Shimano 105 front chainset shifting problems

[Tcr4x4]

I've booked the bike into the LBS tomorrow, but I'd like to go in with at least some idea of the issue so I don't get bent over.

Basically, I bought the bike the other day and on the test ride I had issues getting from the front middle to the big ring. The guy I bought it from tried it and managed to do it, so I presumed it was just me not being used to it. He mentioned the chainset was pretty dirty, which it was, with loads of built up crud, so I cleaned all that thoroughly.

However today I did 20 miles and ended up doing most of it in the middle ring, as more often than not it just wouldn't go up to the big ring. On a couple of occasions I managed to get it to go by holding the lever over as far as I could for about 15 seconds. Once on the big ring, it changes down to the middle again ok, but not as smooth as I feel it should. I didn't try the granny ring just incase it got stuck there!

Is this as simple as a cable/derailler adjustment or something more sinister?
The Internet is a horrible thing, awash with stories of left shifters breaking and costing a fortune to replace, but I'm not convinced that's my issue.

 

[musa]

No tension in cable. Put in small ring pull fd cable and tighten

 

[the_mikey]

It does sound like cable tension is out, also it's possible the limit screws are not set quite right, it's worth checking.

 

[Tcr4x4]

That's the trouble, at this point in time I don't know what's "right"

I'll let the LBS sort it tomorrow and then I'm going to use an old mtb I have laying around to start practicing on. I dont want to start messing with my main bike incase I screw something up.

Give me a car and I have no problem fixing it, but bikes are baffling to me at the moment!

 

[the_mikey]

I apologise, I hadn't considered my comment well! The LBS may be a good place to start, but in time you can learn to do these jobs yourself.

 

[ianrauk]

Sounds like the bike needs a thorough clean, degrease, relube and new cables.

 

[Tcr4x4]

I've done the clean, degrease and relube bit. I had a quick play earlier and tightened the front derailler cable.

With the bike upsidedown it changed seamlessly, but then on the road it was still hit and miss changing from middle to big cog.

I've dropped it off at the LBS, so hopefully will be sorted for this afternoon.

 

[accountantpete]

Just a mental note for you - the Shimano left hand levers work very well but are known for breaking when any serious pressure is applied. Always make sure everything runs smoothly and the pressure you have to apply to the lever is "gentle".

 

[Tcr4x4]

Well, just picked the bike up from the shop and on the short mile long trip home, I still couldn't get it to change from medium to big. Is there some technique or something I'm lacking?
I tried various gears on the rear, different power of pedalling, no pedalling at all.. Confused!

 

[RecordAceFromNew]

The two most obvious possibilities are: 1) inadequate cable tension, and 2) H limit screw setting out.

Inadequate cable tension manifests itself when you are on the smallest front cog - is the inner cable slack? If it is turn the cable tension adjuster (hopefully there is one on the downtube associated with the front gear cable) anti-clockwise until any slack is taken up. This might be all you need.

If it is not inadequate cable tension then if I were you I would find the H limit screw on the front mech (you should see one marked L and one marked H), and wind it anti-clockwise by 360 degrees, and try shifting on to the large ring, and see if it is easier to engage.

If the above simple steps fix it you should get your money back from your LBS...

For a good and extensive front mech adjustment tutorial see this. If nothing works we will probably need more information about your system.

 

[Tcr4x4]

Thanks, I'll have a look later, just started pouring down with rain here.
Could really do with a bike stand, hard work trying to do stuff otherwise. I got it changing perfectly with the bike upsidedown, just doesn't seem to want to when its being ridden.

The bike shop bloke said it needed a lot of adjustment, but it doesn't seem any better than it was.