Rain: quick vs slow

[Whosthedaddy]

Like with the whole debate regarding do you walk or run to keep dry in a shower, could the same be said for riding in it?

What'd ya all think?
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[smegballs]

We made an algorithm for this in maths once.......

I didn't really get it (not good at maths) but it boils down to you front section area versus the "top" section area.

If you have a much larger front section area (most likely) its better to go slower as you intercept less rain and your (relatively) small top section area will have less rain fall down on it even when you factor in the increased exposure time.

If by some strange factor your top section area was much much bigger than it would be better to go fast.

Obviously there are many many variables: how fast, raindrop density etc etc so theres no easy answer.....


HTH :roll

PS: Personally I find on a bike I get soaked in a few seconds, much more than I'd expect to do with the same journey (say across town) than I would on foot.

[iooi]

Given that you still travel the same distance and it rains the whole trip.

It makes no diffrence.



Are you any drier if you stand still or move when it rains....



The only thing you could argue on a bike is that greater speed is more likely to force the water up seams and any places where there is not a good seal. Due to increased wind pressure.

Bit like if you sit on your bike in the rain for 2 hours, but don't go anywhere, will you still be dry inside. Compared to riding for 2 hours at 50 mph.
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Just because my bike was A DIVVY, does not mean i am......

[G]

Greater speed however also leaves you in more of a bubble of air going at a relatively different speed to the rain, meaning that especially with a fairing/screen, the rain is more likely to be forced over you by the airflow.
Depends a lot on the bike design, as some may as you suggest, force that water into rather than over you.

[The View Askew]

So essentially what we are saying is, when it's raining, you will get wet.
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"Do what you always did, get what you always got"

[G]

That's a good point, I should try and spam the Roadcrafter suit I'll have for sale - takes under a minute to put on and keeps you warm, safe and not wet .

[stinkwheel]

Given a fixed number of raindrops per unit volume of air, the speed is irrelevant, you still displace the same volume of air by moving through it from point A to point B and so encounter the same number of raindrops. Let's call this volume of rain Z in litres, representing the volume of rain hanging in the air displaced between the two points. This equals surface area (a) in square metres multiplied by distance travelled (s) in metres multiplied by the volume of rain (r) in litres per cubic metre.
Z = sar

Of course this is not the case because raindrops don't hang stationary in the air, they are falling onto you at the same time. If you had a speed of zero between points A and B you would get infinately wet. The longer you are in the rain, the more rain will hit you and will be directly proportional to time. So the volume of rain hitting you from above (Y) in litres equalls the rate of rainfall (R) in litres per second, multiplied by your top surface area in square metres (b), multiplied by the journey time (t) in seconds.
Y=tRb

So the total volume of rain which hits you over the journey (X) can be expressed:
X= Y+Z
X= sar + tRb

v=s/t (speed = displacement / time)

So, assuming a constant rate of vertical rainfall on an unfaired bike:
https://www.bikechatforums.com/files/eqn4551.png
Where X is the volume of rain you hit in litres where:
v is your speed (metres per second)
s is the distance travelled (metres)
t is the journey time (seconds)
a is the frontal surface area (square metres)
b is the top surface area (square metres)
r is the volume of rain in the air (litres per cubic metre)
R is the rate of rainfall (litres per metres square per second)

Therefore, you stay drier if you go faster.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Digitalize]

If you fall off, you'll get very wet though, as you will be motionless, in pain, then trying to get back on the bike if its ok.

Ride to what you can in the rain, always stay confident, dont worry about getting wet.

[Clanger]

It depends largely on what sort of rain it is.
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Be who you are and say what you feel, because those who mind don't matter, and those who matter won't mind - Dr. Seuss

[metalangel]

I find the really light rain (that forms a fine coating of droplets on your visor) more hazardous and unpleasant than proper, heavier rain... not least of all because it doesn't tend to bead off the visor as quickly (if it all).
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Previous: 2002 Honda CB500 (sold), 2007 Suzuki SV650SK6 (crashed), 2005 Yamaha FZ6 Fazer (sold). Currently bikeless
"A faired bike will get you 10x more clunge than a unfaired one." -Marlboro Matt

[Pete.]

[doggone]

The Stinkwheel formula doesn't take account that if you travel at 30mph rather than 60mph you will be out in the rain getting wet for twice as long.

[Pete.]

TBH If you have a fairing you'll be kept drier behind it at speed, because every drop that hits the fairing doesn't hit your body. Many times I've ridden for miles down the A2 staying fairly dry only to get a soggy crotch doing the last mile and a half to my house at 20-30mph.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stinkwheel]

[Howling TerrorOutOfOffice]

[mark83]

I like clutching it in the rain and spnning my back wheel up. i.e. savour the rain!!

But I'm sure it'll come back to bite me in the arse one day...
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Kawasaki ER6n -> Honda CBR600RR -> Honda VTR 1000 -> Moto Guzzi Norge 1200
Buy my Mercedes 350 Sport AMG Evo

[yuri2085]

Something that has been overlooked is your not REALLY getting wet is rain is just falling on your helmet. (and then past your shoulders?)

Although ones legs do!

[L3G3ND_MTX]

[Howling TerrorOutOfOffice]

[The Artist]

[Pete.]

Raining cats and dogs - they are bastards when they hit your visor!
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Whosthedaddy]

[Clanger]

Don't forget the rain that is so wispy and barely touches you at all, so it couldn't really be defined as wet rain at all!
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Be who you are and say what you feel, because those who mind don't matter, and those who matter won't mind - Dr. Seuss

[Dom]

[warped one]

I must say that with great embrassment that I have been known to do the ped boim at 30pmh in the rain just to keep that little bit drier behind the screen, but here is a rather interesting thing for you.

Differences between me and dad,

Bike-
Me - GT650r (Fast)
Dad - CB250N (Slow)

Average cruising speed-
Me - 70mph
Dad - 50mph

Average wetness-
Me - Dry, sat watching TV in same cloths
Dad - Absolutely soaked

Now to clear up the indiscrepancies-

We both work roughly the same distance from home, we both leave work at roughly the same time. So this means is the rain we both experiance the same amount give or take a few 0.0001mm's of rain. Thus meaning if you want to stay drier in the rain get a faired bike and go faster, works for me.

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.