Bicycle Mechanics - shimano 7400 downtube shifter slipage
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08-07-08, 06:20 PM
I have a shimano dura ace 7400 6 speed sis downtube shifter that I have been using in the friction mode for well...ions. It has been slipping in the smaller cogs (not enough friction). I went out a got a dura ace 6 speed freewheel with hopes of going back to the index shifting to fix the problem. Now I find that there is not a lot of index between the 2 smallest cogs and it slips between them in the index mode. Is there something I can do to fix it? I took it apart and cleaned it up and it made no difference. I am sure parts are non existent. Am I off to ebay to hope to find one that has not had much use?
08-07-08, 10:10 PM
I always just tightened up the shifter to increase friction.
08-08-08, 02:11 AM
What do you mean it slips in index mode? Does it slip from larger to smaller cogs as you ride? That sounds like an issue with too much cable-friction. When you are in the smallest cog, and shift up one click, does the chain shift up? Then if you shift back down, does it go down immediately?
08-08-08, 11:09 AM
I've got the same shifters and there are a couple of indices that are getting pretty sloppy up on the largest cogs of the freewheel. The clicks aren't so loud (sometimes barely audible at all) and the shifts aren't as solid. I don't have any trouble with slipping between gears (at least not yet).
I think these things just wear out. I am somewhat surprised yours have since you say you've run friction. But maybe the friction slipping on smaller cogs and poor indexing is related (maybe something that affects both is worn, bent, or broken). I think you're SOL on repairing and if you want indexing, you'll need to look for replacement levers.
08-08-08, 05:08 PM
That is what I have bearly an audible and little feel in the index between the two smallest cogs. I was hoping it just needs a washer or something. I have never taken it apart before the other day when I cleaned it up in hopes of improvement. I was surprised at how complicated the bad boy was. This is when old bikes are frustrating. I like flawless operation. Guess I am riding the fixed gear for a while.
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