FastJake

Someone should do a double-blind study on this so we can link that thread and never have to discuss it again.

I'm not saying one way or the other is the truth, but these are always exclusively armchair discussions.

PoorInRichfield

Yeah, let's get back to the really important topics discussed on these forums so we aren't wasting our time.

woodcraft

This is at the moment, with not-the-lightest wheels and a porky cassette. Includes bottle cages, front and rear blinkies, computer mount, bell, power meter, and of course, pedals.

Riding weight adds 17oz saddle bag with tire (tubular), pump, levers, pliers, 3 allen wrenches, chain tool, valve extension, valve cores, quicklinks, patch kit, zip ties, tape, knife, paper & pencil, needle & thread, bandages, boot, etc., and usually one water bottle.

djb

Geez Louise, I carry spare water and food on my touring bike that weighs as much as these bikes, sheesh.
No wonder you're concerned about balanced wheels, I just calmly hustle down hills at 70kand worry about other stuff.

PoorInRichfield

We worry about grams to compensate for our puny leg muscles Yeah, ones perspective on this topic will certainly be swayed by the type of riding you do. I'm a roadie and prefer to ride as fast as sanely possible and have a bike that is light as sanely possible. None of this discussion probably makes any sense to a fat-tire bike rider or a touring bike rider.

HTupolev

Wheel balancing makes more sense on cars than on road bikes for two reasons.

Automotive suspension is able to oscillate at a fairly large amplitude at fairly low frequencies. When a car is travelling rapidly, the rotation of the wheel can reach these frequencies, causing the suspension to be driven in resonance.
A road bike is comparatively very rigid, and the rider's body is very heavily damped, so you simply don't see the same sorts of frequency overlaps and resonances. If they exist at all, they are very small in magnitude.

Automotive wheels are very wide relative to their height, so the imbalance can be lateral in addition to radial. This causes the oscillation to directly manifest as steering wobble, which is obviously very bad.
This really doesn't apply to road bike wheels, because they are very narrow relative to their height.

Wheel balancing on bicycles is something that a lot of people believe in, but cannot ever seem to quantify or measure the purported efficiency gains of. Oftentimes it's "proven" that it makes a huge difference because it wobbles a bicycle in the stand, but this is a completely different dynamical system with completely different constraints than how people actually use bicycles. I ride my bicycles on the ground, I don't send them airborne on their own to pedal themselves through the troposphere.

I've clocked 57mph on my road bike with its imbalanced wheels before and it was rock solid.

woodcraft

Oh, I don't know...

BITD, I kept my touring weight to 20lbs including bags and racks. Made a huge difference in the feeling of riding a bike as opposed to being a pack animal.

SethAZ 

Exactly. I'm not sure I ever finished convincing anyone that NFS was the best chain lube, and waxing is for prima donnas.

My take on it is this: there's undoubtedly an effect of imbalance. The spin tests on the stand demonstrate that thanks to the bike on the stand being relatively unconstrained compared to when the bike is being pinned between asphalt and a human being. My guess is that the effects of road vibration from riding over uneven paving surfaces, the natural bounciness of the body due to pedaling motions, etc. are simply of such greater magnitude that the forces due to the wheel imbalance get lost in the noise. If there's any extra flex in the tire or tube that gets turned into heat through the action of the imbalance forces trying to bounce the bike but being pinned in between the rider and the street, then that would represent a power loss (same as suspension losses). Question is: what's the magnitude? Sounds like this could be the most marginal of gains.

But hey, I'd venture to say that it's probably going to be more of an effect than that argument a few weeks ago about power lost due to using a patched inner tube.

djb

no worries, I get it--I'm a chicken legged puny leg muscled old guy, and do all kinds of riding on different bikes, and also absolutely love riding as fast as sanely possible downhill, always have.
But really, on all my bikes, Ive never felt anything not kosher with my wheels at whatever speed I can get up to, whether its now or 30 years ago.

I even did a bit of paved circuit racing on motorcycles, and have ridden up to somewhere over 160mph, so do have experience of riding fast on two wheels and being hyper aware of anything that would feel weird wheel wise. Sure, Ive experienced speed wobbles on bicycles a few times, and tank slappers on motorcycles, but nothing ever associated with bicycle wheels exhibiting any weirdness balance wise at speed.

But yes, when I'm riding my expeditiony type bike through different countries with a whackload of extra crap cuz I have to, my chicken legs use a 44/32/22 and a 11-34 to schlepp that damn 70-80-90lb bike along, especially in mountains and especially in countries where there are stupidly steep hills.

PoorInRichfield

I think a similar analogy to wheel balancing, that would also be considered a marginal gain at best, would be freewheel resistance.

I had my bike up-side-down the other day and spun both my front and rear wheel. The biggest difference between the two wheels obviously being that the rear wheel is subject to resistance by the freewheel where as the front is not. While I did not measure to make sure I spun both wheels with exactly equal force, the front wheel seemed to spin forever where as the rear slowed down noticeably fast. Now if I flip the bike over and ride it down the road, can I "feel" that there's resistance in the rear wheel caused by the freehub pawls? I cannot. Is energy being lost when coasting due to the freewheel. There is. Is it enough resistance to matter on one ride? Not likely. How about 1,000 rides? Well if I had a dollar for every wasted watt...


An unbalanced wheel is wasting energy. If it wasn't, they wouldn't bother balancing things like flywheels. One can get a massively heavy wheel to rotate with very little effort... if it's balanced. Most of the wheel balance deniers focus on not being able to feel an unbalanced wheel, which isn't really the point. The issue is that an unbalanced wheel is wasting energy... not only once the wheel is rotating but in just getting the wheel to rotate in the first place. Sure, there isn't enough force being generated for a 175 lbs rider to be able to feel it when sitting on the bike, but none-the-less, there is a loss of energy and the force certainly can be noticed when spinning an unbalanced wheel when not sitting on the bike. If I can reduce this loss for effort and little cost in conjunction with other small gains, that is what marginal gains is all about.

Thruhiker 

I balance mine if it's bad. At sporting good stores you can get matchbook weights. There a little bigger then a paper match and very flexible. You can cut them with scissors to get the right weight. I tape them to the tire sidewall or to the rim.

FastJake

The "does it affect handling" question can be answered with a double-blind test sending people down a big hill on balanced and unbalanced wheels.

This "wasting energy" question could be answered by a roll-down test (rider on bike, not just in a stand) or with a power meter around a flat track. Is the difference measurable? Is it statistically significant? If not, then it does not matter. You could even compare your data to the energy lost by carrying those extra grams up every hill!

If this is what "marginal gains" is all about, then consider me skeptical of the entire category. Unless some of them are proven with data and analysis.

HTupolev

Wattage is energy-per-time. It doesn't change by riding for more time. If your freewheel is costing you a watt, and you had a dollar for every wasted watt, you'd have a dollar whether you rode your bike 20 feet or 3,000,000 miles.

They balance flywheels because an imbalanced engine doesn't work fluidly. The big issue isn't that an imbalanced spinning mass loses energy in and of itself, it's that the spinning mass in question needs to be balanced in order to do its job of keeping everything else moving fluidly relative to each other. An imbalanced engine setup can produce noticeable noises and vibrations from all throughout the drivetrain, cause components to wear rapidly, and in extreme cases, the fatigue can even lead to devastating crankshaft failure.

On a fundamental physics level, balance has basically zero effect on the amount of energy required to bring a rotating mass of a given rotational inertia to a certain rotational velocity.

Where it can have an effect is if the lack of rotational smoothness is causing other elements of the system to interact unsmoothly with each other. That's why there's the emphasis on detectable things throughout the bike+rider system; if the wheel is moving stably relative to the ground and the frame is moving stably relative to the wheel, it's hard to imagine where any losses would be coming from.
A wheel imbalance should theoretically cause a slight oscillation in the loading at the wheel, which could cause a vertical oscillation in the system, but the expected magnitude of this effect is extremely tiny.

Homebrew01

Adding weight is a marginal hindrance.

woodcraft

I did a test- put a wheel in the truing stand, and spun it using very moderate force, timing until stopped.

Results:
Not balanced- 9 minutes, 9 minutes, 8 1/2 minutes.
Balanced w/ 10g- 7 1/2 minutes, 7 minutes, 7 minutes.
Weight added to heavy side- 11 minutes.
The unbalanced runs were about 5 minutes full revolutions, and the rest pendulum swings.

Maybe unbalanced wheels are better??

mrrabbit 

At this rate, won't be long before bike shops start selling straight jackets...

...for the person wheel balancing for:

1. wheel magnet for speedometer
2. wheel reflector
3. "rad" rim tape
4. stem
5. seam
6. stem nut
7. stem cap
8. runny sealant
9. patch on tube
10. overlapping tire liner
11. wear indicator dot
12. replacement non-matching spoke
13. replacement non-matching nipple
14. missing rim ding material
15. hole left by a nail

...and on and on.

=8-|

djb

I didn't keep track, do pro teams do this?

PoorInRichfield

My useless guess answer would be "no", only because I can't seem to find any info suggesting they do. However, if I was going to be screamin' down the Pyrenees at insane speeds in a pro peloton, I'd want my wheels as straight and balanced as possible to avoid speed shakes and any other disruption from pending doom! I might be surprised though... I'd assume that if maintaining bikes is your living, perhaps you'd be a bit more extreme about bike maintenance than the average Joe.

davidad

Amen brother. I developed eosinophilic asthma 2 year ago and haven't been on my bikes since, but I did manage to find 28 pounds that I lost years ago. The only people who need worry about marginal gains are making a living riding a 6.8 kilo bike and are at less than 5% body fat.

davidad

They will make big bucks on carbon fiber straight jackets.

shelbyfv

It's always interesting when some fringe aspect of the bike hobby surfaces. Folks enjoy all sorts of different stuff. Awhile back there was a poster who was enthusiastic about "detailing" his bike, like teens do with their cars. I think it hurt his feelings when there wasn't much positive feedback.

GamblerGORD53

So lets see you put a crooked Flying Pigeon wheel on a CF bike and go 45 mph round a curve. And then PRETEND nothing is the matter. LOL What a farce. The OP has nowhere near this effect, but saying it's 99% a placebo effect is goofy.
You think the bike jumping around is imaginary and magically goes away just because your bum is holding it down?? LOL

woodcraft

You could apply the "can't feel it so it doesn't matter" argument to latex tubes.

Most folks won't notice a difference vs butyl ones, but those who measure these things say that it is substantial.

70sSanO

This does speak volumes that TdF teams are not balancing wheels. It is not so much the downhills as skill and intestinal fortitude are the difference makers. Some riders are just known for their downhill prowess.

Where it would really matter would be in the time trials, especially individual. The splits are so close that any possible advantage would be employed. Maybe it will be used some day, but it is hard to imagine that none of the pro teams haven’t tested it out.

John

GamblerGORD53

And speaking of other imaginaries.... When I used to do centuries on a defailleur bike, along quiet stretches I could feel the chain flutter from crooked chain line. It did rather bug me. Didn't matter if it was with the 50T or 39T.