Bicycle Wheel Truing (Basics)

The primary reason why Rome burned down was that Emperor Nero refused to turn the flute he was playing into a fire extinguisher. The secondary reason was that the Roman gods and goddess punished the believers for a cardinal sin: that of neglecting to TRUE cart and chariot wheels.

In Shakespeare’s Julius Caesar, Mark Anthony says, “Friends, Romans, countrymen, lend me your ears.” If I were in Rome today, I would ask the citizens for their bicycle rims—for truing, of course.

The whole TRUE

I am sure you all have heard the famous phrase used in courts throughout the world: "I swear that I will tell the truth, the whole truth, and nothing but the truth."

Before you read any further, say aloud: "I swear to TRUE my rims, the whole TRUING, and nothing but TRUING."

A neat person must ride a neater bike. A dirty bike is like bad breath that everybody smells but never complains against. Regular maintenance is like personal hygiene. Most cyclists ignore rim maintenance and keep pedalling with poorly maintained hubs, worn out steel ball bearings and irregular tyre inflation.

Maintaining a good pair of wheels in a TRUED state takes a bit of money and a fair amount of DIY time. The million Riyal question is: when was the last time you had your wheels TRUED, ROUNDED, WEIGHT-BALANCED, TENSION-BALANCED and DISHED? If your answer is ‘never’ or ‘a long time ago’, then you are losing power, riding pleasure and safety.

In this introductory article, I shall only present a simple description of various rim adjustments.

TRUE be told

The sideways wobble on a rim is called lateral true.

An up and down movement is called radial true.

Expect subtle vibrations and poor braking if the above are not precisely brought within limits.

To check, rotate the rim and notice whether the gap between its sides and the fork (or the chain-stay) changes or stays fairly constant.

Mary go ROUND

Imagine your rim’s tummy either bulging or pressed inward at certain locations. These abnormalities can make a perfect ball roll like a potato.

To check, hang the bike on a repair stand and turn the pedals hard for the rear wheel (hand-turn the front wheel). If the bike frame jumps up and down, ‘Houston, we have a problem’.

Weight balance

We balance the wheels of our fancy cars but almost never those of the poor bicycle.

To check, rotate the bike’s wheels to see if they come to a stop at the same spots or stay wherever they stop without oscillating.

Tension balance

Rim spokes literally create tons of tension. The force, measured in kgF units, must be balanced or else the rim will sit oddly in the fork or the chain-stay. Spokes, if tensioned below or above the design limits, compromise safety, lead to injury or damage to the rims and other parts.

I have yet to see a local mechanic use a tensiometer to check and set tensions; they all hand-tension the spokes, insisting, “We have been doing this for many years”.

Dish (centring)

If your wheels sit to the left in the fork or the chain-stay, the bike will pull to the left and vice versa. Check if your wheels are dead-centre.

Dishing centres the wheels in the fork and the chain-stay.

Un-TRUE riders

So, what does science say about poorly adjusted rims? Actually, a lot but simply put, you could lose 3-5 watts of POWER (1-2% at 250 watts of rider output). That amounts to losing 1-2 minutes during an hour-long race or staying behind by 500m-1,000m at 30 km/h average speed (that is 667m-1,333m at 40 km/h).

If you ride 5,000 to 10,000 km annually, you MUST have your rims trued, rounded and balanced at least once a year. Preventive maintenance is cheaper than replacing expensive parts later. Ali Express is not cheap any more due to the imposition of heavy taxes.

The fantabulous truing machine

Eyeballing a rim’s inconsistences does not always help. After years of truing my wheels on a simple truing stand, I bought a fancy machine that came with three dial indicator gauges that precisely show rim abnormalities. Hence, achieving excellent tolerances with great precision became easier.

Dr. Spoke

Many years ago I created an Excel spreadsheet for truing. Regular use and data input yielded great refinement, detailed figures, fancy graphs and sophisticated analysis. It's a mad scientist's dream come true.

After making fine adjustments, I measure the tension units with a tensiometer, feed them into the app for conversion into kgF, and then the let the genii of hundreds of formulae and criteria create a magical analysis.

By comparing pre-truing with post-truing data and graphs, the quality of work can easily be assessed. I fear I have gone too far by noting even more post-truing tension data gathered for analysis:

1. After the first  ride
2. After two months
3. After four months.

The app has aptly been named DR. SPOKE, thus paying homage to the wise character with slanted eyebrows and pointed ears: Dr. Spock of Star Trek. In a future detailed article I hope to present some screenshots of my own Dr. Spoke.

Proof of the pudding

The image on the left shows the abnormalities of an out-of-true Shimano clincher WH-RS100 front rim with 10 spokes on each side. The LEFT side is shown in GREEN colour and the RIGHT in RED.

The irregular edges clearly indicate that the spoke tensions and other parameters are out of spec.

Now compare the pre-truing image (left) with the post-truing one (right) to see how smooth everything looks after making the adjustments. What seem like small changes on paper are in reality huge improvements.

Are your disc brake rotors un-TRUE?

Minor accidents and riding over hundreds of potholes every week make the rims and disc brake rotor(s):

1. Go out of TRUE
2. Produce pad-rub (on rim brakes)
3. Cause uneven braking (on disc brakes)

The riding quality improves tremendously if the rims are set up perfectly. Most bike mechanics here only check one or two out of the FIVE above-mentioned parameters. I went for all five by computerising the entire process with the help of better tools and scientific knowledge.

My new truing machine shows ALL kinds of rim inconsistencies, including those of out-of-true disc-brake rotors.

With THREE very accurate dial indicator gauges on the machine and my computerised analysis, I first achieved pro-level truing and round results to 0.10 mm accuracy (the thickness of printer paper), and then down to 0.05 mm (thickness of human hair). Somebody stop me!

Over the years, my science finally got married to art. All those rim adjustments now let enjoy rides that are very steady, comfortable and powerful. I hope you too will experience the same very soon.

To have your questions answered, please use the COMMENTS section (press the blue icon at the article’s end). You are also welcome to seek sound advice or book a TRUE appointment.

©Tahir Gul Hasan, 2025

NOTE:

Read the left sidebar of this website to understand what CYCLONE stands for.

Thanks to Park Tool (USA) for the dashing DISHING images.