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BMW R18 [message #302786] Sun, 11 October 2020 14:13 Go to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
It seems to be all the buzz right now and either BMW expects to sell wagonloads of them or bike sale figures are a scam because I asked at the BMW dealership and "starting February" there will be plenty available.
At 23 grands bare bone naked it is bloody expensive, but it's the same price as a similar Harley-Davidson, better engineered and for what it is surely handles and brakes much better. If you consider that differently from the old R1200C the engine is wholly purpose built (and given it's an air cooled Euro 4/5 compliant must have cost BMW a small fortune to develop and certify) it's not even that expensive.

I am pretty interested to see how these bikes will hold up long term because some of the engineering solutions (the driveshaft to say one) are basically 50's technology that has long been replaced by more advanced and reliable solutions. It should use ride by wire technology like most other modern boxers, and that apparently has the "purists" up in arm because it's "unreliable". Yes, it'so unreliable it's been in common commercial aeronautic use since 1984. Wink
Re: BMW R18 [message #302788 is a reply to message #302786] Mon, 12 October 2020 20:57 Go to previous messageGo to next message
pecker is currently offline  pecker   United Kingdom
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(11) MotoGP Podium Finisher
Had a look at it while mine was in for a service...
it looks the part, its big, long and low
the only thing i thought might put the cruiser rider types off is the Footpeg position, not being able to put them further forward because of the engine

Re: BMW R18 [message #302790 is a reply to message #302786] Tue, 13 October 2020 21:06 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
I was looking at the long option list for this bike and it's like BMW wants to drive aftermarket manufacturers out of business.

Reverse gear, check.
Cruise control, check.
Passenger seat, check.
Check check check.

You can easily put 27/28 grands in that bike, which would buy an fully loaded R1250GSA with some cash still left.

Wow, I have not bought a new bike in just three years and prices have already increased so much. Laugh
Re: BMW R18 [message #302793 is a reply to message #302790] Tue, 13 October 2020 21:27 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
I'm definitely undecided now I've googled an image. That exhaust eek

https://www.topgear.com/sites/default/files/styles/fit_1960x1102/public/images/news-article/carousel/2020/04/a1c3f43f0fc166c48564e208db40ca5e/bmw_r_18_customisation_2.jpg
Re: BMW R18 [message #302794 is a reply to message #302786] Thu, 15 October 2020 08:45 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Sound Pressure Levels. Wink
From the EU compliance statements I have:

Chainsaw: 119db
Lawnmower: 90db
Bike: 79.2db

The human ear has no linear sensitivity to sound, but generally speaking the human ear has a much higher sensitivity to low frequency sounds (say around and under 400Hz) than anything up to 4,000Hz, after which the sensitivity increases again. That's why a big twin engine sounds much louder than 600cc I4 with the same SPL. Wink
Re: BMW R18 [message #302798 is a reply to message #302794] Fri, 16 October 2020 18:30 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
80db? I recall being disappointed my 929 (when bought new in 2001) was only 90db when my mates bikes where all 95/98db on the limit Sad
Re: BMW R18 [message #302799 is a reply to message #302786] Sat, 17 October 2020 16:00 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Remember the decibel is a logarithm (10), in the specific of the rate between the sound pressure of something (car, lawnmower etc) and the sensitivity threshold for the human ear which is defined as 20 micro Pa (thanks Microsoft for taking away Greek letters from the character map).
This means that 5db are truly a lot, and 10db much more so. eek
Re: BMW R18 [message #302811 is a reply to message #302799] Fri, 23 October 2020 20:25 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
Im sort of aware of the the decibel numbers, not sure how it works as I don't think 91 is twice as loud as 90, but isn't it something like 90 is perhaps (just guessing) twice as loud as 80?

Either way, 80db is shit, might as well go electric if thats where noise levels are headed
Re: BMW R18 [message #302816 is a reply to message #302786] Sat, 24 October 2020 12:07 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
When dealing with sound pressure levels (SPL), they are expressed as:

SPL = 10*log10 (p²/p0²) = 20*log10 (p/p0)

Where p0 is the threshold for human hearing (arbitrarily set at 20 micro Pa) and p is the sound pressure for whatever you are measuring.

Everybody got that?

This means that the SPL halves (or doubles) roughly every 3db but, as said, the human ear has no linear perception of sound so for practical purposes this actually useless. Laugh

What did you expect? I am a chemist, not a sound engineer.
Re: BMW R18 [message #302824 is a reply to message #302816] Thu, 29 October 2020 23:32 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
Kakugo wrote on Sat, 24 October 2020 12:07
This means that the SPL halves (or doubles) roughly every 3db but, as said, the human ear has no linear perception of sound so for practical purposes this actually useless. Laugh

What did you expect? I am a chemist, not a sound engineer.
Mostly understood this bit Cool


btw I didn't realise you're a chemist Thumbs Up
Re: BMW R18 [message #302825 is a reply to message #302786] Fri, 30 October 2020 11:54 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Yeah, and you won't believe the troubles it got me into. eek
Such as when a friend of a friend sent me a list of (borderline legal) drugs her husband was stashing in the refrigerator. They probably had five grands worth of doping substances keeping company to cabbages and onions. Laugh
Re: BMW R18 [message #302832 is a reply to message #302825] Sat, 31 October 2020 20:08 Go to previous messageGo to next message
Pipe is currently offline  Pipe   United Kingdom
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(22) Giacomo Agostini
Is it not true that at very low frequencies the ears make you shit yourself Laugh

Be afraid of riding that bike ... very afraid Laugh
Re: BMW R18 [message #302836 is a reply to message #302786] Sun, 01 November 2020 12:18 Go to previous message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
I remember David Attenborough saying tigers were traditionally believed to emit a low frequency sound to cause "tiger panic" in their prey and hence make them easier to kill.
Turns out tigers do emit low frequency sounds (below 50Hz) but they do so to communicate between themselves. Wink

I could make a rather long and mostly rambling discussion on sound frequency, but suffice to say the human ear is increasingly inefficient at frequencies below 1,000Hz, again in non-linear fashion. 20Hz is usually considered the lower limit for human hearing, but there's much individual variation with some folks able to hear sounds as low as 17Hz and others stopping in the 30Hz range.
However if a low frequency sound is intense enough (as measured in watt) one may "feel" the noise instead of "hear" it.

Pipe, rivers of ink have been poured into the physiological effects of low frequency sounds but it's a sector where there are as many theories as there are "scientists". Kinda like with the present epidemic.
Low frequency sounds have been blamed for everything from nausea to ghostly apparitions ( eek ) but, again like with the present epidemic, nobody has been able to explain why one person gets nauseous and 10 more feel perfectly fine or why we don't see ghosts around industrial diesel engines, which are the most "efficient" low frequency sound generators. think
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