Bicycle Mechanics - Indexed triple chainrings

I frequently have problems getting the indexing right when setting up front mechs, triple chainrings and indexed shifters. often ending up with a shifter that's too hard to push in order to get the mech up onto the largest ring (ie too much tension on cable), and when backing the tension off a bit, can't get the mech to move far enough in order to ride up onto the biggest chainring. It drives me fckn nuts. I dunno if this is to do with parts, it seems to hapen with low-end Sram grip-shifters, some Rapid Rise shifters and others, never in a consistent 'oh, those shifters are arse' fashion, just randomly...
Any hints/sugestions?

check derailleur limit screws first....

ya try adjusting the front derailleur screws they should be marked H and L

I frequently have problems getting the indexing right when setting up front mechs, triple chainrings and indexed shifters. often ending up with a shifter that's too hard to push in order to get the mech up onto the largest ring (ie too much tension on cable), and when backing the tension off a bit, can't get the mech to move far enough in order to ride up onto the biggest chainring. It drives me fckn nuts. I dunno if this is to do with parts, it seems to hapen with low-end Sram grip-shifters, some Rapid Rise shifters and others, never in a consistent 'oh, those shifters are arse' fashion, just randomly...
Any hints/sugestions?

firstly you must make sure that the limit screws are adjusted properly otherwise you may just be fighting your own adjustments when adding tension to the cable. The high limit (H) should be adjusted so that the chain will not be thrown off the cranks, but have enough room for an easy shift into the big ring. with the low (L) you must adjust it so that you can shift into the small ring without dropping the chain as well. In general the derailleur should shadow the chainring which it is in. Also make sure that the derailleur is adjusted in the correct position (verticle on the seat tube) so that it is only 2-3mm above the biggest ring, also check to make sure it is as close to possible parallel to the frame itself (not the chainstays). once you have checked these things then you can fine tune the tension with the barrel adjusters. if it still doesn't work, then you may need to replace the cable housing and cable as they could be rusted/ripped/frayed etc, causing excess friction when shifting. Also it might be worth while to check the grip shifter itself and make sure they is sufficient grease on the body of the shifter.

as a general rule grip shifters are pretty low end and usually do not function 100% correct.... this is what can you expect with low end parts :rolleyes: