Decibel legal limit

Message

Tonyunn · #1 Post by **Tonyunn** » Tue Dec 06, 2011 3:24 pm

Does anyone know what the road legal limit is, i.e. is it 80db or 101db.

I have tried for a couple of hours on the web to find out and I have had 20 different results.

I had a Ducati that had homlogated 80db Sil Moto cans on, I have just looked at a pair of Beowulf rated at 100db but still stated as road legal.

D-Rider · #2 Post by **D-Rider** » Tue Dec 06, 2011 5:19 pm

This is what the government has to say on the subject (and a good number of other motorcycle requirements):

http://www.dft.gov.uk/vca/additional/fi ... vca039.pdf

Tonyunn · #3 Post by **Tonyunn** » Tue Dec 06, 2011 7:38 pm

Thanks for that, so a new bike has to comply to the 82db level but nothing to say what level aftermarket cans are to comply with, in fact the only mention is to say that they have to be stamped correctly.

Have I read this right?

HowardQ · #4 Post by **HowardQ** » Tue Dec 06, 2011 8:08 pm

I think there is a grey area where they may possibly fail an MOT or upset a roadside plod if they are stamped OK but deemed too loud, but it is not really too clear. I suppose they have to cover for people who have genuine legal cans fitted, but may just have not bothered to have them repacked for a while. (could be guilty here!)

I run Beowulf Titanium ovals on mine, they still have the tiny (useless) baffles in. They are fully stamped up as legal, but even I have to admit they are bloody loud like this, (sound good though!). I always back right off and roll past police checks on tickover with fingers crossed.
I also glide slowly into my local test centre.
When I ride away and open it up my mate the tester initially gives it a funny look that always turns to a big smile.
He loves the Falco, and has never failed it on anything over seven years, even the EU headlight which it has alwas had.

Tonyunn · #5 Post by **Tonyunn** » Wed Dec 07, 2011 8:14 am

DVLA don't know either and passed me onto another part odf the government, so I sent them the same question, I await with baited breath.

Got a message from Bikebitz syaing there scorpion cans are rated at 96db at 6500rpm so the 100db amrk seems to be some kind of bench mark for aftermarket cans.

Aladinsaneuk · #6 Post by **Aladinsaneuk** » Wed Dec 07, 2011 8:55 am

iirc the 101+ range is where most tracks get shirty....

there are a couple that still allow upto 105 but - getting fewer i believe

and i think the loudest cans i have heard at tick over are Hanna's Carbon Can Company cans... they are louder than mine!

(Get mine going at full chat and they become very distinctive!)

back_marker · #7 Post by **back_marker** » Wed Dec 07, 2011 10:28 am

Tonyunn wrote:DVLA don't know either and passed me onto another part odf the government, so I sent them the same question, I await with baited breath.

Got a message from Bikebitz syaing there scorpion cans are rated at 96db at 6500rpm so the 100db amrk seems to be some kind of bench mark for aftermarket cans.

I've never worried too much about it apart from places where they actually measure the noise levels, ie trackdays.

A few things that many people forget/don't understand properly about decibel limits:

1. Just listening to something is not a good indicator of how loud it actually is - different pitched sounds ie. high or low, can seem louder or quieter than they actually are, hence the reason for recent tighter noise restrictions on motorsport (especially motocross) where the more widespread use of 4-stroke engines appears louder than the higher pitched stink-wheels even though they are not necessarily any louder, the sound just carries differently.

2. The decibel scale is not linear - a difference of -3 dB doesn't sound like much but actually equates to half the noise level.

D-Rider · #8 Post by **D-Rider** » Wed Dec 07, 2011 10:32 am

3) The distance at which it is measured is crucial.

4) With most of the noise coming out of the back of the can, the angle to the outlet that it is measured is also crucial

Tonyunn · #9 Post by **Tonyunn** » Wed Dec 07, 2011 11:05 am

"The decibel scale is not linear - a difference of -3 dB doesn't sound like much but actually equates to half the noise level."

This is what scares me, I had a new system rated at 82db and they were great, what does 96db sound like, I know I will get crucified for this but I don't want to spend £400 or £500 on a system that I can't use because it is too loud for me let alone anyone else.

D-Rider · #10 Post by **D-Rider** » Wed Dec 07, 2011 12:05 pm

The thing is, although 3dB equates to a doubling in the power of the sound, your hearing is also non-linear and it doesn't sound twice as loud.

HowardQ · #11 Post by **HowardQ** » Wed Dec 07, 2011 1:40 pm

I agree with all these comments, but the distance it has to be in order to set car alarms off is a good induicator as well.

Tonyunn · #12 Post by **Tonyunn** » Wed Dec 07, 2011 2:33 pm

Rustling Leaves 10 dB
Whisper 20 dB
Normal Conversation 60 dB
Busy Street Traffic 70 dB
Vacuum Cleaner 80 dB
Large Orchestra 98 dB (Fuel round carbon)
Walkman at Maximum Level 100 dB
Front Rows of Rock Concert 110 dB
Threshold of Pain 130 dB
Military Jet Takeoff 140 dB
Instant Perforation of Eardrum 160 dB

Nooj · #13 Post by **Nooj** » Thu Dec 08, 2011 12:27 am

Rustling Leaves 10 dB
Whisper 20 dB
Normal Conversation 60 dB
Busy Street Traffic 70 dB
Vacuum Cleaner 80 dB
Large Orchestra 98 dB (Fuel round carbon (Renegade oval cans tested at Cadwell))
Walkman at Maximum Level 100 dB
Renegade oval cans tested at Castle Combe 108 dB
Front Rows of Rock Concert 110 dB
Threshold of Pain (Renegade oval cans at full throttle on a dyno, standing 10 feet away) 130 dB
Military Jet Takeoff 140 dB
Instant Perforation of Eardrum 160 dB

Aladinsaneuk · #14 Post by **Aladinsaneuk** » Thu Dec 08, 2011 6:48 am

pardon?