Problem changing gears

[Ben19912]

Hi all, I need help diagnosing a problem on my 2016 Carrera Subway one with 24 gears

I am able to shift all the gears on the cassette with no issues.

I can shift DOWN from gears 2 to 1 on the crankset, but when I try to shift UP the chain just rubs against the front derailleur and I have to hold the shift paddle in to force it to change, I cannot shift up to gear 3 at all, the shift paddle won't even depress fully in when I try to select 3.

also the gear indicater for my crank set does not change when I change gears, the indicator is stuck on '2'

I will reply if you need more info

thanks

 

[Tim Hall]

By gear 3 do you mean the big or small chain ring?

 

[mrandmrspoves]

Disconnect the front gear cable and test movement of cable while disconnected. Likely that rhe cable has frayed or seized and needs replacing. While the cable is disconnected, give the front derailleur a good clean and lubricate and make sure that it moves freely.

 

[PpPete]

From what I recall 3 would be the larger chain ring.
This is most probably a cable issue of some description rather than anything with the shifter or derailleur mechanism - although it could be caused by the derailleur getting a knock somewhere.
Before you start disconnecting anything:
Can you pull the derailleur mechanism outwards with your hands (and lift the chain onto the biggest chain ring) ?
If so, then cable tension (or lack of) is a likely culprit.
If not, then limit screw might (and I stress might) be the issue - but don't go messing with these until you are sure you know what you are doing and there is no other issue (like a cable needing replacing).

 

[Ben19912]

By gear 3 do you mean the big or small chain ring?

the biggest chain ring

 

[Ben19912]

From what I recall 3 would be the larger chain ring.
This is most probably a cable issue of some description rather than anything with the shifter or derailleur mechanism - although it could be caused by the derailleur getting a knock somewhere.
Before you start disconnecting anything:
Can you pull the derailleur mechanism outwards with your hands (and lift the chain onto the biggest chain ring) ?
If so, then cable tension (or lack of) is a likely culprit.
If not, then limit screw might (and I stress might) be the issue - but don't go messing with these until you are sure you know what you are doing and there is no other issue (like a cable needing replacing).

if the problem is a knock then how can I sort it out ?

 

[PpPete]

Er .... knock it back to where it was ?
But don't worry about that for now.

Check the cable as in my previous post.
If you feel confident you can also disconnect the inner cable from the front derailleur and check it runs freely in the outer, as in @mrandmrspoves post.

When you've done those come back and report, preferably with some close-up photos of the front derailleur.

 

[Tim Hall]

To expand on @PpPete 's post, the front mech should be parallel to the chain rings. If it's had a hard knock it might not be.

 

[PpPete]

To expand on @PpPete 's post, the front mech should be parallel to the chain rings. If it's had a hard knock it might not be.

Depending on how it's attached it could also have been moved up or down the seat post. I've seen cases where rider complains of similar symptoms only to find the FD cannot move outwards because it is set so low that the outer cage fouls the larger chain ring.

But before @Ben19912 starts messing about with derailleur position it would be wise to first eliminate the causes which are more likely & easiest to fix.

 

[vickster]

Or an independent LBS if preferred as it's not new from Halfords

 

[Cycleops]

Depending on how it's attached it could also have been moved up or down the seat post. I've seen cases where rider complains of similar symptoms only to find the FD cannot move outwards because it is set so low that the outer cage fouls the larger chain ring.

The cage should clear the outer chainring by about 2mm.

 

[Ben19912]

- cable moves freely when disconnected

- front gear cable is quite slack but unable to make it taut

as you can see from picture the front derailleur does not seem to clear the chain rings,

 

[PpPete]

Does the derailleur move out far enough when you pull the cable under the down-tube (where I've shown the arrow?)

 

[Cycleops]

Looks like there is not enough tension in the cable to pull the cage onto the big ring. You could try to correct this by tensioning the cable at the barrel adjuster on the cable or on the bar shifter depending on where its located. If that doesn't work start from scratch.

Rather than try and explain what to do have a look at this video to adjust it.

View: https://youtu.be/1uPd-m2uKMY


As far as I can see your derailleur cage is parallel and roughly the correct height above the big chain ring.

 

[Ajax Bay]

Try working through this:
https://www.parktool.com/blog/repair-help/front-derailleur-adjustment#article-section-2