SLX Derailleur - Snapping Cables

[MTBeer]

I have a Trance with 2 x 10. SLX rear derailleur. Since I've had the bike I've had issues with the rear gear cable snapping. I've been through about 5 in the last year and I don't do lots of km's.

So a month ago I take the bike to LBS to check out front derailleur which wasn't shifting lekker despite changing cable, and also look at rear derailleur issues. They show me loads of play in pivots of rear derailleur, so I reckon well that's the problem maybe and get them to put on a new SLX rear and replace all cables and housings.

True as BOB, last weekend the rear gear cable snaps (maybe done 200km since replacement) - luckily at the top of Conters so I could pretty much freewheel home.

Like WTF? Any ideas?

[madmarc]

Where does it snap ?

[ALLMTB]

Check the length and the routing of the rear der cable housing. 

Whoever installed it might not have compensated for the for the suspension, meaning the cable housing might be too short and when the bike cycles through its suspension, especially when full travel is used, it pulls on the housing and the cable can snap.

 

So, remove the rear shock and move the rear wheel up and down and check that the cable housing is not getting pulled tight anywhere. 

[MTBeer]

Where does it snap ?

snaps at clamp point on rear derailleur.

[madmarc]

snaps at clamp point on rear derailleur.

I would hazard a guess that the cable is not being installed or clamped properly. Look on the RD where the cable is clamped and ensure the cable is in the groove under the clamp washer. Many times I have seen the cable is routed on the wrong side and the clamp washer flattens the cable, resulting in it eventually breaking.

 

The cable groove could be on the RD itself or on the clamp washer, depending on the design

[MTBeer]

I would hazard a guess that the cable is not being installed or clamped properly. Look on the RD where the cable is clamped and ensure the cable is in the groove under the clamp washer. Many times I have seen the cable is routed on the wrong side and the clamp washer flattens the cable, resulting in it eventually breaking.

 

The cable groove could be on the RD itself or on the clamp washer, depending on the design

I've checked all that. all good. Even took the clamp washer off and polished it to remove any potential sharp edges.

[Yusran]

snaps at clamp point on rear derailleur.

 

If this is the case then from my experience there are 2 issues:

 

1. The edges of the cable clamp interface are too sharp (bolt/plate edges)

 

2. You are clamping the cable unnecessarily hard

 

 

Solutions I've tried that work are:

 

1. Deburr the cable clamp interface edges with some light sanding, or protect the cable in a protective sleeve - I've used heatshrink (light duty) and pneumatic hose (heavier duty) to do this and it's worked for me every time

 

2. Take it easy on the allen key. In most cases you don't need to torque these things like other fixed parts on the bike; finger tight with a bit of flex in the key will do, the cable won't slip out.

 

 

Some pictures of the culprit would be awesome, and would help us troubleshoot

[MTBeer]

If this is the case then from my experience there are 2 issues:

 

1. The edges of the cable clamp interface are too sharp (bolt/plate edges)

 

2. You are clamping the cable unnecessarily hard

 

 

Solutions I've tried that work are:

 

1. Deburr the cable clamp interface edges with some light sanding, or protect the cable in a protective sleeve - I've used heatshrink (light duty) and pneumatic hose (heavier duty) to do this and it's worked for me every time

 

2. Take it easy on the allen key. In most cases you don't need to torque these things like other fixed parts on the bike; finger tight with a bit of flex in the key will do, the cable won't slip out.

 

 

Some pictures of the culprit would be awesome, and would help us troubleshoot

see my reply above about polishing the clamp.

 

Tightening too much may be a possibility.

[madmarc]

Check the length and the routing of the rear der cable housing. 

Whoever installed it might not have compensated for the for the suspension, meaning the cable housing might be too short and when the bike cycles through its suspension, especially when full travel is used, it pulls on the housing and the cable can snap.

 

So, remove the rear shock and move the rear wheel up and down and check that the cable housing is not getting pulled tight anywhere. 

I disagree, your rear suspension would need serious travel to actually break the cable. The scenario you explain would cause constant ghost shifting while riding.

[madmarc]

I've checked all that. all good. Even took the clamp washer off and polished it to remove any potential sharp edges.

Post some pictures

[Yusran]

see my reply above about polishing the clamp.

 

Tightening too much may be a possibility.

 

Saw it after I posted

 

I have some pneumatic hose if you want to try protect the cable. Your local paintball shop or a place like Hyflo would also be able to give this to you - 1x2mm or 1x3mm air hose. Otherwise x2 layers of heat shrink.

 

Pics! And try with abit less tightening and let us know how it goes

[MTBeer]

will get some hose from Hyflo - just round the corner from where I work.

 

Thanks for the advice.

[Yusran]

will get some hose from Hyflo - just round the corner from where I work.

 

Thanks for the advice.

 

Awesome.

 

After you sheath the cable feel free to clamp as hard necessary.

 

 

Cheers

[BaGearA]

I disagree, your rear suspension would need serious travel to actually break the cable. The scenario you explain would cause constant ghost shifting while riding.

Its more common than you think.

 

And if you run extra housing it won't cause " ghost shifting"