Is my loud exhaust p*ssing off the neighbours?
Vance & Hines risks getting the net curtains twitching
As I get older I’m becoming increasingly sensitive to noise pollution. I live on a very quiet housing estate with some very good neighbours so I’m keen that my “noisy motorbikes” don’t upset the status quo. A lad with his Citroen Saxo and godawful
six-inch tail pipe raises my hackles every time he drives past the house and I don’t want my neighbours to feel the same way about me with my Vance & Hines two-into-one pipe on the Street Twin.
On the other hand, noise is a very important part of motorcycling. Being able to hear the machine working is crucial to the enjoyment and, judging by how many other aftermarket exhausts are sold in the UK, I’m not alone (online retailer sportsbikeshop.co.uk sell more than 600 a year). The standard twointo-two exhausts on the Street Twin are whisper-quiet and make the bike feel, well, a bit wimpy. It’s a 900cc twin and it needs to sound like one.
The Vance & Hines high-level pipe is an official Triumph part (£1150) but is sold for ‘off-road use only’. When the pipe was fitted as part of Triumph’s Scrambler Inspiration pack for the Austin Vince Twin Shock event I entered in Spain last month I was
initially nervous of how loud it was going to be. A passing comment by one my neighbours about my “noisy motorbikes” has encouraged me to do some research.
Sound is measured in decibels, a system that’s logarithmic not linear. The smallest audible sound is 0db. A sound 10 times more powerful is 10db and one that’s 100 times more powerful than near silence is 20db. If a sound is 1000 times more powerful it registers 30db. So as you can see, when sound is measured in isolation it’s difficult to tell just how noisy something is. But with a cheap sound meter and few comparative measurements it’s much easier to gauge how likely I am to cause upset.
All my measurements were taken two metres from a static noise sources (the exhaust) and 20m away from moving sources, at a 90-degree angle. It’s the same method circuits such as Snetterton use when assessing sound levels on trackdays. The ambient sound level outside my house is 37.5DBA (the ‘A’ denotes a weighted measurement that mimics the relative loudness of sounds as perceived by the ear).
At tickover my 2006 Honda Civic car peaks at a very low 50.4DBA, a conversation between two people in the street hits 59.5. In contrast, my 150cc Briggs and Stratton lawnmower peaks at 93.3 (the lawnmower has no throttle control).
At tickover the Street Twin peaks at 77.5DBA, obviously higher than the car’s tickover but way below the 150cc lawnmower and it’s not until I blip the throttle of the Street Twin vigorously that I get the sound level meter to rise above 90DBA.
Drive-by measurements tell a similar story. At 20 metres distance the lawnmower still registers 86.1DBA and the Civic 61.4 (while doing 20mph). In a third gear drive-by the Street Twin registers just 78.6. So while the Street Twin is noisier than my car, it’s quieter than the lawnmower and providing I don’t rev the bike as I’m leaving the estate, I’m pretty confident me and the neighbours will get along just fine.
‘A lad with his Citroen Saxo and godawful six-inch tail pipe raises my hackles every time’
Standard pipe looks nice enough but is barely a whisper
Beefy Vance & Hines looks macho but is it just too loud?