Bicycle Mechanics - front derailleur question - certain amount of speeds (8,9,10, etc...)?

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kevmk81
10-11-11, 10:13 AM
I have an older, 6 speed road bike that has a broken front derailleur. It's a clamp on style Shimano, used on a double chainring.

Looking around I'm seeing front derailleurs say '8 speed', '9 speed', etc...

Would an '8 speed' front dr work with a 6 speed cassette? Doesn't really make any sense why they'd designate a certain speed for the front, when it's really only either a double or triple chain ring.... any help/explanation would be greatly appreciated! Is the cage on 8+ speed front derailleurs wider or something... but not as wide as a triple chain ring derailleur?

rccardr
10-11-11, 10:22 AM
Bingo- you are correct. 9/10/11 speed FDF's typically have narrower cages than 6/7/8 speed ones.

What size is the clamp on your broken FD? I may have a good one in the box here that you could have for the price of postage. PM if interested, always happy to help someone out if I can.
fietsbob
10-11-11, 11:05 AM
Depth of back plate is different between regular and compact and triple.

now STI is just 3 big throws, , misses the fine tuning alignment, as the angle from the rear changes..

Benefit of friction bar cons. narrow cage can be relocated centered over the chain.

reddog3
10-12-11, 09:18 AM
Benefit of friction bar cons. narrow cage can be relocated centered over the chain.

Yeah- give me friction shifters anyday. Must be why I ride quietly while those with STIs ride around with chains rubbing the cages when things go out of adjustment.
Homebrew01
10-12-11, 09:25 AM
Yeah- give me friction shifters anyday. Must be why I ride quietly while those with STIs ride around with chains rubbing the cages when things go out of adjustment.

Campagnolo allows front trim adjustments.
joejack951
10-12-11, 10:00 AM
Campagnolo allows front trim adjustments.

So does Shimano: http://bike.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0030-downloadFile.html/06%29%20Trim%20Function.pdf

They haven't included all of the groups that have trim functions either (Sora for one). On any STI bike that I've used I've been able to set it up to allow for rub-free pedaling in all but the most extreme combinations (that I'd never consider using anyway).