ConstantinosYEA

I am setting up a 7-speed bike. I have a new 7-speed shimano cassette on a HG Shimano 600 hub. I am using a Suntour Cyclone 7000 rear derailler and a shimano 7-speed indeed bar-end shifter.

Now the problem i am having is with the cable tenson. I routed the cable both the normal way, and the alternate way (according to sheldon brown) and both work fine going up the range once and coming back down. The problem is once it gets back into the smallest cog from going all the way up, the cable has lost all its tension and it can't go back up the range. I tried tightening the anchor bolt more to see maybe it was coming loose there but it wasn't. I also checked all the cable stops coming out the shifter, onto the frame, into the derailler, to see if the cable had shifted and it hasn't. I also tried using longer housing going from the last frame cable stop on the chainstay into the derailler to no avail.

I have run out of ideas and I think either my shifter or my derailler must be at fault since there is nothing wrong with the cable routing or housing. Anybody have any suggestions on what else to try?

Thank you.

bikinfool

You may just be experiencing some bed-in of the cable/housing, especially a fresh cable/housing/ferrule setup. This still all in the stand?

ConstantinosYEA

So i tried using a new cable since i was tugging and tearing at this cable for so long and this new cable does work a little bit better now. It doesn't lose as much tension but it still does after going all the way up the range and back down. The thing is it works perfectly in friction mode, it is just the index doesn't work. I have also test ridden it so it messes up both on and off the stand in indexed mode.

bikinfool

I'm not familiar with that derailleur, wonder if it's truly compatible with Shimano's indexing? You're familiar with setting up a rear derailleur well enough?

JonathanGennick 

Are you releasing tension one cog at a time? Does the chain jump two cogs instead of one at any point?

Have you pulled in the slack and run through the cycle again? You should eventually get to the point where additional cycles do not induce additional slack.

jgedwa

Sounds like it is more than just the meager amount of stretching that a new cable will go through.

It sounds like quite a bit of slop in the system. I will throw out a couple of complete guesses:

-are you using the right housing? Brake housing has a larger inside diameter and so the cable can flop around a bit more in there and give you slop.

-Are all the ferrules on and on tight? This is easy to mess up sometimes, so look closely at them to be sure they are not moving.

-(This is a long shot) Is there a cable stop somewhere that is somehow not stopping the cable? Did you bypass one and the housing is not butting against something immoble? Is there a clip-on stop that is not secure?

Also, my experience with derailleur cable tension has been that one or two tiny factors sometimes add up to a noticeable problem. So, even if each individual factor is small, they are still worth tracking down and solving. For me, intuitively, a few tiny sources of either friction or slop should get lost in the system, and time and time again I have learned that my intuitions on this are wrong. Don't get frustrated, just try to work through the system and see where any inefficiencies are. Bikes are simple, and so such things can be rectified with little effort once you set your mind to it.

jim

HillRider

I think the problem is that the Sun Tour rear derailleur isn't compatible with a Shimano shifter/cassette. The spacing and actuation ratios are not the same. Get any Shimano rear derailleur and the problem will go away.