thermite

I've got Mavic Disk rims on my bike and I've noticed if I'm checking the trueness of the wheels
and I'm spinning them whith my hand, I've noticed that there's quite an offset in the balance of the wheel. I think it's where the valve is but if you give either wheel a good quick spin with your hand then hold the bike in the air, you can really feel a wobble with the offset weight. If the wheels are synchronised when I'm rolling along, I can feel this offset of balance forwards and backwards. Does anybody out there notice the same thing and do anything to balance their wheels such as add little weights?

Brian

Once again, I must thank Bill at Torelli for providing some info that you may find interesting. Here's what he says about his wheels:

All bicycle wheels wheels have a slight, inherent imbalance, usually not noticeable because the compliance of the tires and the fork and frame absorb the very slight eccentricity this imbalance imparts. This imbalance has two drawbacks. One, on a very few bikes, at high speed, a wobble or shimmy may be induced. The other is very subtle. The imbalanced wheel is slower. As the rider's energy turns the imbalanced wheel, it rotates like an out-of-balance car tire with the heavy part of the rim being pulled by centrifugal force slightly out of the perfect path of the trued rim. The absorption of this very slight out-of-round rotation by the tires and the frame is lost energy, something no rider chooses to waste.

The Torelli Triumph rim has a small balancing weight at the valve stem hole to completely counterbalance the increased mass needed to join the ends of the rim extrusion. This joint is always opposite the valve stem so that the increased mass of the valve stem will counter-balance the effect of the weight of the joint. However, it does not do this completely. The Torelli Triumph rim, with the balancing weight, does. By adding a few extra grams, we have a faster rim that also often yields a better handling bike at high speed. This is really what we are truly seeking. Not the lightest bike, not the stiffest bike, but the FASTEST bike.


Visit www.torelli.com for more interesting stuff, and support a company owned and run by a true enthusiast.

NJWheelBuilder

I can't imagine the valve of the tube making any difference whatsoever. Sometimes rims are pinned together at the seam. There might be a little extra weight with the pins, but its opposite the valve hole so it shouldn't be an issue. I would not any weight to my bike because of this. Make sure you don't have a problem with your wheel bearings. That seems more likely. If it really is the valve weight causing the problem, I'd ignore it and go ride.

SoonerBent

My valve stem (or something on that side) makes a difference. With the wheels off the ground I can spin the wheels and the stem will always end up at the bottom.

SS

rmfnla

There is a difference but it's usually not pronounced enough to really matter.
I have seen people use split-shot fishing sinkers as balancing weights to deal with it.

Of course, I also remember when people used to wrap & solder their spokes to make their wheels stiffer.

There's no crank like a bike crank...

thermite

Thanks for the helpful feedback guys. I know it's only a trivial thing, I just wondered whether people were doing anything to eliminate it. I had a nice road bike back about 10 years ago, and I'd constantly hang it up and check the wheels were true, I actually got quite anal about it! I never noticed an imbalance back then on those road wheels. with these Mavic rims and 1.5" slick hybrid tyres, I can actually feel it when I'm coasting along at around 10-15mph, it's like being on a very subtle version of one of those kids things in a park which rocks back and forth. It doesn't really bother me as I'm just a leisure rider/commuter.

rmfnla

One last note: It may not be (just) your wheels. 1.5" tires have a lot of rubber in them, and expecting the manufacturing tolerances to be perfect might be a bit unrealistic.

juicemouse

On every wheel I've ever looked at for balance, it always stops with the valve stem at the top. The reason, as described correctly by the Torelli guy, is that most rims are either sleeved and pinned or they are welded at their seems during construction. Either method adds a little bit of weight opposite the valve hole and the valve stem doesn't weigh enough to compensate for this. I realize that it certainly makes no difference whatsoever, but on my good bike I add a couple extra of those nuts that thread onto presta valves. Three nuts total works for me on a Mavic Open Pro. Maybe I'll add some life to my wheel bearings, but probably not. My riding buddies all think I'm a moron.

thermite

I actually think it's the valve side which is the heaviest on my wheels.

juicemouse

Hmmm, well color me confused. This is just a stab in the dark but maybe it's really your MTB tire that's imbalanced, as someone else suggested. You could deflate and rotate the tire on the rim to figure out if it's that or not. Then try taking the tire completely off the wheel and leaving the tube on there partially inflated and see what you end up with. I'd be interested to know.

thermite

It could be the tyres as there are also some small transfers on them, the inbalance is uniform with both wheels. I may just pull a wheel off tonight and remove the tyre, not done that yet so it may be fun for me! :-/

rmfnla

What?! You can't do that; everbody knows if you don't line up the label on the tire w/ the valve stem AND on the drive side terrible things will happen (don't ask me what kind of things; terrible!)!

rmfnla

I'm not going to comment on the moron aspect, but if the weight of three stem nuts will affect the lifespan of your wheel bearings you need to start buying better components...

Brian

No, the hot patch should be opposite the valve. And if your wheel was built by a conscientious builder, you should be able to see the label on the hub through the valve hole in the rim.

rmfnla

"Hot Patch"; is that the label?

If so, why opposite the valve? Racers used to have it lined up to make the valve easier to locate for a quick repair (not everyone has a fancy support team w/ lots of extra wheels).

The rest of us do it that way 'cause it looks cool.

Maybe having the hub label on the same side of the valve hole is adding to the imbalance problem; that laser etching probably removes an easy 1000th of a gram of material...

juicemouse

I'm not saying it will affect their lifespan, I'm saying that it could affect their lifespan and since it's no trouble at all to have them on there, why not? I admit that it probably makes no difference in this case, but having those extra nuts on there certainly isn't hurting my components any. And it's well known that it doesn't take much weight at all to cause a considerable imbalance when stuff gets rotating. But yeah, thanks for not commenting on the moron thing, 'cause it might be a little hard to argue my case.

neil0502

Somehow, I managed to hit a rusted box cutter blade that was laying in my path yesterday. It cut right through my Rubino Pro and tube (what are the freaking odds?!?). Fortunately, only a three block walk to nearest LBS.

Pi$$ed, and anxious to get back to my ride, I forgot to line up the label and stem. With every fiber of my being, I'm trying to resist the urge to remount the tire, but I know deep in my soul . . . those . . . things . . . must . . . line . . . up.

thermite

I'm glad there are so many other people out there as anal as me! Anyone heard of obsessive compulsive dissorder!?? seen Jack in 'As Good as it Gets' ?

rokrover

Ha - that's nothing. Whenever I repack bearings with loose balls I make sure each ball goes back in the exact same circular order in the race. You never know, perhaps there's some cosmic force that makes them wear together in perfect harmony that would be disturbed if they were interchanged

rmfnla

Dude, that's so wrong! Everone knows that you have to rotate your balls regularly to ensure even wear!

This is a disaster just waiting to happen!

rokrover

LOL - I cry "Uncle" You just made my day

rmfnla

Maybe if you add another stem nut...

dbg

Reminds me of an old Steven Wright quote: "I once put instant coffee in the microwave --and went back in time."

Mentor58

How about using extra wheel reflectors to balance the wheel, and if one is too heavy, use 2, but put them at about 60* seperation in relation to point you need to balance. Then if necessary, you could use a third one to fine tune, by sliding it up and down the spokes to find the perfect balance point.

Steve
Who once was asked, what side is up with a ball bearing?

juicemouse

I actually did move the reflector on my commuter wheels. It solved all of my life's problems. By the by, is balance affected by the distance the weight is placed from the center of rotation?