Bicycle Mechanics - how important is radial true

Well i am truing my wheel and now it is within +/- 1mm of being laterally true. But damnit, it seems like no matter what i do i cant get it to be radially true. Its always within 2 mm and whenever i try to fix it it isnt laterally true anymore. What am i doing wrong? If its 2mm out latterally true will it affect my riding? I wouldnt imagine it would have a huge impact

I can't imagine that it will, and it sounds like the rim was not perfectly true and round from the factory.

I would say get it as good as you can, check that the tension is even on all spokes, and ride it for a wekk or two. Then re-true. You might find it comes good.

alright, that is true it may not be round and true from the factory. Also, would it be okay to put a mild adhesive on my velox rim tape? It doesnt always stick the best.

You should be able to get it in round as long as you bring up the tension on both flanges so that it pulls down but not to one side or the other.

Be careful not to jack up the tension too much though or you can pull the nipples through the eyelets. Oops!

But then I'm no expert myself.

alright, that is true it may not be round and true from the factory. Also, would it be okay to put a mild adhesive on my velox rim tape? It doesnt always stick the best.

The world is an oblate spheroid as Tom Cuthberson says. As long as the wheel is pretty close to true and round, ride it for a while, true it and ride it some more. Unless it has a huge flat spot in it that makes the wheel square, you can ride it. Make sure the spokes are the same tension though. Ping it or use a tension tool but check them. Check them after the first ride also, especially if the wheel creaks or pings when you first ride it.

As for the tape, once you pump up the tire, the tape should adhere quite well. I wouldn't worry about it much.

Stuart Black

Well i cheked with my tensiometer and they are all pretty good. I pre stressed it also,

You get radial true by tightening spokes in pairs. If the wheel is already pretty tight you can loosen the low spots(realitive to the feelers) 2mm is a lot in my opinion, .5mm would be acceptable.
Work from the center of the hop, if it is really big you can give the center pair a full turn and then the two outside of them a half turn each. Give the wheel a sopin and se what the change is. Then do it again. After doing this a few times check true again, when you true be sure to loosen the spoke opposite the one you tightened to keep from drawing the wheel up and creating a new hop.

ugh this is frustrating, thanks Rev. CHuck though, i think tommorow i will give it a shot. Its odd though, the whole process of building it all and lateral truing was easy for me, but this damn radial business is no fun

You get radial true by tightening spokes in pairs. If the wheel is already pretty tight you can loosen the low spots(realitive to the feelers) 2mm is a lot in my opinion, .5mm would be acceptable.
Work from the center of the hop, if it is really big you can give the center pair a full turn and then the two outside of them a half turn each. Give the wheel a sopin and se what the change is. Then do it again. After doing this a few times check true again, when you true be sure to loosen the spoke opposite the one you tightened to keep from drawing the wheel up and creating a new hop.

Yes, .5mm is the correct number as defined by Barnett's. For any wheelbuilders that do not own a copy of Barnett's...... you are in luck. You can download and save the chapter on "Wheel Truing and Repair" at:

http://www.bbinstitute.com/BM5%20chap%2017.pdf

This covers truing, dishing, and tensioning in detail, and, tells you how to correct your errors. I think this is much more useful than Brandt or Schraner as far as actually guiding you through the pitfalls of wheelbuilding. Everything RevChuck said is right on, but I doubt he wants to put up 34 pages of details. See the Barnett's chapter for the complete story.

There are also several other chapters that Barnett's very generously offers up for free at:

http://www.bbinstitute.com/manual.htm

See the bottom of this page for the links to the sample chapters. These are obviously teasers to get you to buy the complete manual. At ~$85, IMHO, it's worth every penny. Plus, this is one of the major standards that guide the industry. If your LBS is not doing repair and maintenance work that's at least close to what Barnett's lays out, then maybe it's time to find another LBS.

I agree with Rev.Chuck.
I find it is easier to focus on removing all the hops (radial) first and then focus on lateral.
Once everything is true I tension the wheel and re-check.
Enjoy

In practice, I put more emphasis on radial trueness. But when anything is within 2-3 mm, it's mostly a question of feeling.

Radial trueness:
If the wheel is untrue, you will feel the humps when you ride on smooth pavement. In a way, as long as you don't feel anything uneven, your wheel is OK.
Beware also of the fact that a tire might be irregular or mis-installed. I suspect that a 26" x 2.5" or 3" knobby may easily have a 2-3 mm unevenness (or "unroundness" -- I have seen a few bicycles where the unevenness was obvious to the naked eye); OTOH, if you use 700x23 tires, they probably are even to 0.2 or 0.3 mm.
Likewise, irregularies show much more at 120 psi than at 30 psi.

Lateral trueness:
A 2-3 mm wobble doesn't have any significant effect on steering or stability. So basically, it comes to the point that, as long as the wheel spins freely between brake pads (and fork, chainstays, etc.), you are ok.

The wheel should be true radially and laterally *before* you put any significant tension into the wheel. You should have the wheel trued radially and laterally at ~60kgf on you tensionometer. This allows you to eliminate the wobbles and hops without building uneven tension into the wheel.

ugh this is frustrating, thanks Rev. CHuck though, i think tommorow i will give it a shot. Its odd though, the whole process of building it all and lateral truing was easy for me, but this damn radial business is no fun

For roundness, try working with whole groups of spokes. Start in the middle of the section and loosen (or tighten, depending) that spoke the most, then work on the two spokes on either side but work them a little less, then the next two but a little less then the previous ones. Once you have the roundness where you want it in that section check the rest of the wheel again. The wheel is like a balloon, poke it in one place and the bulge may move to another place.

The best time to work on both trueness and roundness is when the wheel is under low tension. I always work the rim to where I want it and then start tensioning. When the wheel is tensioned working out the defects is much harder.

Stuart Black

This has haughted me also, since I started building my own wheels. I can true any wheels latterally, but radial has been a pain for me. You guys listed some great suggestions here, especially loosening/tightening the opposite side from Rev Chuck. Didn't know about that. Thanks guys!

My bike shop owner/mechanic recently gave me some pointers on wheel truing. One thing we looked at was that a lot of wheels can be a problem just accross from the valve hole. That's where the rim is welded in a lot of cases so the metal there can be thicker. I've been having a problem recently breaking spokes and having my wheel go out of true.