what makes a light bike really light?

[Doug Taylor]

On 1 Mar 2006 13:24:36 -0800, "Mike Reed" <[email protected]>
wrote:

><sarcasm>
>It's pretty cool that people can win 24 hour races on toys, huh?
></sarcasm>

Dude, please identify the animal who WON a 24 hour race on a SS? IIRC,
there might be ONE guy.

99.9% of the time they race in their own division vs. other SS's

>I suppose that they have front suspension

Ya think? Maybe a slight difference between a rigid and front
suspended bike, gears notwithstanding? And I believe I mentioned my
"toy" is fully rigid?

>, but gears and rear
>suspension are /not/ a clear advantage off road. It really depends on
>the course. Here in Austin, I think everyone would be faster on an SS
>with front suspension. When I was in Colorado, I doubt that would be
>the case...

>I have a friend who rides rigid SS exclusively. I joined him for a ride
>on my geared front-supsension Stumpjumper. I couldn't quite keep up
>with him on some moderately technical short-climb 2-hour rides. It was
>close, but he'd always gain time on me. So I revived my old Bridgestone
>MB-3 as a SS, and brought it out to ride with him again. I was keeping
>up with him everywhere, and dropping him on some climbs (as expected --
>I'm in slightly better condition).
>
>I would have never believed that I'd be faster on an SS.

What a man! But remember the sports proverb, grasshopper:

"The quality of the performance is inversely proportional to the
quantity of its self promotion." So be careful.

Surely, bottom line for racing is that it is the motor, not the
machine, so there might be a very few genetically mutated physical
specimens who can beat others even though they have inferior
equipment.

A fully rigid single speed in the VAST majority of conditions is
inferior equipment to either a front suspended hardtail and/or a
dually. How may pros race a rigid single speed given a choice of
equipment? In fact, a pro will chose between a hardtail and a dualie
depending on conditions, realizing that there are conditions where the
weight penalty of the dualie is compensated by its efficiency.

Anyway, my point remains that technological advances in sports
equipment are not per se bad, though there will always be poseurs who
abuse them, on one extreme, and retrogrouches who denigrate them on
the other. The folks in the middle get it.

 

[Vee]

Doug Taylor wrote:

> A fully rigid single speed in the VAST majority of conditions is
> inferior equipment to either a front suspended hardtail and/or a
> dually.

On three of the six trails I regularly ride here in Wisconsin, I'm
faster on my rigid singlespeed than on my hardtail or former full
suspension bike. Unless the terrain is choppy, rigid bikes handle
better because the front end is lighter, lower, and doesn't dive or do
other wierd things.

Of course most race courses are faster on squishy geared bikes.
Sustained climbs and flats reward gears, and race courses are often
choppy from yahoos who skid all the time, so you suspension helps. But
for rolling, technical trails, suspension and gears mostly just get in
the way.

-Vee

 

[[email protected]]

ok, interesting answers to my original question...I would tend to
think, if the rider is in top shape, no matter what he rides, he can be
as competitive as the chump with the $18000 carbon fiber Ferrari
Edition bike outfitted with whatever is the latest parts...it would be
cool to see someone win a major race on an old classic steel frame
alongside other racers using the newer exotic metals/carbon bikes with
all the latest hi tech parts....but if you had to drop weight anywhere
on the bike and wanted to upgrade 1 part, I would go with the wheels.
The drivetrain, steering components, and seat components can pretty
much stay as is (meaning don't spend a lot of $$$$ getting the carbon
fiber/exotic metal parts to replace the current parts) I see a lot of
people wanting to get into riding, right around the Tour De France and
ever since Lance has been wining race after race, they go out and spend
major $$$ only to get disillusioned with riding and the price they paid
and sell it up on ebay and give the whole thing up....because mostly
they are not in shape and believe in the myth, money buys the best
equipment which will make me into a better rider.....I did in fact
upgrade my wheels, going from aero clincher Fir 28 spoke rims(which if
anyone wants them for cheap $$$, let me know) to regular clincher Mavic
Cosmos 28 spoke rims and I do find I can accelerate the bike quicker.
Those aero rims just felt like dead weight, and I'm a pretty atheltic
guy, I like to get out of the saddle and man handle my bike, so to
speak, rocking it back and forth and thrashing down on my cranks to get
a good acceleration going. But I wouldn't trade up on a stock Campy
aluminum seatpost for a tricked out carbon fiber seatpost, or give up
my Campy aluminum steel drivetrain for the latest carbon/titanium
drivetrain, unless of course i got that stuff for free but a pair
of nice light wheels, I think that would be a worthwhile upgrade.
Thanks for the responses.

 

[Mike Reed]

Doug Taylor wrote:
> Dude, please identify the animal who WON a 24 hour race on a SS? IIRC,
> there might be ONE guy.

Yeah, there was that solo guy I heard about from 2005, I think, but
with a quick Google, I came up with these guys:

"4J's from Hayes" on page 16 was all single speed in a normal division
of 24 Hours of 9 mile in 2003
http://www.teamsportsinc.com/249//results/03results/24hr_results03.pdf

One team member's description is here (search for "RedRider"):
http://www.singlespeedoutlaw.com/issue3/features.shtml

Since then, they've had SS divisions, as have most races.

> >I would have never believed that I'd be faster on an SS.
>
> What a man! But remember the sports proverb, grasshopper:
>
> "The quality of the performance is inversely proportional to the
> quantity of its self promotion." So be careful.

Hey, I said I was faster than myself using this other guy as the
benchmark. I didn't say I was the fastest in the world or anything. I
also didn't lay any claim to how much I'd leave you bleeding out of
your eyes from lack of oxygen

> Surely, bottom line for racing is that it is the motor, not the
> machine, so there might be a very few genetically mutated physical
> specimens who can beat others even though they have inferior
> equipment.

I've known three people who are significantly faster on single speeds
than they are on geared. I'll agree it's not for everyone, but on the
right terrain (short climbs), SS is tough to beat.

> A fully rigid single speed in the VAST majority of conditions is
> inferior equipment to either a front suspended hardtail and/or a
> dually.

Duh. Come to Austin on a front suspended geared bike and a front
suspended SS and ride some trails. You'll be as surprised as I was
(though I don't have susp. forks on my SS yet).

I'm not saying that SS is the answer to every meter of dirt trail in
the world, but calling them toys compared to FS geared rigs is
ignorant. If anything's a toy, it's the one with all the goofy parts
hanging off it.

> How may pros race a rigid single speed given a choice of
> equipment?

How many pros are given a choice in equipment? How many of them are
such tech freaks like that they would never give an SS a chance? There
are moderately technical trails where gears and FS get in the way.

> In fact, a pro will chose between a hardtail and a dualie
> depending on conditions, realizing that there are conditions where the
> weight penalty of the dualie is compensated by its efficiency.

Absolutely, which makes my point that FS isn't clearly better except in
certain terrain.

> Anyway, my point remains that technological advances in sports
> equipment are not per se bad, though there will always be poseurs who
> abuse them, on one extreme, and retrogrouches who denigrate them on
> the other. The folks in the middle get it.

Exactly. Oh, and aren't all bikes toys?

 

[Qui si parla Campagnolo]

[email protected] wrote:
> Ozark Bicycle wrote:
> > Qui si parla Campagnolo wrote:
> > > D'ohBoy wrote:
> > > > Quoth QSP:
> > > >
> > > > > ok, and?...........
> > > >
> > > > Not to wax pedantic, but you had made the following double
> > > > condemnation/generalization of/about US sports enthusiasts:
> > > >
> > > > > > Not trying to be personal, PK, but the vast majority of american
> > > > > > cyclists, including me, could afford to lose some portion of or an
> > > > > > entire BW(bike weight, equaling 20 pounds).
> > > >
> > > > > > BUT americans don't train and ride lots, that is hard. They look to buy
> > > > > > equipment to make them better. Whether it be cycling, golf, tennis,
> > > > > > etc.
> > > >
> > > > I just wanted to clarify that despite my personal (1e-10)*(3,584,000
> > > > gm) bulk and my enjoyment of high quality, low weight "go-fast" bikes,
> > > > I didn't fit into you category of not training or riding a lot and
> > > > shopping for equipment that will make me better.
> > > >
> > > > I train and ride a lot and enjoy mucking about with bikes and I could
> > > > stand to lose at least 10% of my body weight. But I know that the
> > > > difference between my 21 lb Schwinn SuperSport and my 16 lb Fuji is
> > > > probably manifests almost completely in how much I enjoy riding each of
> > > > the bikes.
> > > >
> > > > So there ;-)
> > > >
> > > > D'ohBoy
> > >
> > > Ok, but why do you like the Fuji? The weight alone? I enjoy my 20 pound
> > > Merckx and Mondoncio, very high end, very high quality, just 4 pounds
> > > heavier than your Fuji.
> >
> > "Just 4 pounds heavier"? Just??? Do you know that 4 pounds is *over
> > 1800 grams*!?! What are you, a #%&*$% retrogrouch??
> >
> > Or just a realist? ;-)
> >
> >
> > > But I love to ride them and would not ever
> > > consider a carbon anything, bicycle wise. It's like Subarus and Audis
> > > here in the republic.
> >
> > Yep, bicycles that are popped out of a mold; totally lacking in "soul".
> > And they ride as dead as they look.
>
> "Soul"? "Ride as dead"? I see you are a fan of the bicycle factory
> marketing department. Will your next pronouncement be that "aluminum
> will beat you to death"? Or a frame is "stiff but comfortable"? Or
> "light but solid"? Or "lively but stable"?

Guys in some bike shops, like ours, are lucky to see and ride just
about everything. I have ridden Madones, C-50s, C-35s, frames from
Specialized, Orbea, Gios, DeRosa, Giant, geezzz, just about everything,
with every component group and wheelset you care to imagine, and I'm
very very happy with my rides. A Moots fixie, a Mondonico and a merckx
MXLeader. As a bike shop owner, I can own anything i want,
anything....I chose the bikes I mentioned for their....soul, I guess.

 

[David Damerell]

Quoting Paul Hobson <[email protected]>:
>David Damerell wrote:
>>Quoting Paul Hobson <[email protected]>:
>>>I can't quantify this, but my beater (Reynolds 531) has horribly heavy
>>>rims. My nicer bike (Columbus tubing from '87) has Velocity Aeroheads
>>>that are incredibly light (to me). The difference is amazing in both
>>>the heft of the whole bike and how easily it accelerates uphill.
>>Erm, generally when you come to a hill you decelerate.
>Not if you mount your bike on a pretty decent hill (like I do everyday).

Ahhh, so these light rims get you an advantage once a day. Very important.

>>If this wasn't
>>just placebo effect you should perceive the beater as being better
>>initially uphill.
>see first response. lighter rims are easier to move. period.

Well, no, that's not true. If there's any significant effect at all, a
bicycle with heavier rims will be nicer initially as the road goes uphill
from a flat section.

>>Or, gee, maybe the beater has some _other_
>>characteristic that makes it slower?
>Gee, I wonder why I called one bike a beater and the other my "nicer"
>bike. hmmm.

So actually the observed effect may be nothing to do with the wheels at
all.
--
David Damerell <[email protected]> Kill the tomato!
Today is Oneiros, March.

 

[Doug Taylor]

On 1 Mar 2006 19:14:12 -0800, "Mike Reed" <[email protected]>
wrote:

>Exactly. Oh, and aren't all bikes toys?

Indeed.

And I'm going to step up to the plate, bare my breast, and ADMIT that
I spend a fair amount of money for my toys, have a shitload of bling
bling stuff, and spend $$$ on carbon and titanium and other such stuff
to keep the bikes light and efficient, but not stupid light, and not
ostentatious expensive.

I'm not a some rich dude who goes out and buys a Look or Eddie Merckx
or Colnago or Serotta top of the line all carbon 15 lb. $6000
machine, which would be over my head as well as my budget.

But like many of the basement geeks in this n.g., I like playing with
the toys, actually use them constantly, appreciate good craftsmanship
and quality, and will pay for it, to a point. I build my own stuff,
except wheels :-( , and am up to a blue star on e-bay, where you can
buy new components for way below retail. Great way to go all Dura Ace
(XTR) on and Ultegra (XT) budget!

The SS mountain bike is a Ted Wojcik steel frame with horizontal
drops, rigid titanium forks, FSA carbon crank, Spot 32 tooth ring, ACS
17 tooth freewheel, XTR v-brakes, Phil Wood hubs. Why? Why not?

My recent road build started with a budget frame: IRD Scandium with
IRD all carbon forks bought from IRD, 2.55 lbs for less than $900.
Everything else bought on ebay, except for cables, housing, chain, and
bar tape. For less that $3000, I have a 17 lb bike with Dura Ace
drive train, FSA Mega Exo compact cranks and American Classic Sprint
350 wheels. Why? Why not?

To go back to the original question, a what makes a bike really light,
starts with the frame and fork, moves to the wheels, then the crank,
then everything else. You can spend more than what most people spend
on an entire bike, maybe two, just on a full carbon frame or fork (or
a Titanium Litespeed Ghisallo) that weigh less than 2 lbs.

Now most cyclists don't "need" stupid light, and certainly don't have
the mega big bucks necessary to buy. On the other hand, it is not a
sin to appreciate and pay for nice, pretty, efficient, fun, workable,
mechanically sound toys, that don't strain your back to get them on
your roof rack, and either psychologically or physically climb better.
Plus, after making an ample investment, guilt will make you lose
weight and live up to your bike

 

[Qui si parla Campagnolo]

Doug Taylor wrote:
> On 1 Mar 2006 19:14:12 -0800, "Mike Reed" <[email protected]>
> wrote:
>
> >Exactly. Oh, and aren't all bikes toys?
>
> Indeed.
>
> And I'm going to step up to the plate, bare my breast, and ADMIT that
> I spend a fair amount of money for my toys, have a shitload of bling
> bling stuff, and spend $$$ on carbon and titanium and other such stuff
> to keep the bikes light and efficient, but not stupid light, and not
> ostentatious expensive.
>
> I'm not a some rich dude who goes out and buys a Look or Eddie Merckx
> or Colnago or Serotta top of the line all carbon 15 lb. $6000
> machine, which would be over my head as well as my budget.


Top of the line Colnago, Serotta or Merckx a complete bike would be
more than $6000. A Serotta ott-rott frame is $5000, the carbon thing is
$7000, for the frame.
>
> But like many of the basement geeks in this n.g., I like playing with
> the toys, actually use them constantly, appreciate good craftsmanship
> and quality, and will pay for it, to a point. I build my own stuff,
> except wheels :-( , and am up to a blue star on e-bay, where you can
> buy new components for way below retail. Great way to go all Dura Ace
> (XTR) on and Ultegra (XT) budget!
>
> The SS mountain bike is a Ted Wojcik steel frame with horizontal
> drops, rigid titanium forks, FSA carbon crank, Spot 32 tooth ring, ACS
> 17 tooth freewheel, XTR v-brakes, Phil Wood hubs. Why? Why not?
>
> My recent road build started with a budget frame: IRD Scandium with
> IRD all carbon forks bought from IRD, 2.55 lbs for less than $900.
> Everything else bought on ebay, except for cables, housing, chain, and
> bar tape. For less that $3000, I have a 17 lb bike with Dura Ace
> drive train, FSA Mega Exo compact cranks and American Classic Sprint
> 350 wheels. Why? Why not?
>
> To go back to the original question, a what makes a bike really light,
> starts with the frame and fork, moves to the wheels, then the crank,
> then everything else. You can spend more than what most people spend
> on an entire bike, maybe two, just on a full carbon frame or fork (or
> a Titanium Litespeed Ghisallo) that weigh less than 2 lbs.
>
> Now most cyclists don't "need" stupid light, and certainly don't have
> the mega big bucks necessary to buy. On the other hand, it is not a
> sin to appreciate and pay for nice, pretty, efficient, fun, workable,
> mechanically sound toys, that don't strain your back to get them on
> your roof rack, and either psychologically or physically climb better.
> Plus, after making an ample investment, guilt will make you lose
> weight and live up to your bike

Now that is true-if it makes ya ride more, then any amount of $ is
worth it. The object is to ride, not buy.

 

[D'ohBoy]

<snip defense of personal choice>

Peter -

You don't have to defend your bike preference to me. As I shouldn't
to anyone else.

That said, I'd bet that you would perform poorly in the blindfold test
just as others have.

D'ohBoy

 

[(PeteCresswell)]

Per Qui si parla Campagnolo:
>Now that is true-if it makes ya ride more, then any amount of $ is
>worth it. The object is to ride, not buy.

I can't help making a comparison with windsurfing.

In the beginning, we all had 12-foot, 40-pound polyethylene boards with bag
sails that had very little wind range.

We all had fun.


Now most of us have 15-19 pound carbon-over-styrofoam boards less than 9 feet
long with ultra-high-tech sails that have amazing wind range.

We all have fun.


My feeling is that if somehow all this new techie stuff were taken away and we
all had to go back to the 40-pound poly pig boards that, after a certain period
of being unhappy, we'd all go back to having about the same amount of fun.

--
PeteCresswell

 

[Mike Reed]

Qui si parla Campagnolo wrote:
> I chose the bikes I mentioned for their....soul, I guess.

Amen.

You can have my Ritchey Road Logic when you pry it from my cold,
dead... ummm... plastic cleats. It's my only road bike. It's mostly
about soul, but I keep up with the ubiquitous Madones just fine,
depending on the rider...

-Mike

 

[Leo Lichtman]

"David Damerell" wrote: So actually the observed effect may be nothing to
do with the wheels at all.
^^^^^^^^^^^^^^^^^^^^
A slight effect. If you attach a fifty lb weight to your rack, it will have
a considerably greater effect for a few feet, but then...

 

[Paul Hobson]

David Damerell vs Paul Hobson:

>>> PH offered this disclaimer followed by a personal anecdote:
>>>>I can't quantify this, but my beater (Reynolds 531) has horribly heavy
>>>>rims. My nicer bike (Columbus tubing from '87) has Velocity Aeroheads
>>>>that are incredibly light (to me). The difference is amazing in both
>>>>the heft of the whole bike and how easily it accelerates uphill.

>> DD observed the obvious:
>>>Erm, generally when you come to a hill you decelerate.

> PH presents a situation where one *must* accelerate up hill
>>Not if you mount your bike on a pretty decent hill (like I do everyday).

DD Thinks that's the only time it /ever/ happens:
> Ahhh, so these light rims get you an advantage once a day. Very important.

So PH says:
No no no. I ride fixies, so in order to maintain some semblance of a
decent cadence, I have to keep going fast. Since the hills around
Atlanta aren't just 5 ft long, there are many locations on several
routes that I regularly take where I have to accelerate up hills. Maybe
this is something _you_ don't/can't do, but it is possible.
Additionally, to even maintain speed, I have to fight against gravity.
Heavier wheels have greater inertia, therefore require a tougher fight.
Also note: the rims I'm comparing are spanking new Velocity Aeroheads
and old old old Vuelta Typhoons. The latter are significantly more
massive than the former.

>>DD:
>>>If this wasn't
>>>just placebo effect you should perceive the beater as being better
>>>initially uphill.

> PH:
>>see first response. lighter rims are easier to move. period.

DD:
> Well, no, that's not true. If there's any significant effect at all, a
> bicycle with heavier rims will be nicer initially as the road goes uphill
> from a flat section.

Initially? So what? How is that important when the hills here are long
and sometimes quite steep? The first 50 ft of a climb is of no
significance when I'm going north on Peachtree St. with a 1.5 mile
gradual climb with *several* stops along the way. I repeat: Heavier
rims are harder to accelerate. You seem to recognize this, but don't
understand the consequences.

>>DD's sarcasm:
>>>Or, gee, maybe the beater has some _other_
>>>characteristic that makes it slower?

> PH's sarcasm:
>>Gee, I wonder why I called one bike a beater and the other my "nicer"
>>bike. hmmm.

DD:
> So actually the observed effect may be nothing to do with the wheels at
> all.

No it does. You're completely ignoring the crux of my argument. The
funny thing is, we don't disagree -- you're just not paying attention.

All this is consistent with me saying that I can stop the light rims by
back pressure way faster than the heavy rims. That should be fairly
independent of the bb's, cranks (assuming reasonable stiffness), etc.
Most of that effort is directly resisting the rotation of the wheels.
If anything, a poorly packed bb would help me slow down, but it doesn't
overcome the heaviness of the rims IME.

You say:
Heavy rims present an advantage while climbing because they carry
momentum up the hill.

You don't realize:
That means that they are harder to accelerate (because of the increased
inertia).

I say:
Since I often accelerate up hills and use back pressure to maintain a
controllable speed & *stop* going down, heavier rims do not present an
advantage. Instead, I go *much* faster on my light rims. I'm also
willing to wager that even on a freewheeled bike, the *initial*
advantages of maintaining the momentum of overly heavy rims when
starting a significant climb are *easily* negated by the longer term
disadvantages.

\\paul
--
Paul M. Hobson
Georgia Institute of Technology
..:change the f to ph to reply:.

 

[Ron Ruff]

Doug Taylor wrote:
> For less that $3000, I have a 17 lb bike with Dura Ace
> drive train, FSA Mega Exo compact cranks and American Classic Sprint
> 350 wheels. Why? Why not?

Nice bike... but I'm surprised it is so heavy...
http://bikesdirect.com/
Are they lying about the 15lbs? I thought about buying one of these and
parting it out on ebay... but after investigating, I realized I'd only
be able to get about what the thing cost...

 

[Ron Ruff]

Paul Hobson wrote:
> I go *much* faster on my light rims.

Assuming that your light rim and tires are 1 lb lighter (a lot), how
much faster do you suppose you go?

The effect on your momentum will only be 2lb/ whatever you weigh... or
roughly 1%. As far as going faster is concerned, on steep climbs it
will be a 0.5% effect. Everywhere else the benefit is less than 0.1%.
Is that "much" faster?

On a steep climb the low inertia is actually a small detriment
(compared to a bike with the same total weight but heavier rims) since
heavy rims reduce the variations in speed within each pedal stroke.

 

[Doug Taylor]

On 2 Mar 2006 13:17:58 -0800, "Ron Ruff" <[email protected]> wrote:

>
>Doug Taylor wrote:
>> For less that $3000, I have a 17 lb bike with Dura Ace
>> drive train, FSA Mega Exo compact cranks and American Classic Sprint
>> 350 wheels. Why? Why not?
>
>Nice bike... but I'm surprised it is so heavy...
>http://bikesdirect.com/
>Are they lying about the 15lbs? I thought about buying one of these and
>parting it out on ebay... but after investigating, I realized I'd only
>be able to get about what the thing cost...

I have a Bridge in Brooklyn for sale if you're interested... Of
course they're lying.

I don't believe it is possible to build a 15 lb bike without a frame
that costs $3,000 - $5,000 - or more - frame only, weighing less than
2 lbs. Then all carbon fork around $400, boutique wheels in the $1000
range, all Dura Ace or Campy Record, etc. etc.

Do the math.

The IRD frame is about 2.5 lbs, with carbon fork a tad over 3 lbs. You
build from there and then weigh it on your own scale: 17 +/- with all
chi chi parts. No corners cut.

C'est la vie. But who needs a 15 lb bike for a minimum $6,000.00?:

http://www.smartcycles.com/bike_weight.htm

 

[A Muzi]

>>Doug Taylor wrote:
>>>For less that $3000, I have a 17 lb bike with Dura Ace
>>>drive train, FSA Mega Exo compact cranks and American Classic Sprint
>>>350 wheels. Why? Why not?

> On 2 Mar 2006 13:17:58 -0800, "Ron Ruff" <[email protected]> wrote:
>>Nice bike... but I'm surprised it is so heavy...
>>http://bikesdirect.com/
>>Are they lying about the 15lbs? I thought about buying one of these and
>>parting it out on ebay... but after investigating, I realized I'd only
>>be able to get about what the thing cost...

Doug Taylor wrote:
> I have a Bridge in Brooklyn for sale if you're interested... Of
> course they're lying.
> I don't believe it is possible to build a 15 lb bike without a frame
> that costs $3,000 - $5,000 - or more - frame only, weighing less than
> 2 lbs. Then all carbon fork around $400, boutique wheels in the $1000
> range, all Dura Ace or Campy Record, etc. etc.
> Do the math.
> The IRD frame is about 2.5 lbs, with carbon fork a tad over 3 lbs. You
> build from there and then weigh it on your own scale: 17 +/- with all
> chi chi parts. No corners cut.
> C'est la vie. But who needs a 15 lb bike for a minimum $6,000.00?:
>
> http://www.smartcycles.com/bike_weight.htm

We built two 15 pound bikes last year, both Kestrels, over $6k.
Evoke SL $2800 frame, Record Carbon, with vintage 250g rims.

Talon SL $2200 frame, Record Carbon, Zipp wheels. To get to
15 you need to watch every piece. An uncomfortably slim
saddle, no computer, carbon bars, etc.


--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[D'ohBoy]

Andy wrote:

> To get to 15 [lbs] you need to watch every piece. An uncomfortably slim
> saddle, no computer, carbon bars ...

Which carbon bar? All the ones I have seen (Easton, FSA) weigh as much
or more than a triple butted aluminum one.

Just wondering,

D'ohBoy

 

[David Damerell]

Quoting Paul Hobson <[email protected]>:
>David Damerell vs Paul Hobson:
>>PH presents a situation where one *must* accelerate up hill
>>>Not if you mount your bike on a pretty decent hill (like I do everyday).
>DDThinks that's the only time it /ever/ happens:
>>Ahhh, so these light rims get you an advantage once a day. Very important.
>So PH says:
>No no no. I ride fixies, so in order to maintain some semblance of a
>decent cadence, I have to keep going fast. Since the hills around
>Atlanta aren't just 5 ft long, there are many locations on several
>routes that I regularly take where I have to accelerate up hills.

So under those circumstances the rim mass counts slightly less than twice
for the small portion of your power (once you are making any speed) that
goes for acceleration. It is easy to see that we're talking small
percentages here; if you perceive large percentages, that should tell you
immediately that your perceptions are misleading you. Except you're going
to be one of those people who doesn't believe in elementary mechanics.

>Additionally, to even maintain speed, I have to fight against gravity.
>Heavier wheels have greater inertia, therefore require a tougher fight.

This is not particular to wheels and is a straight comparison of one mass
with another (and the mass of the bike+rider system, where we find that
you're talking about maybe a 2% difference).

>>>see first response. lighter rims are easier to move. period.
>>Well, no, that's not true. If there's any significant effect at all, a
>>bicycle with heavier rims will be nicer initially as the road goes uphill
>>from a flat section.
>Initially? So what?

So when you say that "lighter rims are easier to move. period." you are
wrong, because there is a circumstance in which heavier rims are easier to
move.

>All this is consistent with me saying that I can stop the light rims by
>back pressure way faster than the heavy rims.

That helps to illustrate how your perceptions are inaccurate. You can spin
a wheel, heavy or light, up to a good speed with one thrust of your arm.
That rotational momentum cannot be significant next to the much greater
force your legs can exert.
--
David Damerell <[email protected]> Kill the tomato!
Today is Mania, March.

 

[Paul Hobson]

David Damerell wrote:
> Quoting Paul Hobson <[email protected]>:
>
>>David Damerell vs Paul Hobson:
>>>Ahhh, so these light rims get you an advantage once a day. Very important.

>>So PH says:
>>No no no. I ride fixies, so in order to maintain some semblance of a
>>decent cadence, I have to keep going fast. Since the hills around
>>Atlanta aren't just 5 ft long, there are many locations on several
>>routes that I regularly take where I have to accelerate up hills.

> Except you're going
> to be one of those people who doesn't believe in elementary mechanics.

Right that's clearly the case. </sarcasm> The hardest number that I
can give you are as follows (bear in mind that I run lights whenever I
can). Here's the mostly uphill route in question:
http://tinyurl.com/qqkcs

It's about 6 miles. The fastest I've ever gotten there on the slow bike
is about 27 mins (vs. 45 in car<g>). On the fast bike, I've gotten
there in 22 and 24 mins the past two times.

>>Additionally, to even maintain speed, I have to fight against gravity.
>>Heavier wheels have greater inertia, therefore require a tougher fight.

> This is not particular to wheels and is a straight comparison of one mass
> with another (and the mass of the bike+rider system, where we find that
> you're talking about maybe a 2% difference).

Wheels or not, the point (my point) stands. I go faster on my lighter
rims. You say 2%, but keep in mind I only weigh between 125 and 130
lbs. So that percentage is slightly higher than the average 165 - 185
American male.

>>>>see first response. lighter rims are easier to move. period.

>>>Well, no, that's not true. If there's any significant effect at all, a
>>>bicycle with heavier rims will be nicer initially as the road goes uphill
>>>from a flat section.

>>Initially? So what?

> So when you say that "lighter rims are easier to move. period." you are
> wrong, because there is a circumstance in which heavier rims are easier to
> move.

Such as? If you going to say maintaining speed on level ground, that
what I was ever discussing. I think you're the one ignoring elementary
mechanics.

>>All this is consistent with me saying that I can stop the light rims by
>>back pressure way faster than the heavy rims.

> That helps to illustrate how your perceptions are inaccurate. You can spin
> a wheel, heavy or light, up to a good speed with one thrust of your arm.
> That rotational momentum cannot be significant next to the much greater
> force your legs can exert.

Perceptions inaccurate? I don't think stopping distance of 50 ft vs. 75
ft is insignicant? I don't think you've ever tried to stop a fixie
without your brakes while spinning at a high cadence in a decently sized
gear.

--
Paul M. Hobson
Georgia Institute of Technology
..:change the f to ph to reply:.