# Thread: weight weenies...is it worth it?

1. ## weight weenies...is it worth it?

well...i found a site about bike equipment called weight weenies...and i was perusing the sight, figure out where i can cut weight and how much weight i can cut on either my road or tri bike. but is it worth it? if i went ALL OUT and dropped thousands and thousands of dollars...i can cut MAYBE 5 lbs from my bike. but i mean...it's 5-6 freaking pounds! will that really make an appreciable difference? honestly? i mean shoot...my weight fluctuates 10 lbs from month to month...sometimes i can lose or gain 10 lbs in a week!

now...i do remember from physics class that rotational mass matters more. if i spent a ridiculous amount of money...rims, tires, spokes, etc...i can cut maybe 2 lbs of rotational mass. can you feel that? will that significantly improve my splits?

2. rotating mass is a myth. Do the actual math, and you'll find that the difference between 100 grams on the rim and 100 grams on the bike is so insignificant, it's essentially worthless.

that being said, lose 10 lbs and get stronger while you're at it.

3. Originally Posted by brianappleby
rotating mass is a myth.

4. Originally Posted by brianappleby
rotating mass is a myth. Do the actual math, and you'll find that the difference between 100 grams on the rim and 100 grams on the bike is so insignificant, it's essentially worthless.

that being said, lose 10 lbs and get stronger while you're at it.
really? interesting...i was once told by a grad school physics instructor that in many engineering applications, removing 1 lbs of rotation mass can be equivalent to removing 5-10 lbs of non-rotational mass. this was, of course, many years ago...but i recall doing text problems and lab reports bore out to some degree what we were told by our GSI. coure, this was for large automotive applications...but still...

either way...lets say rotational and non-rotational mass are no different...my question is, is shaving a few hundred grams here and there totally overrated? i mean...sure...if i had \$5000-\$6000 to waste on the lightest wheels, tires, spokes, drive line components, handle bars, seat post, etc etc etc...why not? but for us non-wealthy people...i'm not sure the investment is worth it.

crusading after lighter parts seems to be a futile fight against diminishing returns...

5. Rotating mass is certainly not a myth. The argument you're looking for is that after a certain point the cost to reduce weight so much further becomes so cost inefficient that you're better off focusing on losing your own body weight than on the bike.

If you have the money or the sponsors then there is no reason not to get the ultimate in weight reduction though. I can't find the links to any rotational mass physics, but I remember a good line from one of the Steve Prefontaine movies. The coach designed a lightweight shoe, to which one of his runners asked why make a custom shoe that's only marginally smaller. The coach went on to do some simple math. "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."

That's an example of how even the smallest weight savings can go a long way. I'm sure cycling has its own translation of the above example.

6. you dont have to know anything about bikes, to know that rotating mass is not a myth.
thats like saying would you rather wear a 20lb backpack or two 10lb shoes...*sigh*...

7. If your wheels are cheaper than \$5k, I'm sorry but your bike's not even worth riding.

8. Originally Posted by v1k1ng1001
If your wheels are cheaper than \$5k, I'm sorry but your bike's not even worth riding.
he he!

9. If you have money, then buy the lightest wheels you can. It'll make you faster. Going faster will help you enjoy riding more. Riding more will certainly extend your life.

Despite what everyone tells you, riding a lighter bike makes the very act of riding more holy and pleasurable. I spend too much much money on women and cheap thrills, money that should be spent on cycling gears.

10. Originally Posted by TheSurgeonGod
If you have money, then buy the lightest wheels you can. It'll make you faster. Going faster will help you enjoy riding more. Riding more will certainly extend your life.

Despite what everyone tells you, riding a lighter bike makes the very act of riding more holy and pleasurable. I spend too much much money on women and cheap thrills, money that should be spent on cycling gears.
Welcome to BF. Given what you've posted, it is clear that you will fit right in with the rest of the gang around here.

11. I'm sure I am among friends here.

Originally Posted by v1k1ng1001
Welcome to BF. Given what you've posted, it is clear that you will fit right in with the rest of the gang around here.

12. Most of the people in the local cycling (road racing) club that I have just joined don't use valve caps. I haven't been game enough to ask them why, I'm presuming it's because of the rotating mass thing but really how much benefit would you gain from this, immeasurable I would think?

13. Originally Posted by Falchoon
Most of the people in the local cycling (road racing) club that I have just joined don't use valve caps. I haven't been game enough to ask them why, I'm presuming it's because of the rotating mass thing but really how much benefit would you gain from this, immeasurable I would think?
The removal of valve caps and valve stem nuts make two things you don't need to mess with if/when you flat. Pretty elementary...

14. Originally Posted by Falchoon
Most of the people in the local cycling (road racing) club that I have just joined don't use valve caps. I haven't been game enough to ask them why, I'm presuming it's because of the rotating mass thing but really how much benefit would you gain from this, immeasurable I would think?
Valve cap removal have nothing to do with weight saving. It has everything to do with Fred.

15. Rotating mass has a multiplier effect varying between 1 and 2, so yeah, lighter wheels are nice.

That said, is it worth it to be a weight weenie? No. Not at all. Ride what you have and love it. Buy for quality and fit, and if the weight comes down too, then so be it, but if you buy Ti bolts to "tune" your bike, you've wasted your life.

16. Rotating mass is not a myth, but it's magnitude of impact on cycling is a myth. Certainly, if you remove one pound from your tires and rims, it will benefit you more than if you removed them from the frame, but that extra benefit is so small that it's really not worth changing your weight-weenie priorities. We don't accelerate fast enough, or over enough of a speed range to benefit much -- even if we had massless wheels.

Still, it's there, and people will cling to it.

17. Originally Posted by permanentjaun
Rotating mass is certainly not a myth. The argument you're looking for is that after a certain point the cost to reduce weight so much further becomes so cost inefficient that you're better off focusing on losing your own body weight than on the bike.

But that's not a physics argument, that's an economics argument.

ime, Weight Weenies -- and, for that matter, all hobbyists, enthusiasts, and professionals in a hardware-centric field -- aren't interested in the economic argument until after they've addressed the objective motivations. If the first thing you worried about is "that's too expensive" or "that's not a healthy ROI" you'd never get started in the first place.

First solve for X (where X = how much of an asset this thing could potentially be), then let the individual worry about the value of X. Because X is at least objectively measureable in most (many?) circumstances. Value has to take into account that huge variable which is the individual's perception. And bank account.

18. Originally Posted by brianappleby
rotating mass is a myth. Do the actual math, and you'll find that the difference between 100 grams on the rim and 100 grams on the bike is so insignificant, it's essentially worthless.

that being said, lose 10 lbs and get stronger while you're at it.
Unless you file down the deraileur cages to save weight and aerodynamic, that is.

19. so...how much does roational weight savings help?

i have wheels that weigh 1800g...i'm thinking of getting wheels that weight 1000 grams. lets say my average speed for a ride of moderate length is 18mph...will it go up? to what....19? 40? how much of a difference will that weight savings make?

i'm liquidating items from an old hobby to finance this new hobby...so, in a sense, i'm not even really spending money. but even still...i'd be awfully disappointed to spend \$2K on new wheels only to realize i can't feel the difference from my stock wheels.

20. The negative cognitive contribution to rider enjoyment of the weight of rotating and static parts of a bicycle are relative to the overall mass of the rider/bicycle configuration multiplied by any elevation changes and velocity changes demanded by the route and type of ride being experienced by the cyclist.

What else is there to say?

21. Originally Posted by celerystalksme
so...how much does roational weight savings help?

i have wheels that weigh 1800g...i'm thinking of getting wheels that weight 1000 grams. lets say my average speed for a ride of moderate length is 18mph...will it go up? to what....19? 40? how much of a difference will that weight savings make?

i'm liquidating items from an old hobby to finance this new hobby...so, in a sense, i'm not even really spending money. but even still...i'd be awfully disappointed to spend \$2K on new wheels only to realize i can't feel the difference from my stock wheels.
If you really want to know this stuff, spend the afternoon on the following site, http://www.analyticcycling.com/QCHome_Page.html, and not here. Then come back and tell us how much faster you will be with 300g lighter wheels.

22. Originally Posted by celerystalksme
so...how much does roational weight savings help?

i have wheels that weigh 1800g...i'm thinking of getting wheels that weight 1000 grams. lets say my average speed for a ride of moderate length is 18mph...will it go up? to what....19? 40? how much of a difference will that weight savings make?

i'm liquidating items from an old hobby to finance this new hobby...so, in a sense, i'm not even really spending money. but even still...i'd be awfully disappointed to spend \$2K on new wheels only to realize i can't feel the difference from my stock wheels.
I answered that above: there's a 1-2x multiplier effect. So it varies between "no difference" and "twice as much", depending on distance from the center of rotation (that is, the axle). You'd have to integrate over the radius of the rim to find out, and I'm not whipping out the calculus today, but the overall difference is between 1 and 2, so let's approximate and say 1.5x. So 1 lb saved on the wheels is approximately equivalent to 1.5 lbs saved on the bike or body.

The major noticeable difference will be that lighter-rimmed wheels will seemingly spin up faster, but you will NOT be faster on the flats, and imperceptibly so on the hills (you're dropping less than 1% of the total weight you're dragging up the hill). I just dropped a full pound off of my wheelset, and I am every bit as slow going up as before. The new hubs are GREAT and my ride quality is much better, and they do seem to spin up faster due to lighter rims, but I am not faster, and you won't be either. If you want new wheels, get ones with great hubs and light rims, but don't think you'll be a better cyclist because of them.

23. Originally Posted by celerystalksme
so...how much does roational weight savings help?

i have wheels that weigh 1800g...i'm thinking of getting wheels that weight 1000 grams. lets say my average speed for a ride of moderate length is 18mph...will it go up? to what....19? 40? how much of a difference will that weight savings make?

i'm liquidating items from an old hobby to finance this new hobby...so, in a sense, i'm not even really spending money. but even still...i'd be awfully disappointed to spend \$2K on new wheels only to realize i can't feel the difference from my stock wheels.
There is a difference, most definitely, between a set a Zipp 404s at 1200g and a pair of Ksyrium Elites at 1750g. You have a more aerodynamic wheel which is also lighter than the second wheelset. At large power outputs, you gain a couple of TENTHS of a MPH on the flats. The weight savings, if you drop a couple of pounds off your bike and you're in great shape, might give you a VERY slight advantage going up hill. You might go from 26.6 to 27mph during your intervals or during a break in a race. And, and I'll readily admit this, an aero advantage is nothing to scoff at if you have the money to burn. Being a smaller guy, I'll take any aero help I can get. 5 watts saved is 5 watts in the banks for later.

And, I highly doubt that if you weighed yourself every day at the same time (after dinner, for example) you would see any real fluctuations in your weight. If someone is really gaining or losing 10lbs in a week, they are either being starved, or starving themselves.

However, I always smile when I see people doing stupid things like putting aluminum bolts on their bike. I can understand a Ti bolt, as it's plenty strong, and better than a questionable quality steel bolt if you're concerned about durability. But putting your life on the line with two aluminum bolts holding your stem faceplate on? No thanks.

24. Originally Posted by WheresWaldo
If you really want to know this stuff, spend the afternoon on the following site, http://www.analyticcycling.com/QCHome_Page.html, and not here. Then come back and tell us how much faster you will be with 300g lighter wheels.
oh holy fudge...if i knew what i was doing, that'd be EXACTLY what i was looking for! alas...i'm clueless...but i'll try to figure it out! thanks!

25. Duke and michael,

ahhh! alright...now i'm getting answers i can understand. so i will gain very little if any speed increases up hills and on flats. however...according to michael, i'll probably accelerate faster. gotcha.

wow...that sorta doesn't seem worth \$2K. hmmm...i'll have to think about this before selling off more cameras and photography equipment to buy bike stuff! lol

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