STI Cable Issues

Hay Phil

Do you think that Teflon coated cables are worth the extra bucks? I
just installed "aero" brake levers in place of 2 old "not aero" levers,
along w/ new housing & cables. Used hi quality lined Jagwire brake
housing for fr. & rr. For the fr. I installed a drawn stainless steel
non-coated cable. The rr. I discovered didn't have any uncoated road
cables, so I used a Teflon coated one I happened to have. I've always
doubted that coated cables were worth the price over drawn S.S. cables
in lined housings. But I have to admit that the rear brake is smoother
that the front, even though it is 2' longer. I may have to rethink
this.
As to oil or not to oil, I always blow aerosol Tri Flo through the
housing, from both ends. Not so much for the lube but to remove debris
left inside from filling and grinding the ends square & deburing them.
If I had an air compressor, I might not lube them.

Opinions, thoughts, comments.
Thanks, John

john wrote:
Hay Phil

Do you think that Teflon coated cables are worth the extra bucks? I
just installed "aero" brake levers in place of 2 old "not aero"
levers, along w/ new housing & cables. Used hi quality lined Jagwire
brake housing for fr. & rr. For the fr. I installed a drawn stainless
steel non-coated cable. The rr. I discovered didn't have any uncoated
road cables, so I used a Teflon coated one I happened to have. I've
always doubted that coated cables were worth the price over drawn
S.S. cables in lined housings. But I have to admit that the rear
brake is smoother that the front, even though it is 2' longer. I may
have to rethink this.
As to oil or not to oil, I always blow aerosol Tri Flo through the
housing, from both ends. Not so much for the lube but to remove debris
left inside from filling and grinding the ends square & deburing them.
If I had an air compressor, I might not lube them.

Opinions, thoughts, comments.
Thanks, John

I haven't had any experience with Teflon cables. IME, the bends of the
housing at the handlebars exert more drag than anything other factor. Does
your housing on the left and right sides take similar bends? Or does the
rear housing have a straighter path? (not likely). You seem to know what
you're doing. It looks like your Teflon cable is another data point we'll
take into consideration.

Cost-wise, if it's worth the extra couple bucks, then maybe the Teflon would
be a good idea after all, if you don't like to do as much maintenance.

The debris thing you mentioned usually isn't an issue when I grind the
housing down on my bikes, I think because the liner smushes up, sealing out
steel filings during the grinding process. Maybe so, maybe no, I dunno!

--
Phil, Squid-in-Training

Teflon coated cables do not last long. Teflon is a great friction
reducer but the coating is rapidly worn away, leaving the bare steel to
corrode. Oil only hurts because it attracts dirt, causing the coating
to wear faster.

I have NEVER broke a shifter cable when using stainless steel that came
with the original shifters. I found on replacing my 1998 era 9 speed DA
that the original cables had started to corrode (stainless is actually
only corrosion resistant) and might have not made it another
season...but 6 years is quite impressive compared to the old zinc
coated carbon steel of yesteryear.

Yes, steel can fatigue BUT it does have a finite limit, beyond which it
will last forever. This is well-known in the wire rope industry and
applications like elevators NEVER place the wire at radii smaller than
the manufacturer's minimum bend radius. Such is probably the case in
STI/Ergo shifters although I do not know this to be fact. It "looks"
right to me in most cases.

Who brough up mileage? That is about as arbitrary a measure of shifter
use as PowerBar consumption. The fact should be root cause analysis.
If the break looks like a '73 Cutlass in Detroit, chances are fatigue
isn't the cause. Sure, there WILL be broken strands BUT fatigue didn't
cause this failure.

FWIW, I have most problems with housing corrosion. I use Nokon's for
this purpose since they seem to be a better match with my aluminum
frame.


--
Weisse Luft

Weisse Luft wrote:
Teflon coated cables do not last long. Teflon is a great friction
reducer but the coating is rapidly worn away, leaving the bare steel to
corrode. Oil only hurts because it attracts dirt, causing the coating
to wear faster.

I have NEVER broke a shifter cable when using stainless steel that came
with the original shifters. I found on replacing my 1998 era 9 speed DA
that the original cables had started to corrode (stainless is actually
only corrosion resistant) and might have not made it another
season...but 6 years is quite impressive compared to the old zinc
coated carbon steel of yesteryear.

Yes, steel can fatigue BUT it does have a finite limit, beyond which it
will last forever.

not true - /especially/ not true for stainless! many high strength
non-stainless stels don't have fatigue endurance limits either.

This is well-known in the wire rope industry and
applications like elevators NEVER place the wire at radii smaller than
the manufacturer's minimum bend radius.

that's a confusing way of saying it. rope fatigue is well known in the
elevator industry and mitigation requires attention to bend radius, but
it's mitigation, not elimination.

Such is probably the case in
STI/Ergo shifters although I do not know this to be fact. It "looks"
right to me in most cases.

Who brough up mileage? That is about as arbitrary a measure of shifter
use as PowerBar consumption. The fact should be root cause analysis.
If the break looks like a '73 Cutlass in Detroit, chances are fatigue
isn't the cause. Sure, there WILL be broken strands BUT fatigue didn't
cause this failure.

FWIW, I have most problems with housing corrosion. I use Nokon's for
this purpose since they seem to be a better match with my aluminum
frame.

On Tue, 8 Nov 2005 17:52:32 +1100, Weisse Luft
wrote:


Teflon coated cables do not last long. Teflon is a great friction
reducer but the coating is rapidly worn away, leaving the bare steel to
corrode. Oil only hurts because it attracts dirt, causing the coating
to wear faster.

I have NEVER broke a shifter cable when using stainless steel that came
with the original shifters. I found on replacing my 1998 era 9 speed DA
that the original cables had started to corrode (stainless is actually
only corrosion resistant) and might have not made it another
season...but 6 years is quite impressive compared to the old zinc
coated carbon steel of yesteryear.

Yes, steel can fatigue BUT it does have a finite limit, beyond which it
will last forever. This is well-known in the wire rope industry and
applications like elevators NEVER place the wire at radii smaller than
the manufacturer's minimum bend radius. Such is probably the case in
STI/Ergo shifters although I do not know this to be fact. It "looks"
right to me in most cases.

Who brough up mileage? That is about as arbitrary a measure of shifter
use as PowerBar consumption. The fact should be root cause analysis.
If the break looks like a '73 Cutlass in Detroit, chances are fatigue
isn't the cause. Sure, there WILL be broken strands BUT fatigue didn't
cause this failure.
Are you saying that mileage is of no use in determining when a cable
needs to be replaced? Or that mileage and wear don't correspond, in
any way? The amount of shifting would be a factor.

I got 18 months and 5500 miles out of a rear derailleur cable. The
cable was the stock one that came with the DA STI levers. They started
to fray/break up in the lever. In this case, age didn't contribute to
the failure. What did, was a whole lot of shifting in that 5500 miles.
Knowing the mileage and that my riding style is the same, I will most
likely repace the cable at 5000 miles. I used, and have on my shelf,
the replacement Shimano DA shifter cable, which cost a whopping $5.

I shift a lot, for someone who shifts less, they might get twice the
mileage, that I do. I think you may have to take the first cable to
the point of failure, to determine what mileage to use.

The FD cables have failed at 3000 and at 2400 miles. The next one
should go longer, as I found that the cable was rubbing on the Jump
Stop.

It seems to me that time rather than mileage, would be the determining
factor, only when a bike is seldom used. There corrosion might be the
cause.


Life is Good!
Jeff



FWIW, I have most problems with housing corrosion. I use Nokon's for
this purpose since they seem to be a better match with my aluminum
frame.

Weisse Luft wrote:
Who brough up mileage? That is about as arbitrary a measure of shifter
use as PowerBar consumption.

What do you suggest as a better metric?

--
Dave
dvt at psu dot edu

Ya Know, Phil

I never thought of that. I always open up the liner before I start
grinding. And then again slightly after grinding. From now on, I'm
going to not open them up until after grinding.
Good thinking, Phil

John