The Maths of a Dream
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2wheelsagain
ThatOtherGuy
mtbeerwah
1952
8 posters
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The Maths of a Dream
1952 Tue 30 Oct 2012, 11:17 pm
If, in a recent dream, I had gone for a ride, on a beautiful, sunny, non-windy day .. and .. on an empty stretch of dry, straight, high visibility road, (remember this is a dream,) I had given the throttle a twist to give the motor a few moments higher up the rev range .. well, if I had lent forward (in my dream) to keep my weight forward, and thus obscured the gauges with my full-face helmet, so that I only noticed the tachometer dropping back through 8000 as I eased off. Would the scary number I dreamily thought I saw on the digital speedometer, be what I think it was?
Would the following calculation of this dream situation be correct?
KPH =
( (RPM [8000]/Primary Reduction Ratio [1.537])
/Final Reduction Ratio [2.388])
/Sixth Gear Ratio [1.071])
X
circumference of rear tyre in metres [1.98] = metres per minute;
and then, converting metres to kilometres [ Dividing by 1000] and multiply the ‘per minute’ by 60 to express ‘per hour’, e.g.:
8000 / 1.537 = 5205
5205 /2.388 = 2180
2180 / 1.071 = 2035
So that, at 8000 rpm the back wheel is rotating at 2035 revolutions per minute.
2035 X 1.98 (rear wheel circumference in metres) = 4,029 metres per minute
Approx: 4 kilometres per minute
= (4 X 60) = 240 kph
{Does 30 kph per 1000 rpm in top gear seem about right?}
I am just interested because it was such a vivid, life-like dream ... and it got me wondering.
Would the following calculation of this dream situation be correct?
KPH =
( (RPM [8000]/Primary Reduction Ratio [1.537])
/Final Reduction Ratio [2.388])
/Sixth Gear Ratio [1.071])
X
circumference of rear tyre in metres [1.98] = metres per minute;
and then, converting metres to kilometres [ Dividing by 1000] and multiply the ‘per minute’ by 60 to express ‘per hour’, e.g.:
8000 / 1.537 = 5205
5205 /2.388 = 2180
2180 / 1.071 = 2035
So that, at 8000 rpm the back wheel is rotating at 2035 revolutions per minute.
2035 X 1.98 (rear wheel circumference in metres) = 4,029 metres per minute
Approx: 4 kilometres per minute
= (4 X 60) = 240 kph
{Does 30 kph per 1000 rpm in top gear seem about right?}
I am just interested because it was such a vivid, life-like dream ... and it got me wondering.
1952- Posts : 139
Join date : 2010-04-20
Age : 72
mtbeerwah- Posts : 1787
Join date : 2010-02-20
Location : Brisbane
Re: The Maths of a Dream
ThatOtherGuy Thu 01 Nov 2012, 8:51 am
buy a gps that records (I have a cycling one) then you can keep the dream recorded forever. 
ThatOtherGuy- Posts : 203
Join date : 2012-08-18
Age : 58
Location : Albany Creek
Re: The Maths of a Dream
2wheelsagain Thu 01 Nov 2012, 11:16 am
Sounds about right but I'm not sure if you'll crack 8k in 6th in stock form (level rd etc)
The 1250 runs a higher top speed in 5th
(well it does for me anyway)
The 1250 runs a higher top speed in 5th
(well it does for me anyway)
2wheelsagain- Admin
- Posts : 6390
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Age : 60
Location : Sale Area Vic -
'Dream' repeats ... almost!
1952 Tue 06 Nov 2012, 6:17 pm
Amazingly, today I had a repeat of my original 'dream', but the weather was not quite as good. Even more unbelievablely, my mate on his Aprilia had the identical 'dream'!
In this latest episode I saw 224 kph on the spedometer, and my friend saw 215 kph. No shaking, vibration or instability. Just over 7000 rpm. Fuel consumption over 198 kms was 11.7 l. It was a very pleasent experience over a wide variety of major freeway, secondary and tertiary ashphalt. Country looks fabulous, with fields of grain ready to reap, and sheep and cattle looking good enough for McDonalds
(And I agree that there was no way I was going to rev. a lot more in 6th gear - 5th would be the choice if one was 'juvenile' enough to actually be trying for a 'top speed', something I would never advocate on public roads 
In this latest episode I saw 224 kph on the spedometer, and my friend saw 215 kph. No shaking, vibration or instability. Just over 7000 rpm. Fuel consumption over 198 kms was 11.7 l. It was a very pleasent experience over a wide variety of major freeway, secondary and tertiary ashphalt. Country looks fabulous, with fields of grain ready to reap, and sheep and cattle looking good enough for McDonalds
(And I agree that there was no way I was going to rev. a lot more in 6th gear - 5th would be the choice if one was 'juvenile' enough to actually be trying for a 'top speed', something I would never advocate on public roads
1952- Posts : 139
Join date : 2010-04-20
Age : 72
Re: The Maths of a Dream
Reardo Tue 06 Nov 2012, 6:31 pm
2wheelsagain wrote:Sounds about right but I'm not sure if you'll crack 8k in 6th in stock form (level rd etc)
The 1250 runs a higher top speed in 5th
Not stock and of course it was on the centre stand.
Reardo- Posts : 2192
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Age : 45
Location : BROKEN HILL -
Re: The Maths of a Dream
Kiwisteve Wed 07 Nov 2012, 1:51 pm
Reardo wrote:2wheelsagain wrote:Sounds about right but I'm not sure if you'll crack 8k in 6th in stock form (level rd etc)
The 1250 runs a higher top speed in 5th
On a dyno machine, because none of us here on this forum advocate speeding on public roads.
Kiwisteve- Posts : 1420
Join date : 2012-01-25
Age : 61
Location : Coffs Coast
Re: The Maths of a Dream
Reardo Wed 07 Nov 2012, 9:37 pm
That's true...Kiwisteve wrote:Reardo wrote:2wheelsagain wrote:Sounds about right but I'm not sure if you'll crack 8k in 6th in stock form (level rd etc)
The 1250 runs a higher top speed in 5th
On a dyno machine, because none of us here on this forum advocate speeding on public roads.
Reardo- Posts : 2192
Join date : 2010-02-06
Age : 45
Location : BROKEN HILL -
Re: The Maths of a Dream
Sloth_27 Fri 09 Nov 2012, 5:17 pm
Ask Cam, I think he has had his Bandit wound out on the front straight at Eastern Creek.
Although that may have also been in his dreams...
Although that may have also been in his dreams...
Sloth_27- Posts : 227
Join date : 2009-08-20
Age : 35
Location : NSW
Re: The Maths of a Dream
gus Fri 09 Nov 2012, 5:32 pm
I did see the speedo go past the highest reading on my 1200 .Thats 260 + .Speedo error takes it back .
I tried in the 1250 and couldnt get near it .
I tried in the 1250 and couldnt get near it .
gus- Posts : 6176
Join date : 2010-11-23
Age : 73
Location : Cygnet ,Tasmania
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