Ryan_M

I've got a couple threads going on wheel building but wanted to talk about this specifically. The more I look into this, the more I really don't know. I've read that 1mm radial and 0.5mm lateral is considered good. Also the opinion that 20% tension deviation is serviceable, 10% is alright, and 5% is getting good. What is muddying this more is they don't give any qualifiers to what those numbers actually mean. Is that 1mm radial peak to peak, or RMS, average?, deviation from the median? But then some people said +/-1mm... wait, so that implies 2mm p-p. I've also seen (more than one) person say they sand the seam on AL rims so they can acheive 0.001" tolerance.... Thats nearly 2 orders of magnitutde difference! To contrast I saw someone who had a wheel they were quite proud of that was nearly 30% out on tension.

These specs are all over the map. I'm curious what people here consider adequate/good/great, but also if there's some definitive accepted tolerances to compare with. I'm sure all of these wheels are completely usable and the numbers (past a certain point) are only acedemic. Still, as someone who's learning it'd be nice to have solid goals to aim for. Is my wheel ok for a novice? Should I do better? How good do the numbers have to be to be proud of my build if I wanted to be OCD?

Duragrouch

Well first, I doubt anyone speaks on this in RMS average, my guess would be peak-to-peak tolerance.

My standard in radial is as close as I can get it, while maintaining decent evenness in tension. Same for lateral, but my critical standard is no brake rub with the pads adjusted close like I prefer. But I'm way within that. I don't use a dial indicator, but after a full true and spin, the rim seems frozen laterally. Challenge yourself, get it as close as you can. That's the advantage of truing it yourself. You have time.

Others have opined that I don't need to try for such heights:
"If spec wasn't good enough, spec wouldn't be spec."

Ryan_M

Heh, I threw in the RMS for a bit of a joke but it actually doesn't seem like a bad idea. I always assumed p-p was implied until I saw so many people talking +/-. Thanks for the input!

Bill Kapaun

Depends on the rim.
Just run a caliper from brake track to brake track on a cheap rim and you can easily see +/- 0.5mm and not always symmetrical. That can drive you nuts if you only have a "one finger" truing stand.
You have to ignore "flat spots" at rim joints.
Aluminum rim at .001" tolerance? Lay it out in the sun and see what happens to that tolerance when one side gets hot to the touch.

You have to play with the parts you have and suit yourself as to how good.
I found that for myself, the more slow & methodical I was, the sooner I was done.

One trick I've used on rims that have very "wonky" tensions is to take an "average tension by quickly going around 1 side of the wheel with the tension meter.
Make a "mental average tension".
I then take different colored alligator clips to signify different amounts from the norm. You can assign different colors different values as required.
Do the other side the same way.
Rears & disc fronts have different tensions, thus one side at a time.
Now simply LOOK at it. Often you'll see combinations of spokes that are way off that can easily be countered with other spokes that are out of wack the other way.

Using low cost Sun Rims, I can usually keep tension within +/- .5 div on the PARK tension meter on a new build.

Settle for even tension vs absolute "trueness".

Duragrouch

For assemblies of parts like a "stackup" where each part has a tolerance, but you rarely see all parts out + or all - , you can do a more detailed analysis, if worst-case stackup won't get you within the tolerance that you need. But for stuff I designed, I had to make sure that it worked even at worst case stackup. Geometric Dimensioning and Tolerancing (GD&T) really improved on this, because it takes all factors into account, and you make your part function drive your tolerancing, and your gaging and fixture design, so they all match up. If the "GO" gage works, the part will fit in production. A good example is "tolerance of position" in GD&T, a hole diameter versus hole location; If the hole is near the high limit in diameter, you can blow the location of it a bit more, whereas at the low limit in diameter, the location needs to be more precise, so that the bolt goes through adjacent parts. I.e., it related diameter to location, whereas the old way, you just had +/- on the diameter and +/- on the location, with no relation to each other.

awac

Roger Musson's book might be a good download for you and should answer the questions.

https://www.wheelpro.co.uk/wheelbuilding/book.php

0.2 mm lateral, 0.5 mm radial and 1.0 mm dish (0.5mm either side) for the tolerance of a good wheel. This is also the criteria for the Cytech advanced test. Some rims you will get better, some you will not, the trick is knowing which ones you will not. Get some new rims, get some old thin rims and play making pretzel's! You will get a feel for it…

Andrew R Stewart 

Bill K offers real life info.

I almost laughed at the OP's questions about tolerance in wheel building. Real rims are not perfect ones. They have deviations from round and flat right from the factory floor. Often even if the radial/roundness is good about the seam this portion of the rim usually has a different manor in how it responds to the spoke tensions than the rest of the rim does. Then there's the issue of tires having far greater deviation than a nice wheel has...

I long ago accepted the Wheelsmith philosophy that a slightly out of true wheel with more consistent spoke tensions is a better long term part than a wheel that looks dead straight but has spoke tensions all over the place.

How true VS how consistent the spoke tensions are and how high does the tension levels get can be explained with numbers but in my world is not a must be or a given. I let the parts give me feedback and make judgements form that. generally I'll try for around 1ishmm radial and the same for lateral. But there are many wheels I have built that have greater run outs and still are giving miles of pleasure. Andy

mpetry912 

it depends... on your instrumentation

truing with a light gap method like the Park TS-2 you are doing pretty good if you can get sub millimeter tolerance in lateral runout.

Radial is harder because of the rim joint. In either case that's good enough for most riding and what the tolerances are after say 100 miles of riding are a lot more telling.

Do your rims stay true ? is the question not easily answered

I am fortunate (along with @Portlandjim) to have a PK Lie truing stand with non linear deflection guages (they are NOT dial indicators) that have a resolution down to 0.250 mm

and it is possible, with some practice, to achieve that level of accuracy.in a finished wheel, with very good uniformity in spoke tension.

Andrew made reference above to the "wheelsmith" approach. It has been my privilege to know and work closely with master wheelbuilder Ric Hjertberg, and twice attended his wheelbuilding class.

In that class he shares a little trick that transformed my wheel building technique in terms of speed to finished wheel and quality of result. it is counter-intuitive.

By the way the DT rims are the very best I have ever used. They are really really true and very high quality. As are thier 4 sided spoke wrenches.

/markp

Dan Burkhart 

Welcome to the world of functional vs cosmetic true.
To be functionally true. Lateral and radial deviation of one millimeter or more would not present a problem even with rim brakes. As pointed out previously, tires are often less precise than that.
My standards are much more precise though, as the end users of the wheels I build are very discerning as most are high end road wheels.
I don't use dial indicators but I do use feeler gauges and the .008" is the one I strive for, but sometimes a squirm at the seam means settling for about .020" or half a millimeter.
Carbon rims can also be a bit lumpy in the layup making absolute precision impossible.
The gauges only come out as a final check though as I can usually eyeball it that close.
​​

pdlamb

Care to share?

79pmooney

+1 For me, the goal is a "happy wheel" that will give me years and thousands of miles of trouble free riding. And the mix of spoke tensions and trueness, both side to side and roundness depend on the rim, spokes and hub I start with. Some of those happy wheels I can set the brake pads to almost touching, others I need to back off a ways. (I don't like instant contact anyway when I squeeze the brake lever, so that's rarely an issue on my bikes.) Some wheels are better rides with slightly larger and softer riding tires because I could not hit "round".

All rims are made by factories of machines and people. Mondays and Fridays the people are often not so sharp. Machines get old, lose their "edge". Dies for the rims get tired and bigger inside so the extrusions get heavier. The seams are a combined challenge of 1) can that extrusion be bent continuously and perfectly to the ending at the seam? and 2) does that mechanical or weld at the joint distort the extrusion? Different rims are made with different techniques. Some are famous for the extrusions going near straight that last inch or two at the seam. Others for angular distortion caused by the plugging method. Or from the weld head and sequence,. If people were involved, Monday, Wednesday or Friday?

Rims then get sent, perhaps across town, perhaps across continents and oceans. Get stored. Lifted in pallets by forklifts. Hung on racks by near kids who simply don't care. ... We then expect to make dead on perfect wheels out of them. Or just settle for "happy" and sleep better. I build wheels with NOS rims. Some of them were made and shipped from the factory 40 years ago. There's room for a lot to happen over that time span!

zandoval 

Thank You Bill. I have kinda been doing this lately. Of course some of my beat up, bent and straightened rims are lucky to get anywhere close to absolute Tension and Trueness. I am getting better at it.

Lucky foe me my OCD only goes as far as, Well, The brakes dont rub and Its Rideable... Ha

Rideable is most important.

wheelreason

Maybe we should slap some solid rocket boosters to these wheels and send them into space...

Rick

I am really picky about the tolerances. I use english not metric dial indicators. A mm is .0394". I don't build wheels that often but when I do it is easy to finish with much higher tolerances. The last two wheel sets I built. I was able to achieve .005" TIR both ways. Both rim sets had machined sidewalls. I check for even spoke tensioning by sound. I pluck the spokes. I like dial indicators because you can see the imperfections much easier. When I purchased my Rohloff equipped bicycle I had told the shop I wanted the Velocity Cliffhanger rims. They delivered it with the Velocity Aeroheat rims. I found some old stock new velocity Psycho rims. That was near 10 years ago and the Velocity Aeroheat rims are hanging in my garage.

Andrew R Stewart 

A tolerance aspect that I am very picky about is that of the rim's brake tracks. They should be both consistent width and remain smooth at the seam. Nether have much if anything to do with what we generally call "being true" as we look at them but very important when it's the brake pads that are doing the looking. Andy (who's been riding these huge disk rotors, we all call rims, since 1967)

Rick

[QUOTE][A tolerance aspect that I am very picky about is that of the rim's brake tracks. They should be both consistent width and remain smooth at the seam. Nether have much if anything to do with what we generally call "being true" as we look at them but very important when it's the brake pads that are doing the looking. Andy (who's been riding these huge disk rotors, we all call rims, since 1967)/QUOTE]

I like rims compatible with rim brakes because they work better with my dial indicators. The Velocity Psycho rims and the Ryde Andra 30s that I used on my sons touring bike had machined side walls and were very consistent on the width. These rims were some of the heaviest duty rims that I have ever built with.

mpetry912 

have mentioned it before in another thread. you need that fancy stand to be able to take advantage of this trick.

It's NOT a special spray you can order from AMZN

/markp

slow rollin

I.... true it till I get tired of it and I get the spokes tight enough that my park tool gauge says I am in the range for that size spoke. I have rounded nipples off before trying to fix a cheap wobbly rim and have learned that wheel building is just like drywall or paint. Luckily that was a disk brake wheel on a dirt jump mtb so a little wiggle action is nbd. You just have to stop fussing after a while.
I only do wheels for myself, so if they dump me on the ground that's my fault. I just use my ears to check the inital spoke tension to check if they are close and if it's true+close after I use the tension meter I leave it.

grumpus

I aim for better than 1 mm in each direction, with some rims that's the best you can hope for, but a good one could be 0.2 mm or better (guessing, I don't normally use a dial gauge). Check the rim against a known good wheel before lacing it, to see if there's much deviation from flat or round - correcting at this stage might improve the consistency of the spoke tension. I don't use a tensiometer so no idea how tight or consistent the spokes are, they just feel pretty even and firm. The true test of a wheel is not measured in thousandths of an inch or kilograms of force, it's whether it can be used as intended without needing adjustment.

Russ Roth

My newest measurement standard is that the feeler on the stand only rubs at the sticker. Not sure how thick the stickers are but it seems like every disc rim now comes with a sticker that reaches the edge of the rim. That being the case, the sticker is in the way of the feeler and as long as that's the only spot it touches it really is true. As others have mentioned, round is determined by rim quality especially at seams but I try for less than .5mm. Dish is tough but less than a mm off center is fine and no one is noticing it, but this one is also determined in part by the fact that once you're close enough, even tiny turns of the nipples, multiplied over the total number of the spokes, can easily move a wheel from nearly there but off the left to equally nearly there but off to the right. In that situation its best to just leave it slightly off.

Yan 

I don't know what others consider adequate or good, but when I build wheels the deviation in both directions is well under one millimeter. If a bike shop built wheel has that much deviation, I'd think the shop is run by a bunch of clowns.

But in actual practice 1mm doesn't matter.

Andrew R Stewart 

And it is this exact assumption that wheelbuilders take issue with. That outward appearance is the final say of skill and quality. Much like not reading the book because you already know the story by the book's cover. Andy

Yan 

I expect both the book AND the cover to be excellent. Because if I'm paying someone, I expect them not to half ass it. I don't enjoy paying someone like that who has no pride in their work.

Which is why I build my own wheels. Why pay someone to do a half ass job when I can do it myself better AND for free.

pdlamb

Are you planning to ride on that hypothetical wheel, or are you going to mount it in a jig and spin it so you can watch your dial indicators?

Yan 

Yeah, I'm currently at this very moment 7 months into cycling around the world on wheels I built myself.