Originally Posted by yaw (Post 22414214)

I am wondering how many riders balance (not true) their wheels, or have purchased wheels that came balanced with counterweights to offset the heavy spot.

The Aeolus Elite 35 TLR carbon wheels that came with my bike created a noticeable rear wheel vertical wobble when spinning the pedals fast on the stand, which can also be felt when holding the bike up by the seat, and the front wheel rotated quickly with the valve dropping to the bottom when lifting the front up. I would think that this is the case with most wheels out there, some more extreme than others depending on wheel material/construction, weight/size of the valve stem, and so on. Whilst the weight of a rider will not cause the rear up and down wobble to present any real issues and any 'flywheel gains' are extremely marginal, I think the oscillation in the front when rolling fast may contribute to a risk of speed wobbles. This aside, it somehow seems right to me that a contraption that is all about two wheels spinning quickly should be a balanced and smooth system.

For those interested, the procedure is quick, cheap and simple and whilst it can be argued endlessly, the additional weight won't matter in practice, and even in fine print theory the acceleration effort is offset through momentum. The following assumes a modern rim with a wide enough inner diameter and channel so that the weights can be placed on the inside, rather than any external attachments that mess with the look and aerodynamics of the wheel.

1. Determine the heavy spot on the wheel by lifting the front wheel off the ground and experimenting with where it wants to settle at the bottom by letting it go from a few orientations.
2. Mark the exact opposite of the heavy spot at the highest point of the settled wheel.
3. Stick varying amounts of blu tack or similar to the marked spot until the wheel no longer moves away from any rotation it is set to rest in.
4. Weigh the exact amount of blu tack as accurately as you can. You may need 3.4g, you may need 17.8g, who knows.
5. Purchase a few 'golf club adhesive lead weights' (not tape but the little flexible lead slabs with an adhesive side) and rim tape.
6. Determine how many lead weights and what amount of rim tape (make sure it is enough rim tape to cover the length of the required lead weights all aligned in a row) make up your target weight.
7. Remove the wheel and take the tyre/tube off and place a lead strip inside the wheel channel (where the tube lives) exactly on the marked spot and the others, if needed, evenly each side of the central weight.
8. Cover it up with the appropriate length of rim tape, but do make sure that the weight of the rim tape is considered as part of the target weight as it is significant in this case.
9. Pop tube/tyre back on, the tyre ideally in the same orientation as before (but we already know you will keep the tyre brand over the valve anyway), and test whether the trick worked by holding at the hub to see if it stays put wherever you stop it.
10. Mount the wheel and repeat on the other one, the same weight will probably work closely enough if it is the same wheel as the front. Just confirm with the same amount of blu tack as before and vary if needed.

I needed a whopping 12.85g per wheel, or 3 of the little golf lead strips with a length of rim tape that covered the strips and then some more. I just placed the lead weights on the existing rim tape and then taped over the top of it all, these things are so flat that they can be sandwiched by the rim tape and still keep a low profile. The same weight worked on both wheels with 28mm GP5000s on the rear and 25mm on the front, so tyres seem to be even enough. Now the wheels stay wherever they are set when lifting the bike up and the bounce is gone when cranking it up. This proof of improved balance aside, it also appears that the whirr from the hub engagement points now sound more even when coasting fast. Otherwise it rides as before but with a little added confidence on fast descents - yeah it's a mostly subjective undertaking.

Thoughts?

Originally Posted by woodcraft (Post 22414933)

Looks OK IMO.

Originally Posted by tempocyclist (Post 22415079)

Maybe one day.

Originally Posted by downhillmaster (Post 22415144)

You stated that your ten step procedure was quick and simple.
Compared to what? Calculating pi to the last digit?
:eek::eek::eek:

Originally Posted by yaw (Post 22415188)

You'll get away with it!



The lead strips in that video are the ones I am talking about, just for a clincher they can easily sit inside parallel to the rim instead.



Which of the 10 steps sounds time consuming or complicated?

Originally Posted by Racing Dan (Post 22415142)

Would anyone happen to know how to quantify the effect of out of balance wheels? Balancing is common practice in MCs and cars, to improve steering and traction and to prevent uneven tyre wear. Several references to reduced gas mileage caused by unbalanced wheels can be found too. But no where can I find a reference actually quantifying the effects, except to assert its there. I can believe that but In light of other recent debates over the effect of a few hundred grams of wheel weight, etc, Id be interested in knowing the "size" of the "problem".

Anyone?

Originally Posted by downhillmaster (Post 22415219)

Uhh, 1-10 fill half a page and are the very definition of time consuming and complicated.
More specifically; purchasing adhesive lead weights, using the blu tack, weighing exact amounts down to tenths of a gram, filling your wheel with lead weights, factoring in exact weight of rim tape, etc…

Originally Posted by black_box (Post 22415740)

I got some lead tape and put it on the outside of the rim between the spokes, opposite the valve stem, and that did the trick. I covered the lead tape with black gaffer tape (doesn't leave residue like duct tape) and haven't had any issues with it coming loose.

Originally Posted by RChung (Post 22416270)

Yes, I do, but I was unhappy when I had to patch a flat because the patch threw off the balancing, so now when I get a flat I add three patches, one over the hole and two others at 120-degree intervals. I think adding just a single patch at 180-degrees would make the wheel "hop" so it makes more sense to space them out. Speaking of flats, I used to carry a CO2 cartridge but CO2 is heavier than atmospheric air so the CO2 would settle down at the bottom of the tire overnight. Worse, CO2 leaks more quickly than atmospheric air so when you have to top off the tube with a pump (and you do) then the remaining CO2 has a changed distribution. The tube is a smooth and featureless torus so there's really nothing to mix the gases more evenly, so I'd unscrew the valve and add a small BB. The BB would roll around inside the tube and mix the CO2 with the ambient air. But, in the end, I realized that it just makes more environmental sense not to use CO2 cartridges and to use a small mini-pump the size of a fat cigar. The 400 pumps it takes to bring a road tire up to acceptable pressure is just enough to keep me warm. I do miss the "shoop shoop hula hoop hoop" sound of the BB rolling around inside the tube though.

Originally Posted by yaw (Post 22416171)

When you say that did the trick do you mean you got it balanced out (no heavy spot, wheel stays still) or that it reliably stayed out of wobble territory since? I guess too many factors come into play to have any final answer here but likewise I do take the added confidence a balanced set of wheels provides.

Originally Posted by RChung (Post 22416270)

Yes, I do, but I was unhappy when I had to patch a flat because the patch threw off the balancing, so now when I get a flat I add three patches, one over the hole and two others at 120-degree intervals. I think adding just a single patch at 180-degrees would make the wheel "hop" so it makes more sense to space them out. Speaking of flats, I used to carry a CO2 cartridge but CO2 is heavier than atmospheric air so the CO2 would settle down at the bottom of the tire overnight. Worse, CO2 leaks more quickly than atmospheric air so when you have to top off the tube with a pump (and you do) then the remaining CO2 has a changed distribution. The tube is a smooth and featureless torus so there's really nothing to mix the gases more evenly, so I'd unscrew the valve and add a small BB. The BB would roll around inside the tube and mix the CO2 with the ambient air. But, in the end, I realized that it just makes more environmental sense not to use CO2 cartridges and to use a small mini-pump the size of a fat cigar. The 400 pumps it takes to bring a road tire up to acceptable pressure is just enough to keep me warm. I do miss the "shoop shoop hula hoop hoop" sound of the BB rolling around inside the tube though.

Originally Posted by merlinextraligh (Post 22417209)

Speed wobbles has way more to do with the frame’s stiffness and how you fit on it. Willing to bet if you have a speed wobble problem, it’s going to stil wobble even if you chang e wheel sets

Originally Posted by Russ Roth (Post 22417233)

Interesting no one pointed out that your comparison shouldn't be to truing but making it round. Wheels require three things; straight, true, and round. I know this seems obvious but its surprising how much it isn't. Whenever I have had someone experience speed wobbles it came down to straight or round, true just effects tracking and braking.

If your wheel is really experiencing a vertical wobble I would toss it in the stand and spin the wheel and watch where the rim and tire meet to see if it moves up and down, a sign of either the tire not being seated right or the rim out of round, it can sometimes be hard to distinguish since you're seeing movement but not registering where. If so, slow the wheel down and make sure the tire is seated the same all the way around, being slightly off will create slight dip effect (usually the tire is too far in in a spot) that will produce a speed wobble that might be noticeable at 12-15mph but completely unstable at 30. If the tire looks fine, take a spoke wrench, brace it against the stay and hold the end against the rim and spin it, see if it moves. If so, toss it in the stand and make it round.

Less likely but not impossible, especially with cheaper tires, the tire is out of round, again toss the wheel, fully inflated, into the truing stand and check for roundness at the tire, cheap tires can be out of round enough to cause problems. Because of the handmade nature of high end tubulars it is also possible to find these aren't perfectly round, less so than in decades past, in cases where the tubular wasn't perfect on a TT or track bike, we made the wheel round to the tire and not to the rim. Wheels being perfectly balanced is a fairly unimportant thing, wheels being perfectly round, that is important.

Originally Posted by Russ Roth (Post 22417233)

Interesting no one pointed out that your comparison shouldn't be to truing but making it round. Wheels require three things; straight, true, and round. I know this seems obvious but its surprising how much it isn't. Whenever I have had someone experience speed wobbles it came down to straight or round, true just effects tracking and braking.

If your wheel is really experiencing a vertical wobble I would toss it in the stand and spin the wheel and watch where the rim and tire meet to see if it moves up and down, a sign of either the tire not being seated right or the rim out of round, it can sometimes be hard to distinguish since you're seeing movement but not registering where. If so, slow the wheel down and make sure the tire is seated the same all the way around, being slightly off will create slight dip effect (usually the tire is too far in in a spot) that will produce a speed wobble that might be noticeable at 12-15mph but completely unstable at 30. If the tire looks fine, take a spoke wrench, brace it against the stay and hold the end against the rim and spin it, see if it moves. If so, toss it in the stand and make it round.

Less likely but not impossible, especially with cheaper tires, the tire is out of round, again toss the wheel, fully inflated, into the truing stand and check for roundness at the tire, cheap tires can be out of round enough to cause problems. Because of the handmade nature of high end tubulars it is also possible to find these aren't perfectly round, less so than in decades past, in cases where the tubular wasn't perfect on a TT or track bike, we made the wheel round to the tire and not to the rim. Wheels being perfectly balanced is a fairly unimportant thing, wheels being perfectly round, that is important.

Originally Posted by smashndash (Post 22414538)

On BF, you're largely going to get scoffed at for thinking about stuff like this. This forum is mainly populated by curmudgeons who don't care much for the finer aspects of cycling.

Originally Posted by smashndash (Post 22414538)

some pro teams balance their wheels too (don't quote me on that)

Originally Posted by yaw (Post 22417429)

Yes but this does not exclude ANY potential effect of the imbalance on the system. Fortunately I do not have a speed wobble problem, but since I am doing 70kph+ downhills multiple times a week I am taking the extra balancing on board.



It may have been unclear but I do not have a speed wobble problem so this fell under the preventative category - useful post nonetheless! The wobble on the stand was within the usual range and it's quite easy to observe the valve position causing the wobble as the wheel spins, its rotational location obviously coincides with the wobble frequency.

Now that it runs so smooth even on the stand I would not trade the extra 25g to go back to the imbalance, that's for sure.

Originally Posted by merlinextraligh (Post 22419310)

Simple test: go ride the bike as is; then take off (or add as the case may be) the valve cap, and the little nut that screws down on the stem. Bet you dollars to donuts there will not be one iota difference in stability of the bike