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I have a mountain bike and when I am pedaling, it produces an annoying popping(creak) sound.

Any ideas for the source? The sound comes from the area shown in the picture.

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Here is a sound file with the noise.

https://drive.google.com/file/d/1JXKBS3BLEg1NjqCixCLnCtijGfYJ3Bz4/view?usp=sharing

After disassembly. Should the crankshaft just slide out the other end?

I can not get it out.

enter image description here

enter image description here

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  • I got one nut off. How do I get it off the crankshaft? A crowbar did not help. It looks like I need a crank puller or a 3 hook puller. @Warren Burton
    – fixit7
    Commented Sep 25, 2022 at 17:21
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    To go any further without a crankpuller is not possible. The non drive side arm should have needed one. However you can see your bearings are rough and corroded and the cones are too. That’s the source of your noise. Please don’t use a crow bar as a bike tool, you will damage parts irreparably.
    – Warren Burton
    Commented Sep 25, 2022 at 18:26
  • I will take it to a shop. I used a ball joint separator. @ Warren Burton
    – fixit7
    Commented Sep 25, 2022 at 18:34
  • I have been told it will cost around $150 to repair. I do my best. I am no bike mechanic. If it is going to cost $150, I will get another bike. I got 5-6K miles from a $120 Huffy bike. I feel I got my moneys worth. :-) I can salvage the seat, indexed shifters, brake pads, and rims.
    – fixit7
    Commented Sep 25, 2022 at 19:07
  • @ifxit7 That is an extremely expensive quote for that one job, they must be quoting for some other items as well. The bottom bracket job including parts, I would expect $50 or under. You have already done half the disassembly too!
    – Noise
    Commented Sep 28, 2022 at 7:53

2 Answers 2

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As noted by Warren, the source of the noise is likely to be the pedals or the bottom bracket. Given the picture you've added to your question, I would hazard the BB needs replacement, as it looks to be in a bad shape.

It is a cup-and-cone model. The ball bearing cage has fallen apart, and the balls themselves seem rough. Finding replacement ball bearings is easy, but check the surfaces on which the balls roll: the cup (screwed into the frame) and the cone (part of the axle) should be smooth, without pitting.

If no other bike shop is available, my advice would be to find the parts yourself. If I were you, I would also try and fit a cartridge BB. To find out what parts you're looking for, you will need to know which BB shell standard your frame is made to. Measure the width of the shell, and the diameter of the hole. It is likely to be a BSA shell (68-70 mm across, with a 1.37" hole), where one side cup is left-hand threaded, and the other side has a right-hand thread. Also measure the length of the axle, should be around 120 mm.

Replacements are cheap and readily available -- A bike shop asking $150 for a BB replacement is not a bike shop I would ever visit again. A high quality cartridge bottom bracket would cost maybe $20. The fix is an hour's worth of labor if you're a complete beginner, with not many tools involved (wrenches, grease, crank puller, and cassette BB installation tool).

Sheldon Brown has some information on cup-and-cone BBs with regards to dimensions: https://www.sheldonbrown.com/bbsize.html

The ParkTool service tutorial for cup-and-cone BBs is also a great reference: https://www.parktool.com/en-int/blog/repair-help/bottom-bracket-service-adjustable-cup-and-cone

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  • Thanks for the detailed info. I paid 2 cents per mile. Since the bike is 5 yrs + old, I decided to get a better quality bike. The new one will have dual disc brakes etc. I will make a reminder to lube the bearings at least twice a year. :-)
    – fixit7
    Commented Sep 25, 2022 at 23:36
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    My bicycles are 18, 38, and 10 years old, in order of how well I think they ride. You will find that unless your needs differ wildly from when you first acquired the bicycle (e.g. the need for disc brakes, different wheels or tires, or even switching from MTB to road etc.), it is cheaper to replace such cheap worn parts. If nothing else it is easier to sell. A BB is a consumable in the same sense the brake pads are, they are designed to wear out and be replaced. It is likely that your newer bike does not come with a cup and cone BB, so there will be nothing to grease in that area.
    – jayded-bee
    Commented Sep 25, 2022 at 23:48
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Likely culprit is dead or nearly dead ball bearings in the bottom bracket or dead bearings in the pedals.

If you have the correct bicycle tools remove the cranks and open up the bottom bracket. You’ll need a crank extractor to do this job.

  • Check the ball bearings. They should be shiny and perfect.
  • Check the cones on the spindle. They should be perfect and not have funky holes or rough patches.
  • There should be a moderate amount of grease on the cones and bearings.

Ball bearings can be replaced but if the cones are dusted then the best plan is to buy a new bottom bracket. Usually fairly cheap online or at your LBS. You need to match the width of your current bottom bracket and current spindle.

Pedals are easier to inspect and dismantle. There should be a cap with a nut underneath it on the outboard side of the pedal. Make the same inspection of bearings and cones. Dead pedal bearings tend to sound more crackly.

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