How do I true a slightly buckled bike wheel?
Correcting a small side-to-side wobble by quarter turns of the nipples, why you always tighten one side and loosen the other, and the point at which this stops being a home job.
- Difficulty
- advanced
- Time
- 1 hr
- Read
- 5 min
- Safety
- warning
Short answer
Find the high spot with the brake pad or a zip tie as a gauge, then correct it by loosening the spokes on the side the rim leans towards and tightening the ones on the opposite side, a quarter turn at a time, spread over three or four spokes. Anything more than a few millimetres out, or with loose or broken spokes, belongs in a shop.
A wheel is held round and straight by the balance of tension in thirty-odd spokes pulling in opposite directions. Truing changes that balance locally. Done in small steps on a wheel that is basically sound, it works well. Done heavy-handedly, or on a wheel whose tension is already wrong, it makes a wheel that is straight and about to fail.
Safety
What you'll need
- A spoke key of the correct size
- A truing stand, or the bike itself as one (optional)
- A zip tie or a piece of chalk
Step by step
- Decide whether it is a truing job at all.Look for broken spokes, spokes you can move with your fingers, cracks radiating from spoke holes in the rim, a flat spot where the rim has been hit, or a rim that is out of round rather than out of line. Any of those means stop. So does a carbon rim.
- Check the hub for play first.Rock the rim side to side at the top. If there is a knock, the bearings are loose and you are about to true a wheel to a moving reference, which achieves nothing.
- Set up a gauge.Use the brake pads if it is a rim brake, or zip-tie a marker to the frame with the end almost touching the rim. Spin the wheel and mark the sections that move towards the gauge.
- Identify which side the rim moves to.Mark the high spot with chalk and note whether it moves left or right. Everything depends on getting this the right way round.
- Understand which way the nipple turns.You work from above, looking down at the nipple from outside the rim, so the direction is reversed from what feels natural. Turn a nipple anticlockwise from that view to tighten. Try one quarter turn and see which way the rim moves before doing any more.
- Correct by tightening one side and loosening the other.To pull the rim to the right, tighten the right-side spokes and loosen the left-side ones by the same amount. Tightening only raises overall tension every time you make a correction, which is what leads to cracked rims.
- Work in quarter turns, spread over several spokes.A quarter turn on the most out-of-true spoke, an eighth on its neighbours either side. Concentrating a correction on one spoke makes a straight rim with a hard spot in it.
- Spin and re-check after every round of adjustment.Move the gauge in as it improves. Chasing it too fine on an ordinary wheel wastes an evening — half a millimetre of lateral movement is fine.
- Watch out for the wheel going out of round.Truing side to side can pull the rim out of its circle. Check by moving the gauge to point at the outside of the rim rather than the side. A wheel that is out of round needs proper tension work.
- Check spoke tension by feel at the end.Squeeze pairs of spokes all round. They should all feel similar and should ping rather than thud. Wildly different tensions mean the wheel needs proper attention rather than more truing.
- Stress the wheel and re-check.Press firmly inwards on pairs of spokes all the way round to settle the nipples and unwind any twist in the spokes. Then re-check the true. It will have moved slightly, which is normal.
- Know when to stop and pay someone.Wheel building and proper tensioning are a skill with a tension meter behind it. A shop will true a wheel properly for less than the cost of a rim, and far less than the cost of a wheel failing.
Tips
- A drop of light oil at the nipple where it meets the rim, left for a few minutes, makes seized nipples turn without rounding off.
- Use the right size spoke key. A loose one rounds the nipple and then the spoke can only be replaced.
- Note where you started with chalk so you can find your way back if the correction goes the wrong way.
Common mistakes
- Only ever tightening spokes — Every correction then adds tension. After a few sessions the wheel is grossly over-tensioned, which cracks the rim at the spoke holes and can pull nipples through it.
- Making big adjustments to a single spoke — It straightens the rim locally while leaving a hard, over-tensioned spot. That spot fatigues the rim and the spoke, and the wheel goes out of true again quickly.
If it doesn't work
The wobble got worse
Cause: Turned the nipples the wrong way — Fix: Reverse the last adjustment. Always test one quarter turn and observe before continuing.
Nipple turns but nothing changes
Cause: Spoke is twisting rather than threading, or the nipple is seized — Fix: Oil the nipple, and hold the spoke with pliers or a spoke holder while turning so it cannot twist.
Wheel is straight but there is a hop up and down
Cause: Out of round as well as out of true — Fix: This needs radial truing with attention to overall tension — usually a shop job.
Ping and crack noises when riding after truing
Cause: Spokes unwinding stress, or tension too high — Fix: Stress-relieve the wheel by squeezing spoke pairs, re-check true, and have the tension checked if it persists.
Questions people ask
How much wobble is acceptable?
On an ordinary wheel, under about half a millimetre of side-to-side movement is fine and unnoticeable. Up to a millimetre or two is common on well-used wheels and is only a problem if it makes the brake rub.
Is it worth truing a cheap wheel or should I replace it?
A small correction is worth doing on any wheel. A wheel that will not stay true, has uneven tension throughout, or has cracks at the spoke holes has reached the end of its life, and rebuilding a cheap wheel usually costs more than a new one.