ac29593

I hear from everyone I talk to and every thread I read that the front derailleur properly placed is about 2mm from the top of the big ring. I am wondering what the difference is, why this is, and if your chain is not getting thrown does it matter how high it is above the big ring? I had a bigger ring on my bike, with the front derailleur just above it. When I swapped out to smaller rings, I have much more height than the suggested 2mm. I have not once thrown the chain, and my shifting feels perfect. In theory, would I have better shifting, less crosschaining, ect. if I followed the 2mm rule of thumb? Or is "proper placement" only for security reasons so the chain wont jump off track...

Thanks

grahny

According to Park Tool:

"If the derailleur cage is too far above the large chainring, it is more likely to shift poorly. If the derailleur is too low, it may scrape against the chainrings or jam the chain when shifting."

So, if it's shifting perfectly now, don't sweat it.

ac29593

I dont mean to bring this thread back from the dead, but....

Since my bike has been sitting for the winter season I plan to give it a tune before I start riding again this year.

Should I correct the placement of the derailleur while I am at it?

I know I said in my original post that my shifting was "perfect", but keep in mind I that although I am handy with tools I def. dont qualify as a bike mechanic.

bdcheung

If it ain't broke, don't fix it.

JLauren

So be sure and break it first. THEN fix it.

JoesInBoston

I thought the phrase went "If it ain't broke, tear it down and rebuild it anyway!".........