Top and bottom gears issue..

[jal238]

Hello, I'm new here so please forgive me if I don't know what i'm doing.
I own a Carrera Virtuoso road bike and since today i'm having a problem with it. Basically, it started when i made the daft mistake of trying to change down gears whilst the bike wasn't moving. After this, the gears were stuck in the higher gears: 5, 6, 7 & 8 (smallest gear sizes). I looked up the adjustment screws and how they work online and had a go at adjusting them for a while, now I seem to have mostly fixed it, but I have a new problem which is that I cannot get it to go into the highest or lowest gears. I have tried adjusting the 'H-limit screw' and 'L-limit screw' but i cannot adjust them any further than their current position. Any ideas on how I might fix this?

 

[Salty seadog]

Have a look at this video on you tube, it clearly and simply explains how to index your gears from scratch and is how I learned.

View: https://www.youtube.com/watch?feature=player_embedded&v=SkzvfCaIbyQ

 

[Kookas]

If you haven't got the highest gear or the lowest gear in spite of messing with the limit screws, I don't think any amount of indexing will fix it. A bike shop could tell you what's been damaged.

 

[andrew_s]

The original problem will be that the cable slipped in the rear mech clamp. Tight enough to hold against the rear mech spring isn't necessarily tight enough to hold against your hand trying to force a change.

As for now, it's probably best to go back to the beginning and re-index from scratch.
Either the video above (which I haven't watched), or...
a) unclamp the cable and loosen both H and L limit screws
b) put the shifter and chain into top gear
c) adjust the H-limit screw so that the mech is directly below the top gear sprocket
d) screw the cable adjuster on the rear mech all the way in
e) pull the cable tight and clamp it. Take care that there isn't a housing end resting on the edge of a cable stop rather than properly seated in it.
f) screw out the cable adjuster enough that the rear mech just starts to move, then back in a smidgen
g) with the bike in a stand, or upside down if you haven't got a stand, change gear up and down to check that the chain will go back into top gear. If it doesn't, undo the H-limit screw a little until it does
h) Change the gear completely across the cassette, both up and down, one gear at a time, and adjust the cable adjuster in small steps until you get a clean change into all gears. Screwing the adjuster in will move the mech towards high gears, screwing it out will move it towards low gears.
i) Change into bottom gear, and screw the L-limit screw in until you feel it touch the mech stop, then back it off a bit. The purpose of the limit screws is not to decide what gear you are in, but just to stop the chain falling off the end of the cassette.

 

[jal238]

Unfortunately, I can't try it out right now, but i'll have a go as soon as I can.
Thanks to all of you for your help

 

[Trull]

If (with the rear wheel removed) you can't simply push the derailleur over the range you need then you need a quick visit to your LBS, or at least look at the underside of the rear mech to see the limiter screws stopping the cage moving. Once you see how it works you'll be right in there with a screwdriver and you'll probably figure out what's wrong. I'd be shocked if the problem is a broken hanger, perhaps its all in the cables (in which case a complete change will leave you change from a tenner). Good luck!

 

[smokeysmoo]

Could be a sticky cable as well. The last section of outer cable before the rear mech is a favourite for corrosion and causing the cable to stick inside.

Pull the cable through and flush with WD or similar, or better still if in doubt just replace the section of outer.

FWIW I had a sticky cable once but since then I put a dab of grease on the open ends of that cable now and then and it's never happened since.

 

[jal238]

I've had a go at that now, thanks for the information. Unfortunately, it hasn't quite worked. Now what happens is that with the tension adjuster; in order to get the shifter to change down properly, i have to have it on almost maximum tension (turned anticlockwise so it nearly comes undone)m but to get it to change up again i have to adjust the tension again so that it is almost completely turned clockwise... Any ideas?

 

[Globalti]

Sounds like a sticky cable. How often did you change the cable outer at the rear derailleur during the winter? Never, I bet?

 

[jal238]

Possibly, though I doubt it - i've only had the bike since september. Either way, I'll be taking it back to Halfords and i'll let them have a look at it.

 

[smokeysmoo]

Possibly, though I doubt it - I've only had the bike since September.

I once seized the last section of gear cable on a brand new bike within 2 weeks!

It had been very wet though and I was very inexperienced with such matters

I'll be taking it back to Halfords and i'll let them have a look at it.

No worries, but remember that very few Halfords are upto par when it comes to bike fettling.

FWIW I'd ask them to replace that last piece of outer cable for you, they won't do it off their own back and for what it'll cost it'll give you peace of mind.

 

[jal238]

Okay, thank you, I'll keep that in mind