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Old 11-15-07, 03:19 PM   #1
xrazer
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Cable worries

I had my rear derailer cable snap off at the brifter recently. Obviously this is getting used more than the front derailer, but should I be concerned about my other cables now including brake cables? Can brake cables snap off similarly? I guess it may be time to replace them all as I have 14 000 miles and almost 2 years use on them.
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Old 11-15-07, 04:05 PM   #2
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Can brake cables snap off similarly? I guess it may be time to replace them all as I have 14 000 miles and almost 2 years use on them.
They don't often but they sure can. I change them about once a year as the $6 total cost is very cheap insurance.
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Old 11-15-07, 08:21 PM   #3
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If it's been that long you might as well replace the housing. On the MB I change all the cables about 3 times a year. Road just once a year.
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Old 11-15-07, 08:46 PM   #4
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I try to change my cables about once a year and they all are butter smooth.
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Old 11-16-07, 01:35 AM   #5
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Originally Posted by xrazer View Post
I had my rear derailer cable snap off at the brifter recently. ...
Do you know what caused the cable to break? For example, was there a wear point or was the cable kinked or perhaps the end stop ripped out?
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Old 11-16-07, 06:16 AM   #6
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They don't often but they sure can. I change them about once a year as the $6 total cost is very cheap insurance.
+1. Easy and cheap to replace. Go with stainless.

Bob
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Old 11-16-07, 08:45 AM   #7
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Can you get a cable that isn't stainless?
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Old 11-16-07, 01:07 PM   #8
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Can you get a cable that isn't stainless?
Of course not. I just like to waste my time stating the obvious.

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Old 11-17-07, 10:53 AM   #9
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Cables usually break at friction points. Typically:
- in either shifters
- where the cable is bolted onto the front derailleur (there is a better line at the rear derailleur)
- near the brake assembly (exactly where depends on brake model)
- in the brake lever.

So inspect visually those spots and feel them with your finger. Check for broken strands. If there are, change the cables; otherwise, you're OK.

As to how often? It depends on how you use your bike. I have bar-end and downtube shifters and shift a lot. My most frequently used bike – 5000-6000 km per year – needs a rear shifter cable every 2-3 years and a front shifter cable every 4-5 years (approx.). As for brakes, I have only changed a rear cable once, after 50 000 km.

I have changed housing more frequently, usually when I either reconfigure the bars and needed different colour, length..., when it is cracked or kinked.
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Old 11-17-07, 05:54 PM   #10
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Can you get a cable that isn't stainless?
Cheap ones are usually zinc coated steel so, yes, you can get cables that aren't stainless.
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Old 11-17-07, 06:11 PM   #11
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Of course not. I just like to waste my time stating the obvious.


Yes actually you can. There are other cables out there with "teflon" coats and other gimmicky doodads that cost much more than just the regular plain stainless cable. They are worthless and a complete waste of money.

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Cheap ones are usually zinc coated steel so, yes, you can get cables that aren't stainless.
+1

Zinc coated steel bolts and cables should be banned from the industry.
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Old 11-17-07, 07:03 PM   #12
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Zinc coated steel bolts and cables should be banned from the industry.
That's the best idea I have heard in a long time. Teflon coated cables right along with it!
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Old 11-17-07, 07:04 PM   #13
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Do you know what caused the cable to break? For example, was there a wear point or was the cable kinked or perhaps the end stop ripped out?
It was just a case of normal wear I guess in the shifter and there were no kinks. After all it had lasted for a long time before breaking.
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Old 11-17-07, 07:45 PM   #14
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Originally Posted by Bobby Lex: Of course not. I just like to waste my time stating the obvious.

[QUOTE=operator;5651626]Yes actually you can. There are other cables out there with "teflon" coats and other gimmicky doodads that cost much more than just the regular plain stainless cable. They are worthless and a complete waste of money./QUOTE]

Guys, please, for the record this () is the sarcastic emoticon.

Bob
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Old 11-17-07, 10:23 PM   #15
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be sure to grease up the cable as you install them!
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Old 11-17-07, 10:25 PM   #16
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[QUOTE=Bobby Lex;5652097]Originally Posted by Bobby Lex: Of course not. I just like to waste my time stating the obvious.

Quote:
Originally Posted by operator View Post
Yes actually you can. There are other cables out there with "teflon" coats and other gimmicky doodads that cost much more than just the regular plain stainless cable. They are worthless and a complete waste of money./QUOTE]

Guys, please, for the record this () is the sarcastic emoticon.

Bob
The markup says it's rolleyes which indicates derision. But I get your point.
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Old 11-17-07, 11:33 PM   #17
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Brifter cable wraps tightly around a small diameter drum and with its smaller diameter,
the brifter is a high stress area where cable breaks are common. The brake cable are
larger diameter and more of straight pull in the brifter, or a more gentle curve. Brake
cables will last years longer than brifter cables but an annual pull out of the cables and
exam is a good idea. The L shifter cable will last significantly longer than the R shifter
cable but much shorter time than the brake cables.
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Old 11-18-07, 01:33 AM   #18
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I replace the cables and housings about twice a year on my road bike. But then again, it does see about 15,000-20,000 miles of use per year.
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Old 11-18-07, 01:48 AM   #19
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be sure to grease up the cable as you install them!
Not so for modern cables, as far as I am aware. In fact, the grease can be an inhibitor in shifting. The plastic liner on the standard Shimano outers and the stainless steel cables take care of the anti-friction needs. Grease only if you are installing galvanised wire in unlined outers -- which is very definitely unlikely in this case.

I use the Dura-Ace cables that come only in silver outers. It's about all I can afford that is of Dura-Ace level.

Breakages of the mushroom tip from the end of shifter cables are not so unusual. I have had probably four go in around 86,000 accumualted km in the past 10 years. Two were on MTB shifters, and two have been on Tiagra shifters. The diameter of the little pulleywheel inside the shifters that pulls the cable is quite small, and the end of the cable almost needs to kink to get round it.

Regular replacement is the solution. And it all depends on how far you ride a year. If your bike does 2000km, maybe once every two or three years; if it does 16,000km, replace them every year or even more often.

As to other cables -- the brake cables are beefier and the mushroom is larger in proportion. The stresses are somewhat less on the ends of the brake cables because they are more a direct pull than a wrap-around pull like on the shifters. So, they should last quite a bit longer, provided you use cable ends at the brake ends. I probably run up to 10,000km on my most-used bike before thinking about brake cable replacement.
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Old 11-18-07, 09:15 AM   #20
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The Shimano instructions included with new parts say grease the cables. All those pages are on the web.

This is only one example of the Shimano instructions telling you to grease all cables during installation. It is the instructions for the new STI shifters. The cable instructions are on the upper left in a box. Shimano includes this with new parts. They tell you to grease the cables. The new Dura Ace shift cables are grease filled from the factory with a special grease. It's on this page as well

http://techdocs.shimano.com/media/te...9830621413.pdf
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Old 11-18-07, 09:29 AM   #21
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[QUOTE=Bobby Lex;5652097]Originally Posted by Bobby Lex: Of course not. I just like to waste my time stating the obvious.

Quote:
Originally Posted by operator View Post
Yes actually you can. There are other cables out there with "teflon" coats and other gimmicky doodads that cost much more than just the regular plain stainless cable. They are worthless and a complete waste of money./QUOTE]

Guys, please, for the record this () is the sarcastic emoticon.

Bob
Hopefully you were using barbless hooks ;-)
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Old 11-18-07, 11:11 AM   #22
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I would check your shifter. Something is going on there. I have never had a cable, either shifter or brake cable break. It is by far the strongest component of a brake or shifting mechanist. You will break a brake mechanism or the shifter before you break a properly installed cable. The very light loads that modern brifters put on cables will not break them.

I have had cables last for years of average use with no problems whatever.
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Old 11-18-07, 11:30 AM   #23
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The Shimano instructions included with new parts say grease the cables. All those pages are on the web.

This is only one example of the Shimano instructions telling you to grease all cables during installation. It is the instructions for the new STI shifters. The cable instructions are on the upper left in a box. Shimano includes this with new parts. They tell you to grease the cables. The new Dura Ace shift cables are grease filled from the factory with a special grease. It's on this page as well

http://techdocs.shimano.com/media/te...9830621413.pdf
The doc specifically says ONLY use SIS-SP41 and warns against using dura-ace grease. I've never seen this grease before - can anyone comment if shimano is just b.s'ing this requirement (e.g you can substitute anything) or is it really a requirement for proper shifting.
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Old 11-18-07, 03:18 PM   #24
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I would check your shifter. Something is going on there. I have never had a cable, either shifter or brake cable break. It is by far the strongest component of a brake or shifting mechanist. You will break a brake mechanism or the shifter before you break a properly installed cable. The very light loads that modern brifters put on cables will not break them.

I have had cables last for years of average use with no problems whatever.
If one shifts frequently the cable just wears out where it goes around the small diameter corner in the shifting drum in about 7,000 or 6,000 miles. It just bends sharply too many times and the strands start to break from flexing, not a hard pulling force. This is were it bends much more than any other place.

Quote:
Originally Posted by operator
The doc specifically says ONLY use SIS-SP41 and warns against using dura-ace grease. I've never seen this grease before - can anyone comment if shimano is just b.s'ing this requirement (e.g you can substitute anything) or is it really a requirement for proper shifting.
Can you get a Shimano "2006 Bicycle components trade sales & support manual" ? The grey soft cover book. I know this is not an answer but, it's all I have right now.

page 129 says

"SIS-SP41 cable housing--- The cable housing with silicone grease reduces the cable friction by 10%"
It says use this for Dura-Ace, Ultegra, and 105 doubles and triples. It does not mention it for Sora or Tiagra.

Page 125 has a cut away drawing and a few "benefits" (claims?) about the pre greased cables. It says--

"Special silicon based grease is injected into the shifting outer casing to significantly decrease cable resistance. Combined with the wide link derailleur designs (RD-7800/6600/5600) ads key advantages: crisp instantanious shifts that are 10% more efficent from lever to derailleur"

my words- the wider derailleur links make the derailleur stiffer and makes for better shifting. It's in other places in the book.

I think the silicone grease keeps a more even viscosity in a wider range of temperatures. Maybe the silicone grease does not mix well with other grease? My memory is a little fuzzy on that detail, but I think that's right. I think it's not absolutly needed, but it is an improvement. That's just a guess.
They show the pre greased cables and "special grease" next to the "dura ace grease' and the"special freehub body grease" - not the same as either of the other two.
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Old 11-19-07, 01:54 AM   #25
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The Shimano instructions included with new parts say grease the cables. All those pages are on the web.

This is only one example of the Shimano instructions telling you to grease all cables during installation. It is the instructions for the new STI shifters. The cable instructions are on the upper left in a box. Shimano includes this with new parts. They tell you to grease the cables. The new Dura Ace shift cables are grease filled from the factory with a special grease. It's on this page as well

http://techdocs.shimano.com/media/te...9830621413.pdf
I stand corrected.
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