DT Shifter set up help

[p nut]

I recently bought some Silver DT shifters from Rivendell. The rear/right shifter works great. However, I'm getting some slippage from the front shifter. I usually run it on the big ring, but the shifter slips after a short distance and chain starts rubbing on the derailer (not enough to actually make it shift). I emailed Riv, and they said to use a locking washer, as he was thinking it wasn't staying tight. But upon checking, it was just as tight as I had it, but added a lock washer anyway. Still didn't help.

So I thought that maybe having the shifter operate further into it's range of motion would be better (and would have more cable wrap), so I set it up at a perpendicular angle to the downtube. Well, still doesn't work. Aside from going back to the "trusty" STI shifter, anyone have any ideas? Front derailer is a 105 with a double VO Grand Cru cranks.

[cp43]

Is the screw holding the shifter boss bottoming out before it fully compresses the shifter? I've had this with chain ring bolts. They seem tight, because there are no more threads left for the bolt to go further in, but the head of the bolt hasn't reached the point it should have, with the force it needs.

Where did Riv tell you to put the washer? If what I've described is what's going on, you'd want a washer as close to the downtube as possible.

Good luck!

Chris

[Louis]

Maybe too much lube?

A while back, after years and years of use my LH DT shifter (Shimano DA) started to be too hard to move so I took it apart, cleaned it and applied a bit of grease. That was apparently too much, and it would slip. So I took it apart again, wiped down the parts with a paper towel and that was enough to get it to hold properly.

I'm not sure how the Silver compares to Shimano, and what gives you the friction, but maybe you need to jack that up a bit more than what you're currently getting by just tightening the screw. (I assume it has some way to increase the force in there to tweak the moment that resists motion of the lever.)

[Admiral Ackbar]

maybe try reducing the cable tension a tad

[rccardr]

Not a part that should slip, although the grease story is interesting.

Check to see if the bolt is bottoming out in the braze-on before being fully tight on the shifter assembly. You can Dremel off a couple of MM from the bolt length if that's the problem, or put a washer or two under the head of the bolt.

[p nut]

Thanks for the responses. The bolt was not greased. I actually used some Oatey's joint compound on it, which acts like teflon tape. I use this product on my EBB'ed bike and it hasn't slipped once.

The washer was supposed to go right in between the bolt head and the plastic washer. I didn't feel the bolt bottoming out the first time around and putting that washer under there confirmed that it wasn't bottoming out. And I don't think I can tighten it any more by hand. I can use a wrench, but I don't want to risk cracking the plastic washer.

How would I aleviate tension on the cable? Isn't this impossible without changing out the springs?

[Louis]

The issue isn't with grease on the bolt - that will just affect the torque on the bolt.

What's important is the friction for the "rubbing surfaces" that create the moment to resist the F-der spring that will be pulling on the cable.

[Admiral Ackbar]

How would I aleviate tension on the cable? Isn't this impossible without changing out the springs?

shift into the small ring and feel the cable, if its taught you'll probably want to loosen the cable anchor bolt and make it so there is a small amount of slack in the cable.

[p nut]

Louis - That makes sense. In the video put out by Rivbike (youtube), it instructs to grease both sides of the metal washer between the boss and the shifter. Should I try wiping off that grease on the washer? Maybe that will create more friction to help it stay put?

[Louis]

It might. Good luck.

[p nut]

shift into the small ring and feel the cable, if its taught you'll probably want to loosen the cable anchor bolt and make it so there is a small amount of slack in the cable.

I actually have more than enough slack now, since I set the shift points towards the middle of the shifter's range of motion. This gave me a little more cable wrap as well, but really had no affect on the slippage issue...

[don compton]

This brings back memories. I used to have problems with Campy Nuovo Record shifters. Either too tight or they would slip when I stood up on the pedals. Simplex retrofriction shifters magically fixed my problem. I wonder if they are still available.