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Old 04-16-11, 12:07 PM   #1
simonaway427
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Raising front derailleur height - am I overthinking it?

Cervelo S1 with 6600 Ultegra braze on FR, compact 50T outer chainring.

I now have a 50T Rotor Q ring sitting in my basement ready to go on. I can only assume I'll need to raise the FR slightly to clear the oval ring.

Is it as simple as loosening the braze on, raising the FR a bit, and tighten? I'm also assuming I'll have to loosen off the FR cable as I raise it to maintain proper tension. Tighten, then fine tune with barrel adjuster?
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Old 04-16-11, 12:14 PM   #2
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... So no mechanical aptitude? software writer?

The bolt that goes thru the derailleur.. that one..

Think about a K Edge chain catcher, to also bolt on, with that bolt,
perhaps a longer bolt. chain suck destroys carbon frames,
so best be prevented..

http://www.acecosportgroup.com/shop/

Last edited by fietsbob; 04-16-11 at 12:24 PM.
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Old 04-16-11, 12:15 PM   #3
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Yep, that's pretty much it. Disconnect the fd's cable, loosen the clamp bolt and reposition the derailleur so the cage misses the closest chainring teeth by ~2 mm, check alignment and tighten the bolt. Then reconnect the cable and adjust the tension to get the shifting right.
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Old 04-16-11, 07:23 PM   #4
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Yep, that's pretty much it. Disconnect the fd's cable, loosen the clamp bolt and reposition the derailleur so the cage misses the closest chainring teeth by ~2 mm, check alignment and tighten the bolt. Then reconnect the cable and adjust the tension to get the shifting right.
A nickel makes a very nice feeler gauge for the cage/chainring gap.
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Old 04-16-11, 08:31 PM   #5
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but the thing to watch carefully is the angle of the derailler. Even a very small toe-in or toe-out can change shifting characteristics. Getting the vertical height is easy, getting the angle very nicely perfect can be tricky so take care with that.
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Old 04-16-11, 11:13 PM   #6
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but the thing to watch carefully is the angle of the derailler. Even a very small toe-in or toe-out can change shifting characteristics. Getting the vertical height is easy, getting the angle very nicely perfect can be tricky so take care with that.
With a braze-on derailer, alignment of the derailer is much easier and less likely to be too far out of optimal. You can adjust the angle but not nearly as much as you can with a clamp.
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Old 04-17-11, 08:36 AM   #7
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With a braze-on derailer, alignment of the derailer is much easier and less likely to be too far out of optimal. You can adjust the angle but not nearly as much as you can with a clamp.
That's why I like braze-on front derailleurs used with an adapter clamp. I can remove just the derailleur for cleaning and not disturb the height or alignment setting by not removing the adapter.
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Old 04-17-11, 08:51 AM   #8
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Originally Posted by fietsbob View Post
... So no mechanical aptitude? software writer?

The bolt that goes thru the derailleur.. that one..

Think about a K Edge chain catcher, to also bolt on, with that bolt,
perhaps a longer bolt. chain suck destroys carbon frames,
so best be prevented..

http://www.acecosportgroup.com/shop/
Your link doesn't work, looks like you need to put a space between the link and the "innocent" smiley you used.

- a software writer with mechanical aptitude

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Old 04-19-11, 09:17 PM   #9
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Thanks for the help guys.

Very easy process. Had to tweak the cable tension and toe in/out after raising the FR. So far, loving the Q ring.
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Old 04-21-11, 09:03 AM   #10
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if the FD is too low, would that cause binding when shifting into the large chainring? I'm trying to fix my girlfriend's Sora triple FD which does this. The chain seems to get pinched between the FD and the outer chainring when shifting up to it. I've only eyeballed it so far, but both of my bikes seem to have a higher position. The front, inside edge of the cage has a bulge towards the chainring, I think this is what's hitting the chain. Or could it just be the high limit stop is too far outside?
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Old 04-21-11, 10:33 AM   #11
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if the FD is too low, would that cause binding when shifting into the large chainring? I'm trying to fix my girlfriend's Sora triple FD which does this. The chain seems to get pinched between the FD and the outer chainring when shifting up to it. I've only eyeballed it so far, but both of my bikes seem to have a higher position. The front, inside edge of the cage has a bulge towards the chainring, I think this is what's hitting the chain. Or could it just be the high limit stop is too far outside?
If you're doing this test on the stand you might just not be 'pedalling' hard enough.

If it's jamming, check that the inner plate isn't hitting the middle ring. That would be caused by having the derailleur too low, even if it clears the large ring.
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