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Not to bring physics into the discussion but...


You just failed physics 101. A dyno measures torque at the back wheel, so the gearing is already accounted for. Thus those nifty MO charts are already comparing apples to apples since they are taking measurements at the point where the rubber would be contacting the road.


But in your defense, you were replying to a post that contained equally bogus physics, so what the hell....
 

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>You just failed physics 101.



Ok.



>A dyno measures torque at the back wheel, so the gearing is already accounted for.



A dyno measures torque at the back wheel, and then "normalizes" the values to get an accurate representation of what the engine is capable of, after frictional losses.



Manufacturers often quote torque/hp values based on readings taken from an engine dyno. That's why rear wheel dynos are important - they give a more realistic view of the engine's potential.



Think about it: if the dyno charts accurately refected what was supplied to the rear wheel, then you've basically said that the various gears actually don't have any effect on the torque delivered to the road.



So I guess your bike accelerates at the same rate from a standing start in 5th gear as it does in 1st?



Another point to consider: if the dyno shows what is happening at the back wheel, then bikes are insanely fast. For the Vulcan: top rpm is ~5200 rpm. Spinning the rear tire at 5200 rpm is roughly equivalent to a speed of 400 mph. A GSXR with a redline of ~12000 rpm? Good for 900mph.



Does that set off any alarm bells?



-- Michael

 

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You still don't understand what is "torque". If you put speed into equation, you are talking about HP, not torque.



Speed equals to certain revs, OK? But remember torq multiplied by RPM = HP. So you are talking about HP, not torq. No wonder a whiney litrebike has more torq than a 2 litre Kawi.



- cruiz-euro
 

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Re: Excuse me the Army War College is not simple anti-Republican thing

Yes I read it. This is old news to me, as many columnists I read didn't need to go to the War college to come to the same conclusion, moreover they were saying it months ago. The only reason the AP put this on the wire is because they are reactively anti-Bush and anything to that end is fine.

I will reiterate----go to www.LewRockwell.com if you want some prinicpled opinions against the war. Even apart from the agenda of the AP, this article is wholly pragmatic and this paper would likely say the reverse had Saddam posed a significant enough "threat"----as if that alone is justification enough to invade a country. If that were the case, however, we would be at war with half the earth.
 

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Re: Is Motorcycle Online going to change its name to Cruiser Online?

Rolling along on the center of the tire for miles on end (at less than 50% over the speed limit)[.]

Well, that's one way to look at it, sure. I prefer this line of reasoning.

I have to get from point A to point B somehow. I'm sure as hell not going to fly, unless I absolutely have to. Which generally leaves me with some kind of highway transportation to work with, and if the weather is going to be nice, it's a lot more pleasant to cruise those miles on a motorcycle than inside of some 4 wheeled box. Now, if I had some really swank drop-head touring coupe, I might change my tune. Since my real life choices are between a 2002 Yamaha Warrior and a 1985 Dodge Diplomat... I'm probably going with the bike.

Now if only it didn't eat tires every 2500 miles. Damned squishy sportbike rubber. I'm contemplating a 15" conversion (or whatever the 'Wings are running these days) so I can get a tire that might be able to better handle the wear of long freeway miles.

-Kawazuki
 

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Don't confuse the guy...

... it's hard enough getting through the day having to decide between two viewpoints. Giving him the idea that there may be an infinity of viewpoints will cause his brain to turn into mush... well more mush.

Keep it simple:

The Democrats who blundered us in WWI, WWII, Korea and Vietnam are peace loving. We know this because they say so. It's not their fault that they were at the helm at the point of the bloodlettings. Oh no. They are so peaceloving. Remember how Mr. Wonderful Clinton resolved all that Balkans trouble so peacefully? They are so peaceloving. Now they are going to end the strife in the Middle East by sending over "good vibes" or some other equally effective solution. Well I don't know what solution they have actually. All they do is blame Bush for everything.. but they offer no alternative except the old worthless raise taxes and use diplomacy yadda yadda yadda.

Maybe they can bring back Jimmy "Kim Jong-Il is a nice guy" Carter.

Yeah, that'll help.

So Bush has blundered us into Iraq. What is our alternative?

Too bad that the only choices the we get are between two repugnant political extortion gangs.
 

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Re: Don't confuse the guy...

You might want to point Kook to the link in the NY Times showing a video of Wesley Clark in 2002 (before his run for president) claiming that there is a definite link between Saddam and Al Qaeda. I wonder what made him change his mind?

Living in California, where we are so undertaxed, spending has only gone up 45% in the last few years but I'm selfish because I don't want any more money extorted from me.

Political extortion gangs is the exact description.
 

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You are confusing the speed of the bike (mph), with the speed of the engine.(rpm)



I said that if a bike is at the HP peak, then for that road speed, the bike is putting the most torque to the back wheel that it can.



An example:



I'm feeling Buellish, so we'll use an XB12R.



Data for an XB12R:



89.8Hp. @ 6,700rpm

72.6LbFt. @ 5,750rpm



Rear tire: 180/55ZR-17



This isn't entirely exact, but the conversion from rear wheel rpm to mph for such a tire is roughly mph = 0.0738 * rwrpm



Pick any road speed you want. I'm going to go with 40 mph.



In order to go 40 mph, the rear tire must be turning at 40/0.0738 = ~542 rpm



Assuming full throttle...



If you are going 40 mph, and are at the torque peak, the torque being applied to the rear wheel is



72.6 * ( 5750 / 542 ) = 770 lbft



At the horsepower peak, the Buell is putting out



( 89.8 * 5252 ) / 6700 = ~ 70.4 lbft from the engine



but the torque to the rear wheel for 40 mph at the HP peak is



70.4 * ( 6700 /542 ) = 870 lbft



Repeat the calcs for other speeds/bikes/whatever. It doesn't matter.



For a given road speed, you will put the most torque to the back wheel if you are at the HP peak.



-- Michael





 

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Yeah, lots of alarm bells. Sorry, I was not following (blame the flu -- I shouldn't be posting with a fever).

I never intended to imply that dyno charts show rear wheel speed, only that they measure at the rear wheel, not that the dyno chart was reporting rear wheel RPM.

Where I failed reading comprehension was watching you then use gear ratios against these numbers, which failed the smell test. [The gear ratio is implicit in the intial measurement, since the two variables measured are on opposite ends of the powertrain.] But on a re-read I see where you were going....
 
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