Is Upgrading Wheelset Worth It?

[[email protected]]

On Mon, 02 Aug 2004 16:29:24 -0700, Terry Morse
<[email protected]> wrote:

>Carl Fogel wrote:
>
>> Take two identical bicycles powered by identical machines,
>> each with an extra one-pound weight.
>>
>> Which one do you predict will be ahead after thirty seconds
>> from a standing start, the one with the weight tucked inside
>> the frame tube or the one with the weight tucked inside the
>> tire?
>
>As far as acceleration goes, the pound in the tire counts twice.
>Analytic Cycling to the rescue, using default values:
>
>Time to reach 100 meters, from standing start:
>
>"Pound on frame" case: 15.9 s, 8.8 m/s
>"Pound in tire" case: 16.0 s, 8.8 m/s
>
>The difference would be even smaller at 30 seconds, since the
>accleration drops as speed increases. If sprinting performance is
>important, you're better off reducing drag than shaving grams off of
>rims.
>
>At a steady 8.8 m/s, rolling resistance is about 300 grams (18% of
>the total static forces).

Dear Terry,

Thanks--I don't dare go back to the Analytic Cycling site,
having lost an hour there earlier today playing with
downhill speeds. (Chalo wins.)

To be fair, I expect that the 15.9 versus 16.0 was rounded
by the site, so it may not be really be a full tenth of
second (though it could be more, come to think of it).

But at about 10 meters per second and about a tenth of a
second and assuming that you plugged in all the right
numbers and the formulas are correct, it sounds as if the
rider with the 1-pound weight on the frame instead of on the
wheel ends up about a meter ahead for the same effort.

(I appreciate your effort. If I'd plugged in the numbers,
someone would probably have to point out that pounds are not
kilograms.)

For thirty seconds, the difference would be the same or
greater in terms of the 0.1 second lead--the other rider
never makes up his loss. I expect that you mean that the
lead would look less significant because it would involve
larger times--something like 29.9 versus 30.0.

Serious sprinters may be able to accelerate from zero to
more than 8.8 meters per second (19-20 mph) in 100 meters
and 16 seconds. (But I've got to resist the urge to find out
whether that makes any difference, or I'll end up trying to
make the poor site calculate how fast Chalo will be going
half-way down Mt. Everest.)

The advantage is small, but then so are most advantages in
competitive bicycling. For a lead of half a meter to a meter
and a half, most sprinters will encourage their sisters to
have dinner with me--and pick up the check.

Thanks again for the computational work,

Carl Fogel

 

[Robin Hubert]

[email protected] wrote in message news:<[email protected]>...
> On Mon, 2 Aug 2004 20:58:29 +1000, Tuschinski
> <[email protected]> wrote:
>
> >
> >Qui si parla Campagnolo Wrote:
> >> gillies-<< 1 lbs off of your wheels is worth 2 lbs off the frameset.
> >> >><BR><BR>
> >>
> >> Sorry, no. A pound is a pound regardless of where it is, on the butt,
> >> on the
> >> bike, on the wheels.
> >>
> >> This type of reasoning went the way of rod shifters and tires wrapped
> >> around
> >> your shoulders.
> >>
> >> Peter Chisholm
> >> Vecchio's Bicicletteria
> >> 1833 Pearl St.
> >> Boulder, CO, 80302
> >> (303)440-3535
> >> http://www.vecchios.com
> >> "Ruote convenzionali costruite eccezionalmente bene"
> >
> >I agree that a lot is placebo effect, but I was convinced it is true
> >that weigth should best be saved in the wheels.
> >
> >To give a decent claim to this from the real world: with same average
> >heartbeat (wich was 95-100% max) I shaved 5 seconds from my best time
> >at a *curvy* three mile asphalt racing track (its where our club holds
> >its races) when I switched from CXP 33 to light custom wheels (DTswiss
> >RR1.1, 240s hubs, Aerolite spokes). It has extremely sharp curves, so a
> >lot of acc/decelerating.
> >
> >In this case a few seconds is not peanuts, as now I have to do a lot
> >less effort to ride in the pack (after half an hour the pack invariable
> >breaks apat due to the repeated acc/dec stress)
> >
> >Another example: My brother and I have tested wheels (Open pros, cxp33
> >and cosmics) in a five km flat TT with a flat heartbeat(at the same
> >day, good conditions) We both had the best results with the same wheels
> >(cosmics)
> >
> >But for touring: get CXP 33's with good hubs, non aero, 32 DB spokes
> >and you have great, affordable wheels. Stiff, yet comfy and stronger as
> >openpro's(for the unavoidable pothole)
>
> Dear Tuschinski,
>
> Lazy folk like me don't even have to go to the trouble of
> your fierce riding to demonstrate the fact that rotating
> weight suffers a penalty in acceleration.
>
> Just flip the bike upside down and work one pedal to spin
> the rear wheel up to speed. Some of the resistance is wind
> drag, but most of it is the inertia of the wheel--and none
> of the effort produces the slightest linear acceleration.
>
> The resistance is far from massive and occurs only during
> acceleration, but it's considerably more than ordinary
> rolling resistance. It always takes force to accelerate a
> mass, and rotation adds an extra kind of acceleration to
> bicycle wheels (and cranks and chains).
>
> Some day I hope to see a rider arguing that a pound's a
> pound regardless where it is storing his water bottle inside
> the spokes.

So, it isn't a pound (as I understand, about 1.5), Carl. Therefore it
is much about nothing. Bicyclists don't accelerate enought to matter.
So, it really is insignificant as long as your wheels are within a
pound or two of the other guy's. "Far more massive" is way off the
mark. Also, don't forget to consider that, once the wheels are
rolling, the heavier ones will be more likely to continue rolling fast
when encountering resistance (the flywheel effect).


Robin Hubert

 

[[email protected]]

On 2 Aug 2004 19:43:01 -0700, [email protected] (Robin
Hubert) wrote:

>[email protected] wrote in message news:<[email protected]>...
>> On Mon, 2 Aug 2004 20:58:29 +1000, Tuschinski
>> <[email protected]> wrote:
>>
>> >
>> >Qui si parla Campagnolo Wrote:
>> >> gillies-<< 1 lbs off of your wheels is worth 2 lbs off the frameset.
>> >> >><BR><BR>
>> >>
>> >> Sorry, no. A pound is a pound regardless of where it is, on the butt,
>> >> on the
>> >> bike, on the wheels.
>> >>
>> >> This type of reasoning went the way of rod shifters and tires wrapped
>> >> around
>> >> your shoulders.
>> >>
>> >> Peter Chisholm
>> >> Vecchio's Bicicletteria
>> >> 1833 Pearl St.
>> >> Boulder, CO, 80302
>> >> (303)440-3535
>> >> http://www.vecchios.com
>> >> "Ruote convenzionali costruite eccezionalmente bene"
>> >
>> >I agree that a lot is placebo effect, but I was convinced it is true
>> >that weigth should best be saved in the wheels.
>> >
>> >To give a decent claim to this from the real world: with same average
>> >heartbeat (wich was 95-100% max) I shaved 5 seconds from my best time
>> >at a *curvy* three mile asphalt racing track (its where our club holds
>> >its races) when I switched from CXP 33 to light custom wheels (DTswiss
>> >RR1.1, 240s hubs, Aerolite spokes). It has extremely sharp curves, so a
>> >lot of acc/decelerating.
>> >
>> >In this case a few seconds is not peanuts, as now I have to do a lot
>> >less effort to ride in the pack (after half an hour the pack invariable
>> >breaks apat due to the repeated acc/dec stress)
>> >
>> >Another example: My brother and I have tested wheels (Open pros, cxp33
>> >and cosmics) in a five km flat TT with a flat heartbeat(at the same
>> >day, good conditions) We both had the best results with the same wheels
>> >(cosmics)
>> >
>> >But for touring: get CXP 33's with good hubs, non aero, 32 DB spokes
>> >and you have great, affordable wheels. Stiff, yet comfy and stronger as
>> >openpro's(for the unavoidable pothole)
>>
>> Dear Tuschinski,
>>
>> Lazy folk like me don't even have to go to the trouble of
>> your fierce riding to demonstrate the fact that rotating
>> weight suffers a penalty in acceleration.
>>
>> Just flip the bike upside down and work one pedal to spin
>> the rear wheel up to speed. Some of the resistance is wind
>> drag, but most of it is the inertia of the wheel--and none
>> of the effort produces the slightest linear acceleration.
>>
>> The resistance is far from massive and occurs only during
>> acceleration, but it's considerably more than ordinary
>> rolling resistance. It always takes force to accelerate a
>> mass, and rotation adds an extra kind of acceleration to
>> bicycle wheels (and cranks and chains).
>>
>> Some day I hope to see a rider arguing that a pound's a
>> pound regardless where it is storing his water bottle inside
>> the spokes.
>
>So, it isn't a pound (as I understand, about 1.5), Carl. Therefore it
>is much about nothing. Bicyclists don't accelerate enought to matter.
> So, it really is insignificant as long as your wheels are within a
>pound or two of the other guy's. "Far more massive" is way off the
>mark. Also, don't forget to consider that, once the wheels are
>rolling, the heavier ones will be more likely to continue rolling fast
>when encountering resistance (the flywheel effect).
>
>
> Robin Hubert

Dear Robin,

I think that we all agree that removing a pound anywhere is
going to make only a small difference to a rider and bicycle
that together weigh from 150 to 225 pounds.

But unless the laws of physics are revoked, extra force is
required to accelerate a rotating mass like a wheel. Adding
weight to the wheels increases either the power or the time
required to reach the same speed as a bicycle with the same
weight added to the frame.

The common remark that more massive wheels act as a superior
flywheels would apply if bicycles were ridden at full power
over nothing but a roller-coaster path. But enormously
greater losses occur whenever the riders squeeze the brakes,
leaving our pair of imaginary bicycles to re-accelerate.

In every acceleration, the bike with the extra weight added
to the wheel is slightly slower than the bike with the extra
weight added to the frame. In casual riding, we never notice
this, but a bike length here and a bike length there amount
to something that matters when races are won by such small
margins.

I do understand why people consider the difference
insignificant--it is for their kind of riding. But an extra
pound on the wheel slows you down more than an extra pound
on the frame.

True, neither slows you down much at all, but the grossly
simplified adage is that a pound off the wheel would be
worth two off the frame. A hundred grams off either would be
even tinier.

Which would you rather have--five pounds added to the wheel
or five pounds to the frame and rider? The principle still
looks sound to me--under identical circumstances, the bike
with the extra weight added to the wheel is slower than the
bike with the extra weight added to the frame.

Carl Fogel

 

[David Damerell]

Terry Morse <[email protected]> wrote:
>Carl Fogel wrote:
>>Which one do you predict will be ahead after thirty seconds
>>from a standing start, the one with the weight tucked inside
>>the frame tube or the one with the weight tucked inside the
>>tire?
>As far as acceleration goes, the pound in the tire counts twice.

Not necessarily; although the bottom of the tyre deforms slightly, making
it possible that some proportion of the wheel has the same moment of
inertia as the theoretical wheel with all its mass at the very edge, if
your extra pound is added under the rim tape it will have a lesser moment
of inertia.
--
David Damerell <[email protected]> flcl?

 

[David L. Johnson]

On Mon, 02 Aug 2004 14:33:18 -0600, carlfogel wrote:

> On Mon, 02 Aug 2004 15:03:10 -0400, "David L. Johnson"
> <[email protected]> wrote:
>
>>On Mon, 02 Aug 2004 12:40:19 -0600, carlfogel wrote:
>>
>>> Lazy folk like me don't even have to go to the trouble of
>>> your fierce riding to demonstrate the fact that rotating
>>> weight suffers a penalty in acceleration.
>>>
>>> Just flip the bike upside down and work one pedal to spin
>>> the rear wheel up to speed. Some of the resistance is wind
>>> drag, but most of it is the inertia of the wheel--and none
>>> of the effort produces the slightest linear acceleration.
>>>
>>> The resistance is far from massive and occurs only during
>>> acceleration, but it's considerably more than ordinary
>>> rolling resistance.
>>
>>The very fact that you can spin the wheel up to a very high speed with one
>>stroke of one arm, as opposed to hard work with both legs, shows that the
>>weight difference cannot produce "considerably more" resistance.
>>
>>This has been talked to death here.
>
> Dear David,
>
> That's an impressive stroke of one arm that accelerates a
> rear wheel up to "a very high speed."

Not really. Put it in your top gear, give a good spin, and the wheel will
be going as fast as it would with you going 30mph or more.

>
> It is considerably more, as I wrote, than ordinary rolling
> resistance--perhaps you read that sentence a bit too quickly?

How are you determining that? Rolling resistance is mostly tire
flex, which does not occur with the bike upside down. Since the
difference in weight between a fancy wheel and a cheap one are on the
order of 100-200g, and not all of that at the rim, you are talking about
minimal differences in energy input.

--

David L. Johnson

__o | You will say Christ saith this and the apostles say this; but
_`\(,_ | what canst thou say? -- George Fox.
(_)/ (_) |

 

[WINGNUTT]

Whether or not a wheelset is worth it or not depends a lot more on your financial position than anything else. Very few people will earn money from slightly faster wheels, so it's really all about how much you want the wheels and how much the $700 means to you. I could tell you that it's not worth it because the performance difference isn't that great, but you probably shouldn't listen to me if I only have $300 per month in disposable income, and you have 10 times that. So as a financial investment, the wheels are not worth the money. If the (slight) added performance and looks are worth the money to you based on your financial position, then go for it. Don't listen to people who ask if you are a racer or what not - that doesn't make a piece of difference. Buy with your disposable income what gives you the most satisfaction for your dollar.

Technically speaking, aero wheels vs. regular spoked wheels will reduce total force on the rider by approx 2-3% on flat road. There are articles and wind tunnel tests out there and posts about this on www.cyclingforums.com. I don't know of any other single performance upgrade that makes this type of difference (other than the basics like clipless pedals etc.), so investing in an aero wheelset is a good upgrade comparatively speaking.