True a wobbling wheel by spinning it slowly and watching where the rim moves sideways against a fixed pointer or the brake pads, then tightening the spokes on the side opposite the bulge by a quarter turn or loosening those on the bulge side, checking after each small change. A quarter turn of a spoke nipple moves the rim at most about 0.9 mm at that spoke, so use small turns and work slowly around the wheel.
Part of Bicycle Repair & Fabrication
Wheel truing is the adjustment of spoke tension to straighten a bicycle rim so that it runs without sideways wobble or radial hop.
How Far Does A Quarter Turn Move The Rim?
A wobbling wheel rubs the brake and stresses spokes, and truing means adjusting spoke tension. How much does one adjustment do? With assumed dimensions:
- Spoke nipple thread: 56 threads per inch, a pitch of 25.4 / 56 = 0.454 mm (a common spoke thread, recalled)
- A quarter turn shortens the spoke’s effective length by 0.454 / 4 = 0.113 mm
- Spoke geometry: length ℓ = 290 mm, hub flange offset from the rim centre-plane w = 35 mm. The spoke’s pull has a sideways fraction of w / ℓ = 0.12
To move the rim sideways by δ at that spoke, the spoke must shorten by δ × (w / ℓ). So the sideways movement for a shortening of 0.113 mm is 0.113 / 0.12 = 0.94 mm, about 0.9 mm. That is an upper bound, since the stiff rim and neighbouring spokes resist, so the real movement is a little less and spread over several spokes. It shows why a quarter turn is the unit, and why several spokes are adjusted by smaller fractions.
The Direction Rule
Tightening a spoke pulls the rim toward the side of the hub flange it is attached to. If the rim bulges toward the right at some point:
- Tighten the left-side spokes there by a quarter turn, to pull the rim left, or
- Loosen the right-side spokes there by a quarter turn, which lets the rim move left.
This is the carrier’s rule: find the spokes pulling the rim to the wrong side, and tighten those on the opposite side, or loosen those on the wobble side. Do both in small amounts, to keep the average tension where it was.
What You Need
- A spoke wrench that grips the nipple’s flats (pliers work but risk rounding the nipple)
- A fixed pointer: the brake pads, or a nail or stick fixed to the frame or fork
- The wheel in the frame, or a truing stand
- Marker or chalk
Method: True A Wheel
Step 1: Spin slowly and watch where the rim moves toward or away from the pointer.
Step 2: Mark the worst spot. At the wobble, find the spokes pulling the rim to the wrong side.
Step 3: Adjust by a quarter turn: tighten the spokes on the opposite side, or loosen the ones on the wobble side. Spread the change over the 2 or 3 spokes nearest the worst point rather than putting a whole turn on one.
Step 4: Check the direction of the nipple. Look at the spoke thread at the nipple: tightening makes more of the thread disappear into the nipple. If the first adjustment made the wobble worse, you turned the wrong way.
Step 5: Spin again and repeat. Small adjustments, then re-check.
Step 6: For hop (the rim moving in and out, not sideways), tighten or loosen the spokes on both sides equally.
Step 7: Check the tension is even. Squeeze or pluck pairs of spokes: very slack ones will soon fail. Check the wheel is still centred in the frame, so left and right clearance match.
Common Mistakes
- Large turns — one whole turn can throw the rim about 3.8 mm out (4 × 0.94).
- Only tightening — the wheel’s average tension climbs until the rim cracks at the spoke holes.
- Adjusting without a fixed reference — the wobble moves around.
- Leaving spoke ends protruding into the rim well — they puncture the tube; file them flush.
Safety
A weak wheel fails suddenly
A wheel with several slack or broken spokes collapses under load, and rims cracked by over-tightening fail at the spoke holes. Never ride a wheel that rubs the frame or fork, do not leave the spokes in an uneven state, and test the wheel at walking pace before riding fast. File off protruding spoke ends, and wear eye protection when cutting spokes.
What’s Next
- Learn next: Spoke Replacement — when a spoke is broken
- Combine with: Wheel Hub Bearings — a wheel that runs true needs a true axle