Bicycle Mechanics - Rear Derailleur

On my road bike I have a Shimano 105 rear derailleur (with 300-400 miles on it) that shifts like crap compared to my mountain bike with a Shimano Alivio (with 1000 miles on it) that shifts nice and crisp. Is the 105 derailleur that bad of derailleur and would upgrading to a Dura Ace rear derailleur make that big of difference? Could the 105 be that far out of adjustment? Or am I comparing apples to oranges between the two styles of bikes.

In all candor, you haven't really given a very precise definition of what the 105's issue is, but ...

105 is a fine RD. It's probably not adjusted properly.

Take a look at these two sites and give it a whirl ... in the correct order ... and following the details closely.

Once that's done, let us know if/how much improved it is.....

http://www.parktool.com/repair/readhowto.asp?id=64

OR

http://sheldonbrown.com/derailer-adjustment.html#rear

Also make sure your chain is fairly clean and adequately lubricated, and that your cables are in good shape.

A deraileur is simply a fancy spring that does what the shifter tells it to do. If it's not shifting smoothly, the shifter is as likely a cause as the deraileur itself.

A deraileur is simply a fancy spring that does what the shifter tells it to do. If it's not shifting smoothly, the shifter is as likely a cause as the deraileur itself.

right, but lots of things can go wrong with the derailleur, like poor adjustment of limit screws, poor cable tension, or various parts being bent. and with a perfectly good shifter up front telling it "hey man, go to the next gear!" the derailleur will just be all acting like he's drunk or high swaying back and forth like "gaba waka yabbahoo hoo!!!!" and then you get sloppy shifting. when everything is adjusted properly, the shifter can be like "hey man, go to the next cog!" and the derailleur will be like "HELL YEs, I WILL GO TO THE NEXT COG!! I WILL GO TO THE NEXT COG SO FAST AND SO SMOOTHLY YOU WILL THINK I DID NOT WORK BECAUSE IT WILL FEEL SO SEAMLESS, BUT I DID WORK AND NOW THE PEDALLING IS SO EASY FOR YOU YES!!!!!!!"

at least that's what happened on my bikes, when i work on them.

stuff can go wrong with the shifter too, but most of the time, it's the derailleur adjustment. in the shifter, the index points stay the same, and the shifter just doesn't come through as clear, and the shifter gets muffled, and the clicks aren't as defined. or the shifter just plain looses it's voice. in which case, a nice shot of triflow is in order.

My only question is: When your derailleurs talk to you OneTin...do you talk back?


Funny post man...and entirely correct.

Well at least he spelt pedalling correctly.

105 is a fine RD. It's probably not adjusted properly.

["Piece of $hit Honda! Damn thing won't even run!"
"Um...there's nothing wrong with your Honda. It's just out of gas."
"Yeah, but why won't it run??????"]

+1. Don't blame the derailleur, per se. You probably have an adjustment issue. Take it in to the LBS for a tune-up, or learn how to do it yourself.

Bob