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Discussion Starter · #1 · (Edited)
Hey guys,
I'm working on a couple of nice, super clean old Ross bikes for an older couple down the court.

broke everything down, cleaned, lubed, reassembled, new cables, etc., etc.
the rear derailleur's good, but when shifting on the front, the chain seems to hop a bit. this is difficult to explain -- it shifts okay, but when it goes up or back down, it lines up fine and the chain moves okay, but it's like it takes a second for the chainring to take up the chain, and it makes a bit of a slapping sound. does that make sense? not sure what's happening here.

these are 10-speeds -- like early generation comfort/cruiser/mountain bikes.
 

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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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Discussion Starter · #3 ·
Squash, thanks for the response.
yeah, 5 rear, 2 front, and correct, no ramps and friction shifters.
I'm getting ready to head out and work on the second one this evening. I'll mess around with the limit screws and see how things work out.

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.
 

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"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
 

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Discussion Starter · #5 ·
well, more that it goes up okay, climbs fine, but it takes a second to settle onto the chainring once it's up. it just sort of snaps in place. looking down on top of the chainring while riding, once you shift, you can see the chain sort of bulging over the "front" teeth until it settles into place, then it's fine. know what I mean? hard to describe.

rear derailleur works fine.

everything went back together okay, bikes are running smoothly. for all intents and purposes, they shift fine, but I'm such a friggin' perfectionist.
 

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OP, the symptoms you are describing are indications of either a worn chainring, or a worn (ie stretched) chain or both.

Typically, the chain will not mesh properly onto the chainring at the 12 o'clock position, but will pop into place at the 3 o'clock position.

Overly worn chainring and chain combinations may also cause binding if you pedal backwards, and may even lock up the drive train. If you continue to pedal further then the chain will pull on the derailleur hanger and snap it.

So, inspect the chainring for the tell-tale sharks tooth pattern (they look thin, sharp and point in one direction).

Also inspect the chain for wear.

Replace as necessary.
 

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Discussion Starter · #7 ·
excellent.
yes, that's exactly what's happening -- popping on at 3 o'clock.
worn chain would make sense. I'm pretty sure they were original from 20+ years ago.
I returned the bikes Saturday morning, but this is great info for the others I'll be working on shortly.

so what about that blanket statement of people saying that you should replace the drivetrain as a whole, to include the chain, cassette and chainrings?

thanks for the input guys.
 
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