The weight question...
Tony
have about 50 to go so the weight of my derailleur is not really relevant
for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
though, I have heard references to "rolling weight" and I would like an
explanation of how this effects me. Will changing to a lighter freehub,
gears or wheels have a measurable effect?
--
Tony
******************************************
Just because your paranoid doesn't
mean they aren't after you!
******************************************
-ke...@nojunk.rahul.net-
>I am a everyday rider that has lost 125 pounds in the last year. I still
>have about 50 to go so the weight of my derailleur is not really relevant
>for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
>though, I have heard references to "rolling weight" and I would like an
>explanation of how this effects me. Will changing to a lighter freehub,
>gears or wheels have a measurable effect?
Rotating weight has a greater effect (per ounce) on your acceleration
than static weight. The effect increases with distance from the axel
of rotation; tire and rim weight is more important than hub weight.
Also, the effect increases with rotational speed, so wheel weight is
more important than crank weight.
If you're not riding very aggressively (lots of acceleration or fast
climbing), these issues won't have a large impact on your performance.
--
Ken Lee, http://www.rahul.net/kenton/
Andre Charlebois
mass. In other words, pedals, rims, tires, tubes are more important than
cogs, BB's, hubs, etc.
--
Andre Charlebois
BPE in exercise science, MCSE, MCP + I, CNA, A+
webmaster for Triathlon New Brunswick
Tony <boo...@seanet.com> wrote in message news:8bgcmh$f4d$1...@q.seanet.com...
> I am a everyday rider that has lost 125 pounds in the last year. I still
> have about 50 to go so the weight of my derailleur is not really relevant
> for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
> though, I have heard references to "rolling weight" and I would like an
> explanation of how this effects me. Will changing to a lighter freehub,
> gears or wheels have a measurable effect?
>
Jon Isaacs
>gears or wheels have a measurable effect?
Negligible effect on performance. Even for Pros the effect is over done, but
for the rest of us, the effect of some lightweight wheels is about the
difference between a full water bottle and a 1/2 full water bottle.
There is a very measurable effect on durabilty and the effect on your pocket
book is most definitely measureable.
Jon Isaacs
Oh yes and congratulations on your weight loss.
trey...@my-deja.com
Being an engineer I always considered rolling weight important and
looked to optimize the weight of rims, tires, etc. But after watching
the comments on that thread I came to agree with the (heavily debated)
opinion that acceleration of a bicycle is very small, even for racers.
That made the weight of the rims, etc equivalent to the weight of the
water bottle or anything else you are carrying on the frame, like body
weight.
Tom
In article <20000324152857...@ng-de1.aol.com>,
Sent via Deja.com http://www.deja.com/
Before you buy.
Eric Salathe
> I have heard references to "rolling weight" and I would like an
> gears or wheels have a measurable effect?
No.
A very small fraction of the total bike and rider weight, that of the
tires, rims, and spoke nipples, counts double whenever the numbers on
your speedometer change. In cycling, very little energy is expended to
changing the speedometer reading, relative to pushing the wind or
climbing. Heavy parts hurt you most of all when climbing, where every
gram counts the same as every other, whether on the rim, frame, water
bottle, or rider.
Fuhgetaboutit. Get good quality stuff that works and you'll be fine.
Eric Salathe
Phil Holman
pales into insignificance compared to your "50 to go". Good luck on your
continued weight loss and fitness.
Phil Holman
Tony wrote in message <8bgcmh$f4d$1...@q.seanet.com>...
>I am a everyday rider that has lost 125 pounds in the last year. I still
>have about 50 to go so the weight of my derailleur is not really relevant
>for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
>explanation of how this effects me. Will changing to a lighter freehub,
>gears or wheels have a measurable effect?
>
Pete
> have about 50 to go so the weight of my derailleur is not really relevant
> for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
> though, I have heard references to "rolling weight" and I would like an
> explanation of how this effects me. Will changing to a lighter freehub,
> gears or wheels have a measurable effect?
>
> --
> Tony
> ******************************************
> Just because your paranoid doesn't
> mean they aren't after you!
> ******************************************
>
but shedding a bit from an MTB will, not so much in terms of speed which as
you've already said losing a bit of bodyweight is better, but in handling.
This is because the bike weight is a mass that you have to throw around and
is "unsprung weight" relative to your body, also riding off-road calls for a
lot more need to keep re-accelerating. A 25lb bike will feel a lot nicer
than a 31lb one, however, the law of diminishing returns applies and it
starts to get expensive to get an MTB much lighter if it's to remain robust.
Congrats on your success with weight loss, Pete.
Edward Dike, III
think what is being referred to could be described as rotational mass;
and/or angular momentum; the inertia created from 'rotating' parts,
(tires,rims,tubes,spokes,pedals), as opposed to 'static' parts,(frame,etc).
The effects of lightening the frame, say 1-2# would be negligible, and
perhaps imperceptible, compared to lightening the rims/tires/tubes an equal
amount, which would completely change the character of the bike;
faster/easier starting,stopping, quicker turning. Generally speaking, the
'faster' the part is moving( tires,tubes,rims moving very fast;
hubs,freewheel, bottom bracket moving very slow) the greater the effect of
lightening that part will be.
As an demonstration of the effect. Take a small (relatively)heavy
object, say a roll of quarters, carry it around in a pocket for a while.
Take the same roll of quarters, and stick it in your sock, or tape it to
your ankle , and notice the effect on your walking.
ED
Pete <pet...@btinternet.com> wrote in message
news:8bi2td$gpj$1...@uranium.btinternet.com...
Jon Isaacs
>object, say a roll of quarters, carry it around in a pocket for a while.
>Take the same roll of quarters, and stick it in your sock, or tape it to
>your ankle , and notice the effect on your walking.
As another demonstration of the importance of "rotating mass" put your bike on
a trainer with no load. Put it top gear and give it one good spin.
The effort required is the work required to accellerate the entire rear wheel
and drive train to whatever velocity you reached.
I just demonstrated this for myself. With a 52-13 gear and a 32 spoke MA 40
rim with a Continental 700C x23 tire the results were as follows:
Rear Wheel, initially stopped, no load
1/2 crank stroke by hand 41 mph
1/2 crank stroke by bare foot 48 mph
These are indicative of the small amount of effort which is required to
accellerate the wheels.
One way to think of this is that of all the crank strokes required to
accellerate to 48 mph, less than 1 would be used to accellerate some rather
standard wheels.
In other words:
It ain't much.
Jon Isaacs
Gocycle
Ya gotta love it.
Luigi
}}}}}GoCycle}}}}}
Phil Holman
wheel. For one thing it works for you all of the time not just when you are
climbing or accelerating.
Phil Holman
Jon Isaacs wrote in message
<20000325175238...@ng-fa1.aol.com>...
Jobst Brandt
> The most important weight is that which is at the periphery of a
> rotating mass. In other words, pedals, rims, tires, tubes are more
> important than cogs, BB's, hubs, etc.
This is an age old fable in bicycling and useful to cite when an
excuse for some new wheels is needed. If they are aerodynamic, then
that's easy to justify but just a bit lighter ones are less so, so out
comes the rotational inertia bit. Inertia is important when there is
acceleration but not at constant speed where it is probably beneficial
although I don;t know of any study that has quantified this.
Francesco Moser used a large flywheel rear wheel in his last attempt
at increasing his Hour Record but the flesh wouldn't respond. I am
sure they analyzed the effects however.
Although it may seem daunting, when another rider pulls away on a hill
or in a bike race on the flat, accelerations on bicycles, except in
standing starts, are so small as to make the rotating mass story a
hoax. Sure, the mass counts twice as much when accelerating but two
times zero is still zero, and how long does a rider accelerate.
Weight of bicycle components for climbing is the main consideration,
not acceleration. The rotating mass story is a fable that sounds
good and has just enough technical truth to be one that will probably
sustain itself indefinitely. Making equipment choices by it are a
matter of faith, not fact.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> The most important weight is that which is at the periphery of a
> rotating mass. In other words, pedals, rims, tires, tubes are more
> important than cogs, BB's, hubs, etc.
This is an age old fable in bicycling and useful to cite when an
excuse for some new wheels is needed. If they are aerodynamic, then
that's easy to justify even though they are heavier, but just a bit
lighter ones are less so, so out comes the rotational inertia bit.
Inertia is important for acceleration but not at constant speed where
it is probably beneficial, although I don't know of any study that has
quantified this. Francesco Moser used a large flywheel rear wheel in
his last attempt at increasing his Hour Record but the flesh wouldn't
respond. I am sure they analyzed the effects however.
Although it may seem daunting, when another rider pulls away on a hill
or in a bike race on the flat, these accelerations, except in standing
Mark McMaster
>
> Francesco Moser used a large flywheel rear wheel in
> his last attempt at increasing his Hour Record but the flesh wouldn't
> respond.
In actuality, Moser did go faster in his 1994 attempt than
in his 1984 record, due in large part to a more aerodynamic
body position; unfortunately, a few other people had also
bested Moser's original hour record between 1984 and 1994,
and although Moser beat his old distance, he couldn't
surpass the then current record.
Mark McMaster
MMc...@ix.netcom.com
Andy Dingley
>This is an age old fable in bicycling and useful to cite when an
>excuse for some new wheels is needed.
So, it performs a valid function then !
How many of us actually _are_ pro racers ? For the rest of us, it's a
hobby. Buying new kit because it's _cute_ is a perfectly valid reason,
it just needs a little spin-doctoring to convince the non-cyclists.
--
Smert' Spamionam
Pete
> In actuality, Moser did go faster in his 1994 attempt than
> in his 1984 record, due in large part to a more aerodynamic
> body position; unfortunately, a few other people had also
> bested Moser's original hour record between 1984 and 1994,
> and although Moser beat his old distance, he couldn't
> surpass the then current record.
>
> Mark McMaster
> MMc...@ix.netcom.com
Moser 1994: Beat Obrees 51.596 km but failed to reach Boardmans 52.27 km
This at the age of 43, both the other contenders were a fair bit younger,
I'm impressed!
Pete.
Phil Holman
later rides seems to have no effect. The excitement of expectation is a
powerful boost to performance to many but has no lasting effect. You have to
go and buy again to get another fix. He that's fine in my book, there are a
lot of worse things to spend your money on but don't be duped.
Take a look at the picture of US Crit Champion Kenny Williams on the back of
this years 2000 USCF rule book. After trying other wheels he came back to
using his Spinergys.
Phil Holman
Andy Dingley wrote in message ...
Tom Kunich
> I am a everyday rider that has lost 125 pounds in the last year. I still
> have about 50 to go so the weight of my derailleur is not really relevant
> for me. I don't care if my bike weighs 19 pounds or 29 pounds. Recently
> though, I have heard references to "rolling weight" and I would like an
> explanation of how this effects me. Will changing to a lighter freehub,
> gears or wheels have a measurable effect?
In the most extreme case of weight at the outside of your wheels at speed
you can double the weight difference: that is, if you save an ounce you can
count it as saving two ounces for purposes of acceleration.
In other words -- unless you're talking about pretty extreme differences
don't worry about it.
BJCarlton
clinchers vs. tubulars. Since I gather that the only significant
difference induced by weight differences is in acceleration (discounting
for the moment climbing weight), would that mean that the speed on a flat
course of a bike with clinchers should be the same as that of one with
tubulars?
Barry
In article <8bo8sc$ccj$1...@news.cadence.com>,
Edward Dike, III
resistance could lead one to believe that air tire pressure would not effect
'speed' or rolling resistance.
BJCarlton <barr...@my-deja.com> wrote in message
news:8bql40$5k0$1...@nnrp1.deja.com...
Jon Isaacs
> clinchers vs. tubulars. Since I gather that the only significant
> difference induced by weight differences is in acceleration (discounting
> for the moment climbing weight), would that mean that the speed on a flat
> course of a bike with clinchers should be the same as that of one with
> tubulars?
>
> Barry
Except for the fact that different tires have different rolling resistances,
this is true. According to Jobst, tests have shown that modern clinchers can
have a lower rolling resistance than a tubular unless the tubular is glued with
a hard glue like High Tack.
Jon Isaacs