Spokes

Truing your wheel or replacing spokes is well within the capabilities of any home mechanic. Bike designer GEOFF APPS shows you how to do it

TOOLS REQUIRED

The tools that you may require for this work:

Spoke key

Ruler or length of string (or wire)

Medium to large screwdriver

Heavy duty wire cutters

Piece of chalk

PARTS LISTS

The spare parts you should have to hand:

Grease (or Vaseline)

New spokes of the correct length

Non-oil penetrating lube

Although the skill and craft of wheel-building may seem daunting, you can easily sort out a buckled wheel. Before beginning, either mount your bicycle in a workstand, or turn it upside down, putting a piece of carpet or anything soft but firm under the saddle and handlebar to protect them. The point is to have your wheels rotating freely.

Removing buckles and truing the rim can be done with the tyre in place on the rim, but to renew a broken spoke or detect concentric deflections in the rim you will need to remove your tyres.

Spin one wheel at a time and spray a penetrating lube onto the nipples. WD40 (or similar) is ideal for this, but make sure the label says it will not damage rubber. Spin your wheels again to allow the lube to penetrate the threads by centrifugal force. The more time you can allow for this process the better.

(1) GENERAL SPOKE TENSION

You can expect to have some variation in spoke tension, possibly with one or two spokes quite loose. This is sometimes due to poor tolerances at the manufacturing stage and/or subsequent damage to the rim. You may even discover a broken or missing spoke. Since you want to achieve trueness in the rim, having all spokes at the same tension is less important. I have worked on wheels that could have up to three spokes completely removed without affecting trueness.

Grasp a pair of spokes on each side of the wheel, using the index finger and thumb of each hand (four spokes in all). Squeeze the spokes together and feel for any marked differences in tension. Begin this process at the valve and work round until you get back to it again.

Tighten any spokes that seem to be loose, but only up to roughly the same tension as the others. This may or may not make the wheel more wobbly, so refer to 3 to true the wheel.

If a nipple has seized, you will have to break the spoke with a pair of heavy-duty wire cutters (or pliers) and refer to 2 to renew it.

(2) REPLACING A BROKEN SPOKE

If a spoke is missing or you have had to break it, you will need to find out the spoke length as accurately as possible by measuring one of the good spokes in the wheel. Find the distance from the centre of the spoke head to the surface of the rim and add 2mm. If you do not have a suitable ruler, use a length of string pulled as tight as possible, or a length of wire.

If the spoke has pulled out of the nipple complete with thread, use it when you buy spares, to be sure you get the same length. If you want to buy some extras for future use, check the lengths on both sides of each wheel - on the rear wheel, they vary. Even if the shop doesn't have one of the right length, they will be able to cut and thread one for you from a longer spoke.

Remove the wheel from your bicycle.

Remove the tyre and tube. If you a replacing a spoke on the freewheel side of your rear wheel, you will probably need to remove the sprockets first.

Put a dab of grease on the threaded end of the new spoke and feed it through the hole in the hub, ensuring that the spoke head is the right way round.

Weave it in and out of the existing spokes, working the end gradually towards the new spoke's hole in the rim (below).

When deciding whether to weave inside or outside, follow the same pattern as the other spokes.

If you have woven it correctly, you will be able to feed it through the spoke hole in the rim.

Hold the end of the spoke in the centre of the hole and put a nipple through the rim and onto the spoke end.

Take up the initial slack using a screwdriver in the slot in the head of the nipple.

Bring the spoke up to tension with a spoke key.

Having replaced all broken spokes and taken up the slack, refer to 3 to true the rim.

(3) BUCKLES OR WOBBLES

This is often referred to as 'truing' or 'centring' the rim. Look at your hub with the tyre close to (and aligned with) your nose. Looking beyond the tyre and focusing on the hub, note that each spoke is attached to one or other side of the hub. Tightening a spoke attached to the left side of the hub pulls the rim to the left, and vice versa.

Despite what most experts say, buckles are almost always caused by one spoke alone. There is no need to worry about working in pairs or opposite spokes or any stuff like that; unless the

peak of the wobble happens to fall exactly between two spokes, then you work on the spokes either side of the peak. However, once you have reduced the buckling, you may have to tighten or loosen few other spokes at some other point in the wheel -just keep repeating the 'check-and-adjust' process until the rim runs true.

To avoid your wheel going egg-shaped, use only a half-turn at a time when tensioning the spokes. Check the results before making further adjustments and reduce your adjustments to quarter-turns as the rim runs more true.

Always have by you something (clothes peg, bulldog clip, blu-tak) that you can attach to the spoke you are working on in case you're distracted, then you can easily identify that spoke when you come back to it.

Provided your wheels are in generally good condition, a rim that does not run true is not dangerous at all. It will interfere with rim brake operation, although if you have hub or disc brakes, you don't need to worry about a buckled wheel.

Rotate your wheel slowly and hold a stick of chalk steady against the fork or seat-stay (above), gradually bringing it closer to the braking surface of the rim flange until it just touches it, marking the peaks of any lateral deflections.

Identify the single spoke which is causing the problem at the point of maximum deflection. If the spoke is attached to the same side of the hub as the chalk mark on the rim, the spoke tension should be loosened; if to the opposite, it should be tightened.

If the deflection appears to cover a number of spokes, mark the spoke where the deflection begins, and the one where it ends. These two marked spokes should be attached to opposite sides of the hub.

The same principle of tightening and loosening applies - same side spokes should be loosened, opposite side spokes should be tightened.

Continue the 'check-and-adjust' process

until the rim runs true in the side-to-side plane.

Spin the wheel and check to see if the rim moves up and down in relation to the brake block (or other fixed point). If it does, you have an egg-shaped wheel and should refer to 4 to sort that out.

(4) EGG-SHAPED WHEELS

(A) Remove your wheel from the bicycle.

(B) Remove the tyre and tube.

(C) Concentric deflection is detected by using a similar technique as used for sideways deflections but marking on the edges of the rim flanges instead.

Rotate your wheel slowly, and gradually move the chalk towards the rim from the outside. Mark the peaks of deflection.

To adjust in this plane you have to tighten spokes in pairs to pull the rim in (obviously in pairs - one to each side of the hub - to avoid introducing a new wobble).

If the rim goes in towards the hub, it is unlikely that loosening the spokes will drop it out, but do try; it sometimes works. Otherwise, tighten all the other spokes a tiny bit - quarter turn maximum.

Continue the 'check-and-adjust' process until the rim runs true in the side-to-side plane.

After doing any spoke adjusting, you should always finally check the spoke ends to see that they don't protrude through the nipple so far that they could puncture the inner tube. If you think they could, you can simply file the end down until is flush with the nipple head.

Give this a go. You can't do any real damage to your wheels, you may learn a useful skill to dazzle your friends and, should you get into a right pickle, you can always back out of the project and take the wheel to the bike shop and let them sort it.

Read More:

Your Own Home Workshop

Parts and Accessories (Bike Culture)

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