Unable to shift out of rear derailleur

[QuirkyBird]

Disclaimer: I am very new to cycling and as such have very little knowledge.

Hi all,

This evening I was going for a cycle on Zwift when the bike randomly stopped functioning as normal.

I was suddenly unable to shift out of the highest gear (smallest cog) on the rear derailleur. I’ve had tried to figure out what has happened but have been unsuccessful.

I’ve included a photo which shows the current tension when on the highest gear.

Is my bike broken? or is this an easy fix?

Any help would be greatly appreciated.

Thanks in advance.

 

[C R]

Disclaimer: I am very new to cycling and as such have very little knowledge.

Hi all,

This evening I was going for a cycle on Zwift when the bike randomly stopped functioning as normal.

I was suddenly unable to shift out of the highest gear (smallest cog) on the rear derailleur. I’ve had tried to figure out what has happened but have been unsuccessful.

I’ve included a photo which shows the current tension when on the highest gear.

View attachment 588580
Is my bike broken? or is this an easy fix?

Any help would be greatly appreciated.

Thanks in advance.

Possibly a broken cable. If you shift to lower gears, does the slack in that cable reduce? Also, photos of the rear derailleur would help. Possibly an easy fix, depending on where the cable is broken, if it is broken.

 

[QuirkyBird]

Possibly a broken cable. If you shift to lower gears, does the slack in that cable reduce? Also, photos of the rear derailleur would help. Possibly an easy fix, depending on where the cable is broken, if it is broken.

Thanks for the quick response.

The slack in the cable does reduce when shifting to lower gears. I can also shift back up gears and see the tension loosen once again. In terms of normality, nothing feels off in terms of the process of shifting.

I've taken a few more photos, hopefully these'll give you some more information:

Thanks in advance.

 

[I like Skol]

Stuck on the smallest cog with loose cable. Either the cable has snapped (could be at the shifter or the rear mech), the cable has slipped at the clamp bolt (rear mech), or one of the cable outers has jumped out of a frame guide. Not much else it could be, unless something extremely weird or unusual has happened.

 

[QuirkyBird]

Stuck on the smallest cog with loose cable. Either the cable has snapped (could be at the shifter or the rear mech), the cable has slipped at the clamp bolt (rear mech), or one of the cable outers has jumped out of a frame guide. Not much else it could be, unless something extremely weird or unusual has happened.

Appreciate the response.

If it were your bike, what would you attempt to tackle / diagnose first?

Thanks.

 

[Arrowfoot]

Unscrew the part arrowed in red. If it is a broken cable, it will come thru when you pull the end. If it is a slack cable then the screw was not tightened well. As you are already in the lowest cog, just pull the cable with a pair of pliers and tighten the screw with tension. If it does not shift, tension it slightly more. Make sure your shifter is at the lowest setting as well. Just click the shifter until the very end.

If it is a broken cable, just bring it to an LBS for quick fix. Or alternatively go to YouTube to find a video on replacing cable.

 

[C R]

From your photos it looks like the cable slipped in the bolt at the derailleur, so follow @Arrowfoot's instructions and you should be sorted.

It's worth checking YouTube for the park tools videos on derailleur indexing to get an understanding of how things work.

 

[Cycleops]

Yes, the cable looks like it’s slipped, the cable sticking out is too short. As above click the shifter into the highest gear and the chain likewise (smallest cog on cassette). Pull cable tight and nip up the bolt. Follow YouTube adjustmen videos.

 

[Salad Dodger]

If it is a broken cable - and others have already suggested other possible causes - then there are some very good YouTube videos explaining how to replace a gear cable.

 

[T4tomo]

or one of the cable outers has jumped out of a frame guide.

I'd check this first (likely to be on downtube, just out of shot in your first picture.... before adjusting the tension at the clamp bolt

 

[uphillstruggler]

the cable ferrule looks very close to the nut - looks like the cable has slipped.

@QuirkyBird did you get it sorted?

 

[Ajax Bay]

In answer to the OP's Q: 'easy fix'. Think the image shows where the cable has been clamped. The cable has slipped: but agree with Skolly and @T4tomo - make sure the outer ends (ferrules) are correctly lodged.
Click the right hand shifter down to the high gear position (eg 8) before applying tension and reclamping. Will need to index gears, which is easy but requires patience.

 

[battered]

As others say the cable has slipped because the clamp bolt has worked loose. If you look at the cable you can see a kink where it used to be clamped. Put it back here, and it will work. You'll need to adjust it for exact function.
While you are fettling, have a look at how it works. It's simple enough. To go from a smaller cog to a bigger one you have to pull the mechanism inwards with the cable. This is what the shifter does, it pulls in a measured amount for each shift. To go to a smaller gear is easy, the shifter releases that much cable and a spring moves the derailleur outwards. In your case the cable has come loose and there is nothing to stop the spring pulling the derailleur all the way outwards, to the right. When the gears are working you have a balance between the spring, which is trying always to pull the chain to the right, and the cable which limits this. They are an opposing pair, like 2 children on a seesaw. Remove either child and the thing doesn't work any more.

 

[rrarider]

If the part marked in red on @Arrowfoot's post id a machine screw with a hex head (requiring a spanner to tighten) it might be a good idea to replace it with a socket head machine screw which can be tightened with an Allen key and lessen the risk of rounding off the screw.