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BicycleSource Newsletter


Don't lock your wheels

When the brakes on a car are merely close to locking, the braking force is some 30% greater than when the brake is fully applied, locking the wheels in a sliding, screeching, smoke-belching stop. Locked wheels slow down the car so much less quickly because the braking surface is the pavement and a film of molten rubber where the tire contacts it, rather than carefully-engineered brake pads and special discs.

For those with smooth road tires, and especially for tubular racing tires, locking your wheels means melting all that expensive rubber onto the road behind you. A while ago a valve on my tubular rear tire became leaky, and I had to remove it after a few months of use. First, be aware that I had been really gentle with my tires, virtually never locking them when braking. When I did, I noticed that there were about a half dozen splotches where the tread was melted right off, in some cases nearly down to the airtight fabric!

Locked wheels are also terrible for steering and control. You will skid and slide, and at all the worst times.

Don't be Afraid of Using your Front Brake

When at speed and on a properly set-up bike (bending forward and with a low center of gravity), I've never heard of someone doing an end-over by locking their front wheel. Indeed, a good brake should not lock unless you're really trying to lock it (an excellent reason to shell out for expensive brakes).

Your front brakes provide 75% of your braking power, and are more difficult to lock, and won't let your back slide about behind you. On the other hand, you are right to shy away from the front brake when going down a steep hill, especially slowly or on a bike where you sit upright (get a new bike if you do), or if you are turning and need the control.

When you brake, weight transfers from the rear wheel to the front. If you try hard enough and have enough strength in your hands, you can lock any front brake, and braking as quickly as possible without locking the wheels is the goal of any emergency stop. The trick is to know when you you are squeezing as hard as you can short of initiating a pitchover. On a bike with typical geometry, this point will be reached when the cyclist attempts to decelerate at more than 0.67 gees, or to slow by more than 23.6 kph in one second.

To stop as quickly as possible, squeeze your rear brake lever with moderate force and your front lever firmly, aiming for a 3:1 ratio of front brake force to rear brake force. Listen and feel for your rear tire: when it starts to skid, you know that you've lost almost all weight on your rear wheel. When this happens, ease off on your front brake until enough weight is on the back wheel to keep it on the ground, with enough traction and stop the skid.

Put Weight on your Wheels

If you are about to do hard braking with your front wheel, slide back as far as you can, even moving right off the saddle. The limits to the farthest back you can safely ride are to still be able to hold the bars and brakes and be able to steer with some traction. As you ride over slumps and bumps, you'll have to predict to keep in the optimal position before the conditions change.

The more weight on your rear wheel, the harder you can brake before enough weight is transferred to the front to pitch over, and the more traction it will get with the ground, turning or locked. Try the opposite effect by locking your back wheel while leaning on the front -- stopping will take forever, and it will sure make a mess of the Jonses lawn.

Especially for those with dropped handlebars, put weight on your pedals instead of your arms when stopping, especially when stopping with your front brakes. This puts more weight on the rear wheel, and lowers your center of gravity for better steering and stability.

In similar vein, those with dropped bars will want to move to the drops at the first sign of trouble or when descending, as much more leverage is available than when riding with your hands on the hoods. You'll want to use every bit of that extra leverage when riding on roads, where the otherwise tiny risk of endoing is all but nonexistant.

Dodge

Some 80% of all bicycle accidents involve a rider running into something else (usually a car who had just made a traffic violation). In many of these cases, and indeed in many car accidents, braking wasn't the answer (as the rider found out!), but rather steering was the best way to avoid a collision. Especially when in traffic or elsewhere with many unexpected surprises, keep an escape route in mind at all time, so you can quickly veer onto the shoulder or sidewalk should a car appear right in front of you.

If you're braking but it's clear that you won't be able to stop before you hit that truck, then accept that, ease off the brakes to get control of the bike, and steer around it. Easing off to moderate braking is critical, as full braking uses up all of you traction for stopping, making a mess of attempted turns. Whatever you do, don't panic and keep sliding forward until you find yourself sprawled over the hood -- or worse yet, in the hospital.

Choose your Terrain

Especially if your idea of braking is seizing up your wheels, the surface you ride on will make a big difference in the efficiency, safety and stability of braking. Try to choose the smoothest surface with the highest friction and the fewest obstacles.

Slippery, low-friction surfaces abound, so avoid them. Sand and gravel, especially if they're covering a hard surface, are just terrible for turning and braking. The oil slicks on roads, made by many cars braking or making hard turns, can send you sliding into an intersection or right of the road. Oil in the pavement, and oil on top of it, mix with the first rain that falls until it is washed away, making a very slippery surface that can't be easily avoided. Wet cobblestones are terrible even for walking, let alone braking. Wet autumn leaves and wet manhole covers or steel plates should also be avoided when braking or turning, or indeed riding in general.

If you see a region of poor terrain approaching, try to get in all of the braking you can before you reach it, then reduce your braking force to what the new terrain can endure. When stopping hard, turning to avoid the poor terrain is not really an option, so steer straight unless you can ease off your brakes for the steering traction needed to dodge.

Brake Before you Turn

Braking with your front wheel seriously reduces your ability to make corners at the same time. If your front wheel skids due to braking or terrain (sand on the pavement, for example), your bike will follow its momentum instead of its front wheel, and will understeer. Your front brakes provide 70% of your stopping power, and usually work better to boot, so being stuck with only your rear brakes is a nuisance indeed.

The solution, of course, in to do the braking before your turn, and ease off of the front (and back, if you can) brakes as you begin the turn. The extra turning power and stability will allow you to make the turn more quickly, more than offsetting a slower approach.

For more on slowing down for turns, check out our high-speed cornering article.

Learn to Pulse

When riding in the rain, apply your brakes lightly every half minute or so to keep them clear of water. Wet rims, unless you've bought special brake shoes (you probably haven't) will make stopping a disaster, especially when you overcompensate for the slick rims and lock your wheels on wet pavement.

Pulse your brakes on long downhills, don't ride the brakes all the way down. If there's traffic ahead or you want to take it easy, let the bike accelerate, then slow it down, then let it go again.

Aside from eating your brake pads and rims, steady braking cooks the rim to obscene temperatures. With tires inflated near their maximum pressure, or on glued-on tubular tires (!), you definitely want to minimise the time spent on the brakes, especially with that bump in the pavement or mach-speed bend at the bottom...

Get Accustomed

When riding in the rain, snow, or in otherwise unusual conditions, try your brakes out to get a feel for the road. Not only will it let you avoid locking your wheels and help to maintain control, but it will let you judge intuitively how long it will take to stop, and thus if you should dodge, brake, or bail (or when to start shouting to get the hell outta the way).

Don't Try this at Home...

If you have no choice but to stop as quickly as possible from a moderate speed, twist the front wheel as you pull the brakes. The wheel and fork will buckle, melting your bike into the road in a controlled crash.
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