Front Mech Annoying Adjustment Problems!
 

Hello,

I recently tried to re-adjust my front mech. Ive done this a few times now and it has been fine, but Im either doing something wrong now, or something is broken! Its a shimano ultegra front mech with shimano 105 flightdeck shifters.

So I decided to fit a new cable etc. Did it all, set the low, tightened the cable, tried shifting to the highest (big ring) and it just would not go that far - even with the limiter screw all the way out. I literally tried for hours, playing about with cable tension etc, then I realised that the end ferrules going into the shifter had broken and the housing cable was pulling through - I think as a result of pushing the shifter too much to try and get it into the highest gear. So I replaced this etc, but still it will not work well.

If i set the low limiter too tight, then it just about gets into the highest gear, but it wont go back down to the lowest and vice versa. The barrel adjuster is also extremely hard to turn - think it needs replaced, but I dont think it is causing any problem.

So I am now left able to shift from low - middle - (alot of clicking) - high then back from High - low, completely skipping the middle ring. It is proving to be an absolute ball-ache and I just cant figure out where Im going wrong! Help need urgently!

Thank you.

A few things to look at, Is the cable routed correctly into the FD clamp? Is the FD mounted close enough to the chain rings. Is your shifter actually in the bottom position before you tension the cable?

Hi, the cable is attached in the clamp correctly - the fd is in the correct position - 2-3 mm from the large ring - and yes, the shifter and barrel adjuster are both reset to the bottom.

Sounds like the shifter isn't pulling enough cable. Early on in Shimano's progression to STI shifters the front ders had two different cable anchoring specs. The friction DT levers would use the common cable routing over the anchor bolt. But when STI levers were installed the same ft der needed the cable routed UNDER the anchor bolt to have enough cage travel.

I don't remember all the model numbers that needed this mod but it could be your set up is such a combo. Also your STI levers are old enough so that their internal functions might be starting to fail in that the factory lube can be getting gummy. This stickiness causes the ratchets to not engage and only some of no cable pull will be kept when the lever is released.

I don't think this second possibility is going on but... Andy.

Yes, it seemed to me that the shifter wasnt pulling the cable far enough across - it was as if the high limit screw was too tight, however, this is not the case. So currently the cable is coming up from the bottom and going straight up. I will try and change it so there is more pull by changing the way the cable is clamped by the bolt. Cheers

something you said in
your description of the problem
makes me think you are not 100% clear on how the fd functions

low limit screw has no effect on ability to reach high gear
and vice versa
unless you are repositioning the cable
every time you set the limit screws

How old is the Ultegra front derailleur? Is there a part number stamped on it?
Are your chainrings spaced an appropriate amount away from the seattube? From the center of the seattube to the center of the middle chainring should typically be 45mm for a road triple.

Forget about the limit screws as you adjust it - back them both out and set them after it shifts right. If the alternate cable routing with the shorter lever arm doesn't work you may need to look at the DR position.

The last paragraph in my amateur opinion sounds like cable friction or the shifter is gummed up (WD-40!)

Wilfred - Your probably right, im not 100% sure, however, when setting the low limit, it shifts the dr outwards - this ultimately affects how far across the dr will go, or am I incorrect?

wphamilton - If I loosen all the screws then the dr's positioning is pulled right in close to the frame and therefore, the shifter cannot pull it far enough across to reach the big ring - Should I then adjust the cable tension?

Thanks

yes
you are incorrect

the low limit screw only affects how far the derailleur moves inward
and the high limit screw only affects how far it can move outward

a limit screw only has effect on the derailleur
when it is at the limit
and has no effect between limits

edit

if you post a couple of pictures of the derailleur
and how the cable is routed and clamped
it might give someone a better idea