how much a diff is 300grams in wheelsets

[steeevie boy]

Accelerations don't have to be large to have noticeable effects. As for the quote, there is no empirical basis for such assertions. The human body is quite adept at sensing small forces or changes in forces. You should not accept everything you read on the internet as truth. Try reading some textbooks to learn facts about physics.

who gives a sh*t, you still goota ride the tthing.Its all about peddling and enjoying yourselves as far as im concerned.I hav kyseriums......bloody marvelous....(i havnt ridden them yet b cos my bike aint built)i still love riding my sqeaking creaking bike over 200 milke a week!!!!!
Steve

 

[wilmar13]

Yesterday I got to see what the pro's ride at the Tour de Georgia TT. Was surprised to see several riders on conventional wire-spoked wheels both front and rear. Most common seemed to be a wire-spoked aero-rim up front of varying spoke count, plus a disc rear.

My snapshot shows Lance was on HED tri-spoked front, disc rear. Didn't get a photo of Floyd Landis, Phonak, who won the Stage 3 event.

The TT included a significant climb and descent, and the roads were wet; those factors may have affected wheel selection at the start line.

Wait a minute... you mean to tell me that LA with any bike-tech resource in the world and a slew of experts chose a heavy disk and tri-spoke combo for a TT with a long steep climb??? Geesh no wonder he lost, maybe someone should let him know the advantages of superlight wheels

 

[mikael17128]

Well you are mixing apples and oranges. You got different tires on the Zipps no doubt too.

The weights I provided include the tires & tubes. I've said my piece and can't really give anything more than the qualitative analysis I've already provided. There should be someone out there who can take the physics of what I've said and give us some quantitative conclusions. Again, while out of the saddle all the micro accellerations caused by the uneven cadence of the leg pressing onto the crank cause a marked difference between low weight wheels and standard trainers. The weight difference I'm commenting on is, however, 700 grams.

 

[wilmar13]

There should be someone out there who can take the physics of what I've said and give us some quantitative conclusions. The weight difference I'm commenting on is, however, 700 grams.

GO BACK AND READ THIS THREAD! (just ignore the back and forths and ego battles)

Take the example of a 100M climb that is 1KM long (10% grade) and you ride up it at 10km/h putting out 275 watts, by saving 700 grams from your wheels, you will be 2.47 seconds faster to the top, but guess what... you save 2.45 seconds under the same scenario losing static weight from your bike or body. So yes you have gained .02 seconds in this climb over dropping the weight from your ass. Do it 50 times and you have gained an entire second . I do not know how to illustrate this any more simply or clearly.

Here if you are really ambitious you can play for yourself:
www.analyticcycling.com

 

[53-11]

The weights I provided include the tires & tubes. I've said my piece and can't really give anything more than the qualitative analysis I've already provided. There should be someone out there who can take the physics of what I've said and give us some quantitative conclusions. Again, while out of the saddle all the micro accellerations caused by the uneven cadence of the leg pressing onto the crank cause a marked difference between low weight wheels and standard trainers. The weight difference I'm commenting on is, however, 700 grams.

You can't say the difference is soley due to weight.

There are confounding factors you are not taking into consideration. You aren't isolating weight with your example becasue you have rim stiffness (CF and aluminum are different materials with different properties) and completely different tires (tubulars and clinchers are different besides weight) on there muddling up the picture. Not to mention spoke count and even tire pressure may be different too.

As far as taking the numbers you gave us and using physics to give you some qualitative conclusions Wilmar13 already did it. You should go back and read this thread (seriously). I learned a lot myself.

 

[wilmar13]

At the risk of appearing like 53-11 and I are in cahhoots...

You don't even need to read the thread, read what he posted on the first page:
I found this article http://www.biketechreview.com/archive/wheel_theory.htm

"How can it be that wheel inertial forces are nearly insignificant, when the advertisements say that inertia is so important? Quite simply, inertial forces are a function of acceleration. In bike racing this peak acceleration is about .1 to .2 g’s and is generally only seen when beginning from an initial velocity of 0 (see criterium race data in Appendix D ). Furthermore, the 0.3kg/0.66lb difference in wheels, even if this mass is out at the rim, is so small compared to your body mass that the differences in wheel inertia will be unperceivable"

Read it over and over until it makes sense to you, go to the article as well. To be clear I am not saying you wasted your money, not at all. You dropped roughly 1.5 lbs off your bike! But I am saying you are climbing two gears faster because you are putting out more power and that is the only reason. The whole reduction of rotational inertia in climbing and or acceleration never comes into play on a bicycle, even if you have the power of Northstein in the day, or the climbing prowess of Virenque (combined with a terrible pedal technique) vs. saving the weight somewhere else. Get a power meter, and you will see that no matter what you believe that damn thing will shatter all of your preconceived notions about what works and what doesn't.

 

[53-11]

I think a lot of this hype about rotational inertia being a powerful force/factor came from the world of motorsports.

I remember always reading that reducing upsprung weight was beneficial. Of course on a powerful race car the acceleration is much more dramatic and sudden than on a bicycle. Not to mention how suddenly and powerfully a 900 hp formula 1 engine can spin a car wheel. No cyclist can put that kind of sudden power out or force a wheel to "resist" acceleration like that.



Hahaha.....we do sound like we are in cohoots. I just noticed your Avatar Wilmar! (Can anybody accelerate their bicycle like that?)

 

[jrstang473]

Alight i finally have my own opion to put in this thread.First of all i have been through 3 wheelsets and not to mention using my friends and other riders to come to a conclusion.I tried th mavics sl's for about three rides and sold them.I was not pleased with the performance i had gotten from them.In comparence to my race lites i lost 2 mph on my standard ride.I feel this was due to the huge spokes and the rim not having near the aero profile as claimed.I did find best peformance for me in being a full aero wheelset 30mm or more rim.Although the aero choices are far fewer unless carbon and alot of them are heavy weights.The aero wheels seemed to be more consistent over long rides.The race x lite aero's seemed like a really nice wheel to me so i got a set from my friend and iam very happy with them over the mavics that were a bit lighter.Really what it all comes down to is what you want and looks best to you.There are so many choices in wheels and so much diffrent feel to all of them.My best suggestion to anyone else in this seeking market is to ride a few set the scale aside and find what works best for you.Wether that be financially or physically.If your a powerfull sprinter or rider its not gonna matter that much by just a few grams ( maybe in a race) . The biggest thing is i guess that is most important is enjoy riding.Dont get so worked up about upgrades and so on.Just go out and enjoy the sport with a passion and make sure you spend more time in the saddle than picking out parts and putting them on.

 

[dhk]

GO BACK AND READ THIS THREAD! (just ignore the back and forths and ego battles)

Take the example of a 100M climb that is 1KM long (10% grade) and you ride up it at 10km/h putting out 275 watts, by saving 700 grams from your wheels, you will be 2.47 seconds faster to the top, but guess what... you save 2.45 seconds under the same scenario losing static weight from your bike or body. So yes you have gained .02 seconds in this climb over dropping the weight from your ass. Do it 50 times and you have gained an entire second . I do not know how to illustrate this any more simply or clearly.

Here if you are really ambitious you can play for yourself:
www.analyticcycling.com

You got my point about Lance's choice of wheels. If he can afford a few extra grams in a big-money TT, believe the rest of us can as well. Also confirmed Floyd Landis was on Zipps...aero-section rim with regular wire-spokes in front, disc in back.

The fact that there was so much variation, including some pro's on regular, low profile spoked wheels front and rear, indicates to me that the differences can't be huge.

Also agree the torque required for angular acceleration of the wheels is a small % of the that required to accelerate the (static) weight of the bike and rider. If anyone wants to check this out, just put your bike in a stand, select the big ring, and spin the rear wheel with a hand on a pedal. To spin up to 20 mph in 5 seconds (about 0.2 gs acceleration) takes very little force vs. same acceleration on the road.

 

[wilmar13]

To spin up to 20 mph in 5 seconds (about 0.2 gs acceleration) takes very little force vs. same acceleration on the road.

Good post.

Much of that puny force required is parasitic drag of the chain and gears, not accelerating the wheel even. Besides, unless you race track when was the last time it mattered how fast you can go 0-20? Most sprints I am in are more like 25-40, and it is probably less than .2g acceleration(I never clocked myself to see how long it takes to sprint to top speed). Even the track guys don't go much over .2gs, at peak.

In the end it is the motor that matters. But cyclists are people too, and most of us want to be faster. It is the same thing that leads someone that wants to lose weight to go for some stupid fad diet, when in reality the only thing that will allow you to lose weight it simply to digest less than you burn. It is tough to be rational when you want get better and are offered an easy solution. You know this is a good example of why Pros dope, at least that does give you a real advantage .

 

[wilmar13]

I think a lot of this hype about rotational inertia being a powerful force/factor came from the world of motorsports.

Even there is is way over stated, but at times applicable. I am a dork with multiple engineering degrees, and I even wanted to believe the whole, light wheels make me faster "because after all it is rotational weight". Intuitively it makes sense, especially if you want it to be true. Until I actually thought about it and realized, a)oh yeah, my wheels stay attached to my bike and b)even with a peak output of 2HP (about 1500 watts) your acceleration is nothing... The whole nonsense about miniaccelerations while climbing also made sense to me until you start to think about the fact that you are already somewhere around a 1.9:1 gear ratio when climbing, and then go back to revelations "a and b" (and your "b" value will be divided by 4 or 5)and you see that it is more BS than in sprinting. Of course weight loss will help you on climbs, but losing it on your wheels, frame, handlebar, or your body all give you about the same result.

 

[mitosis]

Here goes nothing, opening up this can of worms again

Just skimmed through this thread. Being the proud owner of a set of Zipp 202’s I can say with much assurity that they do make a difference. They help me to accelerate much easier. This ease of acceleration comes into play mostly on climbs, especially when I’m up out of the saddle. I can clunk 2 full gears lower with the Zipp’s while climbing than I can with my Mavic CXP33 trainers. I am not a pro and use gravity to assist me climbing. This leads to a less than perfect cadence. I push down on one side and then with the other. I don’t think there’s any way around the uneven cadence when out of the saddle not matter how good you are. This is where the acceleration comes into play. Every downward stroke from out of the saddle is a mini acceleration and these add up over the course of ¼ mile or so. This also holds true with rolling terrain where short bursts out of the saddle will get you over the hump and onto a downgrade again. They also help with accellerations while seated along switchbacks and the like but not nearly as noticeable. Hammer a hill with the lightweight wheels and you’ll turn into a believer.

One of the advantages of light, aero wheels that is often overlooked is the phsychological effect of having them. You paid good money, people say they are faster so you perform better.

Some of the benefits are due to weight (a gnats fart perhaps), a fair bit is the aero, which is really useful when your bike gets above 40 k's and the greatest variation is in the effect of your mind.

Sounds like most of your improvement comes from the third effect.

 

[Taxman]

I'm not going to try and quote anyone, since there is too many good and bad quotes. BUT..

Rotational weight is the hardest weight to make move. I race a Late Model stock car with close to 500 HP.. I bought a new set of wheels that droped me a total of 8 lbs. I decreased my lap times by .5 seconds. Thats huge. Just take a heavy wheel and a light wheel and hold it in your hand with the skewer and try to spin them. The lighter wheel is MUCH easier. I'm not going to get into physics here because it would take to long. But the rotational weight is the 1st weight that a person should try to reduce on a bike.

As for you people that dont believe it helps, ride your heavy wheels and then try a buddies light wheels. You WILL notice the difference immediatly.

 

[Mansmind]

For those of you that haven't, I suggest reading information on Zipp's website, there is some very interesting analysis there regarding wheels.

It's more geared toward the aerodynamics, but some of it still applies to this discussion.

John

 

[53-11]

I'm not going to try and quote anyone, since there is too many good and bad quotes. BUT..

Rotational weight is the hardest weight to make move. I race a Late Model stock car with close to 500 HP.. I bought a new set of wheels that droped me a total of 8 lbs. I decreased my lap times by .5 seconds. Thats huge. Just take a heavy wheel and a light wheel and hold it in your hand with the skewer and try to spin them. The lighter wheel is MUCH easier. I'm not going to get into physics here because it would take to long. But the rotational weight is the 1st weight that a person should try to reduce on a bike.

As for you people that dont believe it helps, ride your heavy wheels and then try a buddies light wheels. You WILL notice the difference immediatly.

I pointed the motorsports analogy out if you read the later posts (post #67), but people riding bikes don't make the kind of power to cause the rim to resist acceleration like that.

This whole hype about wheels came from motorsports, but if you do the math with the power of a cyclist in mind it doesn't pan out. True spinning the wheels by themselves may be one thing, but you still got a bike and heavy cyclist on top of them that doesn't make a lot of power.

 

[wilmar13]

This whole hype about wheels came from motorsports, but if you do the math with the power of a cyclist in mind it doesn't pan out.

Ignorance is bliss, thinking is hard.

 

[wilmar13]

As for you people that dont believe it helps, ride your heavy wheels and then try a buddies light wheels. You WILL notice the difference immediatly.

It is not a matter of belief, it is facts vs. opinions. Regarding borrowing a buddies wheel, I have no need as I have one of the lighteset wheelsets available that is also somewhat aero (Zipp 303 tubular). Like I said if you don't understand the physics of why it doesn't matter (notice I am talking application, not theory) get a power meter and see for yourself. It is that simple.

 

[Mansmind]

It is not a matter of belief, it is facts vs. opinions. Regarding borrowing a buddies wheel, I have no need as I have one of the lighteset wheelsets available that is also somewhat aero (Zipp 303 tubular). Like I said if you don't understand the physics of why it doesn't matter (notice I am talking application, not theory) get a power meter and see for yourself. It is that simple.

Can you tell if the Zipp 303's are faster at speed? >20mph? Just curiuos, I've been looking close at those wheels.

 

[wilmar13]

But the rotational weight is the 1st weight that a person should try to reduce on a bike.

This is partially true in motorsports, especially where suspension action, turning, braking, accelerating all are very important (i.e. road racing) but are of a magnitude much greater than you will ever see in cycling. IN cycling the additional benefits to reducing rotating mass are virtually non-existent compared to simply reducing mass.

 

[53-11]

This is partially true in motorsports, especially where suspension action, turning, braking, accelerating all are very important (i.e. road racing) but are of a magnitude much greater than you will ever see in cycling. IN cycling the additional benefits to reducing rotating mass are virtually non-existent compared to simply reducing mass.

Good point.


His .5 second a lap faster time was most likely due in part to the suspension having an easier time controlling the lighter wheel in addition to the acceleration.