datlas 

I think I may be cursed. I have been running Ultegra 6700 on my two road bikes for the past decade. About every 2000-2500 miles, the rear shifting gets fiddly and it won't shift to the smaller 2 or 3 cogs in back, and the cause is ALWAYS a frayed shifter cable. I had thought initially I had a "defective" shifter but when I got my Roubaix it had the same problem. I even replaced the shifters when they were worn, a few years back, but the problem persists.

Fast forward to 2022, I recently put on a full Ultegra R8000 groupset on my main road bike. It works like a dream. I have about 2200 miles on it, and today the SAME THING happened.

I am guessing at this point it's not necessarily a design defect from Shimano, but either I am shifting way more than a typical user, or possibly somehow I am not installing the cable correctly. I always use Shimano parts and am pretty sure I am doing everything right.

Other than jump to electronic shifting, any suggestions or comments??

See pic below of today's cable once I extricated it.

Iride01 

Wasn't that what ST-6700 STI's were known for? Seems like there was one particular model around that time period that had more of that issue than others.

But you say this happened with your newer ST-R8000 after just a few thousand. Hmmmmm...

Might it be that the lower limits of your rear DR's are set to where you have to pull it tight against the stop and that's putting some extra stress on the cable in the STI? IMO, DR's shouldn't have to bump against their limits. Limits are just there to keep them from going too far as a last resort when other stuff has gotten out of whack.

Andrew R Stewart 

Shimano has claimed a service recommendation for a cable replacement about every 1000 miles. So getting double that mileage...

This issue has been known since the previous exposed shift cable versions of their road STI. Some riders seem to have far quicker fraying that others do. We have one customer who years back told me to just replace his shift cables every time he has his bikes serviced, he was waiting till year's end before for this. Now it's about twice a year on his two primary bikes. (He rides about 6,000 miles a year in fairly hilly areas and in any weather).

My suggestion is to make that value judgement between no longer using Shimano road STI levers (they really want you to go DI2) or just replace the cables before 2,000 miles. You can do your own math. Andy

Crankycrank

I am trying out these "Alligator- Superior Shine Slick Stainless" cables. Alligator Shift or Brake Cable Superior Shine Slick Stainless fit Shimano Sram | eBay They have thinner but more strands to fit Shimano and Jagwire housing and I'm hoping this may help them last longer. I only have about 2,500 miles on them now for my 6600 shifters and usually get 4-6K miles from the S or J brands so the jury is still out. Might be worth a try with yours. Shop around as prices have gone up a bit from this seller.

JoeTBM 

Are they Teflon coated cable or do you just grease the hell out of them? You did not mention if you have ever changed the housings. I hope you are using lined housings. for the lower resistance factor. Sorry but that is just nasty looking, surprised you were able to get it out without cutting it.

datlas 

I use Shimano Teflon coated cables. This is a brand new groupset with brand new Shimano housing. The shift action has been light and crisp. I am frustrated but the idea of changing my cable every 1000 miles seems nuts, that’s like every 6 weeks!

Koyote

That's nuts. On the other hand, I've had a current generation 105 11sp rear shifter shred a cable in about 1000 miles. More typically it takes about 3500 miles.

Note that the OP is in PA, which is where I was living until recently. If his/her terrain is like mine was, there is a LOT of shifting. I broke rear cables so often that I considered switching to downtube shifters. But I moved to the Great Plains instead.

datlas 

Oh, I shift plenty. I don’t count, but if each “click” counts as a shift, I expect we are talking several hundred (maybe a thousand) in a 50 mile ride.

wesmamyke

They just do that, like all of them. Really bad cable routing, or full housing that requires more effort will speed it up. I put the Shimano special housing grease on everything, even the new stuff that says not to. Grease it and don't use the teflon cable, they are worse when the coating frays and falls apart.

Troul 

I'm aFRAYed that you'll either need to stock up on cables or go E shift. I am all for staying with the mech cable.

SpedFast

Please keep us posted on their durability. I'm tired of fighting internal cables every year.

Andrew R Stewart 

This issue is not exclusive to modern STI shifters. I've had a couple of, personal, Campy Ergo set ups do the same fraying just below the head. A couple of years ago i replaced new Ergo levers on a customer's bike where this happened. Too bad "the other shop" had installed Shimano cables and the not quite fully broken cable (more, it's head) never was able to be removed, hence the new levers. I've replaced more than a few bar ended and DT located friction shifter cables over the years. You'd be surprised how often a cable's condition is not even thought about by many riders. But the Shimano STI levers (both generations of cable routing) really take the cake on this issue. Andy

cxwrench

I'm amazed you've had this happen multiple times and haven't learned from it. You know how Einstein described insanity right?

dsbrantjr

This is the price we pay for that slick under-bar-tape cable routing, I'm afraid.

cxwrench

Doesn't happen w/ SRAM.

Crankycrank

Will do. When one starts fraying, I'll post the mileage. Might be a few months or ?? from now.

Litespud

I replace the cable on my Chorus 10 rear shifter about annually, but it gives me plenty of warning - either shifting to the smallest sprockets becomes sluggish or frayed strands start to stick out from under the hood and poke my fingers. In any case, I keep a couple of spares on hand and it’s a 5-minute job to cut out the old cable and thread a new one up through the system without having to disturb the housing

datlas 

I was hoping it would be less of a problem with the latest mechanical Ultegra groupset, which I just installed on the bike this spring. Sadly, it's still a problem.

oldschoolbike

I can't say that the Campagnolo stuff goes further before this failure, but I can say that it's a LOT easier to deal with when it does happen. To be specific, that's a Veloce 10-speed vs. Shimano 105 comparison. Don't know about SRAM.

It seems that one should change cables before they break. If you shift a lot, indications are that twice a season changes are wise. That's part of the price for riding STI/Ergo. FWIW, cheap down-tube friction shifter cables fail about once a season too, but give plenty of visual warning (and a few sharp stabs!) and are trivial to change. The better ones lasted years or even decades. Maybe some after-market supplier will figure out how to achieve the same durability for STI/Ergo shifters. Or maybe not, I know I shift several times as frequently on my 10-speed Ergo bike than on my 6-speed friction bike.

roadcrankr

On my 11sp Dura Ace (and previous gen 10sp), I reached about 7k-8k miles to the point of the cable fraying inside the right shifter.
That's when I forgot to simply change it at a regular 5k or 6k interval. My rides consist of many rolling hills, which translates into constant shifting.
It astounds me that Shimano never managed to rectify this design flaw. Sigh...the things we put up with to get nice shifting.
My '71 Gitane and '73 Raleigh have their original cables still! lol

rm -rf

It's the bending where the cable guide turns to make under-the-bar-tape housing possible. My Campagnolo 10 speed did this too. Think bending a coat hanger back and forth, it breaks at the flex point.
I, too, shift a lot on the continuous roller hills and mile long climbs around here. Even on the Campagnolo, I'd often shift for just a couple of pedal strokes, then shift again.

(My Sept 2014 6820 Di2 still shifts perfectly after almost 8 years and more than 30,000 miles. That's kind of amazing to me. Even the derailleurs show no sloppiness or wear in their pivot points or motors. I did replace the seatpost battery after about 4 years.)

cxwrench

Because changing a $4.00 cable once year is such a huge ordeal, right?

oldschoolbike

It IS a huge ordeal, on some Shimano systems at least. Maintainability and repairability should be right up there with reliability and durability.

datlas 

I honestly would not mind changing it once a year. I am chewing through 3/year which I think is a bit much. I read on another forum that there was a Shimano Service Bulletin that said change out cables every 1000 miles. That would solve my problem but NFW I am going to change a cable out every 6 weeks.

masi61

If you are using coated cables where the coating is shredding off then I would think you would also need to replace the housing with each cable change. Are you doing this? Also, I had several of my LBS mechanics recommend (non-coated) burnished stainless derailleur cable that Jagwire makes. I bought a 10 pack last year for a good price. I must be jinxed though because in the past year I have had both front and rear cables break on my Dura Ace 7800 bike and one cable (rear I believe) break on my Dura Ace 7700/Ultegra 6500 bike.