Friday, 24 July 2009
Pastime
I have just realised that I have developed a silly pastime when I'm riding. I tend to aggressively overtake guys with their girlfriends pillion behind them to see if they will try to return the manoeuvre. Childish social experiment? Yes. Fun? Absolutely!
Friday, 3 July 2009
Don't Panic!
With that reference to the lord of humour, I'm going to talk today, about braking on wet roads. A lot of people tend to fall while riding on wet roads. This has a lot to do with the manner in which the brakes are applied on a two wheeler. Most people believe that on wet roads you must forgo the use of the front brake and use only the rear brake. This, is a very risky thing to do. I'm going to explain, with the help of a little bit of mechanics, how brakes should be used in the wet (or even dry).
Before we get to the braking though, a few general tips. The water on the road reduces the friction between the road surface and your tyres. While riding on a road with a little bit of water (i.e. not standing water), the water will tend to reduce the friction (or grip) available to you by about 15%. So, for starters, ride about 20% slower than you would on dry roads. Secondly, maintain distance between the vehicle in front of you. On a dry road, I remember rearset saying somewhere that you should maintain a distance to the vehicle in front of you such that you can see the tyres of that vehicle. On a wet road, extending this distance further, as much as a car length is a good idea. Additionally, avoid riding on anything that is not tar/concrete, i.e. painted signs, tiles, metal manhole covers, etc. That 5% difference in grip may be the difference between you being on the bike and on the ground.
Now, on to the braking part. Consider a two wheeler travelling on a stretch of road,
In the picture above, imagine the long straight line to be the body of your two wheeler. Consider four frictional forces in that figure. Fft and Ffb are the frictional forces at the tyre-road interface and brake respectively for the front wheel. Similarly, Frt and and Frb are the frictional forces at the tyre-road interface and brake respectively for the rear wheel.
In order to slow down the bike, without causing a wheel to lock up, the frictional force at the tyre-road interface must exceed the force applied by the brake at all times. As long as Fft exceeds Ffb, the frictional force at the tyre-road interface will force the tyre to keep rotating. If Ffb becomes higher that Fft, the tyre will simply stop rotating and lock up. This would imply that you should apply equal, but limited pressure on both brakes to brake safely. There is another factor though. The moment you start braking, the body of the bike tends to lurch forward due to inertia. This motion compresses the front shock absorbers and allows the rear shocks to expand. So, once you start braking, the picture changes to this,
Shocks are not perfect, and therefore will transmit force (even though they're supposed to absorb it). Therefore, you now have a state where there is a greater load on the front wheel than there is on the rear wheel. This means that Fft now greatly exceeds Frt. It is easy now to lock up the rear wheel, and correspondingly hard to lock up the front wheel, because the limiting values of Ffb and Frb have also changed.
This is the reason why bikes always have a stronger brake on the front wheel. The explanation above holds for dry and wet weather. The correct method for braking therefore, is to start braking with only the rear brake. Once weight transfer to the front begins, slowly start using the front brake, and reduce the pressure on the rear brake. This ensures that you're less likely to lock up either wheel.
Don't Panic
If you understood what I just said, you should be less likely to lock up the front wheel. Rear wheel lock ups are still possible. If you do lock up the rear, whatever you do, don't panic. Because the front wheel still isn't locked, chances are that you'll still be going in a straight line. Gently release the rear brake, more often than not, it'll start rotating again.
Always be prepared to fall. There's no technique in the world that can ensure that you'll never fall. You WILL fall, all you can do is to reduce the frequency. When you are open to the possibility of falling, if you do fall, you'll probably get up, pick up the bike and start riding again. If you believe that you can never fall, when you do, you'll be too stunned to do anything about it.
That does it for my first biking techniques post. Feedback on whether or not that was coherent and understandable is welcome.
Before we get to the braking though, a few general tips. The water on the road reduces the friction between the road surface and your tyres. While riding on a road with a little bit of water (i.e. not standing water), the water will tend to reduce the friction (or grip) available to you by about 15%. So, for starters, ride about 20% slower than you would on dry roads. Secondly, maintain distance between the vehicle in front of you. On a dry road, I remember rearset saying somewhere that you should maintain a distance to the vehicle in front of you such that you can see the tyres of that vehicle. On a wet road, extending this distance further, as much as a car length is a good idea. Additionally, avoid riding on anything that is not tar/concrete, i.e. painted signs, tiles, metal manhole covers, etc. That 5% difference in grip may be the difference between you being on the bike and on the ground.
Now, on to the braking part. Consider a two wheeler travelling on a stretch of road,
In the picture above, imagine the long straight line to be the body of your two wheeler. Consider four frictional forces in that figure. Fft and Ffb are the frictional forces at the tyre-road interface and brake respectively for the front wheel. Similarly, Frt and and Frb are the frictional forces at the tyre-road interface and brake respectively for the rear wheel.
In order to slow down the bike, without causing a wheel to lock up, the frictional force at the tyre-road interface must exceed the force applied by the brake at all times. As long as Fft exceeds Ffb, the frictional force at the tyre-road interface will force the tyre to keep rotating. If Ffb becomes higher that Fft, the tyre will simply stop rotating and lock up. This would imply that you should apply equal, but limited pressure on both brakes to brake safely. There is another factor though. The moment you start braking, the body of the bike tends to lurch forward due to inertia. This motion compresses the front shock absorbers and allows the rear shocks to expand. So, once you start braking, the picture changes to this,
Shocks are not perfect, and therefore will transmit force (even though they're supposed to absorb it). Therefore, you now have a state where there is a greater load on the front wheel than there is on the rear wheel. This means that Fft now greatly exceeds Frt. It is easy now to lock up the rear wheel, and correspondingly hard to lock up the front wheel, because the limiting values of Ffb and Frb have also changed.This is the reason why bikes always have a stronger brake on the front wheel. The explanation above holds for dry and wet weather. The correct method for braking therefore, is to start braking with only the rear brake. Once weight transfer to the front begins, slowly start using the front brake, and reduce the pressure on the rear brake. This ensures that you're less likely to lock up either wheel.
Don't Panic
If you understood what I just said, you should be less likely to lock up the front wheel. Rear wheel lock ups are still possible. If you do lock up the rear, whatever you do, don't panic. Because the front wheel still isn't locked, chances are that you'll still be going in a straight line. Gently release the rear brake, more often than not, it'll start rotating again.
Always be prepared to fall. There's no technique in the world that can ensure that you'll never fall. You WILL fall, all you can do is to reduce the frequency. When you are open to the possibility of falling, if you do fall, you'll probably get up, pick up the bike and start riding again. If you believe that you can never fall, when you do, you'll be too stunned to do anything about it.
That does it for my first biking techniques post. Feedback on whether or not that was coherent and understandable is welcome.
Wednesday, 1 July 2009
Whuh!?
The scenario:
Meeting a couple of friends over lunch. Harsh and I decide to give her a framed photo of the three of us, (taken before lunch) after lunch. The plan is laid out, Harsh makes the tricky part of getting her to pose with us for a pic before lunch rather easy. We gave the camera to one of the dudes at the restaurant. He took a decent pic, except for the fact that the three of us didn't really fill up the frame. Then, part 2. I faked a phone call and walked out of the restaurant with the camera in my hand (she didn't notice, yay!). Smooth until now.
I walk unto Main street, and choose to walk into one of the Fotofasts there (there are two, don't ask me why). I spent ten minutes there, just standing, because there was some sort of miscommunication between a customer and the woman in the store and now they were arguing about it. Annoyed by this point, I walked out and walked into the other Fotofast.
I placed an order for the photo we had just taken. I asked her the cost. She told me. Wasn't much, and was appropriate for the size. Then I thought it would be nicer if the photo was cropped, so that we would fill up more of the frame. So I casually asked the woman whether she could crop it. I assumed it would be like 15-20 rupees. She tells another woman there to 'calculate' the cost of cropping an 8x10 photo. I'm already 'wtf' in my head. Cropping is cropping, on a digital image it takes a few seconds to do and is irrespective of the size of the print! After performing her lengthy calculations, she tells me, 'It'll cost you Rs. 226.'
WHAT!?
1. This is robbery because they do not add anything worth Rs. 226 while cropping a DIGITAL photo. It takes a couple of seconds to do.
2. This is robbery because they want to charge for cropping according to the size of the final print!
Meh, I could come up with a hundred reasons why this is robbery. I obviously chose not to be robbed, and asked the thief... err... woman from fotofast to print the photo as is. Result,
I was unintentionally rude (only for a couple of awkward seconds though) to a friend of the recipient (because I was annoyed).
Happily though, the recipient really liked our gift!
Next time you go to get prints, avoid fotofast, the fiends. I find that 1 Hour Photo yields good results and is very affordable too.
Meeting a couple of friends over lunch. Harsh and I decide to give her a framed photo of the three of us, (taken before lunch) after lunch. The plan is laid out, Harsh makes the tricky part of getting her to pose with us for a pic before lunch rather easy. We gave the camera to one of the dudes at the restaurant. He took a decent pic, except for the fact that the three of us didn't really fill up the frame. Then, part 2. I faked a phone call and walked out of the restaurant with the camera in my hand (she didn't notice, yay!). Smooth until now.
I walk unto Main street, and choose to walk into one of the Fotofasts there (there are two, don't ask me why). I spent ten minutes there, just standing, because there was some sort of miscommunication between a customer and the woman in the store and now they were arguing about it. Annoyed by this point, I walked out and walked into the other Fotofast.
I placed an order for the photo we had just taken. I asked her the cost. She told me. Wasn't much, and was appropriate for the size. Then I thought it would be nicer if the photo was cropped, so that we would fill up more of the frame. So I casually asked the woman whether she could crop it. I assumed it would be like 15-20 rupees. She tells another woman there to 'calculate' the cost of cropping an 8x10 photo. I'm already 'wtf' in my head. Cropping is cropping, on a digital image it takes a few seconds to do and is irrespective of the size of the print! After performing her lengthy calculations, she tells me, 'It'll cost you Rs. 226.'
WHAT!?
1. This is robbery because they do not add anything worth Rs. 226 while cropping a DIGITAL photo. It takes a couple of seconds to do.
2. This is robbery because they want to charge for cropping according to the size of the final print!
Meh, I could come up with a hundred reasons why this is robbery. I obviously chose not to be robbed, and asked the thief... err... woman from fotofast to print the photo as is. Result,
I was unintentionally rude (only for a couple of awkward seconds though) to a friend of the recipient (because I was annoyed).
Happily though, the recipient really liked our gift!
Next time you go to get prints, avoid fotofast, the fiends. I find that 1 Hour Photo yields good results and is very affordable too.
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