Pirelli Sport Demons

[GeorgiaHooligan]

I got my money out of the k630's. Rears so thin and bald , you can almost poke your finger through it.

[Snake]

Originally Posted by GeorgiaHooligan

Cool, just realized there are previous threads on this subject. Pretty sure Im going with the demons.

You can't go wrong with Pirelli Sport Demons.

[greg737]

In the interest of "full disclosure" the following is a public service announcement:

The Sport Demon is a 130/90 16 tire and is larger than the recommended EX-250 tire (which was originally sold with 120/80 and later with a 130/80).

The weight of a larger tire (in this case the Demon) affects a vehicle (motorcycle) in several ways: Unsprung weight, Rotational weight, Total weight, and (unrelated to weight) Overall gearing.

First is "unsprung" weight, which affects suspension performance and is the most complex issue. With no other changes to suspension geometry and damping, more unsprung wieght will negatively affect the suspension's "bump following" ability because the increased mass has more inertia. This is why the designers of racing cars and motorcycles strive for lightness in suspension parts, wheels and tires. A good example of the complexity of this situation is to note the effect of unsprung weight in the interrelations between tires (their weight and bump absorbing ability) and the mass (weight) of the other suspension parts (in total), because it actually creates a "suspension-within-a-suspension" phenomena. This applies to the heavier Sport Demon rear tire because it's extra weight won't accelerate as quickly because of it's greater mass (more mass equals more inertia), but this larger diameter tire itself may have more bump-absorbing ability than the original equipment sized tire, so it's very hard to say what the overall effect it will have on the bike's feel.

Second is "rotating mass" which is easier to understand than unsprung weight because it is simple to see that "more is bad." Any weight added to the bike obviously means less performance, but weight added to any rotating part of the drivetrain not only has to be carried along for the ride, it also has to be accelerated by the engine (i.e. rotated as a means of power transfer) which uses horsepower that could otherwise (in the absense of the extra added rotational weight of the larger Sport Demon rear tire) have been put toward accelerating the vehicle (your EX-250).

Third, which I've already mentioned, is "total vehicle weight." The Sport Demon rear weighs more because it's a larger tire, so it adds to the bike's all-up weight. For any given horsepower, more weight equals less acceleration (damn the inertia, Sir Issac Newton sux! or, did you buy special inertia-free Sport Demons?).

And Forth, an effect unrelated to weight, is that the larger diameter of the Sport Demon affects the overall gearing of the bike's drivetrain. So assuming the bike's horsepower is the same as it was with the old (smaller diameter) tires, the resulting longer gearing will cause slower acceleration. It's the same as changing to a larger front or rear sprocket which lowers RPM at any cruising speed but reduces the bikes ability to accelerate.

[sombo]

Just so you know, all that typing was not really needed. The additional weight it adds is so minimal you won't notice anything on acceleration. What you will notice is a better feel to the road and possibly a reduction from 10% incorrect speedo to about 5% incorrect (at least that's what I noticed when checking against radars). Acceleration wise however, there was no noticeable drop of any kind.

[greg737]

Just so you know, all that typing was not really needed.

It was cut-and-paste from a two year old post.... "just so you know" it took 30 seconds.

The additional weight it adds is so minimal you won't notice anything on acceleration.

Can this "magical thinking" be applied to all weight related issues? Do unicorns eat rainbows and poop butterflys in Orlando?

Acceleration wise however, there was no noticeable drop of any kind.

Okay, but only because you say so.


...and I forgot to include in my post that a heavier tire has more gyroscopic effect, which makes turning more difficult so the bike feels less "flickable" (unless Sombo says it doesn't).


(this is my usual response to anything that starts with "just so you know")

[Alex]

Without measuring the weight differences of the tires, it's hard to say what, if any, the effect would be. Pirelli's are often quite light, and assuming that they weigh significantly more, or even more at all, compared to a 130/80 Dunlop, may turn out to be much ado about nothing. I agree that they are taller, and do affect the gearing ratio, similar to adding a tooth on the front sprocket.

[greg737]

Here are a couple of Amazon.com sales pages. They give the item weight about midway down the page.

http://www.amazon.com/Pirelli-Sport-.../dp/B000GROYZO

http://www.amazon.com/Pirelli-Diablo.../dp/B000IOL61A

Just using the Diablo Scooter 130/80 16 as a comparison example.

The Diablo Scooter 130/80 16 is 11.5 pounds and the Sport Demon 130/90 16 is 14.9 pounds.

That's about 29% more weight.

What's the officially accepted percentage threshold for graduating from "much ado about nothing" to "significant"?

[Alex]

If those weights are accurate, it's a measurable difference. But it still won't affect performance a whit. Those tires are still mounted on identical wheels, which weigh another 20 pounds or so, making the difference 31.5 pounds to 34.9 pounds, a 9% difference in wheel + tire weight. And it's still only a nit compared to the 350 pounds + rider weight of the entire vehicle.

Nothing wrong with choosing the lighter (and more modern) tires, the scooter's are likely a great tire. But choosing the Demons is by no means a performance downgrade due to small weight differences.

[dulplay]

Got mine from motorcyclesuperstore.com last week... quoted $140 at the dealer, and $100 at the local Hyosung dealer to mount/balance... Yowza!!! Almost 12K on the stock Dunlops though!

[greg737]

which weigh another 20 pounds or so, making the difference 31.5 pounds to 34.9 pounds, a 9% difference in wheel + tire weight.

I can't think of any other place on a motorcycle where adding extra weight could make more of a difference (rotating mass, gyroscopic force, unsprung weight) than on the outside of the rear tire+wheel. Like a child on a merry-go-round, being at the outside/perimeter of the motion definitely makes a difference.

Yes, when it's sitting still its just 3.4 pounds. I don't have the physics/mathematics skills (skilz?) to figure out what the effect of 3.4 extra pounds going round-and-round really fast are, but I'm thinking that the energy required to accelerate, decelerate, and overcome the centrifugal force of those extra pounds is substantially more than "3.4 pounds" would suggest.

[Jiggles]

Originally Posted by greg737

I can't think of any other place on a motorcycle where adding extra weight could make more of a difference (rotating mass, gyroscopic force, unsprung weight) than on the outside of the rear tire+wheel. Like a child on a merry-go-round, being at the outside/perimeter of the motion definitely makes a difference.

Yes, when it's sitting still its just 3.4 pounds. I don't have the physics/mathematics skills (skilz?) to figure out what the effect of 3.4 extra pounds going round-and-round really fast are, but I'm thinking that the energy required to accelerate, decelerate, and overcome the centrifugal force of those extra pounds is substantially more than "3.4 pounds" would suggest.

How much slower do you think it would make the bike? Honestly, from 0-60 how much slower do you really think adding 3.4lbs to the tires would really make the bike? My guess is that it would not even be measurable outside of the margin of error. It is such an insignificant amount of weight; air pressure, temperature, and humidity are likely to have a greater effect.

[gfloyd2002]

Just to be clear for those who have joined this thread late or are pulled into oldgen tech forum due to recent merge, discussions of weight are centred around the switch to Sport Demons on the old gen, requiring a different tire size. On the a 2008+ bike, you can get the Sport Demons in precisely the stock sizes of 110/70/17 and 130/70/17. I'm aware of no weight differences on the new gen from moving to the Sport Demons from the stock IRCs, but am aware of major improvement in grip and overall performance.

[sombo]

Originally Posted by greg737

It was cut-and-paste from a two year old post.... "just so you know" it took 30 seconds.




Can this "magical thinking" be applied to all weight related issues? Do unicorns eat rainbows and poop butterflys in Orlando?




Okay, but only because you say so.


...and I forgot to include in my post that a heavier tire has more gyroscopic effect, which makes turning more difficult so the bike feels less "flickable" (unless Sombo says it doesn't).


(this is my usual response to anything that starts with "just so you know")

Was it really necessary to come off sounding like a _________? You are talking a difference in acceleration that would require measuring the tenths of a second to see. Yet you are acting like "OMG don't get the demons cause you will KILL your acceleration and make it a dog of a bike compared to using X tires!!!" Overreacting and being paranoid about maybe a couple tenths of a second difference is no reason to be snippy in your post or to not get what 99% of the rest of pre-gen riders feel are the best tires available for our bikes.

[greg737]

My original post to this thread (#83) if you bothered to read it, was purely informational. It contained none of the things you've accused me of (overreacting, hysteria, paranoia, etc.).

It simply pointed out something that is often overlooked by people when they're buying replacement tires for their EX-250s: Some tires weigh more.

Just bringing the undeniable physics of the situation to people's attention: more weight with the same horsepower means less performance.

I bother to point it out for two reasons: #1. It's true, and #2. It's often ignored/overlooked.

When it comes to the question of who came off sounding like an _______ first. You and I are quite likely from two totally different backgrounds and generations and upbringing. In the generation/background/upbringing you're from it may be okay to start a dialogue with the words "just so you know" but to my ears it sounds like you're being an ________. I guess you didn't realize it, but

Was it really necessary to come off sounding like a _________?

is exactly what I thought when I read your first post (#84) to this thread.

[GeorgiaHooligan]

My set of Demons have been Officialy orderd through Dennis Kirk. Got the set for $223.00 (thats including shipping)
wooohoooo!!!

[GeorgiaHooligan]

yeeeeeeeeeeeeeeeeeeeeeeeeha!

[sombo]

Well your reaction to "just so you know" is more of a personal issue than anything else. All people have little triggers that just set them. I wasn't being anything when I was trying to say you are over-analyzing this.

Sometimes the calculations and mathematics of physics are just not practical or necessary for normal everyday use. In this case we are talking about a factor that is negligible compared to the benefits. You roll in with a report explaining the science of something most won't ever notice in use. Therefore it just really isn't practical or needed.

If you were explaining this to a group of engineers or physicists to discuss the fractions of a second difference in performance of this tire vs that tire in a scientific or racing environment that would be different. But in this case that information is not really going to mean much to anyone for practical everyday purposes.

No one is really going to notice the difference in acceleration from the demons compared to the stock tires. They will however feel a difference in traction, grip, and cushion. These are things that are more of a concern for daily street use.

I don't know what generation/upbringing you are from, nor you I, so to bring that up is also not needed here. Saying that you personally get rubbed the wrong way by someone saying "just so you know" is better than getting snippy with them. Just so you know.

[greg737]

Sometimes the calculations and mathematics of physics are just not practical or necessary for normal everyday use.

Is there a particular time of the day/month/year when physics takes a holiday? Or do I just chant the magic words, "this is normal everyday use" and the physical laws know to look the other way for a while?

I wasn't being anything when I was trying to say you are over-analyzing this.

Textbook passive-aggressive: When somebody states facts you don't want to hear, accuse them of "over-analyzing."

They will however feel a difference in traction, grip, and cushion.

Can I have traction without grip? Or grip without traction?

And what's cushion? Yes, a bigger more balloon-like tire will absorb more bump at a given air pressure, but it's higher weight (more mass = more inertia) will cause it to work less efficiently with the suspension (It's called "unsprung weight" and keeping unsprung weight to a minimum is one of a vehicle engineer's main goals). So in the end the "cushion" factor may actually favor the slightly smaller but lighter tire that works better with the suspension design.

Sometimes the calculations and mathematics of physics are just not practical or necessary for normal everyday use. In this case we are talking about a factor that is negligible compared to the benefits. You roll in with a report explaining the science of something most won't ever notice in use. Therefore it just really isn't practical or needed.

If you were explaining this to a group of engineers or physicists to discuss the fractions of a second difference in performance of this tire vs that tire in a scientific or racing environment that would be different. But in this case that information is not really going to mean much to anyone for practical everyday purposes.

To sum up these two paragraphs: "People are stupid and have really short attention spans" and "if you add weight in small amounts you'll never notice."

The latter goes a long way to explaining the obesity epidemic (although it actually runs counter to the "goatee factor" because if guys aren't actually aware of their weight then how do they know exactly when to grow the full goatee that suggests, "I did this to my body on purpose"?)

[Alex]

Originally Posted by greg737

how do they know exactly when to grow the full goatee that suggests, "I did this to my body on purpose"?)

We set up automatic alerts in Outlook.

[sombo]

Originally Posted by greg737

Is there a particular time of the day/month/year when physics takes a holiday? Or do I just chant the magic words, "this is normal everyday use" and the physical laws know to look the other way for a while?

When the science behind something has no major affect on you daily activities from day to day then it's not practical or necessary to sit there and do the math over it. You don't need to go to a store with scientific measuring equipment to see the exact size, weight, balance of something and then do a multistage equation to figure out the exact fraction of a second it's going to change something. Do you sit there and do that with every single purchase or decision in your life? If so, then you are over-analyzing things. Just go out and live life.

Originally Posted by greg737

Textbook passive-aggressive: When somebody states facts you don't want to hear, accuse them of "over-analyzing."

That's not textbook passive-aggressive. It's being blunt, you're over-analyzing this, as in you're thinking too much about something so small.

Originally Posted by greg737

Can I have traction without grip? Or grip without traction?

Sorry if using such similar terms is confusing. Let me try to explain what I meant. In tires (especially motorcycle tires) you have to worry about how well they hold to the road under both straight line performance and in the corners. Believe it or not one tire can be better in the corners yet worse in the straights in terms of grip/traction as another tire. It comes down to a lot of different factors, but in the end, not all tires are made the same and for the same purposes.

Originally Posted by greg737

And what's cushion? Yes, a bigger more balloon-like tire will absorb more bump at a given air pressure, but it's higher weight (more mass = more inertia) will cause it to work less efficiently with the suspension (It's called "unsprung weight" and keeping unsprung weight to a minimum is one of a vehicle engineer's main goals). So in the end the "cushion" factor may actually favor the slightly smaller but lighter tire that works better with the suspension design.

There's more to cushion than just being larger. You also have to look at the shape, blend of rubber, the materials used to reinforce it and the style in which those layers are constructed. You can have a larger tire that's stiffer than a smaller because of the construction of the tire. Ever see all those reports of how the IIRC's feel like wood or rock and another tire of the exact same size feels so much better, softer, gives more, absorbs more, and makes better contact with the road because more of the tire surface is touching it?

Originally Posted by greg737

To sum up these two paragraphs: "People are stupid and have really short attention spans" and "if you add weight in small amounts you'll never notice."

The latter goes a long way to explaining the obesity epidemic (although it actually runs counter to the "goatee factor" because if guys aren't actually aware of their weight then how do they know exactly when to grow the full goatee that suggests, "I did this to my body on purpose"?)

This shows that you just have a really bad outlook on people and disdain those that don't analyze things as crucially as you do. How about you stop being passive-aggressive and calling anyone that doesn't think or act like you as stupid, lazy, and having short attention spans. Does calling a majority of the world (including most on this forum) those things make you feel better about yourself? If so, then that is textbook passive-aggressive.

[Jiggles]

Don't wear gear as the added weight and size is going to affect your acceleration. You should also shave off all body hair as it will catch the wind and slow you down. Also be sure to cut off all of those little rubber nipples on your tires as they add weight and catch wind.

[Alex]

[sombo]

Originally Posted by Jiggles

Don't wear gear as the added weight and size is going to affect your acceleration. You should also shave off all body hair as it will catch the wind and slow you down. Also be sure to cut off all of those little rubber nipples on your tires as they add weight and catch wind.

I love this response.


Yes alex, I know, I get it and I'm quite done for I have said all I need to say.

[greg737]

Yes alex, I know, I get it and I'm quite done for I have said all I need to say.

Let's test your resolve....

Sorry Alex, I just can't help myself when I hook into somebody who can best be described as "pseudo-right", who needs no actual facts to argue a position and can't or won't stay "on topic."

Nothing in the world is more dangerous than self imposed ignorance and conscientious stupidity.

[Jiggles]

Originally Posted by greg737

Let's test your resolve....

Sorry Alex, I just can't help myself when I hook into somebody who can best be described as "pseudo-right", who needs no actual facts to argue a position and can't or won't stay "on topic."

Nothing in the world is more dangerous than self imposed ignorance and conscientious stupidity.

[JLinde1339]

As amusing as I find this to have become, and I've laughed more than once reading through this, I'm going against the general consensus in saying that there is weight...errmm...merit to Greg's POV. If we were talking about a car, then the added weight of wider tires would amount to molehills. According to my title, my bike weighs 304 dry. I am now without front fairings and cowl, so without having the specs in front of me, I'm guessing that I may have dropped below 300. But whatever. The point is, that someone who is so concerned with performance down to the smallest degree would have to factor in the weight difference of any changes made outside the scope of the engineers' design. An inch of variance over a mile may be insignificant, but an inch per foot is a different story. Just my $.02....
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[Alex]

Originally Posted by JLinde1339

According to my title, my bike weighs 304 dry.

What do mean "title"? The GVWR is the weight rating that the bike can handle; not the actual weight of the bike itself. Pregen's are about 340 pounds without fuel. New-gens are about 370 pounds without fuel.

[JLinde1339]

Well, unless it was entered wrong 10 years ago, my title of ownership shows 304lbs. This number is retrieved from the certificate of origin issued by the factory. Just reporting what the DMV tells me. ;p
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[Alex]

Yeah, it's wrong.

The "dry weight" of motorcycles has been a joke for decades. Some manufacturers are being a bit more honest in their numbers recently (Honda is a good example), but that is not the norm. Your bike doesn't weight 304 pounds, sorry. (unless 30+ pounds of weight has been removed from it).

Some folks believe that the old dry weight numbers came from the manufacturers adding up the nominal weight of each and every part that makes up the machine, and with an error margin on each one, the total is always significantly under the real-world number. Others believe more simply that manufacturers lie.

[JLinde1339]

Well, considering that I don't have the stock mufflers, just chopped cans, the rear footpegs and associated mounting hardware are MIA, I think its quite reasonable that one of the PO's may have submitted an updated weight certificate justifying a difference of 35lbs from stock. Not to poke holes, just letting you know. LOL. NY determines the registration fee by the weight of the vehicle. I know that's true for cars, but not sure about motorcycles. But its possible the person that did this assumed that it may lower the reg fee. I can't say for sure.

As far as dry weight, tho, I always assumed it was the weight of the vehicle minus gas, and fluids (coolant, oil, etc).
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[Alex]

Originally Posted by JLinde1339

As far as dry weight, tho, I always assumed it was the weight of the vehicle minus gas, and fluids (coolant, oil, etc).

That would be logical, but it's not the case. The listed dry weight + the weight of the fluids rarely comes close to the actual weight of the bike. Best way for comparison has always been the multi-bike tests in SportRider, Bike, and similar mags where competing bikes are weighed on the same scale, under the same conditions, with a similar fuel load.

[JLinde1339]

I wish I still worked at my old job. They had a big scale they used to weigh pallets of mail and supplies. I'd ride my bike right up to it and weigh it. Cuz now I'm curious what it does weigh.

But back to topic, 3.4 pounds of difference would amount to 1% a (stock) ninjette's weight. I still agree that should amount to something.
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[Alex]

Originally Posted by JLinde1339

But back to topic, 3.4 pounds of difference would amount to 1% a (stock) ninjette's weight. I still agree that should amount to something.

Is the rider on this bike when it is attempting to accelerate?

[JLinde1339]

Man, you guys are like my ex-wife! If the details don't validate you're POV, they're irrelevant! XD
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[Jiggles]

Originally Posted by JLinde1339

Man, you guys are like my ex-wife! If the details don't validate you're POV, they're irrelevant! XD
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No one here is arguing that adding weight to the bike won't negatively impact performance. But changing the bikes total weight by less than 1% isn't going to amount to any noticeable change in acceleration, stopping distance, nor miles per gallon.

[Alex]

FWIW, other tire sites also are listing similar weight differences between the Demons and the Diablo's, so the 3+ pound weight difference on the rear tire does appear to be accurate (or at least repeated).

[JLinde1339]

Okay, I'll use me as an example. I'm about 230. My bike is 304. So 534. Add some gas and stuff, let's just use 550 lbs. I need 2 tires, BTW, so let's add twice the tire weight. For simplicity. Well, that still works out to about 1%.

Either way, I think some may have glossed over what Greg was trying to point out, that these are not static items on the bike like tank bags or something. These parts are moving parts. Spinning in a circle. I've noticed that my front end tends to hop a bit and I'd attribute that to the fact that my front tire is a 90-aspect ratio tire, instead of the stock 80 that the engineers designed the front suspension around. Who really knows if that's the reason or not, but seems valid enough to me that I'm looking to get the MT75s because they come in the stock size. I'm not really arguing anything. Just trying to put some validity into the POV. If you're just the average street rider, then probably not a big deal. If you're a racer, then something to be considered.
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[GeorgiaHooligan]

Just had my demons installed, should I run the same pressure as the 630's? just curious

[GeorgiaHooligan]

Im going with yes, but just wondering. Im running 28psi in front and 32 at the rear

[Alex]

Originally Posted by JLinde1339

I need 2 tires, BTW, so let's add twice the tire weight. For simplicity.

Right, but the front tires don't have that weight difference. It's only the rear with a noticeable difference in this case.

Originally Posted by JLinde1339

If you're just the average street rider, then probably not a big deal. If you're a racer, then something to be considered.

Agreed in full. When ounces matter, when inches matter, when you're trying to get every advantage over your peers and competitors, all of this matters. Even then, it makes sense to concentrate on those things that make the biggest difference and work your way down the list until you run out of money or time.

But on the street, there are so many additional factors that also play a part in tire selection (steering feel, mileage, sizes available, availability, cost, and likely a few more). Weight may in fact be another factor along with this. Just to clarify my POV, I guess I reacted initially to posts implying that anyone who chose a slightly heavier tire was making the wrong decision. I don't believe that to be the case, and we went down the path of why I believe that.

It's all good. Choose the tires you want, for any reasons you want, and the only person each of us has to justify our reasons to is ourselves anyway.