The axle on my bike that supports the pedals appears to have loosened, so that there is precession in it - I can slightly jiggle the pedals back and forth in a perpendicular direction to the axis.

Since this is a cheap bike, I am not particularly surprised. Is it possible to correct this, for instance by buying a new set of pedals and replacing them?

  • 1
    Sounds like a worn 'bottom bracket'. Probably needs replacing, but if it's an old/cheap bike it might not be possible Commented Jul 22, 2015 at 20:06
  • 2
    What is loose relative to what? Pedals loose on pedal shafts, pedal shafts loose in crank arms, crank arms loose on crank axle, bottom bracket cartridge loose in BB housing? Commented Jul 22, 2015 at 21:29
  • @DanielRHicks I believe Gordon's suggestion is correct - I feel like the entire Z-shaped pedal assembly is moving its socket. I am planning to come back to this question once I've had an opportunity to take a closer look at my bike in the coming days.
    – Superbest
    Commented Jul 24, 2015 at 4:48
  • If you have a single-piece "Z-shaped pedal assembly" then that's a one-piece crank, common less expensive bikes. It is fairly common for the bearings to work loose in these. The "cups" that retain the bearings likely need to be tightened. (But note that often they get so loose that the ball bearings fall out, meaning it must be disassembled and the missing pieces replaced.) However, the image you link to shows a 3-piece crank, which only rarely exhibits this problem. Commented Jul 24, 2015 at 12:03

2 Answers 2


You have a loose bottom bracket. It needs to be replaced.

You need to buy a new bottom bracket, along with two special tools: A crank puller and a bottom-bracket tool.

If your current bottom-bracket is cup-and-cone style (I'm betting it is), it can be removed with basic tools and elbow grease. If it's cartridge style, it can be removed with the BB tool.

Here are links to all three at Amazon:


BB tool

crank puller

Or, you could take the bike to your LBS and have them handle it. This is a common operation and probably wouldn't cost much.

  • Check if your city has a bike co-op where you can use the tools. If you have one, they will most likely already have the tools you need.
    – Kibbee
    Commented Sep 22, 2015 at 11:04

If you are talking about the pedal and pedal spindle(metal piece that threads into the crank arm from the pedal), then yes you are most likely are just going to need to replace the pedals which should be fairly straightforward.

  • It should be noted that some pedals are quite loose on the spindles when they come from the factory. If the pedals are the all-plastic ones then this is probably "normal". Commented Jul 23, 2015 at 3:49

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