I have my road bike inside right now, all nicely hanging from the bike work stand. I have a YouTube video up that shows me how to completely adjust my front derailleur. It's a good video and, a bit like those cooking shows that illustrate the perfect execution of a recipe, shows me everything I intended on doing to the derailleur, smooth and flawless as anything.
Only not an effing thing has worked on my bike the way the video suggests it should.
Most importantly, having lowered the derailleur cage to the desired height, I am now trying to adjust it with the limiting screws. The screws turn fine, except that the cage itself is not moving. Not a bit. Not on the small front ring; nor on the large front ring. The chain just happily rubs away on the inside of the derailleur cage.
So what am I doing wrong?
You've screwed both screws through their full range?
I believe so. I'll try again to be sure.
You've moved it down and now the cable is too tight so it's not letting the mech hinge in far enough?
What height is mech relative to rings?
Right mech and chain?
What mech? When I fitted a new shimano front mech a couple of weeks ago I figured I'd follow the supplied instructions as they were sitting on the worktop. Worked a treat.
Loosened the cable?
I shall try all these things. The mech is a shimano tiara, and I assume that it was stock when the bike was new (it's a 2006 Trek 1200). I don't think the bike has been worked since. It's not in bad shape; I just don't think the previous owner did any work on it other than basic cleaning.
In any case, I think there is enough play in the cable. The cage is sitting about 2mm above the teeth of the large ring.
We'll see what happens now...
So what am I doing wrong?
Well,you are an academic,so [s]the list is endless[/s] things may take longer 😆 😆
Only joking 😉
Try this one>>> [url= http://roadcyclinguk.com/how-to/maintenance/video-how-to-adjust-a-front-derailleur.html#tGtscmuWzWL1yARe.97 ]front mech moving[/url]
[quote=SaxonRider ]In any case, I think there is enough play in the cable. There is or there isn't. Release the cable from the mech and see if it springs back further towards the frame. If it doesn't, use the limit screw.
Back off both range adjustment screws fully
Release the cable and check that you can manually pull the mech thorugh its full range of movement - roadglue™ can sometimes seize a mech solid (hard to shift - drown it in a beaker of nitromors or else spray repeatedly with GT85/WD40)
Assuming that works smoothly, set the lower limit screw before you even refasten the cable (that way you know it's right and if the mech won't go far enough over later on, it's the fault of cable tension)
attach the cable (with shifter set to "granny" and the adjuster on the shifter screwed in). Pull the cable through with your fingers and get it tightish, fasten the cable bolt and then get all the slack out with your adjuster.
Now pull the cable to "bigring" using your shifter and set the big ring limiter
Done
Have a beer
The mech is a shimano tiara
There's your problem too many sparkly bits. (Auto-correct crosses, I'll nod them in)!
Also may be worth noting that if the video instruction you're following is for a top-swing mech (low clamp on the seat tube), the limit screws will operate the opposite way to the bottom-swing Tiagra mech that you have.Another problem that sometimes occurs with non Shimano chainsets is they have a larger than standard inner or middle ring that can foul on the mech's inner cage when you set the mech to the "correct" height, and prevent it moving.
Thanks to all of you for your advice and suggestions. It seems that everything works, except for the big ring limiter.
The top range adjustment screw simply doesn't move anything.
Is it possible I need a new front mech?
Isn't the top range screw a limiter ? You wouldn't expect it to move anything ? It just stops the mech from swinging so far as to ship the chain onto the crank arm ?
[quote=SaxonRider ]Is it possible I need a new front mech?It's possible but then how daft will you feel if you buy a new one and you can't set that one up either?
Any chance you could post a more detailed explanation of what you started with, what you've done, what you've since done to get it sort of working and exactly what's now wrong?
Failing that - LBS?
The top range adjustment screw simply doesn't move anything.Is it possible I need a new front mech?
I doubt it's broken, it's just an incredible faff.
You'll only notice any movement if the cable tension is tugging the derailleur against the limiter. If it's not, it doesn't matter how much you turn the screw, it's not doing anything.
The way I got it working, I think, was to do it without cable tension and phsically push derailleur away from frame as far as it would go. Then turning the limit screw to make sure derailleur cog lines up over biggest ring.
After that, you can forget about limiter. Any further problems will be cable tension related.
Are you saying you have everything shifting fine apart from being able to limit the mech from throwing your chain off by too much movement? The limit screw doesnt adjust anything, it is merely a stop for the mech. If it doesnt stop the mech then either the screw is too short the part of the mech that it bumps against is missing or bent out of the way.
Here's a thought - are you using a 3-speed shifter on two rings? It might be that you need to re-index to use the first two positions, not the second and third.
top range adjuster only acts to either stop the front mech or else try to "push" it back inwards if you screw it in against the pulling cable - trouble is that the latter is hard to do and you risk buggering up the screw head.
When your cable is pulling the mech onto the big ring, how far over does the cage come - too far, just right or not far enough ?
Check derailleur cage is parallel to chainrings as well as correct height. I've found it tricky to set these up without these two things being spot on to start with
I get the mech set up with both limit screws adjusted out. Then I'll screw the outer limit one in until the derailleur won't shift, and then back it off one turn. I'll generally cross the chain over i.e. big sprocket on the rear and shift into big on the front to ensure it will always shift.
Repeat for the inner limit screw but with the chain on the small sprocket at the rear and test shifting into the granny.
Failing that - LBS?
As always, you have all been great. Thank you. I have learnt a great deal from this thread about my own mechanical incompetence.
LBS it is. I will call them tomorrow morning.
That said, Mrs SR has just suggested I sign up for a local mechanics course in January. So all will be well.
My goal is that one day, I should be able to do something more than just use a pen/keyboard. 
Mech fettling is a right of passage. Sod the lbs and get back to the bike and figure it out yourself!
It'll be one of the screws or the cable 🙂 I'm a Luddite with modern tech, but you've got to be able to set a mech up at the very least.Now go away and don't come back until you've mastered it!
You should have texted me, I'd have sorted it out. Front mechs are ready when you know how.
Make sure it's parallel to the chainrings... Also, some times they are just slightly bent in ways you can't tell, and a new one fixes that.
*cough* "rite"
Look on the bright side, you didn't do this
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Look on the bright side, you didn't do this
Well, it's obviously on the wrong side of the seat tube. Otherwise it looks fine.
Look on the bright side, you didn't do this
Wow. My levels of incompetence have been surpassed. 😯
Fitted while the frame was upside down in the workstand?
Fitted while my head was upside down in the garage
Where are you based OP? I'm in Brum and can help if you are near?
Northwind - Member
Look on the bright side, you didn't do this
No wonder you like a single ring setup!