"Simon" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
"Darsh" <[email hidden]> wrote in message news:hiy_9.103878$rM2.49949@rwcrnsc53... <snip>
| > Cable stretch, then returning while you are riding the bike. BS! Cable stretch occurs, but
| > somewhat slowly over the first few
days/weeks/months
Quoted message said:| > (depends on how much you ride) of the life of new cables.
|
| Cable stretch happens IMMEDIATELY. It is not unlike a guitar string.
When
| initially installed, I like to give it an immediate heavy stretch, otherwise, you are tuning
| every 5 minutes for a bit.
|
| Bike cable are not very different. The first shifts in a cables life stretches it more than at
| any point in it's usable life. If the cables
were
Quoted message said:| installed, and given only a few shifts, the cables were never stretched initially. (as I find is
| the case in most LBS builds)
|
| One simple test ride in enough to put rear shifting out of wack.
|
| darsh
|
Darsh your comments got me wondering for a minute there as I always
thought
Quoted message said:cables stretched over time. So I done some searching, reading and noting
and
Quoted message said:found........they do stretch over time. I cant find any references to back up that cables stretch
immediately "only".
They do stretch over time. Don't know why you put 'only' in quotes. I never said only, but I
understand your interpretation of what I wrote.
Of course all through the life of a wound cable, it will stretch. It is obvious that most of this
stretching happens when the cable is new. The stretching of the cable is not consistent throughout
it's life though.
Quoted message said:
I have found through personal experience that prestretched cables do
stretch
Quoted message said:slightly upon first installation and then remain constant, was it this you were referring to?
Prestretched or not, the stretching will occur on initial use, and taper off as the steel settles in
to it's prime elasticity point. Being one of the most elastic substances on the planet, steel
naturally finds it's point of elasticity and holds it for quite some time. It does not hold it
forever, and eventually begins to stretch itself to death.
Take a new rubber band and measure it's circumference. Stretch it nice and tight and release. You
will notice the rubber band has a larger circumference than it did before the test. It did not
retain a lot of it's original elasticity. Now stretch the rubber band again. Now note the change
in circumference. The circumference is larger, but the change is not as considerable as the first
test pull.
This will continue until the rubberband breaks. Sure the rubber looses some of the elasticity as you
test it over and over, but the difference should start to look like a common logarithmic graph.
The cable or rubberband will never remain constant, it will always stretch when stressed, but the
original lose of elasticity is never matched through the life of the cable. The life of the cable
is determined by it's ability to hold it's elastic properties, or when it breaks, whatever
happens first.
Quoted message said:
Would be interested to know which it is.
Don't know if this clarifies something. I am no professor. I only have experience and opinion to
base my findings upon.
I install a new cable and ride about 50 feet down the road shifting like mad, stressing the cable.
It does not take much to stretch the perfectly adjusted, pre-stretched cable to the point of out of
adjustment shifting.
Sometimes I repeat the shifting procedure twice. I then adjust, and the shifting stays where
I want it.
Taking a bike off the rack, riding it on a test and experiencing shifting problems, seems to me a
very common experience.
"So, how did you like it?"
"Well if felt OK, but it didn't shift very well."
"Yea, that is just cable stretch, it happens with new cables. We'll set you up with a free 30-day
tune-up to correct that after the cables settle in."
What bike mechanic/salesman has not had a similar conversation?
darsh
Quoted message said:
Simon.
