Repairing a Bowden cable: soldering nipples, shortening the cable, setting the free play

Workshop guideUpdated 2026-09-13ELDI / Racing Planet editorial team

A snapped clutch cable or a frayed throttle cable puts the moped out of action. Ready-made cables to suit are no longer available for many classics, or they do not fit the modified handlebars. The answer is bulk cable with a soldered-on nipple. That is an hour's work and needs very little in the way of tools.

Here you can read which nipple shapes there are, how to degrease and tin the cable, when a clamp nipple will do and how to bring the outer and the inner cable to length. At the end you set the free play at the adjuster so that clutch, throttle and brake all work cleanly.

How a Bowden cable is built up

A Bowden cable consists of three parts: the inner cable, the outer and the nipples at both ends. The inner cable is a stranded steel wire rope, galvanised or bright, in diameters from about 1.2 to 2.5 mm. The outer is a tightly wound steel spiral with a plastic sheath, and on better cables a PTFE liner inside. At the ends of the outer sit the end caps, which bear against the adjusters or the stops at the lever and at the engine.

The nipple is the connecting piece between the inner cable and the lever. It is soldered or clamped onto the cable and hooks into the lever or into the carburettor slide. A cable transmits pulling force only. That is why the outer has to bear firmly at both ends, otherwise the travel is lost in the outer and you have endless free play.

Typical cables on a moped: throttle cable to the carburettor slide, clutch cable to the release arm, brake cables for the front and rear brake, a choke cable for the starter, and on some models a decompression cable. Which length and which nipple shape your machine needs depends on the model and on the handlebars. The old cable is your pattern.

Nipple shapes: barrel, pear, cylinder, drum

There are four basic shapes found on mopeds and motorcycles. They differ in diameter, in length and in whether the cable comes out in the centre or at the side.

Nipple shape	Appearance	Typical use
Barrel nipple	Short cylinder with a hole across the axis	Hand and foot levers, carburettor slide
Pear nipple	Teardrop shape, cable comes out at the tip	Twistgrip, clutch lever, choke cable
Cylinder nipple	Long cylinder, cable in the centre lengthways	Brake rods, release arm on the engine
Drum nipple	Flat disc with a hole at the side	Twistgrips with a cable drum

Measure the diameter and the length of the old nipple with a vernier caliper and pick the matching shape from the range. The Bowden cable nipple assortment with 83 pieces covers the common sizes for throttle, clutch and brake cables. A nipple that is too thick jams in the lever. A nipple that is too small pulls through the opening, or it tilts and chafes the cable.

Soldered nipple or clamp nipple?

A solder nipple is soldered onto the cable with soft solder. The solder flows into the strands and into the bore of the nipple and holds the joint by form fit. Done properly, a soldered nipple holds more than the cable itself. It is the standard solution for clutch, brake and throttle.

A clamp nipple has a grub screw that clamps the cable in the bore. It is quick to fit and needs no soldering iron. Clamp nipples suit cables under little load, such as the choke or the decompressor, and they work as a get-you-home repair. They have no business on a brake: the screw can work loose, and the clamping squeezes the cable at one point, where it then breaks.

Soldering a nipple: step by step

1. Bring the cable to length

   Lay the old cable next to the new bulk cable and mark the length. Add about 5 cm spare at the free end. Cut the cable with side cutters made for wire rope or with a rotary tool and a cutting disc. Ordinary side cutters crush the strands and the cable frays.

2. Degrease the cable end

   The cable is lightly oiled from the factory. Solder does not stick to grease. Clean the last 2 cm with brake cleaner or methylated spirit and a clean rag. After that, do not touch the end with your fingers again.

3. Splay the strands

   Slide the nipple onto the cable. Splay the strands at the end slightly with a small pair of pliers so that they form a little brush. Pull the nipple back until the brush is flush with the end face of the nipple or stands just proud. The splayed strands stop the nipple from slipping off, even if the solder should ever give way.

4. Tin the cable

   Dip the end of the cable into soldering grease or soldering fluid for steel. Heat it with a powerful soldering iron or a small flame and let electronics or radiator solder run into the strands. The cable has to shine silver all the way through. A cable that is only wetted on the outside will not hold.

5. Solder the nipple on

   Set the nipple in position; a small vice or a helping hand is useful here. Heat the nipple, not just the cable, and feed solder in from above until the bore is full and solder comes out at the bottom. The nipple is hot enough when the solder flows on its own.

6. Cool down and check

   Let the joint cool quietly, do not quench it with water. File off surplus solder and the ends of the strands flush. Clamp the cable in the vice and pull on the nipple with your full body weight. If nothing moves, the joint is sound.

Shortening the outer and fitting end caps

If the handlebars have been changed or the bulk cable is too long, you shorten the outer. Measure the length on the old cable while it is still fitted, not once it is off the machine. The cable should run in generous curves, must not go tight on full lock and must not chafe anywhere on the tank or the frame.

Cut the outer with a rotary tool and a cutting disc or with a cable cutter. With side cutters the spiral is squeezed shut and the inner cable catches. After the cut, open the opening out round again with an awl or a nail and clear the plastic liner. Then fit the end cap. It has to sit tightly; if need be, nip it up lightly with a pair of pliers.

Before you thread the inner cable in, spray thin oil into the outer until it comes out at the bottom. Cables with a PTFE liner stay dry. Pull the inner cable through, hook the finished nipple into the lever and let the free end hang down towards the engine. The second nipple goes on there, or a clamp screw at the release arm, depending on the model.

Setting the free play at the adjuster

Every cable needs a little free play so that the outer transmits no force to the lever when the bars are turned or the suspension moves. The adjuster sits at the hand lever, at the engine or at both points. Screw it out and the outer becomes longer and the free play smaller. Screw it in and the free play grows.

• Clutch cable: there should be a noticeable amount of free play at the hand lever before the release arm on the engine starts to pull. The exact figure is given in the workshop manual for your machine. With no free play the clutch slips, with too much it does not separate cleanly.
• Throttle cable: a little free travel at the twistgrip, so that the slide is not lifted on full lock. Check this with the engine running: the engine speed must not rise as you steer.
• Brake cable: the lever must not be able to be pulled all the way to the grip. Adjust it so that the wheel turns freely with the lever released.

After adjusting, tighten the locknut on the adjuster and check every function with the machine stationary. For the clutch that includes being able to push the machine without resistance with the lever pulled in and a gear engaged.

Care and fault finding

A stiff cable is rarely broken, usually just dry or kinked. Unhook the inner cable at the lever and pull it through the outer a few times. If it catches at one point, the spiral is kinked or a strand has broken. Then only a replacement will do. If it runs rough, oil goes into the outer.

Frayed cables at the nipple occur when the nipple cannot turn freely in the lever. Check that the nipple seat is clean and round. A drop of grease on the nipple in the lever extends its life considerably.

When fault finding on the clutch you should also know the release mechanism inside the engine. How to locate the piston and the crankshaft during a cylinder change is shown in the guide changing the piston on a two-stroke. You will find all the tools for your model in the tool finder, and the sizes across flats for the locknuts in the across flats table.