Thanks for the motivation !
 

Broke down the front and rear wheels and sure enough, the welds were a little on the fat side inside the rims. Carefully used a file to shave enough of the material off without creating any sharp edges and now both wheels randomly settle with the valve stem oriented when spun while the bike is turned upside down. That's solved.

To verify, here are pics of the front wheel. The first pic was taken about 4:18 PM demonstrates where the wheel was settling every time I spun it and it came to a complete stop. Other pics taken after 9:30 PM demonstrating the various random positions the valve stem settled. spins were roughly 2 minutes apart for the pictures taken after 9:30 PM.

I'm a little lost...what's happening?

You should have reflectors.

Yeah, what did you shave to get the valve settling correctly? Little burrs on the valve hole?

See the last couple of pages on this thread:

http://www.bikeforums.net/showthread...y-new-Masi-%29

Others told me I was crazy and couldn't tell the difference. Well, I took that as motivation and put forth the effort in an attempt to balance my wheels better than what they were and this is the result of what transpired over the last few hour(s) of work with a few breaks in between. Now that I think about it, I should've snapped a few pics of the rim weld (before and after). But I figured I had the two wheels to do and wanted to get both done asap. I must say, I'm rather pleased with the results.

Are you exerting the same amount of force everytime you spin?

are you a turtle?

so. you can tell when it's only the wheel spinning, and the bike is upside down.

the real question: could you honestly tell before you flipped the bike over? Can you honestly feel a difference when riding it now?

Nothing, the valve holes on the rim had no burrs, but were relatively clean cut so I left them alone. I think if they were cutting thru the tube, then I'd have to look into that as a problem. The whole discussion we had centered on whether I would balance these wheels with lead tape or a weight like an automobiles wheel gets when it's balanced. Instead of adding weight to balance it, removing weight in certain location(s), if it was possible would do the same thing as adding weight to balance it better. What was happening was that everytime I spun the wheel it would settle and stop with the valve stem oriented at between 1 and 2 o'clock position. I had the wheels trued so I knew laterally and radially the wheels were fine in terms of being round so it wasn't a lopsided wheel. The wheel settling at the same location every time told me that the bottom most point was the heaviest spot on the wheel. I had to determine what was causing the weight to be located there. Was it a lopsided tire, fat rim weld, something/anything.

Read the appropriate literature. Still haven't the faintest, bro.

Keep an eye on the seams, just in case.

Ohhhhh.....I'm going to go investigate and test this theory.

Double up, accidentally, son!

Are both wheels pumped to the same PSI?

Do they weigh the same?

That didn't matter before I performed the work. I was spinning it both slower and faster and it always wound up settling in the same spot, regardless of whether it spun for 30 seconds or a minute or two. I don't think I could ever control spin rate exactly with the same inertia every time like that anyway. Now regardless of how slow or fast it's spun the valve stem winds up settling in a random orientation which is what I wanted out of the effort. That tells me when the inertia runs out it stops whereever it happens to be and not a heavier spot on the wheel at the bottom of the wheel. I bet if I could float this in a pool, prior to this work, the heaviest point of the wheel would be at the bottom most point ? But spinning it was the best I had to work with.

Well, my front wheel valve stem settles naturally at the 1 o'clock position.

This thread reminds me of a conversation I had with my neighbor about the weight of pressurized air.

are you a retired physicist?

I see where you're going with that, The front and rear are obviously different weights, They both are lighter now by whatever material that was shaved off. But what's more relevant is that the location and balance of the wheel has changed in a single location that is the width of the weld where the material was shaved off. I was very careful to not compromise the weld and take too much material off. As for PSI, air gets spread around the wheel evenly, it's in the inner tube and flows freely. My goal wasn't to make the wheels weigh the same, it was to eliminate a heavy spot on each wheel. The rear wheel was a little harder to apply the theory too, because it has the gears on both sides, SS/FG. Whatever else the rear wheel has were a couple of variables more to be a possible cause.

don't need to be a physicist to know basic stuff about physics.

edit: then again, I'm a chemist, and otherwise self proclaimed huge geek/nerd. so what do i know about what "normal" people should/shouldnt/do know...

Another thing/a question, when it settles, does it rock back into that position ? That might be indicative of a slightly out of round or untrue wheel just the same as a true & imbalanced wheel. Because that will most assuredly also be imbalanced. An untrue wheel behaves like a trued and imbalanced wheel. There is a lateral and radial trueness that applies to a true wheel. Others offered that a cheap tire might be the culprit too and that could be the case as well. Consistency of the parts is key.

Aye, one set spins and settles without rocking. Clinchers.

The other, rocks back and forth. Rim looks true to the eye. Tubular.

I can tell when the wheel was untrue and can also tell when it's not balanced. With the bike turned upside down that's the easiest way to see it. When the bike gets flipped over into riding position, whatever is untrue or imbalanced is still there. The point of contact becomes the road and the rest of the bike simply rests on what imperfections exist and like a car those parts simply translate what is happening at the bottom most point of the wheels, which contacts the road. The way I think of it, should I be able to discern that difference at 10, 15, 20 or 25 mph ? I know when a car wheel is imbalanced the ride gets worse the faster you go.

Where to start with that, Accountant for a little while, Configuration Management Engineer for a few more years, and most recent gig Computer Systems and Database Analyst. Industries include DoD manufacturing, marine pleasurecraft, Transportation & Logistics and Healthcare & Insurance.

This is where I have to be careful. Since there are several things that could be the culprit, even that I'd need to take things apart and inspect/study it to familiarize myself as anyone would naturally have to do as well. The bike I have is 2 1/2 months old and I've had it apart several times, just not down to the basest parts of the wheel. I'll leave any exploratory up to you. It all depends on how hard you want to pursue it is what I'm saying.

Seems like no-one understands the concept of balancing a wheel.

If your bearings are set properly, or even a little loose, and you un weight your front wheel it should come to rest with the valve stem at the lowest point (no spinning required) as this should be the heaviest point on the wheel.

I used to true 300 pound brake rotors... it required an overhead crane and a drill press that was twenty feet tall with an 80,000 psi rating as we balanced them by removing excess material from the machined castings.

Anyways... if a bicycle wheel is a little unbalanced only a princess would be able to notice it.

In the old days when tyres and wheels were not as consistent folks would use wire and weights to balance their bicycle wheels.

:popcorn

That was what Scrodzilla suggested in a post that the valve stem itself would be the cause of imbalance. Yet on the three bikes I have the valve stem rarely if ever wound up oriented at the 6 o'clock position. I can't explain that beyond the rim itself being manufactured to counterbalance the valve stem ? As for the bearings, they're basically brand new and there is no sloppyness or play in them, new parts, no wear and not too tight. So again, I have no explanation why the valve stem doesn't wind up at the bottom every time ? As for a princess being the only one that could tell the difference ? When I first assembled the bike and rode it, I was hoping I could get away with not having to true the wheels. I rode it and rode it and it was really so darn close to being true, but I could still feel it every time I rode it. Literally, the only way I could find the spot was to put my finger between the rear tire and seat tube and feeling where the tire lifted off my finger in some spots. That drove me nuts the radial being untrue like that, I rode the bike that way for a couple of weeks and took it in to have the tech true it up. Riding it home after it was trued was such a relief and a significantly more enjoyable ride. That was only about 1/8" in that case, maybe only 1/16" with the tires at 105 psi. I do have the luxury of having a freshly paved road in the neighborhood. I won't say it's perfect with whatever crown it has but there are stretches of it that I wish every road I ridden on during a ride were like.

do u also have ur wheels perfectly true radially and laterally using a dial gauge and spoke tension perfectly even all over?

+10,000