[Closed] Advice - front derailleur won't shift down

New or old?
Muck and grit in mechs can cause all sorts of issues IME.
Also could be bent...
Have you adjusted the correct limit screw? (not that I would do such a thing 😳 )

Give it a tap, sounds like its stuck.

old ish! front mech is new shifter are 2010 purchase from the bay.

i have deffinatly got the right screw lol with the cable off the mech comes to a solid stop at its bottom but this still dosent seem to be enough to drop it down a ring.

how would i know if its bent? it looks okay

off to give it a tap!

The screww you altered,is it marked H or L?

It's worth working through this guide,it's easy to knock the front mech out of whack. http://www.parktool.com/blog/repair-help/front-derailleur-adjustments.

I had this in spates on my mtb-come-commuter. Couple of causes: 1. Cable was routed under the bottom bracket shell through a small plastic tube that got gunned up, worn and grabbed onto the cable. Resolved by a squirt of WD40. 2. Spring was bunked up and corroded due to salt, again Mr WD40 to the rescue.

screw adjusted is marked L

Tap didnt work - removed AGAIN and there is no grit or shit stopping it. it goes down to its max

Will look through the guide now, thanks thejes

I use one of those shimano round green plastic wedges that come with new mechs(the little bit of ring clearance tape is handy too). As long as the chainline and the cage angle is right solves most fuss.

Have you changed a set up that was previously working or is it a new build?
Is it the right mech for the the chain ring size?
Are the rings old - hooked?
On some full sus too much sag can cause down shift issues.

grime in cables causing it not release properly?

Have you got the cable routed directly?

Where the cable bends round the top before the cable clamp, are you on the correct side of the little torque lever.

It looks the cable should run between the the torque lever and the nut, but it actually goes over the top and then to the nut.

Ive got this same issue on one of my bikes.

Was running a Middleburn RS8 with three rings and all was well. Swapped to a cheap Shimano chainset and cant get granny ring for love or money. Even with the cable unattached and the limit screw wound right off the mech does not move far enough in to line up with the granny.

Tried a new XT mech but no change.

Have fitted a wider BB ie 118mm but still no joy.

Looks like the cheap Shimano chainset is designed for a very different chainline to the Middleburn.

that was a great article on adjusting. followed it word for word and there is a slight improvment. cables were all new a few weeks back. it was working fine on XT set up and this problem has come since new shifters (XTR) as its a stumpy it is a full cable runand it is as smooth as silk

labwormy. the cable is a bottom pull and seems to be routed properly but i dont follow your directions! are they for top pull?

Hi

If I was in the highest gear at the rear (smallest cog) I would not be too concerned if it would not drop onto the middle ring. Maybe you should be looking at changing onto the big ring at the front to keep a better chainline when using the high (small) gears at the rear.

I would definately not be using small ring at the front and small (high gears) at the rear. This would be pulling the chain out of line and wearing the pins in the chain quickly (which will make the possibility of the chain snapping more likely)

If the front mech cage is running parrallel (sp) to the rings and you have set the height correctly approx 2 mm from the top of the big ring to the bottom of the mech cage the mech is set correctly. Then get the chain onto the small ring at the front and big cog at the back. Disconnect the cable. Then adjust the low stop until the cage is barely clear of the chain (not rubbing). Then make sure that the shifter is in low gear (1), reconnect the cable so that there is no slack. Click the shifter to middle ring, if it does not change gear, tighten cable till it does. Jobs a good un 🙂

Adjusting the stops will not have any influence on changing from the big to middle ring. If you have set the cable tension correctly, all should be good. Only a resitance / blockage or the shifter itself would cause this problem.

Hope this makes sense / helps

Been trying to find a picture to explain what I mean and a thread that helped me when mine would not shift down after putting in new cables. Failed I'm afraid.

On my bottom pull XT front derailleur (C 2010) the cable feeds from the bottom and up and over to the bolt/fastener.

There is a small (5-6mm) protrusion near the top, it looks just like a small lip to form a cable clamp with the bolt/fastener.

Route to the inside of it and the gears are all bit impossible to shift down. Route round the outside and all is fine.

You could have another problem of course 🙂

I think i have found the problem. correct me if im wrong, Please.

it is a 73mm shell with a clamp type mech - as such there should be a 2.5mm space on the drive side (the right with the 3 gears)

but what i have is the spacer fitted to the left (non drive side no gears)

what this means is the chain ring is further flet than it should be. changing the spacer around would in effect result in the front bderailleur being further left at its lowset possible setting!?

im a right?

I understand what your saying ray about it not being necessary to go small cog small cog, but, it annoys me that it dosent when it should. as an engineer i have an intollerance to things not working as they should 🙄

Spacer should be drive side

cheers. this came from new fitted this way and didnt come to light with this problem untill i started fitting XT.

i mean XTR

Perhaps the only way to achieve reasonable chainline with the previous components was to set up that way, perhaps just done wrong.

I presume the crank arm on non-drive side has more clearance to the chainstay than the drive- side (with spacer on wrong side of bb shell)?

Had this problem with a cheap tourney chainset, wouldn't shift onto the granny, incorrect chainline I needed a 122mm or something bottom bracket and I even might've put a 2mm spacer in too on the drive side.

Might be worth checking the bottom bracket shell again. Just fitted a new bb to the wife's stumpy (2006) and was surprised to find it was a 68mm.

The thing is its [i]not[/i] supposed to go small cog to small cog, or big to big for that matter. It was ok on older bikes with less gears but with new stuff it just pulls the chain out of line.

It's bound to be the axle length on the BB, assuming its an internal type BB or maybe too many spacers on the drive side of an external BB

Measure the middle ring to centre line of the frame. It should be 50mm. I bet yours measures more. Get a new BB with a suitable shorter axle (internal type)

If its an external BB, measure he shell tube bit the BB screws into. If its 68, you need 2 spacers, one on each side. If its 73mm you don't need any spacers.

Failing that, there is something stuck un the swing mechanism of the front mech.

solved - its an external BB with clamp fitting front mech - have shifted the single 2.5 mm spacer to the drive side and none on the no drive side and its sorted. shifts around in all gears.

I know its not meant to be riden or used in small small or big big cogs but it should at least shft.

what should the measurment be from the centre of the shell to the middle ring with with a 73mm shell and external BB, anyone know?

Old XTR were 50mm, and I think the new ones are the same (3x10).

Glad you got it sorted

cheers Suffolk - not half as glad as i am. wanted it sorted before new brakes and wheels arrive.