awer1

Hi helpful people of Bikeforums.

I have a right annoying inexplicable front mech issue that I have failed to get my head round as have all the mechanics at the bike shop I work at. I hope that the wealth of knowledge on here may be able to shine some light on this...

I have recently changed the drive train on my touring bike [a Trek 520] from Shimano 105 chainset and Deore LX rear mech to SLX rear mech and Deore XT front mech with SLX triple chainset.

But much to my chagrin after much tweaking and setting up the mech does not want to shift down from the middle chain ring to the inner chain ring when riding under load [slight hill etc] although it's fine in a bike stand.

The derailleur wobbles and hesitates as if the spring tension is not up to the job before finally snapping [alarmingly] onto the chainring or not at all. I am using Dura Ace bar end shifters which are friction shifters with a new cable.

I swapped out the Deore XT front mech with a SLX front mech today to see if the mech was the cause and it's not made much difference. the shifting is far from smooth and the shifter still wavers.

I would greatly appreciate any input from anyone with some idea of what maybe the problem as I really need to get the bike set up for a tour of China I am planning this Summer.

Pictures can be added if it will help illustrate the set up.

Thank you,

Jon.