A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Calculating value of shaving off weight



 
 
Thread Tools Display Modes
  #1  
Old September 15th 04, 11:39 PM
Ivar Hesselager
external usenet poster
 
Posts: n/a
Default Calculating value of shaving off weight

The thread below on sprung/unsprung weight inspired me to calculate the
cost - and to speculate on the value - of my latest weigh saving investment.
I thought I would share my results with you.

After having to give up on the third mountain in the Ötztaler Radmarathon
two weeks ago, I realized I had to loose a lot of weigh before my next
attempt.So I bought new very slim spokes ( 2.0-1.5-2.0 mm) to replace the
plain gauge (2.0) that the bike shop had put in, because they considered me
a heavy rider . i.e. 86 kg = 187 lbs. But Jobst Brandt's great book on
wheels has told me, that heavy riders don't need heavy spokes - just very
tight spokes and strong rims. So that's what I got. The weight saved on the
two wheels is 368 g.- and the price for the spokes & nipples is exactly 50
US $. This gives a price per saved kg of 136 $.

Is it worth that money? The following considerations tell me it is:

I figure, that if I want to make it over all four Alp mountains next year, I
will have to loose 7 kg - going back to what I weighed, when I was 40, -
gee! thats 15 years ago. Loosing 7 kg is worth 7*136 = 951 $ - and though
that's a lot of money to me, it is also a lot of work to drop 7 kg of body
weight and stay there. I mean, I do a LOT of cycling already.

So would I be willing to pay almost a thousand dollars for a weight loss of
7 kg, that would last for - say 7 years? Yes, definately, I think it is more
than fair - it is cheap, considering the effort of carrying that load up
5.500 meters in the Alps. So saving weight by putting in butted spokes IS
good value for money.

But I still need to find the limit for how much I would be willing pay?
Chosing between two different Shimano derailleurs, 105 or Ultegra, the weigh
difference is a mere 13 g and the prise difference is 14.29 $ - making the
price of one saved kg: 1099 $. Or 7,700 $ for loosing 7 kg. At that prise,
I would rather do the hard work or suffer the privations needed to loose 7
kg of body weight and keeping it down. Unfortunately I bought the Ultegra
Group already. What a waste!

So I look for my limit somwhere between those two exambles. I guess I would
be willing to pay 50 $ pr month to be 7 kg. lighter without really trying
(besides what I do allready) So if the weight saving parts lasts for 7
years, I guess 600 $ pr. kg saved weight is still a fair deal.

Now I have the rule of thumb I need, when I consider buying lighter parts
for my road racer: 60 cents per gram saved weight is my limit. Although I
think, that's a lot of money to be willing to spend, and wouldn't telle my
wife about it, there probably aren't many lighter parts available at that
price for my 10 kg middle level road bike. Maybe a saddle, maybe shoes. But
that will be it.

Ivar of Denmark





Ads
  #2  
Old September 16th 04, 03:59 AM
David L. Johnson
external usenet poster
 
Posts: n/a
Default

On Thu, 16 Sep 2004 00:39:01 +0200, Ivar Hesselager wrote:

After having to give up on the third mountain in the Ötztaler Radmarathon
two weeks ago, I realized I had to loose a lot of weigh before my next
attempt.So I bought new very slim spokes ( 2.0-1.5-2.0 mm) to replace the
plain gauge (2.0) that the bike shop had put in, because they considered
me a heavy rider . i.e. 86 kg = 187 lbs.


I _wish_ that were my weight.

But Jobst Brandt's great book on
wheels has told me, that heavy riders don't need heavy spokes - just very
tight spokes and strong rims. So that's what I got. The weight saved on
the two wheels is 368 g.- and the price for the spokes & nipples is
exactly 50 US $. This gives a price per saved kg of 136 $.


How do you compute that weight saving? Did you have steel rims
previously? That is a huge difference for just changing spokes.

OTOH, I don't see the advantage of using straight-gauge spokes. I claim
there is no advantage in overall strength between staight-gauge and butted
spokes. Conversely, I*would not use 2/1.5/2mm spokes, since that center
section would be a RPITA in terms of wind-up. A more conservative 2/1.8/2
or 1.8/1.6/1.8 would give a more resiliant, and thus stronger wheel,
without making it impossible to build.

So saving weight by putting in butted
spokes IS good value for money.


No way are you saving 368 grams by switching spokes. For even 36-spoke
wheels, that is supposedly a nearly 10g/spoke saving. DT reports that its
1.8/1.6/1.8 spokes weigh 311g for 64, and the 2.0/1.8/2.0 weigh 382g/64.
Plain 2.0 weigh 444g/64. So, the difference between lighter than
yours and the heaviest spokes in general use, is less than 150g.

At that prise, I would rather do the hard work or suffer the privations
needed to loose 7 kg of body weight and keeping it down.


You're fussing about grams, versus dropping 7kg for "free". You know what
is the best bet.

--

David L. Johnson

__o | Some people used to claim that, if enough monkeys sat in front
_`\(,_ | of enough typewriters and typed long enough, eventually one of
(_)/ (_) | them would reproduce the collected works of Shakespeare. The
internet has proven this not to be the case.

  #3  
Old September 16th 04, 05:16 AM
DirtRoadie
external usenet poster
 
Posts: n/a
Default

"Ivar Hesselager" wrote in message ...
The thread below on sprung/unsprung weight inspired me to calculate the
cost - and to speculate on the value - of my latest weigh saving investment.
I thought I would share my results with you.

After having to give up on the third mountain in the Ötztaler Radmarathon
two weeks ago, I realized I had to loose a lot of weigh before my next
attempt.So I bought new very slim spokes ( 2.0-1.5-2.0 mm) to replace the
plain gauge (2.0) that the bike shop had put in, because they considered me
a heavy rider . i.e. 86 kg = 187 lbs. But Jobst Brandt's great book on
wheels has told me, that heavy riders don't need heavy spokes - just very
tight spokes and strong rims. So that's what I got. The weight saved on the
two wheels is 368 g.- and the price for the spokes & nipples is exactly 50
US $. This gives a price per saved kg of 136 $.

Is it worth that money? The following considerations tell me it is:

I figure, that if I want to make it over all four Alp mountains next year, I
will have to loose 7 kg - going back to what I weighed, when I was 40, -
gee! thats 15 years ago. Loosing 7 kg is worth 7*136 = 951 $ - and though
that's a lot of money to me, it is also a lot of work to drop 7 kg of body
weight and stay there. I mean, I do a LOT of cycling already.

So would I be willing to pay almost a thousand dollars for a weight loss of
7 kg, that would last for - say 7 years? Yes, definately, I think it is more
than fair - it is cheap, considering the effort of carrying that load up
5.500 meters in the Alps. So saving weight by putting in butted spokes IS
good value for money.

But I still need to find the limit for how much I would be willing pay?
Chosing between two different Shimano derailleurs, 105 or Ultegra, the weigh
difference is a mere 13 g and the prise difference is 14.29 $ - making the
price of one saved kg: 1099 $. Or 7,700 $ for loosing 7 kg. At that prise,
I would rather do the hard work or suffer the privations needed to loose 7
kg of body weight and keeping it down. Unfortunately I bought the Ultegra
Group already. What a waste!

So I look for my limit somwhere between those two exambles. I guess I would
be willing to pay 50 $ pr month to be 7 kg. lighter without really trying
(besides what I do allready) So if the weight saving parts lasts for 7
years, I guess 600 $ pr. kg saved weight is still a fair deal.

Now I have the rule of thumb I need, when I consider buying lighter parts
for my road racer: 60 cents per gram saved weight is my limit. Although I
think, that's a lot of money to be willing to spend, and wouldn't telle my
wife about it, there probably aren't many lighter parts available at that
price for my 10 kg middle level road bike. Maybe a saddle, maybe shoes. But
that will be it.


ROTFLMAO! Sorry, nothing personal.


DR
  #4  
Old September 16th 04, 06:48 PM
LioNiNoiL_a t_Y a h 0 0_d 0 t_c 0 m
external usenet poster
 
Posts: n/a
Default

So would I be willing to pay almost a thousand dollars for
a weight loss of 7 kg, that would last for - say 7 years?
Yes, definately, I think it is more than fair - it is cheap,
considering the effort of carrying that load up 5.500 meters
in the Alps.


Ivar, this is the stuff of a weight-loss product marketer's dream.

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

  #5  
Old September 17th 04, 02:03 AM
Ivar Hesselager
external usenet poster
 
Posts: n/a
Default


"David L. Johnson" wrote
How do you compute that weight saving? Did you have steel rims
previously? That is a huge difference for just changing spokes.

OTOH, I don't see the advantage of using straight-gauge spokes. I claim
there is no advantage in overall strength between staight-gauge and butted
spokes. Conversely, I would not use 2/1.5/2mm spokes, since that center
section would be a RPITA in terms of wind-up. A more conservative 2/1.8/2
or 1.8/1.6/1.8 would give a more resiliant, and thus stronger wheel,
without making it impossible to build.

So saving weight by putting in butted
spokes IS good value for money.


No way are you saving 368 grams by switching spokes. For even 36-spoke
wheels, that is supposedly a nearly 10g/spoke saving. DT reports that its
1.8/1.6/1.8 spokes weigh 311g for 64, and the 2.0/1.8/2.0 weigh 382g/64.
Plain 2.0 weigh 444g/64. So, the difference between lighter than
yours and the heaviest spokes in general use, is less than 150g.

At that prise, I would rather do the hard work or suffer the privations
needed to loose 7 kg of body weight and keeping it down.


You're fussing about grams, versus dropping 7kg for "free". You know what
is the best bet.

You are right David, the wight saving can't be that much. I checked the
figures I found on the www.sapim.be homepage, and I have to admit, I
misinterprited it. The weight saving was only half i.e. 184 grams - making
the price per saved kg twice as high: 272 $ per kg. I'm not proud of that
mistake, and it is no longer cheep. But it is still a fair price for the
weight saving,

Chosing very slim spokes - 1. 5 mm - is logical, since thin spokes (as Jobst
Brandt tells us) is not a problem for a 85 kg rider, as long as the wheel I
build is real tight. I also e-mailed the manifacturer, Sapim in Belgium,
and they said "no problem" wiht the slim spokes for a heavy rider. So I
oiled the spokes and the nipples at every joint to ease the tightening, and
the wheels are now so tight that I really must depend on the strength of
the Mavic CPX 33 rim. So far it seems to work allright - and I count on
that it will last for at least seven years.

I still like the idea of relating the cost of weight savings to the
suffering and privation of loosing the 7 kg of body weight necessary to
cross the four mountains of the Ötztaler Radmarthonh. To evaluate it, you
need to relate it to something, and I have a very concrete aim - and
experience, that I can relate it to. The alternative to buying lighter
bicylcle parts is dropping body weight, but I don't accept the idea of that
being "free". It's a lot of effort and a lot of privation to a man, who is
cycling a lot already.

So to estimate, if buying lighter parts for my road racer is worht the
money, I need to relatate it to 1) the impact on the mountain riding, that I
aim at,
and 2) to my perception of what my time and effort is worth in dollars.

I will stick to a max of 600 $ pr. kg saved weight - still maiking the slim
spokes a good investment - but not justifying Shimano Ultegra in stead of
Shimano 105.

This calculation will be a marketer's NIGHT MARE, since it shows, that it is
a waste of money to buy the high class group - even for well to do riders
that are willing to pay 600 $ to get rid of one kg. If I had made this
calculation before, I would not have bought the Ultegra group for my road
racer.
I know that some will be rolling on the floor laughing of what I'm willing
to spend, to cross those mountains. But very many bicycle enthuthiasts
have been spending at whole lot more, never knowing how to evaluate if it
was worth their money.

Ivar of Demark



  #6  
Old September 17th 04, 03:22 AM
Leo Lichtman
external usenet poster
 
Posts: n/a
Default

IMO, it is not the actual numbers that matter here--it is the kind of
thinking which can affect your behavior. What to take along and what to
leave behind--how much water to carry--what to wear, etc. It points up the
silliness of comparing the gram weight of two cyclometers, and then throwing
in a few extra tools "just in case."


  #7  
Old September 17th 04, 04:04 PM
DirtRoadie
external usenet poster
 
Posts: n/a
Default

"Leo Lichtman" wrote in message ...
IMO, it is not the actual numbers that matter here--it is the kind of
thinking which can affect your behavior. What to take along and what to
leave behind--how much water to carry--what to wear, etc. It points up the
silliness of comparing the gram weight of two cyclometers, and then throwing
in a few extra tools "just in case."


And "Should I wear a 3/4 pound (340 g) helmet?" After all it's very
rare that it is actually needed and you'll be SO much faster without
it.

DR
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cycling and vegetarianism Preston Crawford General 434 September 25th 04 09:38 PM
aus.bicycle FAQ (Monthly(ish) Posting) kingsley Australia 3 February 24th 04 09:44 PM
target weights for cyclist-specific weight training kitchen Racing 10 January 13th 04 05:47 PM
Braking Technique asqui Racing 55 July 25th 03 04:16 PM


All times are GMT +1. The time now is 06:10 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright ©2004-2022 CycleBanter.com.
The comments are property of their posters.