Bicycle Mechanics - Need expert mechanical help re: F Derailleur

Ok so I posted a while back about this same issue and I thought it got resolved but it is like it got worse tonight when I tried to make an adjustment and I can't figure out how it EVER seemed like it was working right.

Bike: 54 cm Specialized Sirrus Sport Disc 04 all stock (http://www.specialized.com/SBCBkModel.jsp?spid=5996&JServSessionIdroot=w8manv5u6s.j27005) Check the link for the equipment on the bike.

The situation has been that the chain will jump off the inside and do the chain suck thing. As a result my wife (this is her bike) only rides on the middle ring for fear of the chain falling off. So we were going to go on a ride tonight and I figured I could make an adjustment to make he shifting a bit better...well I wound up tearing down the whole drivetrain. Here is what I have done. Check the centering of the BB (it is centered), checked the height of the FD, checked the limits of the FD, check and adjusted and adjusted and adjusted the tension of the FD cable...there is no good tension. Checked the angle of the FD and tried several different angles...I think it is currently optimized.

The only thing I can figure is that the front shifter isn't functioning properly and here is why: The Shimano flatbar front shifter work like the road systems and have a trim in the middle ring, so essentially there are 4 FD positions for the 3 rings. If I set the tension properly on the front in the small ring a push of the shifter does NOT get me to the middle ring I have to push it to the next click...this is also the way it works on my Marin (same Shimano flatbar setup but it is a 9 spd rather than 8) but then you can do a "small" click and get to the inside of the middle ring...this is the trim feature. On the Specialized you have to give it 2 clicks to get on to the middle ring but then if you try to do the small click to goes ring back down to the small ring. Also if the tension is set properly when you are in the small ring (i.e. very little to no rub when in small ring and large cog) when you go to the big ring it will rub like a mother even though it hasn't reaching the outer limit as set by the limit screw. If you then try to shift to the middle ring it gives a micro click (my Marin doesn't do this) but doesn't shift down...another click will send it to the small ring so there is no way to get the middle ring from the large ring. If you add tension to the point that there is little to no rubbing when in the large ring and the small cog you can now get a small click then another down to the middle ring and then another big one down to the small ring but there is constant rubbing when in the small ring as the cable still has tension and the FD isn't at the lower limit.

So all I can say is WTF?!?!?! I am totally baffled. My Marin with nearly the same components works differently and...well it works.

Anyone got a clue here?

Edit: Seems I was not clear: This ISN'T a limit screw issue. This also isn't a cable tension issue, I spent 2 hours on this last night and tried even imagineable amount of cable tension. This also isn't a FD height issue...it is 2mm above the big right as it is supposed to be. This could be a FD angle issue but I don't think it is as I tried it a bunch of different ways from the heel of the FD in to square to the heel of the FD out...nothing works.

Just like a road triple,If it is setup right you should ve able to get from the small to the middle ring with one full push of the lever.You setting the low limit with the chain on the small ring and big cog,and The shifter in the full granny position, and the cable LOOSE. Attach cable Atrer setting low limit Don't pull too tight,and don't leave slack.Final tensiion adjustment can be made with the adjuster.

My first suggestion is to read sydney's post twice. Then do it. Sydney can be a little crusty, but he's usually right.

My second suggestion is spelled "Third Eye Chain Watcher."

Ok so DUH! I know how to adjust a FD. I built my La Raza and rebuilt my Mill Valley which has the same front shifter and FD. I know how it is supposed to work and I AM setting it up properly. IT ISN'T WORKING PROPERLY. After fiddling with it the way the LBS had the cable set I took the whole thing apart including the cable out of the shifter and re-did everything, limits, tension, height, angle, everything. The only thing I didn't do...and it is the next thing I am going to try...is switch the shifter with the one on my Marin. I am going to swing by the LBS tomorrow and see what they have to say, would have done that tonight but the person that answered the phone was pretty straight up in telling me that the tech on the late shift was new and pretty raw so I didn't waste my time going down.

Proper setup as Sydney suggests gets me a shift into the middle ring in 2 clicks and constant rubbing in any gear on th eback on the big ring. Adding tension to stop the rubbing in the back gets you constant rubbing in the small ring. The derailleur isn't traveling far enough on each click, you can add tension to get it over but that messes up the bottom of the shifting (inside ring).

As I have it set right now in small front and big back there is slight rubbing. A click and a half gets you on the middle ring. Next click stays there. One more click gets you to the big ring but you are slightly rubbing in big front and small back. Now trying to come down the rings, one click just gets you rubbing more but no down shift. THe next click sends you to the small ring.

I think the only possibility is that I have a defective shifter.

Get a friction thumb shifter for the front.

FD cage distorted? Happened to me when I started getting chain suck, the cage got mangled a tiny bit, just enough to wreck the shifting no matter how I adjusted it.

Is your front derailleur doing something like this:

http://www.bikeforums.net/showthread.php?t=98610

It took a while to convince the LBS, but they eventually agreed that the front shifter was defective and replaced it under warranty. This problem is apparently not unknown to the bike shops and Shimano.

Get a friction thumb shifter for the front.

Great that is really insiteful help with the problem.



FD cage distorted? Happened to me when I started getting chain suck, the cage got mangled a tiny bit, just enough to wreck the shifting no matter how I adjusted it.

I don't think but I will take a look at it. How much was yours distorted? Easy to see or really minor?



It took a while to convince the LBS, but they eventually agreed that the front shifter was defective and replaced it under warranty. This problem is apparently not unknown to the bike shops and Shimano.

See this is the kind of answer I was looking for...someone with actual expierence with a similar issue of a mechanice who had run across a similar issue and knows a fix. Sounds similar..at first I was going to say it simply sounded like a tension and setup issue but then that is the same thing Syndey was saying to me. I am taking it to the LBS today so we will see what they have to say about it.

Ok so DUH!

Great that is really insiteful help with the problem.

See this is the kind of answer I was looking for

Nice attitude dude. Ever wonder why you may not be getting a lot of responses to your problem?

Nice attitude dude. Ever wonder why you may not be getting a lot of responses to your problem?

Ok so in the first post i state pretty clearly that I already did what Sydney said to do. Either he didn't read the entire post or he was being an a$$ intentionally. It isn't a setup issue, then he posts another time with more usless comments...clearly the correct answer is not go buy a friction shifter. If there is a probelm with this shifter I will get it fixed or replaced with a functional unit that is similar. My wife is a recreational rider and if I stuck a friction shifter on there she would again only ride in the middle ring, doesn't solve the issue.

As for your last quote....huh? I was serious...that poster DOES have something to give to the discussion. I mistakenly thought that by asking for an expierenced mechanic I would get someone with some knowledge and could say something like the last poster did. I was also hoping that MAYBE there was some trick that only someone who had delt with this before would know, or some defect that again someone in the know would know about.

I don't think but I will take a look at it. How much was yours distorted? Easy to see or really minor?Quite a small amount, I could see it didn't look quite right but when looking in detail, it was hard to see what was wrong. I had to compare it side by side with a straight one to see where it was schew, because that cage shape is quite subtle.

Quite a small amount, I could see it didn't look quite right but when looking in detail, it was hard to see what was wrong. I had to compare it side by side with a straight one to see where it was schew, because that cage shape is quite subtle.

Thanks I will have a look at it and bring it up as a possibility with my LBS this afternoon.

It's not nice to insult the people trying to help you. Do I hear bridges burning.

One other thing. I positively demonstrated to the mechanic that my shifter was defective by going to a new bike in the store with the same shifter and showing how it worked "differently" than mine. Prior to that the mechanic maintained that nothing was wrong with my shifter and "...that is the way the shifter works...."

alter the angle of the FD. I found that my shift issues, which was similar (all downshifts, regardless of gear were directly to the smallest ring, and sometimes blows off into the BB area), and that was a by product of the deraileur being misaligned by a few degrees.


Also keep in mind some setups will always have some degree of rub. My truvativ/105 triple setup has a slight amount of rub (on slow pedaling the chain rivets touch a point inside the FD cage, once you get some power into it, it's no longer an issue) that no amount of adjusting will get out...I just learned to live with it.

Also keep in mind some setups will always have some degree of rub. My truvativ/105 triple setup has a slight amount of rub (on slow pedaling the chain rivets touch a point inside the FD cage, once you get some power into it, it's no longer an issue) that no amount of adjusting will get out...I just learned to live with it.You don't have to live with rub,assuming correct setup,using trim and or avoiding combinations you probably shouldn't be in anyway.

Took it to the LBS and had a mechanic look at it. He said he hadn't seen anything like it before but for sure it wasn't working properly. Asked how old the bike was (about 6 mo) and said he assumed it would be covered under warrenty but that his manager would have to look at it and he wouldn't be in until Tuesday. So the bike is going back down on Tues. (I asked my wife if she wanted it like it was for the weekend and she did) and hopefully I get a new shifter from Shimano...if not I guess I will be upgrading it to 9 speed as I will have to buy a new pair and 9 spd is all I could find on the net.

Thanks to those that had helpful responses.