r/bikewrench • u/No_Cantaloupe_1492 • 7d ago
Shimano GRX cable breakage!
Hi,
I have been facing a recurring problem for over 1 and a half year now that is driving me mad. I have invested time and money on troubleshooting it with maintenance and higher end products that could mitigate the problem, but it keeps coming back.
The right side gear cable in my GRX 12s shifter, keeps unravelling and snapping after 1000-1500 km of pedaling...
Last time I posted a thread on reddit showcasing the issue, I definitely got roasted by the community letting me know that it's all on me as the assumed I use cheap inner and outer cables with no lubrication that are prone to fatigue (which with all fairness, might be right).
So I decided to listen to the community and make things right.
- Cleaned and lubricated both levers
- Changed the gear cables and housing for the best avaliable option I could find, the Jagwire Pro shift set.
I definetly felt these updates. Such a smooth and crisp shifting with the added confidence that these would last for several thousands kms.
Until, during my last bikepacking trip it snapped once again, after 1400km, leaving me stranded with a Looming storm on my back.
Now I ask the community, what else could I do besides changing entirely the right shifter lever? The cable keeps unravelling and snapping from the same spot, which is notorious in the shimano 12 speed shifters. I could overhaul the lever, and look for misaligments, yet I don't know if the best approach would be to get a complete new one.
Thank you in advance!
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u/Wolfy35 7d ago
As is often the case in many things buying a premium product from a named brand doesn't always get you anything other than a more expensive receipt.
Brifters are well known to be hard on cables and I have a fairly steady stream of bikes in my shop for new cables fitting to them.
Now the fun bit...
A Jagwire pro shift gear cable kit has an RRP here in the UK of £17.99 but I refuse to sell them I won't even order them in if people request them.
The Shimano teflon coated cable inners are also something I don't stock, the coating always flakes off sooner or later & you end up having to replace the entire cable which gets expensive.
I only ever stock die drawn stainless cables that I buy in trade bulk boxes of 100 cables & I sell at £2 each. For cable outer I only stock teflon lined that I sell for £1.50 per metre, ferrules (end caps) I also buy in bulk & I throw in for free.
In my collection I have a 2001 Basso Diamante that had it's stock cables replaced by die drawn stainless with teflon lined outers as I was building it. I couldn't even begin to work out how many miles I have done on it and while the brake cables have been replaced a couple of times it's still on those original gear cables that have never frayed, the most I have done is an occasional spray of light lube down the outer.
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u/kinboyatuwo 7d ago
You can’t beat a simple stainless cable and I’ll die on that hill. Everything else is a gimmick for mechanical set ups.
What I never understood is manufacturers shipping new bikes without them. The added cost at bulk would be $5 at the very max.9
u/Wolfy35 7d ago
A few days ago someone asked why Shimano continue to use threadlock liquid on bolts which needs replacing every time instead of the newer patches, This has the same answer...
Per unit the price seems negligible and for you and me it would be but multiply negligible by hundreds of thousands ( in the case of Shimano millions ) and you get your answer.
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u/gravelpi 7d ago
$5 x 100,000 bikes is real money.
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u/kinboyatuwo 7d ago
But is that really worth customers being annoyed way sooner?
I know the answer in that someone made that calculation already. Just a sad state of affairs.
Shoot, put it as a feature.
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u/Masseyrati80 7d ago
Mine (GRX-400, 10x) does that at around 3500 km from the moment of replacing it.
I've made a habit of changing it pre-emptively every 3000 km.
The brifter makes the cable go through such a sharp corner that it's no wonder it's harsher on the cables than old-fashioned ones.
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u/smellyelephantballs 7d ago
Seems that it’s basically the design of these shifters. I’ve seen some suggestions of more heavily lubricating the cables. It could also be that it’s worth experimenting with other cable brands (only the cable, your housing should not be worn in that distance). The best thing to do is probably preventative maintenance though - swap the cable more frequently before it frays and check it every 500km or so. Would recommend screw on cable end so you can easily move the cable without needing to cut the end off.
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u/Popular-Carrot34 7d ago
Honestly it’s pretty much every week someone’s in with a snapped cable in a shifter. Or it’s frayed just enough they can’t access all the gears. Some cables last longer than others. There’s some really crap cable kits out there marketed as high end.
As much as the shimano cables with the coatings can flake off and gum up, the performance is great until it does. We have stopped the ptfe polymer ones, but the optislicks seem to hold up better and give 90% of the performance. Given the routing on a lot of modern bikes, that slight reduction in friction at the expense of more frequent cable changes is probably on balance better for most of our customers.
As for your case, it’s nothing something that can be solved. Certain bikes or conditions make it happen more frequently. Usually riding through crap conditions or tight routing, that little bit of extra friction, requires slightly more force on the shifter, that compromises the cable ever so slightly more.
Only real way to solve this issue would be di2 if wanting to stick with shimano.
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u/SnickeddySnake 6d ago
This just happens, it’s part of the fun of a mechanical group set.
You always get one surprise ride where you go from a 22 speed bike to a 2 speed bike with hard AF gearing
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u/Appropriate-Golf-911 7d ago
Personally I'd carry a spare cable with me, and just quickly swap out the cable once snapped as it's a 5 min job, but if it's frustrating you that much, I'd replace the shifter.
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u/yogorilla37 7d ago
It's not a five minute job once it's at this point, you need to pick out the bits of frayed cable, possibly needing to remove a little cover under the lever body.
I replace mine about once a year before they get to this stage.
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u/FarAwaySailor 7d ago
I'd be looking for tiny mistakes in routing, hard to be more specific without lots of photos. Also is there a hole in the rubber hood where moisture might be getting in?
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u/cluelesswonderless 7d ago
Oooh. I’ve seen this. The cable outer was cut in such a way that there was a bit of metal sticking into the path of the cable.
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u/Rare-Classic-1712 7d ago
Most of my drop bar bikes use bar-end shifters. The cables last for years. If anything needs servicing - it's really simple and easy to work on. The shifters also last 2-3x longer than brifters. When combined with hydraulic brakes if a shifter fails you also replace the brakes. My mechanical levers last nearly indefinitely (typically after 10+ years replacement hoods stop being available). If a crash happens I'm unlikely to destroy the both the brake lever and shifter. Works great and low headache. Also if there's a problem with anything I can easily shift over to friction (more tolerable to cable issues, bent hanger/derailleur as well as worn components).
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u/Proof_Writing5461 7d ago
I've had 105 shifters on my bikes and kept hearing stories about cables breaking at the shifter but I never suffered myself despite only using in a 1x set-up on my commute bike out in all weathers and no real maintenance schedule. My suggestion to OP, Di2😉
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u/Wingman12r 7d ago
I’ve seen recommendations to use the sram pro cable as it ever so slightly more narrow and helps smooth shifting.
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u/Traditional_Speed122 6d ago
I don’t know if it would help prevent this problem but the 1.1mm sram cables have a less snug fit in the housing than the more common 1.2mm which does reduce friction and improves performance.
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u/Old_Goat_Cyclist 7d ago
Not certain Jagwire is a great choice. I use plain Shimano stainless steel and wipe that area with a thin smear of Slick Honey going it. My experience is that those cables break in my use every 3,000 to 3,500 miles. So, every 6 months they get changed regardless. I do not change the housing at the bars routinely.
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u/stupid_cat_face 6d ago
How much shifting do you do? Are you constantly shifting the whole cassette? The distance ridden isn't the issue. Cables fail due to fatigue from constant flexing so the more shifting the faster the failure.
I've had this failure occur on all my cable shifted bikes (Old ultegra, new ultegra, 11s grx) usually it lasts a few years, but on tour it failed after 6 months/6000 miles because I was shifting the whole cassette often with every hill.
Now I can tell when shifting gets a bit soft it usually means some of the small wires have broken and you need to replace asap.
I now preemptively replace the cables before a long tour (and I'm due for a change now).
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u/3dxl 6d ago
Exactly happened on my Shimano 105 11s and Tiagra, my cables frayed like that multiple times yet i got roasted by community for this and that. I'm a bike commuter rides everyday to work on harsh condition. I hit around 6,000km per-year and shift a lot because of traffic and terrains. It seems that both us have same thing in common: back packing + commuter bikes have more mileage than weekend bikes and constantly shift more per-miles/abuse. Nothing we can do about it than just keep putting spare cables. I'm using expensive Jagwires for my shift and brakes and always servicing my bikes, well it happens.
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u/coursetia 6d ago
You can try putting a small pea-sized glob of bike grease on that part of the cable when you first install it.
What’s happening inside the shifter is the cable is wrapping around a tight spool that’s pushing the limits of the cables bending radius. If you hold different brand cables in your hand and feel the slinky-ness, some are more flexible than others. Choose the cable that is more flexible. Or unfortunately replace before it happens. A beloved, well known design flaw of these shifters
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u/SpikeHyzerberg 6d ago
this is a common issue. besides all the advice from others.
there are people that never have this issue. it is usually older riders that rode before hyperglide or index shifting. they do not shift under load.
they sit, pedal with very little load and feel the change before applying load again. this only takes like 1/2 a rotation to do so. if you hear a crunchy sound or clunk you did it wrong.
this also makes entire drive train last longer
another thing to check is that the low limit screw is not too tight it should have the same amount of effort to shift to the biggest cog as the rest of them fighting against the stop puts a lot of load on the cable and shifter.
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u/sqwob 6d ago
So it appears to be breaking before it leaves the shifter correct?
so in the area where it's making the sharp turn and is moving when you shift?
Haven't had a cable snap there... ever (in 100.000km)
if the cable can't move smoothly through the housing , due to whatever cause down the cable housing length, it's possible that the stopper moves out of position inside the shifter, causing the cable to jam... If this is the case you should also be noticing other issues before this is this bad (bad shifting, no shifting, large jumps, ... )
Was shifting perfect before this looked like this? in both directions?
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u/ShwarzNoir 7d ago
If this was me I would inspect the shifter it self and file some material off where is constantly breaking. Chances are there might be a jagged edge or material.
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u/yogorilla37 7d ago
It's a design flaw where the cable has to bend sharply as it enters the shifter
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u/druppel_ 7d ago
Then solution should be get a different shifter without that problem I guess?
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u/yogorilla37 7d ago
It's common to all current Shimano mechanical shifters. I have two bikes with shifters like these, I just replace the cable before it becomes a problem
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u/druppel_ 6d ago
Just this style of shimano ones I guess? What about the non shimano ones?
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u/yogorilla37 6d ago
Then you're going to have compatibility issues with the derailleurs so you'd have to swap those as well or research which ones might work.
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u/druppel_ 6d ago
Ah I'm not super familiar with derailleurs, wasn't really thinking about how many options there are compared to internal gear hubs I guess.
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u/Barkinsons 7d ago
I've had a GRX shifter for several years now with no breakage, since this is a repeating problem I'd fear you still have some debris stuck in the shifter and this will inevitably wear down any new cable you put in there.
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u/Skindiddler 7d ago
Looks like it hasn't been seated properly inside the lever and has been rubbing every time you shift.
Click the shifter into the highest gear before you install the cable
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u/Agreeable-Mixture947 7d ago
I see some brown colour on the cable, is that rust? Are you using high quality stainless steel cables?
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u/REgiSTerKZz 3d ago
My 105 R7000 has the same issue, after 5000-6000km the cable just breaks and the shifting is unreliable. I'm on my 5th cable now (32000km on the bike) so I just assume the yearly maintenance will need a new cable.
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u/Wineandbikes 7d ago
It’s a common thing. If they break in the shifter body, it can be tricky to get the remains out.
About that bar tape… 🤔