qualia8

I don't know where people are getting the wattage to accelerate. If you were going to accelerate from 30-40kph in 1 second, that would be a completely different number from accelerating in 10 seconds. It would be infinite wattage to accelerate from one velocity to another instantaneously and almost no additional wattage to accelerate gradually. Sprinterdellacasa probably makes *really* quick jumps, at the limits of his ability. So his rate of velocity change (acceleration) is faster than some old fart ambling up to cruising speed. Hence, it takes *more* watts for him to accelerate between the same two speeds, because he's doing it faster.

What would be really helpful is to take a Strava file and then calculate the difference in forces required for all of *those* accelerations, in *those* time frames. Short of that, talk about the wattage to go from one speed to another is meaningless.

Edit: ok, I just saw the third study, which kind of did this. It claimed a 1% reduction in force required during a 5 second acceleration. That doesn't reflect the fact that the acceleration happens only during a tiny portion of the pedal stroke, really, and therefore is more severe during those crucial sub-moments. He shouldn't average it over 5 seconds. But also, there's an error, and it should be 3%. 3% is a pretty big deal when you're on your limit. See this comment:

Tim Eckel · Owner at Dog BlockerIf this is about wheels, the calculations should be for spinning mass, not static. Which would make it 3% not 1%, and that green wedge would be 3 times as big. So, I'll take the light AND aero option as 3% less effort I'll take any day! Ride on!
Reply · · February 15, 2012 at 1:53pm

achoo

The power to accelerate a rolling wheel is easy to calculate. The kinetic energy of a rolling ideal hoop is

m * v ** 2

Mass times velocity squared.

Power is energy divided by time.

Calculate the energy at the speed before the acceleration. Calculate the energy at the speed after the acceleration. Take the difference. Divide by the amount of time the acceleration occurred.

Done.

If you use meters, kilograms, and seconds, the resulting value is in watts.

Oh, and since that's the kinetic energy of an ideal hoop with all its weight the same distance from the axis of rotation, a real-world wheel will take LESS energy to accelerate because it has a lot of mass near the axis of rotation so a real-world wheel has a lower moment of inertia than an ideal hoop of the same radius.

Siu Blue Wind

*comes in, looks around, sees everything is nice, goes to next thread*

3alarmer 

.
...is she gone ?

znomit

I don't think light wheels make sense in the 41. We're more likely to get spat out the back than make a break off the front... So deceleration hurts us more than acceleration helps us.
Heavy wheels FTW.

MrCharlie

This thread was so much better last night. Can we get the Major back? I want him brought back every morning so we can have fun getting him banned every evening.

WhyFi

Awww, I didn't even notice that he'd gotten banhammered - I didn't see it mentioned in the banned users thread.

achoo

That thread's always a great read.

Some of the sock puppet names mentioned make you wonder how that same species managed to put members on another celestial body?

"Huh?!?!? That guy is of the same biological species as one smart enough to travel to the moon and back? "

3alarmer 

OldsCOOL

****

Minion1

...

UnfilteredDregs

I saw that.

I can understand the ride quality angle but, for an accomplished rider in your area they'd be a performance asset...Horses for courses.

I like chocolate.

svtmike

I think I understand rpenman's position. He doesn't race, and doesn't group ride much anymore so relative speed really isn't important at all. The stiffness, crosswind handling, braking, weight, and cost penalties of carbon wheels just don't make any sense for his riding. His horses simply don't need deep carbon shoes.

BillyD

Where the hell did all you level-headed, reasonable people come from all of a sudden? Please stay. Can I get you anything? A beverage? Snack?

UnfilteredDregs

Agreed... I just can't grok the whole weight weenie non-aero approach in a mostly no hills, flat area, other than from a "just because" (and a legitimate ride feel..) angle. Considering how much from the engineering side Robert tends to present his rationales I find it puzzling in the the sense that it's not performance driven...but that's on me!

UnfilteredDregs

18 year old scotch? Enough of that and maybe I'll brag about something and get banned. lmao

BoSoxYacht

Robert and I seem to have the same preference in wheel builds, and somewhat similar terrain to ride nearby. The area of AZ I live in is mostly flat, but it's often quite breezey. Most rides are solo, but even on group rides, there's rarely a time that aero wheels would benefit me.

I use aero wheels when I'm TTing, but not on training rides or hillclimb events.

rpenmanparker 

You can't get anyone to stay for just a beverage. You have to offer at HOT beverage. It is a Texas thing.

Siu Blue Wind

Never.

Okay!

rpenmanparker 

Well I guess I should have made that clear. I absolutely accept the superiority of aero wheels on technical grounds for improved speed under just about any conditions. And a really light (like ENVE tubular) carbon wheel set likely can't be beat. Sorry if anyone got the idea I was denying that. But I really didn't enjoy the rather good 50 mm carbon wheels I built and was happy to get back to my Kinlin XR-200s. Thing is at 66 years old, after a full blown heart attack and with a hefty daily dose of beta blocker, I ain't going to be setting any land speed records. My flatland solo endurance PB speed used to be just over 20 mph for 50 miles. That is all in the past. I'm a good 10-15% off that now. So I might as well just be happy, and that is what the low profile aluminum wheels do for me. I would never pooh pooh a competitive rider opting for deep carbon however.

BoSoxYacht

The funny thing about Major Frisbee is that the photos he posted of his bike has Zipp wheels, not the Enve ones he claimed to have.

MrCharlie

Those were being built. Don't worry, I'm an expert on the illustrious Major.

UnfilteredDregs

Aha...Perfectly sensible in context...I keep thinking I'm not fast enough, others have said otherwise but I continue to believe they're drinking the aero Kool-aid as well...

I'm more interested in carbon in terms of lightening up my wheels, I do hear they're more responsive when you get up on it, and if a not quite deep profile gives me some aero benefit I may go further with it down the line when I build up a dedicated road bike. I have a hard time rationalizing $3k for wheels though...

My other criteria limits my choices as well...tubeless ready & disc brake.

BoSoxYacht

Thanks.

BoSoxYacht

look into Stan's wheels. You could have lightweight disk wheels for much less than $3k. They would not be aero, but they would be everything else, for much less$$$