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Old 12-15-06, 07:24 PM
  #5  
rschleicher
Retro-guy
 
Join Date: Oct 2006
Location: Danville, CA
Posts: 285

Bikes: 1980 Raleigh Super Record

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If it is only slipping while in the lowest gear (largest rear cog), then you may be able to get a little relief by relaxing the travel limit screw (for adjusting the limit of travel for the rear derailleur, toward the spokes) just a tad. In other words, let the rear derailleur move just a little bit past dead-center on the largest cog, before it hits the stop. (But don't allow it to move so far that you risk dropping the chain next to the spokes.)

I had the same problem with the Suntour friction shifters and rear derailleur on my bike, and the above helped a lot. Of course a bit of tightening down of the friction adjust will also help, but it will make it stiffer-feeling in all gears.

One other idea is to find a ratcheting shifter for the rear. These are still friction shifters, but the ratchet mechanism means that they are stiffer to move from low to high (i.e., stiffer in the direction your shifter is slipping), but easier to move from high to low gears. Basically they are easier to move when you are pulling against the spring force of the derailleur, and stiffer when you are going in the same direction as the spring force, which serves to sort of even out the overall effort. I guess I don't know if Campy made a down-tube friction shifter with a ratchet mechanism. But Suntour made their friction shifters in both forms - straight friction, and the so-called "power shifters" with ratcheting. (The ones I have seen have had the ratcheting only on the right shifter for the rear, and straight friction for the front derailleur, where you are having to do more tweaking of the derailleur position.)
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