Jim’s Tech Talk
By Jim Langley
A few Tech Talks ago, we wrote about how to use bicycle repair stands, one of the foundation tools of home bike shops. If you missed that column, here it is: How to Safely Put Bicycles in Clamping Repair Stands.
In response to that article, we received a request to do a piece on bicycle wheel truing stands, which are the other foundation tools of home bike shops – at least for mechanics that enjoy wheel repairs and wheel building. The email came from regular contributor “Fixieguy.” In it he gave his perspective on why it’s good to have both a repair stand and a truing stand:
“Your article on repair stands motivated me to write. You might want to do a column on truing stands. One can true a wheel that’s on a bike when the bike is on a repair stand, but it’s going to be only “eyeball” straight and then only laterally true but not vertically round. The only way to true a wheel properly is on a truing stand.
And, of course, every time you get near to true laterally, you’ve got to check to see whether you’ve affected your vertical truing and vice versa. You must go back and forth trying to get them both right. However, because of this, for some people such as myself, truing a wheel can be a Zen-like experience. There’s always this sense of reaching for perfection.
However, the mathematical reality is that perfect roundness does not exist and cannot be attained. This is because a circle’s circumference divided by its diameter equals Pi, which is an inexact fraction comprising infinite nonrepeating decimals. Nevertheless, trying to approach perfection while truing a wheel can help while away a cold winter afternoon.”
My response
Thanks for your points, Fixieguy, especially for so nicely capturing in words the Zen-like experience of truing wheels. I’d like to offer a few thoughts about what you wrote.
Is a truing stand needed?
I agree that it’s more difficult to true a wheel when it’s still on a bicycle in a repair stand. Yet that’s exactly the way the majority of wheels on bikes are trued when pro mechanics do tune-ups – the most common routine repair job at most bike stores.
It’s done that way because unless the bike has two flat tires, or worn out ones, the tires won’t be removed. The wheels might not even be removed either. And in that case, the easiest way to true the wheels for the tune-up is to check for loose spokes by hand and then spin the wheels to check if they need any truing.
If there are loose spokes or wobbles, the mechanic will rest a thumb against a seatstay to be able to sight the gap between their thumb and the rim, spin the wheel and true it as needed focusing mainly on lateral issues first. The thumb will also reveal any significant hops or dips in the wheel and those can be addressed too. That’s usually the extent to which wheels are trued during tune-ups. And it’s all done on the bike.
With some bikes now set up with tubeless tires, it makes even more sense to work with the wheels on the bike. Because you wouldn’t want to remove the tires and sealant if you didn’t have to. The same goes for tubular tires (AKA “sew-ups”) which are glued on – if you remember them.
Truing Stands with Tires Still on the Wheels
You can true wheels in truing stands with the tires still on the wheels as long as the truing stand has clearance for the tire. If it does, the pointer(s) on the stand will let you sight lateral wheel wobbles. But because the tire is on the wheel, you won’t be able to rest the pointer beneath the rim (because the tire’s in the way), which is the best way to check for and fix vertical issues with wheels.
The workaround is to place the pointer close to the top of the rim and do your best to spot and address any roundness issues, which Fixieguy correctly states is only going to result in your best “eyeball round.”
That’s why if the tires don’t need to be removed, it usually makes more sense to just check and true the wheels while they’re on the bike.
Advantages of Truing Stands
The thing that is easier on a truing stand is seeing what you’re doing since the truing stand has adjustable pointers that can reveal the slightest of gaps. And because with the wheel held in the stand it’s easier to see what you’re looking at, which helps when trying to get wheels as true and round as you can.
For fixing lateral issues the pointer is placed next to the side of the rim. For roundness issues, the pointer is placed beneath the rim.
A nice benefit of truing stands is that you can quickly adjust the pointers and in tiny increments so as wheels get truer and rounder you can keep shrinking the gap. When wheels are near perfect, you can set the pointer to barely brush the rim and find and remove imperfections of less than tenths of a mm by listening to the change in the sound of the rim as it barely contacts the spinning wheel. It’s very satisfying as the wheel gets truer and rounder.
For those who enjoy approaching perfection as Fixieguy so elegantly put it, there are truing stand dial indicator gauges that come on some stands and can be added to others. These put a number on the lateral and vertical runout and you will find that the wheel still appears a tiny amount out of true and round according to the gauges even after it looks perfectly round and true to the eye. If you’d like to see a stand with gauges, I wrote one up some years ago: https://www.roadbikerider.com/more-modern-wheel-tools-part-2-d3/
Final Take
I think that if you enjoy working on wheels and especially if you like building them or would like to learn how to build them, you’ll love having a truing stand. It’s a fun tool to own and use and like all good tools makes the job easier. For more on using truing stands and a look at some different types – including my newest stand, here are a couple of videos of mine.
And please leave a comment if you have any questions about truing stands. As a pro wheel builder I have literally made my living with them and am happy to help.
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
Chuck Matson says
Truing stands aren’t only for rims. They can also be used for rotors. I used them for rotors for a number of years. But contrary to my earlier assertion, I now true rotors on the bike because final minuscule adjustments work best for me with the brake pads to show wobbles.
Jim Langley says
Yes, you’re right Chuck. Park Tool even makes a rotor truing gauge for their truing stands, here it is: https://amzn.to/4aVrkIy
Thanks!
Jim
Dave Minden says
For those 10ths of mms, do they really matter? How long will those minute adjustments be true, once you are again riding over bumps?
Jim Langley says
Thanks for the questions Dave. To professional wheel builders 10ths of a mm definitely matter. But where the rubber meets the road or dirt, they don’t matter that much and even more if you have disc brakes – UNLESS those 10ths of a mm are the result of tension imbalance in the spokes, which will often mean the 10ths of a mm become mms pretty soon.
Which relates to your second question. If the wheel is nice and true, round and the spokes are properly tensioned, a wheel should not come out of true simply by riding over bumps. I had a wheel once that got run over by a truck and it remained true. Bicycle wheels are incredible that way. If they’re built right they can handle a lot. And getting a wheel as perfect as you can usually results in a better wheel because the tension becomes more even.
Thanks,
Jim
Chris Landry says
“However, the mathematical reality is that perfect roundness does not exist and cannot be attained. This is because a circle’s circumference divided by its diameter equals Pi, which is an inexact fraction comprising infinite nonrepeating decimals” Not that it really impacts the trueness of your bicycle wheels, but that statement is complete BS.
Stephen Turk says
Agreed. Perfect roundness of a bicycle wheel cannot be attained due to a combination of manufacturing tolerances (primarily of the rim) and finite patience of the wheelbuilder to make the ever-finer adjustments required. Ultimately, “perfect roundness” would be limited by the molecular structure of the rim material. The value of Pi, and whether it’s an irrational number, is of no releveance whatsoever.
To put it another way, how would wheelbuilding techniques change if suddenly Pi was an exact fraction (22/7) rather than an irrational number? The answer is, of course, not at all.
Walt says
I agree that truing stands allow a more accurate/better results than truing the wheel on the bike.
However, unless the rider is a racer or competes, I true wheels on the bike and use the brake pads as a guide (assuming the bike has rim brakes – otherwise, a thumb is required or I use a device which I made which clamps on the seat stay and has an adjustable “pointer”). I often use a light so that I can clearly see the gap between the brake pad and the rim. I can usually see both lateral movement and any hops or out-of-round areas. I find that this is adequate for most wheels/riders.
If the wheel has come out of true because of a broken spoke or hitting an object (and sometimes even if spokes have become loose over time and ridden for a period of time that way), it is often impossible to true a wheel back to perfection…but often close enough to save the wheel.
Just my experience….
Kerry Irons says
I have built wheels in the middle of a tour using the rim-brake pads as my wheel stand. Works great. On the rare occasion when I build a new wheel, I still use my wheel stand, but the vast majority of my wheel truing now takes place using the brakes as a guide.
And to answer Dave Minden’s question: No, those last few fractions of a mm don’t mean a thing. It reminds me of that old school “wheel balancing” people used to do by wrapping short segments of solder around their spokes. Yes, the wheel was in better balance but it made zero difference on the road.
Dave C says
I have used several of the “professional” truing stands in previous years in bike shops. They are expensive! Now, I use a $5 piece of angle iron with a hole/slot sized to fit hub axle. Clamp it in a shop vise. Then using a skewer (for QR hubs) or a 10mm bolt (for disc wheels) attach the wheel. I happen to have a dial indicator with magnetic stand for VERY precise measurement but you could improvise with a scale or??
It does take some thought for correct dishing but I can true both laterally and radially in same or less time than on the commercial stands. At a LOT less $$!
Jim Langley says
Thanks Dave, sound like a nice home made truing stand. Good job!
Jim
David Mulej says
I have been using a Minoura truing stand for almost 20 years to build and rebuild wheels for myself and my family. It has allowed me to upgrade wheels and convert drive systems (Campagnolo to SRAM). I learned how to build wheels using Sheldon Brown’s guide and have watched some of Jim Langley’s videos. It would have been challenging to accomplish what I have done without a truing stand and I am glad I took the time to learn this skill. My one comment about the Park Tool TS-4.2 truing stand is that $600 is a lot of money to spend for anyone who is not a professional bicycle mechanic.
Jim Langley says
Thanks for the great comment David. For anyone interested Minoura truing stands are sold by the company on Amazon: https://amzn.to/3SiO1ij And, yes Park’s 4.2 – their most versatile truing stand is also their most expensive. They do make their 2.3 model which will still work with 99.9% of the wheels out there and has all the same pro features at $400: https://amzn.to/3U3VkvE
Thanks again,
Jim