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The other day, I was riding up a hill and crack, something happened to my front derailleur. The chain rings now wobble back and forth on the horizontal axis as I pedal.

I decided to take a look and took off the dustcaps and 14mm bolts. I now see the following on both sides.

enter image description here

It says shimano on the chain stays but can't see a marking on the front chainset. Does anyone know what I need to do next to remove? I don't have a crank extractor but happy to purchase if I knew the right one.

I'm guessing the roller in this broke. e.g.

enter image description here

Do I need a new chainset or is possible to buy the complicated looking roller thingy? How would I even find out what I need (eurotrek bike but model unknown).

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  • Did the 14mm bolts come off easily? It could mean that the cranks wobble. Do you own a crank extractor. Remove the cranks and check the behaviour of the axle. Tell us from there onwards.
    – Carel
    Mar 4 at 8:00

1 Answer 1

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Your bike has a square taper crankset, so its unlikely to have outboard bearings as pictured.

Firstly you need to identify where the slop is that causes the observed motion.

  1. Grab a pedal and move it side-to-side. Look to see if the bottom bracket axle moves, which moves the pedal on the opposite side. If this is the case, your Bottom Bracket has play and likely needs an adjustment or replacement, and the CRACK was the noise of a bearing ball shattering.
    If you have a cup-and-cone BB then it may just need a clean and grease and adjustment, but if a bearing ball has damage then you'll need replacement balls.
    If you have a cartridge and it has play then you'll need to replace it completely.

  2. If wiggling a pedal pivots only one crank-arm on the bottom bracket axle, then the crank/axle interface has play. Further inspection is needed, you may have cracked the crank arm, or there may be damage to the square taper.

  3. Less likely, you may have broken some part of the spider that supports your chainrings. If the chainrings have sideways play, or are bent, or can move independently of the crank arm then look for play. You may have cracked the spider somewhere, or a chainring bolt.

Please look closer and let us know what you find.

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