Front derailleur shifting issue’s

huntswheelers wrote:

Now that is pretty sloppy…. not putting an inline barrel adjuster in the cable….. typical short cut these days… see it quite often in the workshop…. internal cable run, should be ok… have you also checked the cable guide under the Bottom Bracket for cleanliness?…a bit of wet chain lube helps there…. anyway…sounds to me like the cable is the issue and probably a cheap galvanised one oxidised and giving resistance….  what we do in these circumstances….is to whip the old cable out… pop a barrel adjuster in the outer at the bars….run a new stainless cable thru and hook it up to the front mech…. and adjust accordingly to the makers spec….. 

Some newer shimano front mechs (eg R8000) have a built in tensioner in the form of a small grub screw so in-line adjusters not neccessarily required. 

rob39 wrote:

rob39 wrote:

Thanks folks but its internal cables and no barrel adjuster fitted. From the 32t down to around the 18t sprocket it wants to shift over but just cant make it, lot of rattling and just not engaging with the teeth but from 16t to the 11t shifts fine.

Derailluer is fine

Chain perfect

No one has touched the limit screws

Well then, when the derailleur is on the inner chainring, feel the exposed cable. It should be tight with no play. I suspect that the cable has slipped in the clamp slightly. Undo the clamp, pull cable tight and retighten. Check function again

As Kil0ran suggests it now

As Kil0ran suggests it now sounds like you need to set the cable tension using the cable clamp bolt. Shift onto the small ring, loosen the cable clamp bolt and using a pair of pliers pull the cable tight then do the clamp back up whilst keeping the cable tight. 

Most likely cable tension if
Most likely cable tension if nothing has been knocked out of position. Sometime chain maintenance can also spoil smooth shifting, is the chain well maintained?

If you pull the cable

If you pull the cable manually (assuming you’ve got external routing) will it complete the shift? If so then it’s definitely tension.

Wind out the barrel adjuster half a turn at a time with the chain on the 3rd-to-biggest sprocket and try the shift again. Repeat until it’s clean. If you run out of adjustment, wind the adjuster all the way back in, then half a turn out, then disconnect the cable and reattach. Pay attention to which side of the pinch bolt the cable enters as that’s critical to a clean shift.

Barrel adjuster will either be on the frame near the head tube or near where the cable exits the bar tape. If it’s on the frame double-check you’ve got the correct one as some bikes get set up with the cables crossed (i.e. front mech cable runs to the right hand side of the frame)

If it is tension it won’t need much adjustment if it completes the shift on the smaller cogs. Half a turn and repeat until it’s clean.

Unless someone has fiddled with the limit screws the only other thing it might be is that the derailleur has taken a knock and got slightly out of alignment. Fixing that is a bit more involved – read the Shimano dealer manual (assuming it’s a Shimano FD)

Its not cable stretch. It
Its not cable stretch insofar as adding more tension isnt the way to deal with it. Put it on the small ring and biggest sprocket at back, detach the cable, check that the derailleur doesnt rub at the inside. If it does, adjust the L limits. Wind the barrel adjuster all the way back in, wherever it is. Pull the slack out of the cable, reattach it, then retension the cable with the barrel adjuster again until you get a positive shift. Now check the H limits, so that you dont have any chain rub when in the big ring and small sprocket.