Relacing rear derailleur

Welshkev

Going to replace my rear derailleur this evening (Ultegra 6800 11 speed). Have never done this before, so any tips / advice before attempting? Don't want to make a pigs ear of it!
Thanks

cdaly_

First hunt down articles and videos on how to set it up. Check Sheldon Brown's website.

Most important thing is to get the limit screws correctly set up. If you get the low limit screw wrong, your derailleur could end up in the spokes doing significant damage.

Welshkev

Thanks cdaly. I have a couple of videos, such as the GCN one, but I always seem to find out little tips afterwards (usually once I've made a mess!) - for example, should I set the chain up in the smallest/outter most cog before removing the old one? And can I use where the limit screws are currently set up on the exisitng one as a guide (assume not, but just in case)

cdaly_

You would normally break the chain to change a derailleur so which cog to use is not at issue. You can set the high limit screw without the cable connected and then, with the cable connected, carefully shift to the lowest gear and set the low limit screw.

Welshkev

cdaly_ wrote: »

You would normally break the chain to change a derailleur so which cog to use is not at issue. You can set the high limit screw without the cable connected and then, with the cable connected, carefully shift to the lowest gear and set the low limit screw.

Thanks. I was hoping to not have to break the chain and was just going to undo the bottom pulley wheel and thread it through that way and reattach the wheel.
Appreciate the info on the limit screws.

clog

Do change down to the smallest sprocket before changing as it will be near impossible to hold the new mech exactly in place on one of the other sprockets while tightening the cable. It also makes sure that the shifter is in the right position for re indexing.

clog

Kevinleeowen wrote: »

Thanks. I was hoping to not have to break the chain and was just going to undo the bottom pulley wheel and thread it through that way and reattach the wheel.
Appreciate the info on the limit screws.

I don't think that way will work as there is a tab between the jockey wheels which the chain will get caught on unless you bend it out. You would also need to bend the tab on the new mech in order to get it on without breaking the chain. You could easily ruin the new mech before it is even ridden. Break the chain and get a quicklink

Brian?

Kevinleeowen wrote: »

Thanks. I was hoping to not have to break the chain and was just going to undo the bottom pulley wheel and thread it through that way and reattach the wheel.
Appreciate the info on the limit screws.

Break the chain, it's the only way to do it properly.

lgk

Kevinleeowen wrote: »

I was hoping to not have to break the chain and was just going to undo the bottom pulley wheel and thread it through that way and reattach the wheel.

I've done a few removing both jockey wheels, easy enough.