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PostPosted: Fri Oct 19, 2007 7:02 pm 
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celerystalksme wrote:
according to many people at bf...and according to velonews...and lennard zinn...and s.s. wilson in 'scientific america'..and countless other "experts"...a pound off the wheels is worth more than a pound off the frame


Very true. According to this analysis:
http://www.biketechreview.com/archive/wheel_theory.htm

a pound off the wheels is worth 1.1 pounds off the frame :).

Dan


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PostPosted: Fri Oct 19, 2007 7:03 pm 
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:popcorn:

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Posted: Fri Oct 19, 2007 7:03 pm 


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PostPosted: Fri Oct 19, 2007 7:07 pm 
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de zwarten wrote:
stella-azzurra wrote:
Since WW has a more finacially established population...


WW has a fair amount of competition riders, reviewers, people working in the bike industry and shop owners. Those can all get the nice stuff fast without being very rich. And WW also has more than one (like me) who doesn't have one single posh bike or one single WW bike in their (small) stable. We all ride our hourses, though.

And remember, expensive stuff has better value on the second hand market. A used alu frame won't be worth anything after 5 years, but a used titanium frame will be much sought for at a good price.


Most bikes and bike parts are comodities and not assets. Actually the depreciation percentage of an expensive part might be greater then a cheaper part.
The segment of the population you are talking about is much smaller then the one I am talking about when comparing WW to the other bike forums like fixed gear, single speed or the plain jane bicycle forum.


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PostPosted: Fri Oct 19, 2007 7:22 pm 
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Who cares.


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PostPosted: Fri Oct 19, 2007 7:54 pm 
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gumgardner wrote:
Who cares.


I CARE :twisted:


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PostPosted: Sat Oct 20, 2007 7:20 am 
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the beuty of the web is that you can have a forum/community of like-minded folk with a shared interest no matter how odd that interest might be, if someone else says something you don't like or don't agree with well... that's life, you can laugh at them, laugh at yourself or choose to ignore it and plough your own furrow. I get ribbed locally because of my bikes, but as a passion it beats stamp collecting or test card music....(see below) ..... in my opinion. On the face of it though it is a little bit odd, folk, many of whom could probably lose a few lb of body weight spending 1000's of $ to shave grams off their bikes :D http://mikesimagination.wordpress.com/2007/08/16/test-card-appreciation/

right, i'm going riding now...

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PostPosted: Sat Oct 20, 2007 1:22 pm 
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jalapeno wrote:
I get ribbed locally because of my bikes, but as a passion it beats stamp collecting or test card music....(see below) ..... in my opinion.


Exactly!

jalapeno wrote:
right, i'm going riding now...


It sure beats arguing on a gotdamned innurnet forum. :lol:

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PostPosted: Sat Oct 20, 2007 5:34 pm 
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RoadKill wrote:
Possible placebo, but I gain between 1.4 to 1.6 mph to my average speed, at the same perceived level of effort, when I switch from my Kyserium SL's to my Zipp 404's. That has been repeatable and consistent. Throwing out "bad days" and "good days" of physical performance.


1) My comment was in regard to the effect of a slight weight reduction not a more significant reduction in wheel drag. 2) Given there is a fairly significant drag reduction moving from Kyserium SLs to Zipp 404s, a speed increase is expected; however, about 0.5 mph is more reasonable and there are other factors providing your increased performance. Did you change tires too?

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PostPosted: Sat Oct 20, 2007 6:58 pm 
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celerystalksme wrote:
according to many people at bf...and according to velonews...and lennard zinn...and s.s. wilson in 'scientific america'..and countless other "experts"...a pound off the wheels is worth more than a pound off the frame. weight distribution on the wheels also makes a difference...if these "experts" are to be believed.

i have no reason to doubt them or their tests or their formulas...i figure they know more than i do!

having said that, ondrej sosenka believes in heavier rims because they're better at maintaining momentum on steady efforts on the track...


Unfortunately, I don't have a copy of S.S Wilson's oft quoted Scientific American article, so I cannot comment upon its conclusions, which may have been taken out of context. However, I do have a copy of David Gordon's comprehensive book "Bicycling Science" which for all its detail, does not address the concept of rotating weight.

Regarding Zinn and Velonews, time and time again I find Zinn simply regurgitating anything said to him by any manufacturer and he simply perpetuates myths instead of debunking them...

Now, on to rotating weight, for the Nth time.

Outside the bicycling system, rotating weight does matter and the moment of inertia between wheelset can greatly vary. For example, the moment of inertia (0-30 kph) for a set of 1985 gram Mavic Cosmic Carbone SLs is 143 joules, while the moment of inertia for a set of 1065 gram Lightweight Obermayers is 84 joules, over 40 percent less -- pick up a set of each and spin them and you can discern the difference.

The problem is that the energy required to accelerate an average rider+bicycle to this speed is much, much greater -- 5000 joules or more. Hence, the LWs require only 1.6% of the total energy required to accelerate the entire system to 30 kph, and the Cosmics 2.9%. So, in this extreme example of removing nearly a kilogram of rotating weight, 1.3% of the total energy is saved. More typically, wheel upgrades save about 500 grams; therefore, the difference in acceleration due to rotating mass is imperceptible.

Finally, can the combination of reduced rotating weight plus reduced aerodynamic drag plus reduced rolling resistance due to a tire chance make for a perceptible difference in acceleration? Maybe, but the difference is not going to be huge...

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PostPosted: Sat Oct 20, 2007 11:26 pm 
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John979 wrote:
Outside the bicycling system, rotating weight does matter and the moment of inertia between wheelset can greatly vary. For example, the moment of inertia (0-30 kph) for a set of 1985 gram Mavic Cosmic Carbone SLs is 143 joules, while the moment of inertia for a set of 1065 gram Lightweight Obermayers is 84 joules, over 40 percent less -- pick up a set of each and spin them and you can discern the difference.


And this price needs to be paid once, during the initial acceleration, then for each time you brake and have to reaccelerate. The reason for the first is obvious, for the second that you need to brake harder to lose a given amount of speed if you have greater inertia and therefore lose more kinetic energy doing so.

For speed loss due to coast-down or due to grades or due to rolling resistance, more rotational inertia (for the same total mass) actually helps -- you lose less speed as a result, and therefore have less to regain. You still may lose the same kinetic energy, and therefore resupply the same kinetic energy after, but the distance/time lost is less, as speed reduction is less.

So for a crit, where you're maybe braking every corner, maybe it can add up to a few watts. But for most riding/racing, the effect is quite small. For example, if you brake from 50 kph down to 30 kph four times per kilometer, and you're averaging 40 kph, then the cost in rotational inertia from your 920 gram difference, assuming half at the rim and half at the hub (obviously the reality is it's distributed over a range of radii, and you need to integrate mass * r^2), is 1.3 watts. The translational (as opposed to rotational) cost of the added weight is then an additional 2.6 watts, plus the cost from rolling resistance, but the issue here was frame-versus-wheel, not wheel-versus-nothing.

Dan


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PostPosted: Sun Oct 21, 2007 11:02 pm 
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I like this site. "Weight weenies". People have different opinions, experiences, knowledge, body weights, etc. I rode and raced a 10.5 lb. bike for many years, then a 9.2 lb. bike for many years, and now a 8.4 lb. bike. The total cost of these bikes was never very expensive, as I modify less expensive parts to get them light, after all I am a weight weenie. Also in many, many years of light bikes, I have had very few problems with things breaking. I have never broke anything that caused a crash. I have been riding road bikes for 37 years. That's my experience


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PostPosted: Wed Oct 24, 2007 11:10 pm 
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¿Do you have a weight scale?. They don´t. That´s all

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Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b


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PostPosted: Wed Oct 24, 2007 11:14 pm 
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donald wrote:
I like this site. "Weight weenies". People have different opinions, experiences, knowledge, body weights, etc. I rode and raced a 10.5 lb. bike for many years, then a 9.2 lb. bike for many years, and now a 8.4 lb. bike. The total cost of these bikes was never very expensive, as I modify less expensive parts to get them light, after all I am a weight weenie. Also in many, many years of light bikes, I have had very few problems with things breaking. I have never broke anything that caused a crash. I have been riding road bikes for 37 years. That's my experience


8.4 lb bike. We want pictures :lol:

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http://weightweenies.starbike.com/forum ... 8e319d185b


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PostPosted: Wed Oct 24, 2007 11:31 pm 
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beatnik wrote:
donald wrote:
I like this site. "Weight weenies". People have different opinions, experiences, knowledge, body weights, etc. I rode and raced a 10.5 lb. bike for many years, then a 9.2 lb. bike for many years, and now a 8.4 lb. bike. The total cost of these bikes was never very expensive, as I modify less expensive parts to get them light, after all I am a weight weenie. Also in many, many years of light bikes, I have had very few problems with things breaking. I have never broke anything that caused a crash. I have been riding road bikes for 37 years. That's my experience


8.4 lb bike. We want pictures :lol:


http://weightweenies.starbike.com/forum ... hp?t=31333


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PostPosted: Sat Jan 26, 2008 1:41 am 
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[quote="King Weel"](Quote Permanentjaun (senior member)): "A runner takes an average of 5,000 strides in a marathon. If I shave 1/4 of a pound off of each shoe that is 1250 lbs less that the runner has to move than someone wearing shoes 1/4 of a pound heavier."
=====
interesting- I am a marathon runner. Your 5000 strides means approx 28 ft per stride. You must be math challenged. Are you a right-brainer neo-con???
Andy Partner :twisted:


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Posted: Sat Jan 26, 2008 1:41 am 


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