Bicycle Mechanics - fine tuning front derailler triple sora

having trouble adjusting front derailer to avoid chain drag against mechanism when on extremes of cluster [cassette] been told by local bike store you get that but i dont buy it i would appreciate any info that could assist in fine tuning. by the way this is the first thread i have posted

how many speed is the bike, how many sprokets in the front. Could be that there are too many gears and the setup can't accomodate for such a change. If so fine tuning wount help, it's eather gonna be rubbing in low or high gears. I have the same problem on my bike cuz it's old and a bit beat up so I can't really do anything about it. My shifter adjust on the fly so when I go riding on trails i set it so my lower hears work good. When I ride on the road I set to so that the higher gears work well.

having trouble adjusting front derailer to avoid chain drag against mechanism when on extremes of cluster [cassette] been told by local bike store you get that but i dont buy it i would appreciate any info that could assist in fine tuning. by the way this is the first thread i have posted
With a triple, it's gonna happen if you use the small cogs when in the small ring and big cogs when in the big ring. There is no trim function in the sora triple levers, so just don't do it. The shop is right,assuming the derailer is properly positioned and aligned, and adjusted.

As a general rule, you should avoid the small chainring-small cog and large chainring-large cog combos whenever possible. These extreme combos put a lot of stress on the chain. Shift into one of those combos and take look at the chain line from the rear of the bike- it's pretty nasty! These combos can lead to accelerated chain and sprocket wear due to the extreme angles that are created with these combos.

It is normal, especially on triples, to have derailleur chain rub when you get closer and closer to these extremes. A triple should have enough gear combos to get you over just about any terrain without any chain rub.

the rear cassette has 8 gears and the front three the bike is a giant ocr3 and has short chain stays being a compact frame which produces huge chain angle.this must have a detrimental wear factor on chain so i do most of my riding in centre chainring and use the small gear for the climbs however there is not a crossver without having the chain rub this setup is standard from giant as i bought the bike new i love this bike and would like to sort this problem out.i guess i should have included more info in original thread. :)