Shimano altus 24 speed gearing problems

[sannesley]

Hi,

Bought a Carerra Subway 2 out of Halfords last Summer and it has worked flawlessly until about a week ago when it started to develop a fault with the gearing.

When the chain is on the largest ring of the cassette, i.e. gear 1 it only registers as being in gear 2 on the gear selector at the handlebars. In addition the chain will not drop down onto the lowest ring of the cassette at all. I fettled a bit at home to try and correct it and took it back to Halfords yesterday where they charged £6 for their services.

Took it home and tried it on the street and have to say the problem is still there and in addition the chain can slip off the largest ring of the cassette which it never managed to do before it went into Halfords.

Any suggestions as to what the problem could be. Normally I wouldn't criticize Halfords as the normal guys in the bike section are very helpful and knowledgable. The guy on duty yesterday wasn't one of the regulars. Looks like its back to Halfords with the bike

 

[martint235]

Hi,

Bought a Carerra Subway 2 out of Halfords last Summer and it has worked flawlessly until about a week ago when it started to develop a fault with the gearing.

When the chain is on the largest ring of the cassette, i.e. gear 1 it only registers as being in gear 2 on the gear selector at the handlebars. In addition the chain will not drop down onto the lowest ring of the cassette at all. I fettled a bit at home to try and correct it and took it back to Halfords yesterday where they charged £6 for their services.

Took it home and tried it on the street and have to say the problem is still there and in addition the chain can slip off the largest ring of the cassette which it never managed to do before it went into Halfords.

Any suggestions as to what the problem could be. Normally I wouldn't criticize Halfords as the normal guys in the bike section are very helpful and knowledgable. The guy on duty yesterday wasn't one of the regulars. Looks like its back to Halfords with the bike

Ok first off, switch until the gear selector suggests you should be on the smallest cog. Undo the cable on the derailleur and pull it as tight as you can with your hands and then tighten it up again. That should have reset your gear selectors.

Next shift it into what you are referring to as gear 1. Does the chain still slip off? If yes, then on the derailleur you'll see two screws (often marked H and L). Tighten the one closest to the wheel by a quarter turn. See if the chain still slips off, if yes another quarter turn.

Now just to check all the gears are ok, switch down the cassette and back up. If there is any bit where the chain struggles to move you'll need to turn the barrel adjuster (may be at the bars or at the derailleur). If the chain isn't shifting to larger cogs properly turn the adjuster anti clockwise, clockwise if it's an issue shifting down the cassette.

Don't take it to Halfords.

 

[sannesley]

Don't take it to Halfords.

Martin thanks for that. I agree with you about Halfords; But in this instance there's the issue of my paying for a service from Halfords which in my opinion I did not receive, i.e., to get the rear gears indexing properly. This means I will have to revisit them to either get a refund or get them to do the job properly second time round.

Depending on how it works out I'd be inclined to take a refund and try your solution at home. TBH I'm worried that I will mess up the gears and have to end up taking it to my LBS instead of Halfords to then get it sorted.

 

[sannesley]

Is the threaded tubing on the barrel adjuster at the rear derailleur supposed to be able to come free of the main derailleur body? If I turn the barrel adjuster too much the threaded tubing comes away from the barrel adjuster.

 

[martint235]

Is the threaded tubing on the barrel adjuster at the rear derailleur supposed to be able to come free of the main derailleur body? If I turn the barrel adjuster too much the threaded tubing comes away from the barrel adjuster.

Yes it all comes apart if you unscrew it. You should aim for halfway in then it gives you leeway in both directions.

I always used to mess my gears up until someone explained the hand tightening the cable when on the smallest cog effectively resets them. After that it's just a bit of fine adjustment and nothing to worry about.

It's always worth building up that relationship with your LBS though, you never know when you may need them.

And to be honest, I'd be happy writing off the £6 just so I didn't have to go near Halfords again.

 

[sannesley]

Well I went back to Halfords and one of the full time bike mechanics was at the desk this morning. I explained the problem and he smiled and I could tell from his expression that he though that the other guy basically didn't have a clue about bikes even though he'd been on the training.

Anyhow he carried out the procedure you described and I'd have no problem doing the same at home the next time I have a gear issue as I already have all the bike stand and tools at home.

Thanks for the help.

 

[JMAG]

Ok first off, switch until the gear selector suggests you should be on the smallest cog. Undo the cable on the derailleur and pull it as tight as you can with your hands and then tighten it up again. That should have reset your gear selectors.

Great advice. I would just make clear that you want to leave the chain on one of the middle cogs when you move the gear selector to the position for the smallest cog as this will create the slack necessary to be able to pull the cable by hand. Don't do what I used to do and grab the cable end with pliers to pull it tight as you will probably pull the end cap off and cause the cable end to fray.