FatBottomedGirl

Quick question here: as long as the chain *never* falls towards the bracket, and as long as shifting from small to middle and from middle to large rings works smoothly, is there anything such as a too loose LOW screw setting?
Because on my derailleur, small to middle, middle to large, large to middle shift very smoothly but middle to small is a bit harder.
The chain is not even remotely threatening to fall towards the bracket, so can I go as loose as I can to improve this exact downshifting?

Phil_gretz

FBG-
Understanding the spirit of your question, the answer is that no, in principle, the LOW adjustment screw cannot be too loose. But in practice, yes, it is too loose if it no longer makes contact with the little cam mechanism that is the lower limit stop for the cage movement. Too loose a screw, in the extreme, could rattle loose and fall out, I guess.

The correct setting is found when the shifter is set to its innermost (slackest cable) gear, and the cable anchor bolt is loosened until the cable tension is released. Then the LOW setting screw is adjusted so that when the rear derailleur is shifted into the LARGEST, innermost cog and the chain is on the front SMALLEST, innermost chainring, the front derailleur cage just clears the inside edge of the chain by a millimeter or so. Then the front derailleur cable is drawn tight again (grabbing with needlenose pliers and pulling and holding it firmly) while the cable anchor bolt is retightened.

That should give the proper shift between the inner and middle rings...

Hope that this helps you.

There are videos and manufacturer's spec sheets available on the web to illustrate this. Your bike shop can show you the procedure, too.

e_guevara

Seems like the LOW limit screw is too far in. How did you get the chain down to the smallest ring in the first place? Check also the cable tension as it may be preventing the derailleur cage from swinging back in. Is there an inline adjuster? Try to loosen it a bit and see if it fixes things.

With the chain on the smallest ring-biggest cog combo the chain should "just" intermittently brush against the FD's inner plate. Loosen the cable then adjust the LOW limit screw until so.

Parktool has a very good tutorial on how to adjust your front derailleur.

cny-bikeman

On a front derailleur proper shifting is not a matter of only limit screw settings. You must first confirm that the height and rotation are correct. The Park tool site will also explain how to determine that. Don't skip that part, and you should also confirm that the shift cable has low enough friction so as to not interfere with the downshift, which is completely spring-driven.

HillRider

Assuming the front derailleur isn't hitting the seattube and can't move inward far enough, the low limit screw should be set to allow a firm middle to small shift. A worthwhile precaution for any triple (or even compact doubles) is to install a "chain watcher" such as the Third Eye, N-Gear Jump Stop, etc. that will positively prevent the chain from derailing inboard.

bradtx

FBG, The low limiting screw only effects downshifts to the innermost chain ring. I like to set it before attaching the shifter cable and generally start with the chain just NOT completly shifting onto the chain ring. I'll then adjust it more finely to allow a complete shift taking into account different chain positions on the rear cogs. The main reason for this is to prevent the possibility of the inner travel of the FD being determined by a taut shifter cable alone.

Brad