Quote:
Originally Posted by dddd
On the subject from another thread/topic (of worn-out shifters, and the related premature failure of cables), I find that both of these problems relate to the habit or tendency of mechanics and (owner/mechanics) leaving the low-limit (hi limit in front) screw too tightly adjusted.
Thus, there is no overshift movement allowed at the derailers, which puts tremendously increased stress on cables and shifter mechanisms, and even forces cables/housings and shifter detents to endure cyclic overloading as the rider pedals and flexes the frame.
I would like to say that this is just an amateur's mistake, but no, I still see bikes coming from this or that shop (not all shops) with the limit screws set "on the safe side" with respect to chain control, the "better" to keep the chain out of the spokes and off of the crankarm.
So if anyone has wondered why today's shifters seem to eat cables, or why their Ergolever detent springs don't last as long as they should, this is the main reason, from what I have seen.
Also note that Shimano is addressing this with cable travel-limiting stops now incorporated in their latest STI shifters, and with their front derailers no longer even having a hi-limit screw. The hi-limit screw having been replaced by the lever's own limit stop, and the hi-limit function of cage travel limit now being adjusted via a booster screw that adjusts cage travel from the push side instead of using a screw stop, and with a separate cable-adjusting spool screw.
Leaving the derailers free to overshift slightly eases the force at the lever to the largest cog or chainring, which further helps the rider adapt to a consistently less ham-fisted use of the levers while shifting "up" to larger sprockets, so cabling (and the service interval of cable adjustments) can last a whole lot longer.
Does anyone else here find it strange that this issue seems to never get mentioned?
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I think it does get mentioned in that limit screws for low gear cogs or big ring, the limit screw should be turned in so it just gently touches the stop, along with a thumb on rear der to make sure a thumb force can't have the der even tickle the spokes. Most chain shuck off big ring is front der alignment/height, not limit screw.
I think at least as responsible is the 'busy' cable spool routing of the STI that are 'famous' for breaking/fraying cables...7800/6600/9000...
And broken spring carriers for 2008 and older ERGO...glad the 2009 US don't have these. Nothing in there to really 'break' except shift lever blades('fiber ones) or thumb buttons(rusty pivots), and those are replaceable.
I have all the parts for 1992-2017 ERGO-shameless pitch...