FBinNY 

Before making any permanent modifications, try slipping some weights over the valve, and balance it so it spins evenly in air (off the ground). The ride the wheel and I suspect you'll still feel an imbalance.

That's because the effects of radial error on the mounted tire is making the wheel like a big cam and the axle rises and falls (and/or the tire compresses) with each revolution. The cam effect is greater than the effects of the imbalance, so there's a good chance that you're correcting the wrong thing.

mrrabbit 

Can't wait for the day the OP comes back telling us about ingressed water sloshing around...

=8-p

Soil_Sampler

half an ounce.
motorcycle wheel weight, or stick-on weight.

DannoXYZ 

If you've got your wheels trued to 0.18mm, I doubt you'd be able to feel the difference in 17g of imbalance. The RPMs and speeds that a bicycle wheel achieves isn't sufficient for that amount to be noticeable. Heck, when I upgraded my wheels for downhilling (and hit 72mph), I removed about 100gm of lead-weights and didn't have any imbalance issues.

HillRider

Sporting goods stores with well equipped fishing sections sell lead split-shot or lead "tape' that can be wrapped around the spokes opposite the heavy spot.

BikeWise1

I've been riding bikes and building wheels, oh, for about 30 years and have never, ever been able to detect any issues with wheel imbalance while riding, and I'm pretty anal about vibrations. I'd love to see this wheel in person. When I can feel a consistent vibe up through the steering when riding at speed, it's inevitably tire related. ALL bike wheels are out of balance. I've been to shops in all 50 states and never seen a bicycle wheel balancing machine....probably because the need never comes up.

But I will say engineers and those who fancy themselves as such are inevitably the worst customers. Dunno why.....

oldskoolwrench

Water ingress? I'd worry more about the compromised structural integrity of the rim, let alone the potential liability issue should it fail!

unterhausen

as a mechanical engineer who used to work as a bike mechanic, I have to say you might be right. My favorite bike shop moment was when I told someone he'd be back. He asserted he wouldn't because he was a grad student in mechanical engineering. I was kinda surprised when he came back.

IthaDan 

This might be the craziest picture I've seen on this site. Is there a thread about this creation?

What hills do you go down, equinox?

hueyhoolihan

OP is machinist with, as you would guess, a machinist's personality. some of the most precision obsessed people in the world. who else could build a v-12 engine (f1 ferrari) that revs to 18,000 rpm without exploding? let'em fuss with it.

reddog3

Really? Not sure the method you used to find "17 grams heavier at the joint," but stop to think about it. There is no way in hell that the materials, or the method used to make that joint weighs 17 grams.

Kimmo

17g sounds like a bloody lot; I wouldn't be all that surprised if that's verging on perceivable. Even it isn't, I'd be inclined to balance it out just to appease my anal streak; done it before. I used a blob of electrical solder, melted to a shape that could be taped into the rim well without interfering with the beads. I knew it made stuff-all difference, but banishing the pendulum effect just made me feel better about my bike.

Oh yeah, Velocity lists the A23's weight as 426g.

What the flying ****?! That's a hell of a wheel upgrade.

+1 more info on this insane creation. You must have a thread...

FBinNY 

There's no way, might be too strong, but it is highly unlikely. Aluminum weighs 2.7grams/cmł so there would have to be 5cmł of added material in the joint area, plus a bit more to make up the weight of the valve.

In any case, it's academic because you couldn't feel that imbalance at bicycle speeds, especially when masked by the wheels eccentricity.

roobydoo

I taped the bolts to the opposite side of the wheel, kept on adjusting till the wheel didn't fall either way, then weighed the tape and bolts.

I am mostly stunned at how a wheel can have that much extra on one side. It's 4% of the weight of the rim. Now, once built up the wheels are 816g and 653g, so the difference percentage wise is much less. (even less so once I add 300G of tube, rubber and rim tape)

I re-trued them to be within .010" radially and axially using a dial indicator. I'm going to re-assemble them, and get a bunch of extra valve nuts, and try them again with and without the extra weight to see if I can tell at all or if it's just in my head.

And, yes I am not discounting that this could be a futile question, but discoveries don't happen by adhering to status quo.

bored117 

Here is my suggestion. If you are using Aluminum nipples... get some brass ones for the side that is "light"... Should help you on balancing the wheel a little more Okay... I am amateur machinist

tomato coupe

Campy's approach (on their lower priced wheels) is to use a heavier spoke opposite the seam. On their more expensive wheels, they machine away varying amounts of material from the inside of the rim.

bobotech

What you will end up feeling will probably be tire imperfections and/or road imperfections. I don't know what it is about roadies, but man, they have some pretty serious OCD and psychosomatic sensations. I like the threads where someone will say something like "I knocked off 2 grams of weight off of my seatpost and I can really tell the difference in my acceleration". I'm being facetious of course but there is some reality in it.

DannoXYZ 

You'll want to separate balancing the wheel from balancing the tube & tyre. This way, you can have their imbalances oppose each other and end up with minimal amounts of extra weights to even them all out:

Now remove all components and weights. Mount tyre on wheel and position heavy-spot (Tp) somewhere between the rim's heavy-spot (Rp) and tube's heavy-spot (Up) on the side with greater separation. So if rim's heavy-spot is at 180-degrees and tube's heaviness is at 20-degrees, place the tyre's heavy-spot at 280-degrees. Then mount the tube and pump up.

Finally, balance the entire assembly and you'll find that the weight needed is minimized. This is similar to how auto-tyres are mounted. Tyres have a painted dot on them where the lightest spot is (opposite the heavy end). The auto-tech then mounts the tyre with the spot next to the valve-stem to place the heavy spot of the tyre opposite the heavy spot of rim. On my high-speed cars, like the +240mph 968-Turbo Bonneville contender, I balance the wheels after they're mounted on the car. This will incorporate the imbalance caused by lug-nuts of different masses and brake-rotor imperfections as well. At 210mph, I had to use metal valve-caps with O-ring seals because the centripetal forces causes the shraeder valve-core to depress and leak out air...

fietsbob

The valve stem is on the opposite side of the wheel,

if the OCD based issue,
of the bridge piece weight across the seam bothers you,
maybe a carbon fiber rimmed wheel set will be more satisfactory..

dabac

Really?

I rather doubt that. It'd either have to be a minimal seam, or a ridiculously heavier spoke for that to work out. And unless you pick a really oddball material, the heavier spoke won't stretch the same as the other spokes, and I can't imagine a trusted manufacturer doing that deliberately - even if it isn't immediately critical.

DannoXYZ 

Soil_Sampler

Hell? Yes, way!

It all depends on the method. Some welded rims use a sleeve, or tooling jig inserted before welding.

A method of flash/butt welding an aluminum bicycle wheel rim, in which an aluminum sleeve having a dielectric anodized hardcoat surface finish is inserted into the center of the rim in order to support the interior walls of the rim during the welding process, is disclosed. The walls of a wheel rim or other similar metal profile defines an inner space in a tubular section of the rim. The sleeve is partially inserted into a first end of the rim and partially inserted into a second end of the rim. During the welding process, an electric current flows across a small space or gap between the two ends. The electric current melts the ends, at which time the two ends are pressed together in order to forge them into a single piece. The metal sleeve supports the inner walls of the profile in order to prevent collapse of the wall during welding. Due to the dielectric coating, the sleeve does not affect the welding circuit.



Both Campy and Fulcrum use this. No Doubt!

"For entry-level models, Dynamic Balance™ is obtained by using two oversized spokes in the section opposite the joint.
The result is a wheel with perfectly balanced rotational dynamics."

https://www.fulcrumwheels.com/en/tech.../road/rdb-road

Kimmo

Actually, removing weight from the seat or seatpost is surprisingly noticeable. 2g not so much, but you might notice 50g - when you stand on it and throw the bike from side to side, that weight matters.

I have in fact read Campy marketing guff to that effect, it's an actual feature. I can only imagine it's all about the perceptions of noobs, since it's their lower-end wheelsets.

Shimagnolo

Don't just tease us with a pic like that!
We need to see the *whole* bike!

Kimmo

Yeah Danno.

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