105 front derailleur issue
 

I'm tearing my hair out trying to get my front derailleur set up right. I have the 2008 version of 105 (I think - it's on a 2008 Specialized Roubaix it's supposed to be "31.8mm clamp, bottom pull") and use a compact front crankset - FSA 50x34.

For a while now the chain has been falling off the big chain ring when I change up. I asked my LBS to sort it, which worked for a few days but they were pretty useless, so I've played about with the top limiter but can't find the perfect balance of changing up easily and but not falling off the top gear. It's really turning into being a pain in the A.

So here's the question. Can I simply switch to an Ultegra front derailleur? If so, do I have to change the brake levers/flight deck as well? Also, which Ultegra derailleur would I need to run a compact chainset?

Any other suggestions also welcome!

Just changing to an Ultegra front derailleur will accomplish nothing. A 105 is every bit as good and properly adjusting your current 105 is all you need to do. Here is Park Tools website tutorial for fd adjustments. Start from the very beginning and follow it exactly:

http://www.parktool.com/repair/readhowto.asp?id=75

To start with, if the front derailleur worked before and didn't loosen up then don't touch it. If you have moved it then it will need to be set up before you do anything else. First remove the cable and crank the lower screw in till the outer edge of the derailluer is flush with the large chainring. If it won't travel that far then you need to put something in the mechanism to get the outer edge of the guide flush with the big ring. Holding it by hand can be done but it is a bit tougher that way. New derailluers come with a plastic block to hold the guide out. Now tighten the clamp when the guide is parrallel to the large chainring and clears the teeth by about 1/8 inch or just a little less. When you played around with the top limiter did you remove the cable? Adjusting the front derailleur is very simple as long as you do things in the right order. Now with the cable off and the derailluer in position unscrew the lower limit screw so the guide returns back to normal. Then with the crank on the smallest chain ring and the rear on the biggest sprocket, adjust the lower set screw so the guide just clears the inside of the chain when you turn the crank. Now move the rear to the smallest spocket and move the derailleur by hand to shift to the large chainring. Adjust this set screw so it just clears the outside of the chain when you turn the crank. Let it go and it will shift back to the small chainring. Now attach the cable with a strong pull from your hand and tighten it up. You may need to add some cable tension at the down tube to get it properly tensioned but you should be able to shift it up to the large chainring and not have the cable too tight. If you do this in this order than it should work perfectly. If the front derailluer was never damaged then replacing it will give you the same trouble. Just get this properly adjusted in the right order without the cable attached and you should be fine.

Good luck.

Greg

Opps I took to long to write this. HillRider sent you to the right place.

My five cents : I had the same issue with my compact crank and a 105 FD on my CX. The roadsalt killed it so I put on an Ultegra FD. Voila ; problem gone. Might be luck but I'm happy with the change.

I was having this problem this week also and thinking about switching to Ultegra as well. But, I got out my book, and followed the instructions for adjusting the screws exactly, and problem is gone. Cable stretch is my guess as to it happening.

Well, yes, if the 105 fd is badly damaged then replacing it with a new Ultegra is indeed a good change. However, if the 105 is mechanically sound, all the OP need to do is set it up properly. A mis-adjusted Ultegra won't be any better.

Thanks for very useful replies guys. Looks like I should have another go at a proper adjustment, following the letter this time rather than my experimenting with the lower and upper limiters - then I'll consider the Ultegra if I still can't fix it.

There is nothing magic with Ultegra. As HillRider stated, as long as there is nothing mechanically wrong with the 105, switching to Ultegra (or Dura-Ace for that matter) will not solve the problem.

The shifting problem was there long before the salt killed it. I probaby could have adjusted it to work better. The Ultegra FD just worked flawlessly with the old wires and hosing .

Let's get the name of the compact crank please. The FSA gossamer (50x34) compact is one of THE worst shifting cranksets on the face of the planet. This is with 100% proper derailleur setup. The cage must be setup to rub in the small/big combo in order for shifts to the big ring to be "quick".

It has nothing to do with the front derailleur. Do not bend it to try and make it shift better.

The solution is to buy a shimano compact - it will shift 30 thousand % better. Guaranteed. This issue has come up and been dealt with at the shop level also about 30 thousand times. **** that crankset.

operator, surely it can't be the entire crankset causing the problem. If anything, it could be that the large chainring on the FSA crankset is not very good, but rather than changing the whole crankset, only the large ring needs to be replaced. On pretty much all cranksets, the Shimano rings are better shifting than FSA's IME.

Good to know about the FSA as I too have an FSA Compact 50 x 34. I have upgraded all the other components from 105 to Ultegra 6600 last winter, just not the FD or crank. That sounds like next winters project. And I have to have the chain rub the cage to run in the big-big gear, cross chaining. It shifts alright, just not as crisp as I think it should.

Well that's very interesting, and the crank is... a FSA Gossamer MegaExo compact set. Sounds like I need to factor that into the equation. I have to say, I didn't think it would be the crankset given there used to be no issue and the rings are still well aligned, at least to my eye there is no obvious miss-alignment when revolving the rings.

Sometimes a derailluer get's knocked and bent or is no longer parallel with the chain and can cause problems like this. If you don't realize it got knocked you'll wonder why your bike suddenly started shifting funny. So give the FD a good look over, make sure the cage is not bent and make sure the cage is parallel with the chain. Also probably worth checking the height of the cage in relation to the big ring.

I changed the crankset at the same time I changed the FD. The old one was a Megaexo. My excuses to the 105 FD.