As long as your bike wheels are reasonably true, you can probably ride your bike. But what happens when the bend in the wheel is pronounced?
A badly buckled wheel rim is not rideable without you fixing it first.
This article will tell you how to get a bent bike wheel back into shape and keep yourself riding. It could even help you get home after “tacoing” your wheel out on the trail.
Why Do Bike Wheels Become “Tacoed” And Need To Be Trued?
Bike wheels are tremendously strong, generally speaking, but if you hit them with excessive force, they’re likely to bend.
A “tacoed” (badly buckled) wheel is one that has typically hit a pothole or landed awkwardly on a jump or been turned aggressively with a lot of forward momentum.
Bike wheels, especially those with weaker single-wall rims, are also liable to bend if subjected to an overly heavy load. That means bigger riders and/or any luggage they may be carrying. Wheel strength is part of a bike’s recommended weight limit.
On a road, a tacoed wheel is less likely. Heavier riders or fully-loaded bicycle tourers may cause spokes to break and the wheel to go out of true, but road wheels take less abuse than MTB wheels, for instance.
If you have multiple broken spokes, don’t ride the bike (or ride it home very gingerly), as the wheel is then seriously compromised.
What Spokes Do
A primary role of bicycle spokes is to pull the wheel rim towards the hub. In doing this, and by adjusting the tension of each, you can “true” the wheel by pulling it into shape.
Spokes also fulfill the vital role of supporting the weight of you, the bike, and everything carried by both. They and their number are a vital part of wheel strength, and they transmit power from you and the hub to the wheel rim.
There are four essential elements to truing a wheel:
- Lateral truing – side-to-side trueness
- Radial truing – circular trueness
- Dishing wheels – centering the wheels in the frame and aligning them
- Spoke tension – adjusted for lateral or radial truing
Lateral truing needs adjustments on the left or right, whereas radial truing means adjusting spokes on both sides of the hub to pull the rim in and let it out. The balance of spoke tension between left and right affects wheel dishing.
Straightening Before Adjusting Spoke Tension
A wheel that is not intrinsically true can be brought into true by adjusting spoke tension. However, this suboptimal solution creates wildly uneven spoke tension between spokes, which in turn causes the wheel to go frequently out of true again.
Because of the above, when a wheel is tacoed, it must be straightened out as much as possible before any attempt on truing it makes sense.
What Tools Do You Need To True Your Bike Wheel?
You won’t true a wheel with the same speed and efficiency as a pro mechanic or wheel builder, but it’s a rewarding skill to learn. Below are some of the tools you might need.
- Wheel truing stand – you can true a wheel without a wheel truing stand, but it makes the job quicker and easier. The stand supports the wheel as you spin it and allows you to easily see any lateral or radial deviations.
- Spoke wrenches – the most fundamental tool for truing a wheel is the spoke wrench, which comes in a variety of sizes to suit different spoke nipple sizes. You can invest in a durable product like the Park Tool Spoke Wrench Set or opt for a cheaper single spoke wrench with multiple sizes included.
- Bladed spoke holder – when adjusting spoke tension on a wheel with bladed spokes, you need a second tool to hold the spoke in place and prevent twisting. That’s where a bladed spoke holder is essential.
- Spoke tension tool – to ensure spokes are tensioned with the desired uniformity and check for problems, a spoke tension meter is useful.
- C-Clamps – when trying to mend a tacoed wheel at home, c-clamps can be useful as a means of clamping it to a bench, usually shielded by pieces of wood.
- Mallet – a rubber mallet is sometimes useful for straightening out a badly tacoed wheel at home.
Note: a carbon rim cracks or breaks before it badly buckles. Do not use clamps or exert any kind of extreme lateral pressure on such a rim. Rather, true it using the spokes as long as there is no sign of damage.
How To Fix Your Bent Wheel Rim
The way you’ll fix a bent wheel depends on how bad the bend is. If it’s tacoed, brutal methods are employed to get it roughly straight before truing. These methods include standing on the rim and pulling it back into shape or hitting it with a rubber mallet.
Video: Unbending A Wheel Using Two Blocks Of Wood
Let’s say your wheel is rideable but still out of true and threatening to get worse. Below is the procedure for fixing it.
1. How To Find The Buckle In Your Wheel
Even when a wheel is rideable, it can still be significantly out of true. How do you find out exactly where the buckle is so you can properly fix it?
The easiest way is with a wheel-truing stand, which supports your wheel and allows you to easily spin it.
As you spin the wheel on the stand, a caliper is held very close to the rim. Anywhere the caliper catches on the wheel as you spin it is out of true or bent.
The caliper is used to test lateral or radial trueness. It sits to the side of the rim when laterally truing the wheel and below it during radial truing.
If you don’t have a wheel-truing stand and can’t afford or justify one, you can achieve similar by attaching a zip-tie to the fork or a chain stayas per the video below.
Video: Truing a Wheel Using a Zip Tie
2. Fixing Lateral Bends
So, you’ve found a place on the wheel that is out of true after it has rubbed against the caliper arm on the truing stand. How do you set about truing it?
Locate any loose spoke on the opposite side of the bend.
You can locate loose spokes by “plucking” them with your fingers and listening for the tone. Loose spokes yield a lower note compared to tensioned spokes.
Tighten the loose spoke to true the wheel. Make small quarter or half turns at a time with your spoke wrench and recheck the wheel for trueness.
Counter-clockwise turns viewed from above the wrench tighten spoke nipples and clockwise turns loosen them.
3. Rounding The Wheel
Fixing the wheel so that it is round also requires you to adjust spoke tension. Unlike a lateral deviation, you will fix “high spots” and “low spots” in wheel roundness by adjusting spoke tension on both sides of the hub.
By adjusting an even number of spokes on either side of the hub, you move areas of the rim up and down rather than make lateral, unsymmetrical adjustments.
Address any high spots in the rim before looking for low spots. A wheel that is round to within 1mm is considered acceptable (same with lateral trueness).
A high spot on the rim will typically require you to tighten two or four neighboring spokes, whereas a low spot would require you to loosen spokes.
4. Double Checking
Having rounded the wheel, or trued it radially in other words, you may have to re-check its lateral trueness again. Truing the rim radially can affect lateral truing, so there may be some back and forth before it’s fixed.
Video: Radial Truing Of A Wheel (For Roundness)
Wheel Straightening FAQs
Below are some common questions asked about wheel straightening.
Can The Spokes Be Over-Tightened?
Yes, spokes can be overtightened. This can result in cracks or deformation near the nipple holes of the rim, stripped spoke nipples and damaged hub flanges.
How Often Does A Bike Wheel Need Truing?
A bike wheel may stay true for as long as you own it if you’re lucky, but it also may need truing regularly. Signs that a wheel needs truing include a noticeable deviation when you spin it, loose spokes, and rubbing against a rim brake.
Is It Dangerous To Ride With A Slightly Buckled Wheel?
A slightly buckled wheel is unlikely to be structurally compromised, so it’s not dangerous in that sense. How quickly it may worsen hinges on various factors, like the nature of riding, terrain and rider weight. A prompt check for loose or broken spokes is wise.
Wheel truing is a skill that extends far beyond the scope of this article. The Sheldon Brown website is a good place to start. A book called “The Bicycle Wheel” by Jobst Brandt provides in-depth knowledge on wheels and wheel building.
We hope you’ve enjoyed this article and that it expanded your wheel-truing knowledge. If it made you want to investigate further and learn a new skill—that’s great!
Please feel free to share the article with friends or add to it with comments of your own.