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overshift hopping?

762 views 6 replies 3 participants last post by  msgvb 
"so do you understand the symptom I'm trying to describe? I've seen it on indexed systems as well, but never been able to really figure the problem or fix."

Yeah I thinkg I've got it. When you go to shift up or down in the front, but especially up to the bit ring the chain just kind of jumps around, wants to climb up, but just sort of slips, makes noise etc. right?

The problem with these old systems is no ramps or pins, only 4 profiled teeth to pick up the chain or allow the chain to drop easily. The key to snapping up the shift is to allow the front cage to move just a bit more than is recommended for a modern system, yet not let it move so much that you drop the chain off the crank. It's touchy but not hard to do. And there's no "perfect solution" for the porblem especially on older worn rings. It will never be near as good or as snappy as say a modern STI system. You just have to fiddle with it and get it as good as you can. Just a little side note. The shifting in the front with a friction thumby will be best when the rear is in the middle of the cassette. It will be at it's worst when in either the small or large cog in the rear when going for a cross chain configuration. Cross chaining on the old 5 speed/double set ups isn't that critical as the angle of the chain isn't that severe, and those ranges are usable when riding. So you still need to be able to make the shifts, but it can be a pain to get it to happen smoothly. Just work at it and get it the best you can. That's all you can do. Good Luck. :thumbsup:

Good Dirt
 
Okay, by 10 speed....

I assume you mean 5 cogs in the rear and two chain rings up front? Some of the older Ross bikes didn't use shimano cranks and chain rings so no shift ramps or pins to help. Even some of the older shimano stuff didn't have these more modern shifting enhancements. So you may be dealing with that. But from the sound of it you are likely dealing with friction shifters as well? The key here is whether the front shifter is indexed, i.e. has a click for each position as you move the shifter. Usually and older 10 speed drive train has an indexed rear, but a simple friction front. There's allot of information missing on these bikes that would help. Anyway, in either case though the fix may be quite simple. Start by backing out both the high and low limit screws of the front derailleur 1/4 turn each. With the old 10 speed doubles the front d has to "overshift" just a hair to make for quick shifts. The extra movement of the derailleur cage was required to move the chain sufficiently to affect the shift. That's why most older doubles and tripples like that had a friction shifter for the front. The mechanic dialed in the extra cage movement, just enough to make the shifts as crisp as possible, but without dropping the chain off of either chain ring. From there it was up to the rider to adjust for chain rub with the shifter in either extreme in the rear, i.e. big ring/front small cog rear etc. So back out the limits a tad and see what that does for you. Just keep in mind that this is an older drive train and probably won't shift as well as a modern drive train, even when porperly set up.

Good Dirt
 
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