Bike Maintenance 101: Maintain and replace brake and gear cables

In our previous issues of Bike Maintenance 101, we covered What Not To Do with your bikeHow to Clean Your Bikeand after that Fixing Annoying Noises.

In What Not To Do, we showed you the major no-nos when it comes to tweaking with your bike, in the absence of a professional bike mechanic. Meanwhile How to Clean Your Bike was a basic guide to what you should be doing to clean your bike at home, so you don't need to bring it into the shop and pay someone to do it for you. In Fixing Annoying Noises we walked you through how to tackle those infuriating creaks and squeaks. 

In this issue, we look at your cabling instead. While many brands and riders are opting for electronic systems like the Shimano Di2 and SRAM eTap, and hydaulic disc brakes, mechanical gearing and calliper brakes are still the most common systems around.

It is our belief that if you look after your bike’s cables they should give you years of safe and efficient service. Continue reading to learn how to do it yourself at home.

ROUTINE CHECKS

Modern gear and brake cables require little maintenance except to occasionally index the gears and adjust the brakes.

Inspect outer cables regularly for damage where they enter the adjuster, either at the rear derailleur or on the down-tube adjusters.

Lubricating inner cables attracts dirt and could do more harm than good, and for this reason many manufacturers recommend not doing so.

LENGTH MATTERS

Check that the outer brake cable length is correct – long enough from the levers and along the bar so the bar can be turned without tugging.

The outer cable to the rear should be long enough not to be tugged when the calliper is fully applied. Use the old outer cables as a cutting guide.

Use side cutters to cut between the spiral, a small file to trim each end and a small pointer to open the liner. Fit a ferrule.

CABLE FITTING 1

Back off cable adjusters, undo the inner cable at the calliper and cut or pull off the cable end. Pull the brake lever and push the cable through the lever.

Undo the top half of the bar tape, remove brake outers and slide the new inner through the brake lever and out of the housing bottom. It’s often easier to undo the lever from the bar before threading the cable.

Slide the first section of outer over the inner making sure the cable fits tight to the lever body.

CABLE FITTING 2

Tape the outer cable to the bar, running along one of the grooves. The protective casing can then be fitted over the outer, taped in place, and then you can fit bar tape.

Feed the rear brake’s outer cable to the frame stops or through the guides. Ensure any quick release is closed, thread the inner through the cable-clamp eye or slot and fasten roughly in place.

Turn the brake cable adjuster about one turn anti-clockwise.

GEAR CABLE FITTING

Check that the outer gear cable length is correct (step 2). The rear piece of outer cable should be long enough that the curve is not too tight but not longer than needed.

Use old outers as a cutting guide if they’re okay. Use sharp cable cutters to trim the outer gear cable.

The end may flatten slightly; squeeze it into shape, file to get it as flat as possible and open the liner with a sharp pointer before fitting the ferrule.

REMOVING OLD CABLES

Select top gear (small sprocket, big chainring). Back off the adjustment on all the cable adjusters – derailleur, down-tube stop and shifters if fitted.

With both derailleurs, loosen the cable clamp bolt and push the inner cable out through the shifter – you might have to pull the lever hood to one side.

Remove the outer cabling – you’ll have to undo the top section of bar tape.

FIT NEW CABLES

Feed the new inner through the shifter lever and housing and the first section of outer cable. Make sure the cable fits tight up to the lever body then tape to the bar in the most natural position.

Continue feeding the inner cables through the stops, bottom bracket guides and outer cable. Check the ferrules are properly seated.

Feed the inner wire the correct side of the derailleur clamps and, pulling the inner taut, tighten the clamp bolt.

FINISHING OFF

 

It is essential to fit end caps to all cables. Trim all but about 5cm of inner cable protruding from cable clamps and, taking care not to splay the cable ends, slide a cable end cap over its end.

Hold in place and crimp it gently with side cutters two or three times. Be careful not to slice through it. Alternatively super glue an end cap into place.

Finally, road test your bike, and you will almost certainly notice an improvement.