BHPian Jupizire recently shared this with other enthusiasts.THE PROBLEM:The bikers in India face many problems – like bad road conditions, drenching in rain, risk of getting hit by other vehicles, having to tolerate air pollution etc. Much has been written about these common problems. But I would like to highlight a unique challenge faced by bikers today – increased risk of directly inhaling bike exhaust gas due to badly designed silencer / muffler. We end up riding bumper to bumper in cities due to congestion. It’s very common for 1 bike to be riding directly behind another. Similarly at a signal, a bike mostly would be directly behind another bike. Image Credit 1 Image Credit 2 Now a days, most of the bikes have their silencer angling upward, may be to increase the design appeal of the bike. But what this does is that the exhaust gas is pumped upward in the air, as shown by the 2 green dotted lines below. More often than not, this would gush the exhaust gas directly onto the face of the biker behind him, leading to his suffocation and eventually health problems. Feels very suffocating, like in this tractor exhaust inhalation scene from Dabangg (Or watch on youtube — start @ 2:00:42 & watch only for next 15-20 seconds) I have myself faced this issue many times, and was wondering why bike makers are not conscious of this peril! Hence writing this post.THE SOLUTION:I got into analyzing the exhaust angle of a few bikes, in fact all the bikes from the Honda stable. Found an online protractor tool to check the angle of exhaust using which I checked the angle manually for all the Honda bikes. Couple of samples are shown below: 1. Honda SP-160 -> has an angle of exhaust of 154 degrees. Check the blue line marked on the silencer. Protractor shows the angle of exhaust as 154 deg (from origin, measured in anti-clockwise direction, which is the right way to measure an angle). But for the sake of this post, I would prefer to use smaller numbers which are more intuitive. Hence, I will do 180 deg minus the angle (154 deg) to get it as 26 deg. It actually represents by how much angle the silencer exhaust hole (not the entire silencer in itself, but the projected pipe/hole at the end) is tilted upwards (in clockwise direction). Zoomed-in view for easier understanding of the angle measurement: A few more examples: 2. Honda CB 200x -> has an angle of exhaust of 32 deg. 3. Honda Shine 125 -> has the angle of exhaust of 8 deg. 4. Honda Activa 125 -> has the angle of exhaust of (-15 deg). It’s pointing downwards by 15 degrees. The full list of Honda bikes along with their angle of exhaust is shown below. Let me know if anyone needs the measurement images, and I can share. So what is the maximum angle of exhaust that should be allowed so that it doesn’t affect fellow bikers on the road? We can find it through simple trigonometry and a few assumptions. The length (x) depends on the 2 bikes and how distant the rider of backside bike is from the silencer exhaust of the frontside bike. The length (y) depends on the bike height, rider height, silencer height of the vehicle ahead and road elevation (in case of riding/standing at an incline) I did some measurements by keeping 2 bikes one behind the other and deployed a rider with a height of 5′ 6″. The measurements I got were: x = 80 inch y = 35 inch This gives the angle as 23.6 deg, which is approximately 24 deg. Which means, any bike that has a higher angle of exhaust than 24 degrees is likely to cause direct pollution trouble to fellow bikers. For this sole reason, I love the exhaust angles of Royal Enfield Bullet, Yamaha RX 100 (though it’s a different issue that the 2 stroke RS causes more air pollution!) and other such bikes with an absolutely horizontal silencer. Better, the scooter type of vehicles (Activa, Jupiter etc.) have negative angles of exhaust as the silencer let-out pipe at the end is bent downwards. Applying the above threshold to Honda bikes, we can see which models cross the limit and hence are more damage causing to other bikers on the road. THE ENFORCEMENTHow to persuade the auto makers to adopt a certain maximum angle of exhaust, which in no way alters the bike’s attractiveness-quotient? The silencer can still be in any direction – fully horizontal like in a RE Bullet to fully vertical like in a tractor if they want. But the small projected pipe at the end of silencer should not exceed the threshold for the betterment of humanity on road. I feel the influential forums and communities like Team-BHP can put in a word to the auto companies. And they can also recommend to SIAM to enforce this as a rule that all 2-weheeler companies must adhere to. Thus we can bring about a positive change in the society. Else, we run the risk of status-quo, which usually only worsens over time and increases the health issues owing to the direct-inhalation of polluted air. Comments and reactions are welcome. Check out BHPian comments for more insights and information.
