I have a Ultegra SL rear derailer, it is a 20 speed bike.
The bike shifts smoothly and is quiet except for when I am in the smallest ring up front and the biggest gear on the cassette. Does it a little less when in the big ring up front.
Then it makes a clicking, almost baseball card in the spokes sound.
I cannot replicate this on the stand, it has to be when under a lot of power. I cannot replicate it by pedaling backwards.
I removed the plastic spoke protector thinking that could be it.
The bike is a few months old and just started doing this.
Anyone have an idea?
Be very careful if you adjust the low limit screw. If you back it out too much you could throw the chain into the spokes.
Try adjusting the "B" screw to add clearance between the derailleur pulley and the largest cog.
Try adding a bit of tension to the shift cable with 1/2 counter-clockwise turn on the barrel adjuster. If you turn it too far shifting will become sluggish going to smaller cogs.