sethbob

I don't have any experience repairing bikes, so I thought I'd look for some help online. Here's the problem I'm having.

When I'm riding, I hear a crunch or click. It happens with every revolution of the pedals and in the same spot every time. If it matters, it's when the left pedal is at the bottom of its rotation.

I have also noticed, while looking for a possible source of the the noise, that the action of the crank isn't smooth at all.

Al1943

Have the pedal bearings been greased?
Do you have a cone-and-cup bottom bracket or a sealed bottom bracket?
Has the bottom bracket been torqued to specs?

sethbob

They haven't been greased.
I'm afraid I don't know the answer to your second question. How do I tell the difference?
I haven't put any work into the bike, and it's a few years old. I'm sure everything was fine when it was new, but I haven't done anything to it since.

Thanks the reply.

Mondo734

I am also pretty new to the bike repair scene but here is what I think.
1. You should probably add whatever info you can about your bike in the post make model and the same for your crank since it sounds like that is the problem.
2. This may not be accurate but I would think that if your crank isnt smooth and the noise your hearing is in fact coming from the crank you can find out mechanical info about fixing it here https://www.parktool.com/blog/repair-help just click on the part of the bike(crank) that you think is the problem.

sametheman576

Its probably a loose bottom bracket. That noise is common when that happens. You can determine if its loose by grabbing the cranks and moving them sideways, if there is play, then its a loose bottom bracket. Another problem that I have encountered with this type of noise is a loose pedal. Grab a 15mm wrench and check it out. (The left side is left hand thread.)

BHOFM

Dry pedal bearings,, loose crank arm?

FBinNY 

First check for a loose bottom bracket as follows.

Set the cranks horizontal, and hold one arm and the chainstay by pinching both between the thumb and forefinger. Then tap or push the opposite arm sideways. The pinch hold is very sensitive, so if there's any play in the BB, you'll feel the reaction come through the BB to the arm you're holding.

Also switch the pedals for another set, if that solves the problem it's in the pedals.

The other possibility for toughness felt in only one part of the crank rotation is the chain not winding smoothly onto the chainring. Check the section of the ring engaging the chain just when the vibration occurs. Look for damaged or teeth or teeth showing a different wear pattern. If in doubt, oil the chain and see if things change.

So far you haven't taken anything apart, but hopefully got a clue to where the problem might be. If you haven't found the issue yet, it's time to play a hunch and start taking things apart. Start with the BB, since that's now most likely.

mechBgon

Also check to make sure your crank isn't colliding with your front derailleur as it goes by. If it is, you might have a FD adjustment problem or (rarely) a crankarm that's been bent inwards, usually caused by the bike being pinned against a garage wall by a car bumper.

pdlamb

If you don't have any experience fixing bikes, you'd be well advised to take your bike to the shop. Something is going wrong with the bottom bracket; it could be dry bearings, rusting bearings, or something's broke like a bearing or race.

Bottom brackets can be had cheaply, and it's probably easiest and cheapest just to replace what's in there. The alternative would be for you to buy a crank remover, the correct bottom bracket tool, and probably a torque wrench. The cost of the tools will be less than or similar to what the bike shop will charge to replace it for you, and you'll have the benefit of some certainty it'll be done right.