Bobfjt

Hi,

Recently, I replaced my bike shifter and derailluers, using a microSHIFT R8 (2x8) system. I found that the R8 shifter for the front derailluer has a half shifting position between low and high chainrings. I can up-shifting to that position from the low, but can not find a method to down-shifting to that position from high. Does anyone know and teach me how to do it, please?

Thank you.

Broctoon

It’s called trim. There is an inner position, inner trim position, and outer position. It allows for a somewhat cross-chain situation without rubbing on the derailleur cage.

My 11 speed Campy Centaur works the same as your Microshift, will only go to the trim position when up-shifting. You just have to adjust your shifting patterns, or shift down and then back up a half shift.

Bobfjt

Thank you, Broctoon.

I will try to adjust the shifting patterns first.

Iride01 

Trim should only be needed when you are in a cross chaining situation between the front and rear. Sometimes you'll hear the chain rubbing on the FD cage when in the last cog on the rear or even the one cog prior. It simply lets the FD move over a little bit to allow for the sharp angle that is being made in the chain line from rear to front.

If you add trim to help with the chain noise, then you need to remember to remove it if you shift the rear back in the other direction and don't shift the front to the other ring.

You really need to pay attention to how they tell you to set up the FD and adjust it in the instructions. Sometimes with Shimano FD's, the trim setting won't work well if things aren't adjusted correctly enough.

Bobfjt

Thank you Iride01.

I do having the chain robbing FD cage problem. When I use the large chainring and shift to the last 2 large cogs, the robbing starts. When I use the small chainring and the smallest cog, it also robs but I can do up-shifting to the trim to handle it. I can not find a method how to get the front derailluer down-shifting from the high position to the trim. When I press the down-shift lever, the front derailluer put the chain to the low chainring. It does not keep the chain on the large chainring and move a little to the trim to resolve the robbing.

Iride01 

Just realize that when you are in the big/big or the small/small, that there are virtually the same gear ratios available in the other chain ring or rings. So if you are going to need that ratio for more than just a minute to top a quick hill or rise, then find that other combo that give the same effort on the pedals. Might save some wear and tear on your chain and cogs as well as save you from the rubbing FD cage.

Usually for a 2x if in the big/big, then go to the small ring and shift 2 cogs smaller (by tooth count) on the rear. Vice versa for the small/small combo.

Bobfjt

Thank you for your advise. I will try it.