it started with "it pulls 100MPH at only 1/2 throttle"

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Whoa! This ain't no Three Mile Island, this is a full blown Fukushima or Chernobyl type-o-meltdown!

Hobot, care to come out of retirement for some tag-team?

Too funny and yes; now more suitable for the pub (brawl) and, yes, great time for a ride for at least one person....in my humble opinion.

Can't wait to hear what is next.
 
Can dish it out, but can't take it ?


Care to explain these words, oh wise one ?

Postby Dances with Shrapnel
<snip>
Your commonly quoted motorcycle numbers continue to not add up as they defy the laws of fluid dynamics. Plug in the numbers and you will see or are you disputing the laws of fluid dynamics?.
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Nope, 30 hp and 60 mph are rock solid.
Those numbers are as graphed in Tuning for Speed, p192 in my edition.

Perhaps you don't really understand those laws of fluid dynamics ?!
more "sand dribbling out of ears " ?

This shoulda all been in The Pub from the get go, LAB ?
 
Can't explain now your words, can you.
"All the sand dribbled out your ears ?"

Dances with Shrapnel said:
For the benefit of the readers, I am not suggesting, I am stating they are wrong. Do the math. But this is not about understanding and enlightenment for you, right?
<snip>
<snip>
<snip>
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Rohan said:
P.S. And before anyone says anything silly, and for those mathematically inclined, it is generally quoted it takes the average moddersickle plus rider just over 30 hp to do 100 mph.
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Apologies for reverting to previous cr*p, but jist for the record.
If you'd kept it polite, we could have had an interesting discussion....
 
Dances with Shrapnel said:
Oh, help me LAB, please help me. Pathetic.
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Yes, the two threads will have to be locked soon at this rate. :roll:
 
Desperate, are we? I would say very desperate if you have to resort to manipulating quotes out of context and out of order. A real Chernobyl melt down. :lol: Showing us all what you are about.

Easy to cut and paste out of context. Note in the quote below I state "they are", not "it is", clearly referring more than one number (in fact two sets of numbers or the now famous "Commonly Quoted Numbers"). I have no problem with the 30 hp number at 100mph as it is a number comprised of rolling resistance and aero drag (not aero drag alone as we had initiated this discussion on).

You cut and paste quotes in a lame attempt to dig yourself out of a deep hole. I challenge you to show us all where I said that the 30 hp number was wrong.

Another classic Rohanism.

Rohan said:
Can't explain now your words, can you.

"All the sand dribbled out your ears ?"

Dances with Shrapnel said:
For the benefit of the readers, I am not suggesting, I am stating they are wrong. Do the math. But this is not about understanding and enlightenment for you, right?
<snip>
<snip>
<snip>
Click to expand...

Rohan said:
P.S. And before anyone says anything silly, and for those mathematically inclined, it is generally quoted it takes the average moddersickle plus rider just over 30 hp to do 100 mph.
Click to expand...

Apologies for reverting to previous cr*p, but jist for the record.
If you'd kept it polite, we could have had an interesting discussion....
Click to expand...

You continue to soil yourself. I suggested numerous times throughout for you to challenge the numbers you quoted against the aero drag calculations but you have not for if you did, you would see.
 
+ 1, this thread stays open (a vent thread), even a sticky, for anyone that may like to go there,

if unrelated stuff starts up in any thread, they can be (suggested) linked to this one, or the pub,

folks that wanna go at it, can also of course, at any time, start a fresh dedicated thread,

here's a suggestion for a thread, shrapnel vs rohan,

a declined invitation, is a done deal of course, cos anyone else can also chime in

then again........ i could care less, or decline the invitation could mean..

eitherway, with options 1 - 2 - 3 offered, the majority will likely sort it out quick
 
acotrel said:
L.A.B. - Please don't lock this thread. The guys might actually discover the difference between theory and practice.

88 MPH AVERAGE lap speed on a 250cc four stroke:

https://www.youtube.com/watch?v=PvdG1qNEX30
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What hp did the 250 have though.
I've had something to do recently with a little 4 cylinder, with a claimed 45 hp.
And its a road bike, suitable for learners !

Averages are averages too - with your feet in the freezer and your head in the oven , on average you feel fine !
A fast open track or a tight twisty track 88 mph averages would be completely different kettles of fish.
 
My friend rode a 500cc Manx on the IOM a few times. He said 'the first time I went there, I did an 84 MPH lap, but if you keep going there, you get faster'. Hailwood's 88 MPH lap on a 250 must have involved bits over 100MPH. The best British 250 cc single in the 50s was the 1958 7R AJS - Mike Duff lapped with the 350cc Gilera fours on one. A 350 single which turns out 40 BHP is bloody fast, so what horsepower would a 250 turn out ?
 
Rohan, there is probably one factor which has not been considered and you touchéd on it yourself. When you try to do 100 MPH on a road bike you often don't have enough long road, so how you get into the straight bit is important. With a lighter bike, your acceleration out of the preceding corner is always better, so you get to the high speed more easily.
 
acotrel said:
so what horsepower would a 250 turn out ?
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How many cylinders did it have, and what era was it ?
And how many gears did it have
(at some point they limited them to 6 speed, after some were turning up with a 14 speed box)

Those little 125cc 5 cyl H*ndas revved to 25,000 rpms.
the 250/6 was similar.
Don't think they released the hp numbers.

And the last of the Aprilia 250 GP bikes (250cc) were producing a whopping 440 hp/litre
(and more for the factory ones !), for 110 hp under your belt.
Thats a lot of ponies for a small lightish bike...
 
We are talking about four-strokes, two-strokes are a different ball game. Most of the 50s four cylinder bikes had 6 gears, only the Gilera had 7. The 12 speed two-stroke was the Suzuki (125 ? 0r 50 ?) that Hugh Anderson rode. None of the others had more than 6. When racing with 6 close gears and an underpowered bike, rather than four speeds - you get further down the straights before you get passed by more powerful bikes, because you use the torque better.
 
hobot said:
I said what I mean and mean what I wrote, I quit public forums that risks pissing contests with Rohand and his several supporting groupies apparently too timid to chime in on this thread. hobot moved on, lurks to stay current. Peel Peeks in Pub w/o Rohand distractions.

it started with "it pulls 100MPH at only 1/2 throttle"
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I blocked Rohand a long time ago Steve. It makes for funny reading especially in threads like this when all of his comments are gone. :D
 
With close ratio gearboxes, the acceleration is faster once you get mobile. So if you are constrained by the length of available straight road, you are more likely to reach the higher speeds.
 
In 50cc, 125cc, 250cc, 350cc and 500 cc GP races, you are only battling machines of that capacity.
It was pretty rare that they mixed them, they had learned that differential speeds don't mix...

Underpowered ??
Maybe by GP standards.

1966, 250cc, six cylinders, 20,000 rpms, claimed 65 hp
it started with "it pulls 100MPH at only 1/2 throttle"

Pressed up crank too....

We diverge, slightly - its all about that 30 hp & 100 mph.
 
We are talking about 30 BHP 250s, so that is probably limiting the conversation to single cylinder four-strokes such as the 250cc Aermacchi Ala D Oro. Would that do 100 MPH ?
 
Well that 30 hp is bang on the money for 100 mph - as long as thats not marketing hp numbers ?

A fairing is said to give an extra 10 to 15 mph (15 at higher speeds), theres that aero again,
so 110 or even 115 might be possible.

Places like the IoM have had speed traps for eons, it might be recorded somewhere.
They don't ping em going uphill, so it'd be a genuine number.
 
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