Chain hitting the front derailleur before and after crank set change?

dickie.baxterLGiPxAKR
dickie.baxterLGiPxAKR Posts: 4
in Workshop
After many kms on the road, I am getting a lot of chain wobble (side to side movement on the top ring, the bottom one is fine). Initially I thought it was the chain ring that was buckled so I ordered new crank set.

However, I brought an FSA Gossamer for BB30 but the spindle was too short, so I took the chain rings of that, and put them on the originally installed FSA Omega spider. I still got chain wobble (if not worse). So, I pulled everything apart and after further inspection, none of the chain rings are buckled. There is no side-to-side movement in the bottom bracket, bearings are also new, so is it the spindle/spider that is the issue? Any ideas what could be wrong?

Thanks in advance for any advice on this

Comments

  • First.Aspect
    First.Aspect Posts: 14,630
    edited April 2023
    Take it to a bike shop. I'd put money on the two fsa cranks being for the same bb width, in which case you didn't install the bb30 one correctly, or the bb is knackered on the omega, or one or both are installed wrong.
  • trevor.hall12
    trevor.hall12 Posts: 416
    How is the chain tension and length .Are the springs in the RD operating OK .How old is the chain
  • dickie.baxterLGiPxAKR
    dickie.baxterLGiPxAKR Posts: 4
    First.Aspect said:

    Take it to a bike shop. I'd put money on the two fsa cranks being for the same bb width, in which case you didn't install the bb30 one correctly, or the bb is knackered on the omega, or one or both are installed wrong.

    Thanks for the reply. I am leaning on the omega being knackered...indeed the new spindle was shorter so i changed the rings from the new one to the omega. Sadly, we don't have a local bike shop.
  • dickie.baxterLGiPxAKR
    dickie.baxterLGiPxAKR Posts: 4
    trevor.hall12 said:

    How is the chain tension and length .Are the springs in the RD operating OK .How old is the chain

    thanks. Chain is quite new <300km and the RD is in good nick. I just can't imagine the spider/spindle can buckle like that. The BB has new bearings in it as well and there is no movement side-to-side of the cranks - just on the big ring in one part. very odd
  • First.Aspect
    First.Aspect Posts: 14,630
    dickie.baxterLGiPxAKR said:

    First.Aspect said:

    Take it to a bike shop. I'd put money on the two fsa cranks being for the same bb width, in which case you didn't install the bb30 one correctly, or the bb is knackered on the omega, or one or both are installed wrong.

    Thanks for the reply. I am leaning on the omega being knackered...indeed the new spindle was shorter so i changed the rings from the new one to the omega. Sadly, we don't have a local bike shop.
    Just looked it up. The Omega mega exotic bb standard is compatible with 68 and 70 mm / 30mm diameter spindles. So is the bb30 standard.

    Are you missing a spacer?

    https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.riteway-jp.com/bike_img/felt/2012/sonota/list/fsa_bb30.pdf&ved=2ahUKEwjmqbPHvtn-AhWBUsAKHR7SA40QFnoECAwQAQ&usg=AOvVaw0E5g3MieigYauroA-NnwVC
  • trevor.hall12
    trevor.hall12 Posts: 416
    edited May 2023
    Also are the bearing covers in place ? The operate as spacers on mega exo if thats what it is
    Also how old is the top chainring ? If you put a new chain on( you say only 300km so that's very new ) a worn ring it will do what you describe

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