CountryBiking

Hello again. I am getting my Centurion Pro Tour back together and have a question on the front derailleur cable anchor. This is a Suntour Letech derailleur. The cable has quite a sharp bend when going through the derailleur actuation. The pictures below show the difference in cable position (angle) between the big chainwheel (rest) position and the small chainwheel position. Do I have this anchored correctly? I do not see another way to do it. I am concerned with excessive flexing on the derailleur cable during actuation and subsequent breakage; but maybe this is the way it is supposed to be and I just did not notice it before (it seemed to work fine). Thank you.

jimmuller 

I'm not familiar with that particular FD but the cable angles look reasonable. The thing is, it depends on how much angle the actuator arm moves through. If it swings, say, 45 degrees then angle of the cable w.r.t. the arm will vary by 45 deg from full in to full out. You might check that the derailleur stops are set okay. Perhaps the derailleur is moving more than it has to across the chainrings. Also it will take more movement to move across the rings of a triple than a double. Otherwise there isn't a whole you can do to change it.

CountryBiking

Yea, I should have mentioned that this is for a triple chainring. I think the stops are set about right. Thank you for the response.

The Golden Boy 

I don't know how similar the Mountech is to the LeTech- but here's mine. The cable stop is on this one.

CountryBiking

Thank you Golden Boy. Mine does not have the cable guide that yours has. My FD is probably fine, it just does not seem to be a very good design. It seems that they should have provided a bit of strain relief as it goes through the actuation motion.


One thing that is weird about the Le Tech is that as you actuate the control from the "rest" position it moves from the large chainring to the smaller chainrings. All other FDs that I have used, "rest" at the smallest chainring. This took some getting used to when I got this bike.

The Golden Boy 

So this is a "top normal" derailleur?

Cool!

Keep in mind the LeTech was a top of the line derailleur- It was Suntour's most expensive ATB FD. It may be (I haven't used it) that it's designed to run the cable a little differently (remember the Superbe Tech RD of the same time- it was designed to not have a cable housing from the stop to the RD).

If you could, post a couple of pix of the whole unit and the cable routing (man, posting pix is now a pain without photobucket).

jimmuller 

As I described before, the change in angle of the cable on the clamp is simply how much angle the arm itself moves to shift from one ring to another. The only design factor to make it "better" would be a longer arm and a correspondingly longer parallelogram holding the cage. The parallelogram is sized the way it is to make the cage move upward some as it moves outward. A longer parallelogram would place the clamp slightly higher on the ST, which would decrease the vertical movement of the cage. It's all a tradeoff. A different clamp design could have had the cable run over a rounded surface before heading down. But the clamp itself would have been clunky and larger. In any case, FD's tend to be like this and they work pretty well.

Many FD cable arrangements don't need a guide below the arm. It was common as a housing stop when FD cable went through a housing above the BB. However the better bikes usually came with cable routing under the BB shell or with brazed-on cable guides above the BB. That housing stop hole makes a nice but quite unnecessary guide for the cable.

Velocivixen

Looking closely it appears that your cable is not quite seated in the tiny "channel" on the inside surface f the anchor mechanism. If it were my bike I'd fix that.

CountryBiking

Thank you all for the thoughts and comments.


Velocivixen, I noticed the same thing you did when I was looking at the pictures and corrected it, thank you (it's amazing what you can see in big pictures that you miss live).


Golden Boy, I will attempt to get another picture showing the entire FD and cable routing.

CountryBiking

I found some old pictures of the FD and cable routing...


It looks like I did it the same as it was. Thank you!!