How true is true?

[Seattle51]

I'm in the process of building my first set of wheels and I'm pretty close to having the first one true'd up. I'm curious though how true do I need to get? I've read up to 2mm in either lateral or radial runout is "within" spec. I'm actually closer than that both ways measured with a dial meter, measured closer to 1-1.5mm laterally and about the same radially. I can see a very slight wobble when I spin the wheel though so I feel like maybe it should be closer? Anyone with more experience than I (that includes anyone who's ever trued a wheel) please let me know what your thoughts are. I absolutely only want to do each wheel once (they're heritage specials with twice the number of spokes) and I'd love to put new tires on these and put this part of my build to bed...

Thanks for the help!

 

[gggGary]

The rims are welded up from extrusions so they have a seam, a bit of wobble at the weld is unavoidable. Sounds like you are good to go.

 

[5twins]

Yes, the spec is 2mm in either plane which is about .080". I routinely get them to within .010" without too much trouble. Keep at it a little longer, you can probably get it closer than you are now. I've usually found the weld seam to be barely visible to the naked eye but, yes, it does show as a "bump" on the dial indicator.

 

[bradshaw106]

I have billy lanes, how to build old school choppers book. he does 0.005 runout, side and radial.... I'm sure he has done it a few times though...

 

[5twins]

I'm sure that's entirely possible with a new rim, on a used one maybe not so much. I use just a pointer, actually a length of stainless strap mini C-clamped to my stand leg, for the radial. On used rims, the outer lip or bead seat area is usually too gnarled up to run a dial gauge on .....

..... and here you can see the weld "bump" throwing the gauge off .008" or so ......

 

[Seattle51]

So I guess my real question is where does the point of diminishing return begin. Is 2mm the point where there are going to be issues in handling, and if possible getting it closer clears them up? I imagine that although Billy Lane CAN get his rims within a few thousandths of an inch, I'll bet that there isn't a motorcycle tire produced that is anywhere near that true, so if your somewheres in between is it going to be close enough to ride correct but not be so close that you've spent unnecessary time and energy?

 

[5twins]

If you're within the 2mm spec, I'm sure the bike will ride and handle fine. If you can see any wobble as you spin the wheel by hand, I'd spend some more time on it.

 

[moparmatt91]

.040 is harley davidson spec so anything around theres is fine. your tires is not perfectly round either so done worry to much about it. Anything .050" or less is fine

 

[Goldy]

Your're good to go, I have seen guys race with ones that were way, way, WAY further out than than 2mm.

 

[jd750ace]

.040 is 1 mm. I have not personally laced a wheel, but a guy who used to do them for Stroker's told me that sometimes mounting a tire changes it up, because it can shift the nipples in the dimples. You might mount up a tire and inflate it, deflate, then check the runout. He says it can shift either way. It sounds like you're good.

Like lots of things, I haven't done it yet, but inquiries have been made.

 

[OakBehringer]

I was under the impression that these old steel rims don't true as much as say a aluminum bike rim, and that equal tension on the spokes is actually more important than trueness, within reason. Is that wrong?

 

[5twins]

I don't go for exact equal tension on all the spokes, just get them all tight. You'll never get an old used rim true if you set all the spokes at exact equal tension. It may be next to impossible to get them all equal anyway. When you tighten the spokes on one side of the hub, it tightens the ones on the other side as well because the hub is pulled away from them towards the ones you just tightened.

 

[OakBehringer]

Roger that.

 

[KUSHLIFE]

all great info fellas- i just finished painting my rims & hubs this week and laced em up last night for the first time and was easier than i thought- just had to take my time and wrap my head around the whole process. good to know spec info on the truing as i didn't. as well as diff spoke tensions with original rims i'm actually also sealing up the wheels and running tubless so i don't want to have to true them again either.