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How to install Deore XT thumb shifters in 6 easy steps

In this article I’m going to explain how to install a pair of 2nd generation Deore XT thumb shifters from 1987.

It was this Deore XT set that introduced indexed shifting to the world, but only for the rear derailleur.

These thumb shifters we’re found on the Koga Miyata Adventure I bought. The overall condition of the bike was bad, and both Deore XT thumb shifters weren’t working.

I’d already installed a new bottom bracket and restored the Biopace crankset. Now it was time for the rest of the drivetrain to work.

I’d received the last parts I needed on December 31st last year and I thought it was a nice send-off to 2020.

Video Tutorial

Step 1 Cleaning the derailleurs

Obviously the shifters operate both front- and rear derailleurs. Both of these were in absolute horrendous condition. No so much damaged but covered in years of muck and dirt.

They needed a very thorough cleaning, which I achieved by removing most of the dirt with a toothpick and getting rid of the rest with white spirit.

Step 2 Cleaning the Deore XT thumb shifters

Since they are far removed from the wheels, the shifters themselves weren’t all that dirty. They just needed a little wipe and polish.

Step 3 Installing the derailleurs

After cleaning the derailleurs I installed them onto the frame.

Step 4 Setting up the front derailleur

I made sure the front derailleur was correctly set up. Look at the top of the derailleur cage to see if it is positioned in a straight line with respect to the chainrings.

The outer edge of the derailleur cage should also be positioned 2mm. above the biggest chainring. Since this is an oval Biopace chainring make sure the widest diameter of the biggest chainring is used.

Step 5 Cutting the shifter housing

I bought Jagwire Sport shift cables. They come in a variety of colors. I went for the carbon silver version, since the color closely mimmicks that of the original cable housing.

The set is pretty expensive but offers plenty of length to probably do 2 bikes if you wanted. It also includes a set of 5G tube top frame protectors, which are pretty expensive if bought loose. A set of cable donuts and a set of cable hooks.

When installing them I found that the end caps had a rubber inner which prevents dirt from getting into the housing; nice touch.

I received the Park Tool cable and housing cutter CN-10, which made cutting the cables at the right length an absolute breeze.

Before putting them on the bike I poured some sewing machine oil in the housing.

Step 6 Installing the shifter cables

Each Deore XT thumb shifter has a hole in the side through which you pull the shifter cable. Getting everything into place is easy enough

I tension the cable with a pair of pliers since I don’t have a cable tensioner. Make sure the Deore XT thumb shifters are always in the lowest gear for the front derailleur and highest for the rear.

I also place 3 cable donuts on each cable. They run underneath the down tube. This is mostly cosmetic since the frame is already heavily damaged but it doesn’t hurt to do it.

With both cables installed it basically wraps up the installation of the Deore XT thumb shifters. The derailleurs are operative but naturally still need to be fine-tuned. And as you can see I hadn’t installed the Shimano chain yet at this moment.