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I research for the auto industry and this was very well known by the authorities. Fixed test cycles like the New European Driving Cycle https://upload.wikimedia

by JorgeGT 11y ago

I research for the auto industry and this was very well known by the authorities. Fixed test cycles like the New European Driving Cycle https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/New_European_Driving_Cycle.svg/640px-New_European_Driving_Cycle.svg.png?1442593779002 https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Ne... were easy to detect, and easy to optimize against. That's why coming regulations introduce more realistic cycles like WLTC https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/WLTC_class_3.svg/1024px-WLTC_class_3.svg.png?1442593767685 https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/WL... and real road tests, where particle emissions will be trapped and compared against the lab test, and only a certain % of deviation will be allowed (last time I looked they didn't decided this % yet).

1ris 11y ago
I hope this gets fixed, although I don't believe it. I care about the noise emissions. AFAIK they are measured on a real road, but only up to 50 km/h and in a ridiculous narrow test. Harley Davidson and other are known to optimise for this test with movable parts in the exhaust pipes so these get much louder when the bikes goes faster than 50 Km/h.
- JorgeGT 11y ago
  I actually work on aeroacoustics! My specialty is turbomachinery but regarding combustion noise, let me say that it is a very tricky subject... even slight variations on the fuel injection settings and valve openings can have a high impact on noise!
- Raphmedia 11y ago
  Well, as much as a cheat it is, I'm happy that those bikes can go quiet on slow (city) streets but as loud as possible on the highway (increase security and swag).
  - bardworx 11y ago
    I'm always surprised when people don't realize that large bikes are suppose to be loud so that drivers can hear them coming. It's a necessary evil.
    - jboggan 11y ago
      I'm a motorcyclist and I'm downvoting this fallacy. If this were seriously the case then good beginner bikes like the Ninja 250 and Honda CBR250R would be unsafe, especially for new riders. Enjoy your loud pipes if you like (I do on my throaty Aprilia) but don't pretend they give you any safety benefit to balance the annoyance it causes some people.
      - luckydude 11y ago
        I too am a motorcyclist (85K miles of sport bike riding, Sunday morning ride to Pt Reyes was a lot of that, current stable is r1200gs and wr250r). I despise loud pipes, just frigging hate them. But I live in deer country (Santa Cruz mountains) and I've hit a deer at speed on the GS (did not wipe out, lifted the front end and had my front tire hit it square in the hind quarters, spun the deer around, I dropped the front wheel down and did a very shaky coast to a stop. My hands were shaking like a vibrator on steroids). After that experience I really wonder if loud pipes would have scared the deer off. I tend to doubt it, I've not installed a louder pipe, but it's made me less pissed off at the loud pipe people. Not a lot less pissed off, but some. BTW, shoutout to the Ninja 250 and especially the 500 version. I had two of the EX500's and those were by far my favorite sport bikes. Lots of torque, could pull any 600rr off the light (yeah, the 600 was blasting by me 2/3rds of the way down the block, but do you really want to ride a sewing machine? I don't. Loved my 500 twins.)
        emp_zealoth 11y ago
        I despise overly loud pipes - like, you have to scream loud. But,Ive been riding a bike a lot as well. Way too quiet exhausts (like EU is constantly pushing on us) are dangerous - ive seen it myself - my dad with a louder exhaust passes with no issues and I, silently, get cut off and nearly run off the road by a guy that assumes that mirrors are for pussies. It happened quite a few times already.
  - brc 11y ago
    Loud Harleys frustrate and annoy me. Most owners seem to remove the factory pipes and fit the loudest ones possible. It's not true this helps on the highway. In my car, which has double glazed glass, you can't hear a bit until it's right outside the window. When I'm walking along with the dog and kids, an open pipe Harley riding past is particularly not safe, because it scares the crap out of them. One idling Harley is louder than a thousand idling Volkswagen diesels.
    - rconti 11y ago
      I'm a motorcyclist too, and straight piped Harleys make me stabby. I don't believe they're louder on the highway. I believe they're louder whenever they're within earshot of any place where people congregate without earplugs (cafes, restaurants, pedestrian areas), whereupon the scumbag on the seat finds it necessary to go wide-open throttle to show off how terrible their bike sounds. It never fails.

by JorgeGT 11y ago

1ris 11y ago

I hope this gets fixed, although I don't believe it. I care about the noise emissions. AFAIK they are measured on a real road, but only up to 50 km/h and in a ridiculous narrow test. Harley Davidson and other are known to optimise for this test with movable parts in the exhaust pipes so these get much louder when the bikes goes faster than 50 Km/h.

JorgeGT 11y ago
I actually work on aeroacoustics! My specialty is turbomachinery but regarding combustion noise, let me say that it is a very tricky subject... even slight variations on the fuel injection settings and valve openings can have a high impact on noise!
Raphmedia 11y ago
Well, as much as a cheat it is, I'm happy that those bikes can go quiet on slow (city) streets but as loud as possible on the highway (increase security and swag).
- bardworx 11y ago
  I'm always surprised when people don't realize that large bikes are suppose to be loud so that drivers can hear them coming. It's a necessary evil.
  - jboggan 11y ago
    I'm a motorcyclist and I'm downvoting this fallacy. If this were seriously the case then good beginner bikes like the Ninja 250 and Honda CBR250R would be unsafe, especially for new riders. Enjoy your loud pipes if you like (I do on my throaty Aprilia) but don't pretend they give you any safety benefit to balance the annoyance it causes some people.
    - luckydude 11y ago
      I too am a motorcyclist (85K miles of sport bike riding, Sunday morning ride to Pt Reyes was a lot of that, current stable is r1200gs and wr250r). I despise loud pipes, just frigging hate them. But I live in deer country (Santa Cruz mountains) and I've hit a deer at speed on the GS (did not wipe out, lifted the front end and had my front tire hit it square in the hind quarters, spun the deer around, I dropped the front wheel down and did a very shaky coast to a stop. My hands were shaking like a vibrator on steroids). After that experience I really wonder if loud pipes would have scared the deer off. I tend to doubt it, I've not installed a louder pipe, but it's made me less pissed off at the loud pipe people. Not a lot less pissed off, but some. BTW, shoutout to the Ninja 250 and especially the 500 version. I had two of the EX500's and those were by far my favorite sport bikes. Lots of torque, could pull any 600rr off the light (yeah, the 600 was blasting by me 2/3rds of the way down the block, but do you really want to ride a sewing machine? I don't. Loved my 500 twins.)
      - emp_zealoth 11y ago
        I despise overly loud pipes - like, you have to scream loud. But,Ive been riding a bike a lot as well. Way too quiet exhausts (like EU is constantly pushing on us) are dangerous - ive seen it myself - my dad with a louder exhaust passes with no issues and I, silently, get cut off and nearly run off the road by a guy that assumes that mirrors are for pussies. It happened quite a few times already.
- brc 11y ago
  Loud Harleys frustrate and annoy me. Most owners seem to remove the factory pipes and fit the loudest ones possible. It's not true this helps on the highway. In my car, which has double glazed glass, you can't hear a bit until it's right outside the window. When I'm walking along with the dog and kids, an open pipe Harley riding past is particularly not safe, because it scares the crap out of them. One idling Harley is louder than a thousand idling Volkswagen diesels.
  - rconti 11y ago
    I'm a motorcyclist too, and straight piped Harleys make me stabby. I don't believe they're louder on the highway. I believe they're louder whenever they're within earshot of any place where people congregate without earplugs (cafes, restaurants, pedestrian areas), whereupon the scumbag on the seat finds it necessary to go wide-open throttle to show off how terrible their bike sounds. It never fails.