Cranky Crank

Another fantastic day here in Florida with just a touch of morning fog, so I started my ride a bit later than normal to let it all burn off. During the ride I noticed that my crank was making a creaking type noise. Not only could I hear it, especially when on power, but I could actually feel it a bit through the pedals. Mind you it wasn’t something drastic, but it was something that should not be there. I continued my ride to Lakes Regional Park via the Linear Park (a nice change of pace), and gave the bike a good look over while refueling with some granola.

A quick inspection proved noting drastically wrong, and everything was mechanically sound, so I broke out my trusty iPhone, jumped on the net and did a few searches on creaky cranks. In short, a crank is not supposed to creak. In fact the only sound you should really hear on a road bike is the tires on the pavement (they are very stealthy as I am always having to shout out “on your left” to pedestrians at the park). So if a click, creak or clunk occurs once or twice per pedal revolution you need to check the following:

Loose Pedals
Check this first, the pedals should be snuggly screwed into the cranks. The left pedal has a left (“reverse”) thread. The threads of the pedals should be lubricated with grease.

Loose Crank Fixing Bolts
For typical cotterless 3-piece cranks, it is very important that the fixing bolts (hold the crank to the bottom bracket spindle) be properly tightened. The hole where the crank attaches to the axle will quickly become misshapen if not addressed. A slightly-loose crank will creak loudly. By the time it moves noticeably, it will probalby require replacement. The threads of the bolt (or nut), and the underside of the bolt (or nut) head (where it presses against the crank) should be lubricated with grease.

Loose Stack Bolts
The stack bolts are the 4 or 5 bolts that hold the chainrings to the crank spider. They should be good and tight. The threads and the Allen bolt head should be lubricated with grease or oil, but try to avoid getting lubricant on the outside of the nuts. The nuts for typical stack bolts have only two small notches to permit a tool to keep them from turning as the bolt is tightened, but if you leave the outsides of the nuts dry, there is usually enough friction between the nut and the inner/middle chainring to keep it from rotating.

Loose Bottom Bracket Cups/Retaining Rings
Because of the threading of normal bottom brackets, the cups are self-tightening to a point. This sometimes leads to careless installation, particularly on the right (fixed cup) side. If the right cup is slightly loose, it won’t necessarily unscrew itself, but it won’t really tighten itself up fully either. The symptom of this is an occasional creak or clunk usually as the left crank goes “over the top” when pedaling hard (this was my main symptom). This is a surprisingly common, and frequently missed, casue of unwanted noises. Generally you should check the items above first, because they’re easier to deal with. You can’t reliably check the tightness of the bottom bracket mounting without removing the cranks, but sometimes you can diagnose it by turning the crank so that the left crank is alongside the seat tube, wrap both hands around the crank and seat tube and squeeze the crank hard toward the seat tube. Then turn the cranks so that the right crank is alongside the seat tube and repeat this. Listen for a creak/click.

Just to be on the safe side, upon returning home, I packed up my bike and headed off to my local trek store. They immediately got it up on the stand and in less than 30 seconds had the entire bottom bracket disassembled. They immediately found the issues, corrected them and gave the bike a full adjustment. Did I mention they did this gratis! The staff at my local Trek shop continue to go far and beyond the normal call of duty. I really run out of accolades when talking about them.

This is the perfect example of why bikes should always be purchased from your local bike store and not online or a big box store!

So to the creaky cranky ride… A delightful ride via the Linear Park to Lakes Regional Park and back.

Route: Lakes Regional Park
Activity: Cycle
Started: Feb 23, 2011 9:31:51 AM
Ride Time: 1:44:50
Stopped Time: 1:12:18
Distance: 25.62 miles
Average: 14.66 miles/h
Fastest Speed: 22.30 miles/h
Ascent: 111 feet
Descent: 157 feet
Calories: 1614
Official: No

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