Front mech problem on Halfords bike.

[killiekosmos]

Last summer I got my son a cheap bike from Halfords so he could zoom around the park, visit his pals etc.

I had a few problems getting it set up properly: brakes squeaked, gears stiff etc.

During last weekend I decided to give it a check before he starts using it this year. I managed to get most things set up but I'm having a b****r of a job with indexing the front (triple ) mech.

I've undone the cable and set up the lower and upper limits fine. Then I reconnect the cable and take up most of the slack. The change from inner to middle is fine but the jump to outer (biggest) ring takes two hands on the Sram revoshifter (even then it jumps out). I've double checked the outer limit (which seems OK).

I've done this sort of work on 3 other bikes we have with triples and always managed to get good shifting. BUT this is driving me mad - any suggestions? (Apart from 'avoid Halfords')? Have I overlooked anything obvious.

(It's an XC MTB if that matters)

 

[softpeadals]

Put the chain on the inner ring, undo the cable clamp then take up all the slack before reclamping the cable.
I don't understand what you mean by (it jumps out); do you mean the chain drops back onto the middle ring?
If so the above should remedy this.

 

[spandex]

What you did was take up to much of the slack just back off the adjuster and it will be fine.

 

[softpeadals]

What you did was take up to much of the slack just back off the adjuster and it will be fine.

If he slackens the cable it would make it harder to get the chain on the big ring not easier.

 

[fossyant]

Does the mech or shifter move smoothly to the biggest sprocket when the cable is disconnected - you could have something wrong if it's stiff to shift that last sprocket !

 

[spandex]

1) If there is to much tension it will not stay in 3nd. 2) the limit stop is in to far.

 

[softpeadals]

I agree on your second point spandex but I got the impression that the ratchet mechanism in the shifter isn't holding the mech on the big ring. i.e. limited movement of the mech caused by the cable being too slack.
Maybe I misunderstood the OP.

 

[killiekosmos]

Thanks for the suggestions. A few things to try tomorrow.

I think the limit settings are OK.

At present there is a little slack when on the smallest ring and it shifts to middle ring with no problem. The shift to biggest ring takes a lot of effort and it jumps out (probably because the tension is so great).

Thanks again.

 

[killiekosmos]

Problem solved. Too much tension on cable. By trial and error I got it sorted - lots of slack when on the smallest ring and then it changes up to middle and largest ring OK.

Thanks for the suggestions