Replacing Shifter Cable - Shimano Ultegra


Replacing a shifter cable on a Shimano Ultegra shifter

October 2009


This is generally a fairly simple procedure.  But remember that you are dealing with a complex mechanism for index shifting.  Don’t unscrew something without thinking about it.

There are a lot of adjustments on the rear derailleur.  This isn’t meant to explain everything.  It’s just my notes on how I last replaced the shifter cable on my bike.

Never turn a screw or yank on something without thinking about it.  Your local bike shop has folks who do this everyday and they are GOOD at it.  You may be doing it yourself to try to save a few dollars or to learn about your bike.  But your bike gives you a lot of pleasure in this life.  Treat it to a trip to your local bike shop once in a while for a tune-up or repair.  Also, if you mess something up on your bike, most of the time the local bike shop “wrench” can fix it for you.  Be humble and know that they are the professionals and you are not.

OK, enough with the disclaimers….

For about $3 you can buy a new shifter cable from your local bike shop.  (If they want $4 or $5 for it, why argue with them?  It costs money to keep a shop open and you’ll need them someday.)  Ask the guy or gal for a couple of those little end-caps (called crimps?) so when you are done, you can slip it over the end of the cable and squeeze it tight and keep the cable from fraying.

Rule #1:  Always get all of the old cable out before replacing it with the new one.  Nothing will work if you don’t follow this rule.

Rule #1:  Yes, there are two Rule #1s.  Be sure to get the chain onto the smallest gear in the back and shift the shifter lever to the lowest gear.  The derailleur will automatically go the smallest gear on the back when the cable breaks.  But when you get home, be sure to shift the little lever until you have it in the position to match the smallest gear on the back.

It seems like my shifter cable breaks inside the dual-lever shifter-brake mechanism.  The long piece of cable will easily slide out.  You will need to partially unscrew the holding screw at the bottom of the derailleur.  Pull the old cable out and throw it away or use it for hanging picture frames or Christmas decorations.

Now, do you remember rule number 1?  Squeeze the brake lever and peek inside the openings and look for the end piece of the shifter cable.  It might be right in front of you or it might have slipped down to the lower side of the shifter mechanism.  I once had to turn the bike upside down before I was able to see the broken end piece of the old cable.

Use a little wooden toothpick if you need to poke around a little to pry out the old cable end piece.  Be very careful.  The mechanism that makes that index shifter work is like a watch mechanism.  Don’t take anything apart.  Just squeeze on the brake and move the shifter levers to see inside.  If you have to, take a pair of needle nose pliers and pull the broken piece of the old cable out.  Just be careful!  If in doubt, take your bike to your local bike shop.  They probably won’t charge more than $25 - $50 or so to replace it for you, if it can be replaced.

Did you get the end piece of the old cable out?   Good.  Now just feed the new cable through the outside hole.  You will need to squeeze the brake lever to make it visible.  Just keep feeding the cable through and guiding it back down the down tube and back to the rear derailleur.  Don’t let it kink up.  The cable should be a foot or more longer than you need.  When you have fed the new cable through, pull it enough to pull the new cable end piece into the handle of the shifter.

Now you are ready to pull the cable tight down on the end of the rear derailleur.  You should probably use a pair of needle nose pliers for that.  Pull the new cable tight with one hand while it is slipped under the screw and hold-down part on the bottom of the rear derailleur.  Keep it tight while you screw down the hold-down part.  It you’re lucky and careful, you’ll get it just right the first time.

Now turn the crank a little to spin the rear wheel.  Does the chain turn and the gear stay on the smallest gear?  Good.  Hold your breather and try shifting to a larger gear.  Click it a few times.  Does the chain move to the larger gears?  If not, try turning the small knob counter-clockwise to take up more slack in the cable.  Try shifting again.  If it still doesn’t work, then stop, and then try grabbing the end of the cable again with the needle nose plies while you unscrew the hold-down screw.  Pull that cable pretty tight again and without letting go, turn the screw down tight to hold the cable in place.  Try shifting again.  You should be able to get the slack out of the cable to make the shifter work.

The last time I did this, I needed to turn the little tightening knob a few turns counter-clockwise before it shifted correctly.  I did not have to adjust anything else on the derailleur.  No guarantees that you won’t, however.

Remember, the cable will initially stretch after a few days or so of use.  You will have to turn that little knob a quarter turn to take the slack out.  Remember to turn it counter-clockwise.  To remember which direction to turn, just make a fist with your right hand and see which way your fingers curl.  Just remember, “right hand – shifts grand” or something like that.

There are a lot of adjustments on the rear derailleur.  This isn’t meant to explain everything.  It’s just my notes on how I last replaced the shifter cable on my bike.