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Problems with Compact crank hitting front deraileur
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I just installed a FSA mega-exo gossamer crank on my Cervelo P3 and I am having problems with the outer cage of the deraileur scraping the inner crank arm surface. It make a really annoying slight scraping noise with each crank revolution. It's only the back part of the cage that contacts. I can trim the deraileur to stop the scraping but then the inner part of the cage almost drags the chain. I friend of mine has a new soloist with the same crank and his doesn't even come close to the crank arm. Any thoughts?
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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Which derailleur is it? I have and FSA that is perfect, and an IRD that scrapes a little if the derailleur isn't set just right. I couldn't get my Chorus derailleur to work right.
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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Sounds like you're missing a spacer on your bottom bracket.
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Re: Problems with Compact crank hitting front deraileur [JohnA] [ In reply to ]
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At first it was an Ultegra then I swapped it for a FSA.
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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Hello

Have have the same FSA MegaExpo compact crank on my P3C. I'm using a campy chorus compact front derailleur without any problems.

Regards,

Eric

Eric - "Train Smart, Race Smart, Finish Strong"
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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Hmm.. Could also be that the alignment is off a bit. Have you had a pro look at it yet?
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Re: Problems with Compact crank hitting front deraileur [JohnA] [ In reply to ]
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What alignment are you talking about? The bottom bracket isn't cross threaded. Perhaps there is a spacer missing from where the crank arm meets the bottom bracket as someone else mentioned. I'll have to take the arms off tonight and check?
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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I meant alignment with the chainline. Could be that the derailleur is angled too far from the frame - causing it to rub the crank.
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Re: Problems with Compact crank hitting front deraileur [JohnA] [ In reply to ]
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How would the deraileur be angled too far out from the frame? It's a braze on so I really cain't adjust it's position in any manner other than up or down. When I look down the chain line it appears to be straight.
Last edited by: csteeds: Apr 17, 06 14:39
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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I must need another spacer on the drive side. As I took a closer look at it last night, I noticed that when I'm in the small chainring and in either of the last three smallest rear cogs the chain actually rubs the inside of the big chainring. The crank spacers are installed as per the instructions but there must be some slight variations in these things.
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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If you are running a 34/50 I don't think the chain rubbing the big ring when you are in small chaingring/small cog is uncommon.

If your derailleur is hitting the crank arm can't you adjust the limit screw so it doesn't go out so far. I can't imagine you need it to go out that far to get in the big ring.


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Justin in Austin, get it? :)

Cool races:
- Redman
- Desoto American Triple T
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Re: Problems with Compact crank hitting front deraileur [Justin in OK] [ In reply to ]
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If I adjust the limit screw until it doesn't hit the crank then it won't shift to the big ring.
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Re: Problems with Compact crank hitting front deraileur [csteeds] [ In reply to ]
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Can't be a spacer issue then, as that won't change the distance between the crank arm and big ring. It sounds like the derailleur is twisted outward at the back. I know you have braze-on, but something may be bent in the derailleur or the way it is attached to the seat-tube.

This doesn't sound like a crank/chainring problem. It sounds like a derailleur alignment problem.


----------------------------------
Justin in Austin, get it? :)

Cool races:
- Redman
- Desoto American Triple T
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Re: Problems with Compact crank hitting front deraileur [Justin in OK] [ In reply to ]
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My first thought was that the deraileur was bent or something, however both my ultegra and fsa deraileurs do it. I think I've finally got it adjusted to were it doesn't hit but there is only a hair of space between it and the crank arm. It just looks odd because when I look at my buddies soloist with the exact same set up there is tons of room between the two.
Last edited by: csteeds: Apr 18, 06 9:23
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