korean

What is the most effective way of braking from a high speed?

aggro_jo

pull the levers back towards you.

you're welcome

robbie_vlad

This, but not so much that you lock-up and start to skid, that will just make your stopping distance increase.

roadiejorge 

Well if you've sorted out how to pedal then I'm assuming you get the concept of braking, now define "emergency" or do you mean the right technique to slow down while on a descent?

rumrunn6

had to do it today. get up on the pedals and shift your body weight as far back ass possible without losing the saddle and press both front and back brakes firmly applying increasing pressure as you gauge your stopping distance and remaining pavement before doom. it's not a bad idea to have a plan "B" in case of catastrophic brake failure or in case your stopping distance exceeds your remaining pavement before doom. a plan "B" would be how to divert your trajectory to avoid the doom, or somehow bail off the bike entirely. I never had to use a plan "B" that I recall, but then I tend to block out bad memories ...

4000Miles

The above, plus I would highly recommend unclipping if you have the presence of mind to do so...

korean

i've driven motorcycles before and hard braking is a tedious art.

once you lock up the rears, you have to stay committed or you'll wiggle and likely top side.

once you lock up the fronts, you're... screwed.

is it the same on a bicycle?

furballi

Lock both hands on the handlebar so you don't flip over. Lean back as far as you can. Apply only the front brake and modulate it so that the rear wheel is barely making contact with the road. Practice this in a large parking lot. Shoot for 1 ft stopping distance for each mph. I'm right-handed, so I set my front brake lever on the right side. I only use the rear brake when coasting to a stop.

korean

why wouldn't you use the rear brake?

wens

At maximum braking, assuming you reach that when you would endo and skidding doesn't occur, there's 0 weight on the rear tire, so no braking force is possible. You'll just lock up the rear tire, which might cause it to whip around sideways.

furballi

That's why it's best to stay off the rear brake during an emergency stop. The front brake is strong enough to flip the bike. +70% of the braking power comes from the front. As you quickly ramp up front brake pressure, the down-force at the rear wheel will also drop quickly to zero, which can often result in sudden rear wheel lock-up if you apply the rear brake, sending the bike into a fish-tail.

rollin

Balance the brakes. Three or four times as much squeeze on the front than the back. Back may lock up, no big issue. Front does most of the work but if your front wheel locks you'll be doing well to stay upright.

Practice.

Enjoy!

chasm54

All of the above with one qualification. If the surface is poor - wet, gravelly, or slippery for any other reason - that's the only time to give more emphasis to the back brake. You might be able to control a back wheel skid, but if you lose the front wheel you're gone.

merlinextraligh

It isn't the same on a bike, because the weight and torque are different.

You can easily modulate the rear brake, and let off when it begins to skid without top siding.

rm -rf

Yes, I've grabbed both brakes in panic stop situation, and the back wheel locked up. Then it can slide sideways very easily, so I was fishtailing until I let off both brakes for an instant. (I could have just let off the back, but a panic stop with fishtailing added on doesn't help with decision making)

So, both brakes in a normal stop, but front only for a maximum braking effort. And get back on the saddle and brace your arms so you will stay back.

This all applies to straight line braking. I still involuntarily brake in a sharper than expected turn. The best strategy is to brake before the turn, then let off, so the tires can use all their traction to follow the curve.

carpediemracing 

1. Drops. If you think you may be getting into a dicey situation, get into the drops first.

2. Brake both brakes hard and even. When the rear starts to get light or lift, you've reached maximum braking. This does NOT include steering, i.e. if you need to turn also then you can't use this general rule.

If you don't turn and you're reasonably stable, you can "stoppie", i.e. slow hard with rear wheel in air.

3. If you need to turn, ease on the brakes, turn, and brake again.

4. If you lock the front, get off of the front brake immediately, unless you feel supremely confident, you zen out and know you can make it, or can't think that fast.

cdr

merlinextraligh

This is why you push your weight back. Butt cantilevered just above the rear wheel,and chest on the seat, you are not going to flip the bike, and you'll have enough weight on the back wheel to get some effective braking force.

You're right that most of the braking force comes from the front wheel, but in a true emergency situation where a foot of stopping distance could be life or death, you want all the braking force you can get.

And if you've ever mountain biked, correcting from a locked rear tire is not that big of deal.

rumrunn6

when you get up on the pedals you lower your center of gravity and so that's why there's is still a benefit from using the rear brake

rumrunn6

in winter (snow and ice) you use just the back brake. same can be said for a sandy road

merlinextraligh

The problem with argument is that it assumes that maximum braking force of the front tire is limited by endo'ing, which it is not.

Maximum braking force occurs just before the tire skids. You can easily skid a front tire without endo'ing simply by pushing your weight back.

So you can have the front wheel at the threshold of locking,and still have weight on the rear wheel, allowing some additional braking force to be added by the rear brake.

furballi

Experience cyclists also go with a larger front tire on their road bikes. As the weight transfers from the back to the front, the larger contact patch of the front tire gives you much shorter stopping distance. I've done the dual brakes modulation, but the shortest emergency stopping distance for me is always with the front brake. I can flip the bike 1/2 second into braking. That too fast for any human to modulate the rear brake. Normal reaction time is 0.1 second.

If you don't have a powerful front brake that could quickly lock the front wheel, then you should use both brakes to stop. Always slow down way down on slippery surface.

rumrunn6

re: motorcycle same as bike. yes. you can skid the rear and stay in control but once you lock up and skid the front you've lost steering.

merlinextraligh

You realize you are contradicting yourself here. In the lower part of this post,and in your previous post, you imply that front braking force is limited by the point at which the bike endo's. Thus a larger front wheel, giving a larger contact patch will do nothing for stopping distance, because you're still limited by the rate of acceleration that flips the bike, by your assumption.


If you're flipping the bike you're not doing it right. Push your weight way back, and I guarantee you the front wheel will skid before the bike flips.

Phantoj

No, I think max. braking force is endo limited. Jobst Brandt says it's at around 0.6g (not very much, really). Except on tandems and recumbents, or on dicey surfaces. If you can skid a front tire "easily", please post to youtube...



PS -- I have recovered from a front wheel slide when I hit a frost patch while braking, not sure what that proves, though.

merlinextraligh

I think the big difference with a motorcycle is if you lock the rear wheel, then let off the rear brake, regain traction, while power is still being applied to the rear wheel, it often leads to a high side, which can be very bad at motorcycle speeds. Hence the hesitancy to use rear brake on a Motorcycle.

A bicycle doesn't have the same problem with a sudden application of power as the rear wheel regains traction.