dynaryder

https://www.motortrend.com/roadtests/...data_cont.html

'98 Corolla,132ft.

I-Like-To-Bike

You are giving advice to report no injury, no damage reports to the police, and expecting results.
BTW, Covered for/from what exactly?
If you discover significant "damage" later to your bike, the obvious retort is that the "damage" was either pre-existing or happened after the accident. Good luck with your "coverage".
As I guessed you have never put your own advice into practice to see the results.

ROJA

Keep in mind that real-world braking distances are much longer, due to reaction time and lack of skill on the part of many drivers (especially those who do not know how to threshold brake, for non-ABS cars, or properly use ABS, for ABS-equipped cars). Although your car can stop from 60 in 120 feet, most drivers on the road would not be able to come close to that figure in a real-world panic situation.

wickedcold

I realize what you're saying, but reaction time between a bike rider and a driver is going to be pretty much the same and therefore irrelevant to the argument here.

As far as skill, I would wager a guess that 95% of the cars on the road now have ABS and it is stupid simple to operate. No skill required. Just stomp on the pedal. Hard.

genec

Well if you estimated 120 feet, and left room for 120 feet, then like the driver that hit the OP, you too would have crashed 3 feet into him.

Yeah it was a bit of a jab... I see far too many motorists out there that have no idea of the 2 second rule or keeping a safe following distance. Perhaps they too are "hyper aware" of their stopping distance... + 3 feet.

Oh and that stopping distance is no doubt based on dry clean pavement, near new tires and brakes...

genec

And sadly that is about how ~80% of motorists drive... stomp the gas hard, drive right up to the red light, stomp the brake hard...

"Gee, I don't get anywhere near that mileage... and my brakes wear out soooo fast... "

dougmc

Assuming constant acceleration, a 60 mph initial speed and stopping in 120 feet, that works out to 9.83 m/s^2 -- almost exactly the acceleration due to gravity. (The formula is acceleration= 1/2 * speed^2 / distance. You can let google do the heavy lifting for you like this, if you wish.

It's possible, but not likely for a real-world car under real-world conditions. But it's not too far from more likely values. (And of course we're ignoring reaction times, but a bicycle would have a similar reaction time, unless your hands aren't already on the brakes, in which case your reaction time is slower ...)

And yes, a car can stop faster than a bike, and the biggest reason is that a bike will flip if stopped too quickly. (Though I think a standard bike can do better a little better than 0.5 g if the rider stops crouching and instead shifts his weight back as far as he can, and LWB recumbents are harder to flip as well.)

But while the difference is significant (with cars perhaps panic-stopping something around 40% faster), it's not really *that* big, and it really isn't the reason that bicycles don't usually have brake lights. Bicycles don't have brake lights (or turn lights, for that matter) because they're supposed to be simple, and they don't usually go that fast anyways. And besides, hand signals are usually adequate. (Counter example: when you're braking hard, most of the braking comes from your front brake, usually controlled by your left hand, the one you're supposed to be signaling with. Well, to me, any need for hard braking (and staying in control during it) trumps signaling, and I doubt I'm alone there.)

Doohickie

This is a lot different from my experience. Most cars stop a full car length or more behind me at a red light, especially in left turn lanes. I almost want to tell them to squeeze up behind me to make sure they trip the trigger for the light.

10 Wheels

I experience the same thing.
Most of the time I motion for them to move up. Some of them will.

The Paper Boy

Force = Mass x Acceleration

Simple physics chum. If you want to (de)accelerate a body, the force applied is in direct proportion to the mass.

Takes a ****load more energy to stop a 20 ton truck than a 20 lb bike, assuming both are moving at the same speed and the stopping distance is equal.

justin70

The argument really revolves around how well the brakes can apply that force to negatively accelerate either vehicle. I think the posters who claim that bikes have longer stopping distances are making those statements with respect to the quality of brakes found on a car vs a bicycle; that is, the car's brakes work much better than the bicycle's secondary to their inherent design.

dougmc

Yes, Newton was a wise man. But that formula is only a part of the picture when you're trying to stop.

Ultimately, both the brakes on a car and those on a bike are usually good enough that the brakes are no longer what keeps you from stopping more quickly. Instead, what limits your braking ability is the traction of your wheels (in a car) or how hard you can apply the brakes before you flip (in a bike.) Putting better brakes on usually won't help, because they're usually not the limiting factor. (Now, if they are the limiting factor, then by all means, replace them.)

If the weight of your vehicle doubles, then the force required to give you a given deacceleration doubles as well -- we get this from the formula you so thoughtfully provided. However, doubling the weight also doubles the force exerted by gravity, and so it doubles the force between your tires and the road. So, assuming that you brakes can handle it (and in general, in a car, they are capable of locking the wheels even while carrying the maximum load the car is designed to carry), your stopping distance is still approximately the same. Do you remember the coefficient of friction from physics class? (Note that I'm ignoring things like aerodynamic effects -- at maximum braking, their effects are usually much smaller than the other factors, at least for non-race cars.)

Now, I did say approximately. The coefficient of friction isn't really a constant in the real world -- it's fairly constant for metal on metal, but for rubber on concrete it's not quite so neat. Wide rubber tires on a car will often help it stop faster than narrow rubber tires. But the difference is far smaller than the difference between the widths of the tire.

As for a bike, if you put the extra weight on the back where it helps the bike not flip over, adding that extra weight may actually help it stop faster. If you put enough weight on the back, or made the bike longer (like a 'bent or a tandem) or kept the center of gravity low enough, you may actually find that the traction of the front wheel could become the limiting factor -- and once you reach that point, you'll probably find that the bicycle can stop almost as quickly as a car. (Though the higher tire pressure probably means that the bike still has more weight per square inch of rubber on the road, so the car will probably still stop slightly faster than that bicycle. And of course, you can safely bring a car closer to the point of skidding, because it won't fall over if it skids.)

Heatherbikes

I got hit a couple of years ago while riding home in the dark. I was lit up like Las Vegas! Luckily my paniers were stuffed which took the brunt of the hit. I was in utter shock but there was no damage other than a scrape on the paniers and I think my leg hurt for awhile... The driver was an old man who took off in a hurry before I could do anything. In Canada if you ride a bike it is considered a vehicle so you have to follow the rules of the road. However I'd say most drivers are completely unaware of this. I ride on the shoulder as much as possible, in fact that is all that one can do where I live because it is all highway and rural unlit roads. I occasionally see cyclists trying to take the lane and pray for their safety.
But can you really get brake lights for a bike?!

wickedcold

Yes, that is precisely the point I was making.

dougmc

Yes, you can. And even if you couldn't, they wouldn't be hard to make yourself.

Now, I'm not sure how useful they'd be, but you can certainly buy them easily enough.

riva

What doug and wickedcold said. If you're in the average car, braking is limited by tires. Bike with decent brakes and tires, limited by wheelbase.

bikesafer

I am not giving advice, I'm simply stating what I would do in that situation. Also, I was not "expecting" anything, I just said I would report any accident so there is a record if something would come up later. I'm not quite sure what you mean by my "coverage" but as far as never putting my advice into practice, I've thankfully never been hit in such a way that could result in any damage to me or my bike.

I-Like-To-Bike

Fair enuff. My advice/comment is that if you don't mind wasting your time, do what you want if you end up in that situation. What you expect to be "covered," by reporting no-harm-events as accidents to the police, is still a mystery.

dogbitteneear

Did you happen to get the tag number from the offenders' car. If so go to the State insurance
commissioners office and report him through there. By the way did you happen to exchange
info as required in any accident?
dogbitteneear

dogbitteneear

I have had problems with being at a stop light and the sensors not working.
Anyone have any suggestions?
dogbitteneear

bkrownd

the basic idea

riva

Get a couple magnets and zip tie them to the bottom of your pedals.

Chris516

I am 50/50 on how close a motorist stops behind me. Last night(around 6pm EST), it wasn't quite pitch black. But, It definitely was dark. I had two back lights flashing red. Yet, There was a motorist, less than 5ft. from my back wheel. I was extremely glad I didn't have to hit the brakes. Because, Almost assuredly, I would have ended up in the hospital. It almost felt like the guy was after me. Since I was going 20-25mph. The faster I went, never widened the distance between the motorist n' I.

oboeguy

It's more fun to get rear-ended while in motion. By a couple of former bike messengers cruising in a car. Yeah. Tacoed wheel but I was otherwise OK. This was more than 10 years ago, getting off the Brooklyn Bridge (Manhattan side).

Ahem. As for the whole turn signal and brake light business, I use hand signals with great success all the time.

hotbike

There are three ways to make a left turn. You can cross at the crosswalk(s), stay to the right and cross one street and then the other, or use the left turn lane (as you were attempting to do).

I would not use the left turn lane unless it was open, free of motor vehicles.

And if I was stuck in a predicament like you describe, I would have finished the turn, despite the light being red.