by the stem. A catastrophic failure was imminent.