Acera with STi's

MountainMonster

All- I've been on Singlespeed for the last few months, and I just bought a Shimano Acera rear mech. I've got either Sora or Tiagra STI shifters. It doesn't say which one it is on the shifters, but both mechs and shifters are 8 speed.

I can't seem to get the rear mech to shift at all, it holds tension without problems, but when I shift the cable just gets loosened and doesn't actually do anything to the mech.

I've been told this system should work, but I've never had problems like this before. Does anyone have any recommendations for what to try? I've tried doing this as cheap as possible, and if it won't work I will end up just waiting to get gears again in the spring, probably switching to 10 speed.

MountainMonster

Could it have something to do with the fact I have not changed the outers yet? If these parts should work together then it could be that.

Ber Nard

So when you shift down the cassette (to smaller sprockets) the mech doesn't move but you end up with slack cable under the down tube? That would suggest the shifter is doing its job but the mech isn't. Does it shift the other way?

Detach the cable from the mech, the mech should spring across toward the smallest sprocket. If it doesn't, the pivots on it may have seized or the spring may be damaged. If it does then it may be the cable if it's really filthy or kinked.

Hope that helps.

Rob

desweller

Sounds like your cables are properly gunked up. Replace and all will be well.

MountainMonster

Ber Nard wrote:

So when you shift down the cassette (to smaller sprockets) the mech doesn't move but you end up with slack cable under the down tube? That would suggest the shifter is doing its job but the mech isn't. Does it shift the other way?

Detach the cable from the mech, the mech should spring across toward the smallest sprocket. If it doesn't, the pivots on it may have seized or the spring may be damaged. If it does then it may be the cable if it's really filthy or kinked.

Hope that helps.

Rob

Thanks mate, it is a brand new mech, and the action is fine on it. It springs back easily, and moves up the cassette fairly easily. Kinked may be the problem, I think there is a small one on it.

Thanks as well DesWeller!

desweller

The other thing it might be is, if you've got it on the workstand and you've clamped the cable with the workstand arm. I have never done anything as silly as this, obviously - it was a friend.

MountainMonster

Of course the friend excuse!

No workstand for me. I just checked the cables and it was kinked inside one of the stretches of outer, so managed to miss it some how. Off to the shop early AM to get a new cable and outers. Hopefully it will work!