Triple front derailleur

[CharleyFarley]

A couple of years ago I bought a new front derailleur from my LBS. He said it will work for a triple chain ring. I didn't install it right away, and in the meanwhile I stopped dealing with him because of numerous botch jobs. When I put the derailleur on the bike, it won't work on a triple chain ring. I can make it work on the small and middle ring, or the middle and large ring. So I'm stuck with the Shimano Deore XT.

Although the original el cheapo front derailleur has no brand name, it works, but I had to straighten it out in a vise after I had to do an emergency job on it miles from home. I guess it's okay but I'm thinking of putting a better one on the bike.

My question is: Why does it matter how many speeds the freewheel has if it's only dealing with the chain rings? I'm guessing it has to do with the width of the chain. In my case I believe I need a 3 x 9 for the 7-speed freewheel.

[Joe_W]

What happened to the answer (well, set of questions) that @painkiller posted?

Are you sure about the cable routing? Does the shifter run out of travel or is it limited by how far the derailleur moves (guess not, otherwise you could not get either smallest or highest chairing to work, which you could - just not at the same time). Front dérailleurs are more difficult than rear ones (to me), getting it 1. parallel to the centre line and 2
at the correct height can be a faff (or I just don't do it often enough). My guess is you messed up 1. That's usually my problem when I have these symptoms.

The biggest difference is between road and mtb dérailleurs, as the cage has a very different shape to accommodate the different sizes of chain rings. And then there's the brand (and for 10spd and higher also use specific) specific cable pull. That could be the other problem (hence my question) - sometimes you can do nasty things with cable routing to overcome that. In this sense FDs are simpler than RDs.

[CharleyFarley]

(01-03-2020, 03:30 AM)Joe_W Wrote:  Are you sure about the cable routing? Does the shifter run out of travel or is it limited by how far the derailleur moves (guess not, otherwise you could not get either smallest or highest chairing to work, which you could - just not at the same time).

The shifter is fine. After putting the original derailleur back, I experimented by clamping the new derailleur to the tube and operating it by hand. I measured the amount of sideways travel with the original derailleur, then measuring the new one for sideways travel, it would not go the same distance, no matter how far in or far out the limit screws were.

Quote:Front dérailleurs are more difficult than rear ones (to me), getting it 1. parallel to the centre line and 2 at the correct height can be a faff (or I just don't do it often enough). My guess is you messed up 1. That's usually my problem when I have these symptoms.

Nope. I did it by the book after viewing a professional video. It was parallel with the chain ring, and about 2 millimeters above the teeth of the large ring.

Quote:The biggest difference is between road and mtb dérailleurs, as the cage has a very different shape to accommodate the different sizes of chain rings.

I knew nothing about derailleurs at the time I bought it. I told the LBS owner what bike I had, and what I needed. He picked the derailleur and said it would work. It's not the first time he was wrong with his advice. And it was because of his botch jobs that I started to do my own mechanical work. There isn't anything I haven't successfully done, now, including dismantling and rebuilding a wheel.

Quote:And then there's the brand (and for 10spd and higher also use specific) specific cable pull. That could be the other problem (hence my question) - sometimes you can do nasty things with cable routing to overcome that. In this sense FDs are simpler than RDs.

It's all Shimano, derailleurs and shifters, including the new derailleur. It will work fine with two chain rings, just not three. I've given up with the new derailleur; maybe I can sell it if I ever get around to it.

But we've gotten off the question I asked: "Why does it matter how many speeds the freewheel has if it's only dealing with the chain rings? I'm guessing it has to do with the width of the chain. In my case I believe I need a 3 x 9 for the 7-speed freewheel."

[Joe_W]

I was confused by

(12-31-2019, 05:59 PM)CharleyFarley Wrote:  I can make it work on the small and middle ring, or the middle and large ring. So I'm stuck with the Shimano Deore XT.

To me this sounded like the lower and upper limit are in fact quite wide enough. If they are not, then I misunderstood (clearly). So my interpretation was that the shifter cannot pull enough cable to make that specific FD move far enough.

I have not had problems like that, and I did run mixes of 9x3 and 10x3 parts (FD, chain rings) on a 6 sprocket cassette (Helicomatic) with the 6/7 speed chain. But I used downtube shifters then. I might have replaced the chain for a 9spd one eventually, not 100% sure, this was a while ago. The width of the chains is not that different that it should be impossible to run your combination, imo. What tripped me up the first times was cable tension. Oh, and the old time favourite frayed shifter cables. I now replace them first thing when anything is weird

[Painkiller]

(01-03-2020, 03:30 AM)Joe_W Wrote:  What happened to the answer (well, set of questions) that @painkiller posted?

Are you sure about the cable routing? Does the shifter run out of travel or is it limited by how far the derailleur moves (guess not, otherwise you could not get either smallest or highest chairing to work, which you could - just not at the same time). Front dérailleurs are more difficult than rear ones (to me), getting it 1. parallel to the centre line and 2
at the correct height can be a faff (or I just don't do it often enough). My guess is you messed up 1. That's usually my problem when I have these symptoms.

The biggest difference is between road and mtb dérailleurs, as the cage has a very different shape to accommodate the different sizes of chain rings. And then there's the brand (and for 10spd and higher also use specific) specific cable pull. That could be the other problem (hence my question) - sometimes you can do nasty things with cable routing to overcome that. In this sense FDs are simpler than RDs.

Joe, I removed my post because of no response after a few days and considered it to be a dead thread.