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Front derailer problems....help


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I've got a full Shim 105 bike. There is  a problem with the front shifting. If I want to shift up to the big blade I have to push again and somethimes hold for the chain to go up.


There are 2 blades, but I think that the STI is made for a 3 blade setup (Thats why there is a extra shift in there?)


What do I have to raplace to sort out this problem? The STI or the STI and the front derailer?


Or do you guys think its better to upgrade to a new groupo like Dura Ace 7800 or Ultegra 08 models?


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I do not think you get a two shift only STi Lever. Your stops on the derraileur wil determine the amount of travel of your lever and they are most likely not set up properly. Try the following...... while you are shifting up you shift to a lighter gear on the rear derraileur. It will most likely jump up and then quickly shift down. In the meantime get your front derraileur adjusted properly.


Go here to find instructions.....




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If you go to Campag you won't have that problem.


OK, seriously. Shimano's 105, Ultegra and DA have a trim function in their STI's. JBornman will be able to explain better. If you're on the small chain ring and the largest sprocket and you want to move to the big chain ring (or blade as you call it), your first move on the STI will be more efficient, if you move from the largest sprocket down 2 or 3 sprockets. (You should avoid crossing the chain from biggest sprocket to big ring, and from smallest sprocket to small ring because it increases the stresses on the chain, although there are those who argue that modern chains can accommodate that kind of flex).


When you shift from small to big ring, you may also find that the chain will rub against the front derailleur. If this happens, that's when you use the trim on the STI and shift again, to stop the chain rub on the FD. This happens by shifting the FD a little further outwards. Poor lubrication also contributes to the problem of the chain not shifting up to the large ring so make sure the chain, cables and derailleurs are lubbed.


The main point then is that Shimano 105, Uletrga and DA have a trim function on their STI's.


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I have a Shim 105 too - the front derailleur has what's referred to as Trim. It's an intermediate setting between the two blades. If you want to gear up - you can either push twice, or give it one longer push. Gearing down it skips the trim.


When you are on the small blade in the front (which is on the left of the bigger blade), and you go to the smaller gears on the back (which are on the right side of the cluster), the chain starts rubbing agains the front derailleur. This is where you use the Trim - to move the front derailleur slightly to the right, so that it stops rubbing against the chain, without chaning to the bigger blade.


Nor sure if I'm making sense - also not sure if it answers your question - but I think that's what's happening.




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So the trim is something I tune in myself or at a shop - or does this only refer to the fact that I need to either hold in to shift up to the bigger ring or do a small / half shift to move the FD to stop the chain from rubbing on the FD?


Thanx for the help
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