frenar en bici

8/14/2019 Frenar en Bici

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Braking and Turning Your Bicycle

Braking--Front, Rear or Both?

Since your bike has two brakes, one for each hand, if you want to stop as safely as possible, you need to pay attention to how you use each of them.

Conventional Wisdom

Conventional wisdom says to use both brakes at the same time. This is probably goodadvice for beginners, who have not yet learned to use their brakes skillfully, but if youdon't graduate past this stage, you will never be able to stop as short safely as a cyclistwho has learned to use the front brake by itself.

Maximum Deceleration--Emergency to!s

The fastest that you can stop any bike of normal wheelbase is to apply the front brake sohard that the rear wheel is ust about to lift off the ground. !n this situation, the rearwheel cannot contribute to stopping power, since it has no traction.

Won"t # $o %ver &he Bars?

The rear brake is ".#. for situations where traction is poor, or for when your front tire blows, but for stopping on dry pavement, the front brake alone provides the ma$imumstopping power, both in theory and in practice.

!f you take the time to learn to use the front brake correctly, you will be a safer cyclist.

%any cyclists shy away from using the front brake, due to fear of flying over thehandlebars. This does happen, but mainly to people who have not learned to modulatethe front brake.

The cyclist who relies on the rear brake for general stopping can get by until anemergency arises, and, in a panic, he or she grabs the unfamiliar front brake as well asthe rear, for e$tra stopping power. This can cause the classic &over the bars& crash.

obst Brandt has a (uite plausible theory that the typical &over)the)bars& crash is caused,not so much by braking too hard, but by braking hard without using the rider's arms to

brace against the deceleration* The bike stops, the rider keeps going until the rider'sthighs bump into the handlebars, and the bike, which is no longer supporting the weightof the rider, flips.

This cannot happen when you are using only the rear brake, because as soon as the rearwheel starts to lift, the rear wheel skids, limiting its braking force. +nfortunately,though, it takes twice as long to stop with the rear brake alone as with the front brakealone, so reliance on the rear brake is unsafe for cyclists who ever go fast. !t is

important to use your arms to brace yourself securely during hard braking, to preventthis. !ndeed, good techni(ue involves moving back on your saddle as far as you can


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comfortably go, to keep the center of gravity as far back as possible. This applieswhether you are using the front, rear or both brakes. +sing both brakes together cancause &fishtailing.& !f the rear wheel skids while braking force is also being applied tothe front, the rear of the bike will tend to swing past the front, since the front is applyinga greater decelerating force than the rear. "nce the rear tire starts to skid, it can move

sideways as easily as forward.

!f you don't believe me, perhaps ohn orester can convince you...see his -ntry in therec.bicycles / on ront Brake +sage 0Sub ect* 1.234. 0+nfortunately, the maintainerof that site has a habit of breaking links, so you may need to go to the rec.bicycles /inde$ to find the article.4 "r read ohn llen's advice .

Skidding the rear wheel also wears the rear tire very (uickly. single rear)brake)onlystop from 56 km7h 086 mph4 with a locked rear wheel can wear the tread of a road tireright down to the fabric9

'earning to (se &he Front Brake

%a$imum braking occurs when the front brake is applied so hard that the rear wheel is ust about to lift off. t that point, the slightest amount of rear brake will cause the rearwheel to skid.

!f you ride a conventional bike, the best way to master the use of your front brake is to practice in a parking lot or other safe space, applying both brakes at once, but puttingmost of the effort into the front brake. #eep pedaling as you brake, so that your legs willtell you immediately when the rear wheel starts to skid. S(uee:e, don't grab, the brake

levers, so you can sense when this happens. ;ractice harder and harder stops, so that youwill learn the feel of stopping fast, on the edge of rear)wheel liftoff.

Test the brakes in this way whenever you are about to ride an unfamiliar bike. Some brakes are more sensitive than others, and you need to know the &feel& of the brakes.

"nce you are comfortable with the front brake, also practice releasing the brakes torecover control, until this is an automatic, refle$ action. t a very low speed, apply the

brakes hard enough that the rear wheel skids, or ust begins to lift.


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Skilled cyclists use the front brake alone probably 15? of the time, but there areinstances when the rear brake is preferred*

Slippery surfaces. "n good, dry pavement, unless leaning in a turn, it isimpossible to skid the front wheel by braking. "n slippery surfaces, however, itis possible. front wheel skid almost always leads to a fall, so if there is a high

risk of skidding, you're better off controlling your speed with the rear brake. Bumpy surfaces. "n rough surfaces, your wheels may actually bounce up into

the air. !f there is a chance of this, don't use the front brake. !f you ride into a bump while applying the front brake, the bicycle will have a harder timemounting the bump. !f you apply the front brake while the wheel is airborne, itwill stop, and coming down on a stopped front wheel is a @ery Bad Thing.

ront flat. !f you have tire blowout or a sudden flat on the front wheel, youshould use the rear brake alone to bring yourself to a safe stop. Braking a wheelthat has a deflated tire can cause the tire to come off the rim, and is likely tocause a crash.

Broken cable...or other failure of the front brake.

When to (se Both Brakes &ogether

=enerally ! advise against using both brakes at the same time. There are e$ceptions,however*

!f the front brake is not sufficiently powerful to lift the rear wheel, the rear brakecan help, but the best thing to do is to repair the front brake.

Typical rim brakes lose a great deal of their effectiveness when the rims are wet,so using them both together can reduce stopping distances.

!f the front brake grabs or chatters so you can not modulate it smoothly, youmust only use it lightly. gain, repair is in order.

"n long, straight mountain descents, your front brake hand may get tired, or youmay be at risk of overheating a tire and blowing it out, so it is best to spread thework between both brakes. ;umping the brakes, alternating between one and theother, will briefly heat the surface of each rim more and dissipate more heat

before it spreads inwards to the tires.


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Which Brake Which ide?

There is considerable disagreement as to which brake should be connected to whichlever*

Some cyclists say it is best to have the stronger right hand 0presuming a right)

handed cyclist4 operate the rear brake. %otorcycles always have the right hand control the front brake, so cyclists who

are also motorcyclists often prefer this setup. moment of confusion in anemergency situation can be deadly. The left lever on a motorcycle operates theclutch, which will not stop you9

There are also observable national trends* !n countries where vehicles drive on the right, it is common to set the brakes up

so that the front brake is operated by the left lever. !n countries where vehicles drive on the left, it is common to set the brakes up so

that the front brake is operated by the right lever. The -uropean +nion hasadopted this as a standard, even though only the +nited #ingdom and !relandare left)side driving countries. The standard is not universally observed a readerhas written in to say that the left lever usually controls the front brake in

enmark.

The theory that seems most probable to me is that the national standards arose from aconcern that the cyclist be able to make hand signals, and still be able to reach the

primary brake. This logical idea is, unfortunately, accompanied by the incorrect premisethat the rear brake is the primary brake.

or this reason, ! set my own bikes up so that the right hand controls the front brake,which is not the norm in the +.S.

! also do this because !'m right)handed, and wish to have my more skillful hand operatethe more critical brake.

"n the other hand, if you have already developed a preference, it is usually best to stickwith it )) or at least, choose a few weeks of riding under undemanding conditions toretrain your refle$es. !n an emergency, you must act faster than you can think. !f youswitch between a %ac and a


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To turn a bicycle, you must lean inward toward the direction of the turn. The faster youare going, and the sharper the turn, the more you must lean. You have no choice aboutthis, for a given speed and turn radius, the center of gravity of the bike7rider must bemoved sideways a particular amount or the bicycle will not balance.


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handling characteristics of the bicycle, and makes a skid less likely. You canverify this yourself by performing an e$periment suggested by obst Brandt *

&Some riders believe that sticking out their knee or leaning their body away fromthe bike, improves cornering. Sticking out a knee is the same thing that riders

without cleats do when they stick out a foot in dirt track motorcycle fashion. !t isa useless but reassuring gesture that, on uneven roads, actually works againstyou. ny body weight that is not centered over the bicycle 0leaning the bike orsticking out a knee4 puts a side load on the bicycle, and side loads cause steeringmotions if the road is not smooth. =etting weight off the saddle is also mademore difficult by such maneuvers.

&To verify this, ride down a straight but rough road standing on one pedal withthe bike slanted, and note how the bike follows an erratic line. !n contrast, if youride centered on the bike you can ride no)hands perfectly straight over roughroad.


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unlikely on a bicycle that is in good repair, ridden by a cyclist who has learned to usethe front brake sensitively.

The danger is more real for bicycles with damaged rims, or mis)ad usted brakes. Thedanger is even greater for the cyclist who habitually relies on the rear brake alone when

suddenly faced with the need for a panic stop. panicky rider who is unused to thefront brake may indeed grab it full)force as a last resort, and may take a header.

!f you will forgive an automotive analogy in these green pages, a driver who has neverdriven a car with power brakes is likely to skid a few times the first time he or she triesdriving a car that has them. This does not mean that there is something wrong with

power brakes, however, it means that the driver needs to learn how to use them.

! fre(uently ride a fi$ed)gear bike with a front brake only. This is an e$cellent way tolearn subtle control of the front brake, as the fi$ed gear gives very good feedback of thetraction available at the rear wheel.

!n the early 'J6s, ! became infatuated with mountain bike riding in the woods, andcompletely re)adapted my braking style to cope with the loose surfaces common onwoods trails.

!n 21JJ, ! moved to rance for a year, and got back into road riding. Fear my house wasa wonderful bit of road down the side of a valley, called Aa >oute des Sept Tournants. !tis a series of sweeping switch backs, beautifully paved, very well engineered. ! used todescend it regularly on one of my favorite loops. The problem was, ! could never reallygo fast down it, ! always felt that ! was on the verge of losing traction with my rearwheel and spinning out. fter a few months of this, ! was beginning to conclude that !had ust become a coward as ! reached middle age. ! remembered ! used to go fasteraround similar bends on my old fi$ed gear with no rear brake))))wait a minute, maybethat's it9 The ne$t time ! went that way, ! decided not to use my rear brake unless ! felt !really needed it))! would ust go slowly at first, only as fast as ! felt comfortable withusing the front brake alone.

%irable dictu, ! found that ! was my old self again9 !t had indeed been the rear wheelthat was on the verge of slipping, and only because ! was using its brake.


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while doing this, the braking force e$erts a steering force through the now off)centerheadset. obst Brandt has an e$cellent way of proving this to yourself* try riding down astraight, but bumpy stretch of road while leaning the bike to one side and your body tothe other. !f you are brave, try applying the front brake very gently.

! must admit to a bit of ambivalence as to whether a government body should tell peoplehow to set up their bicycles. !n the +.S. ., de)facto government regulation has madeleft)front all but compulsory for new bikes to be sold. ! strongly ob ect to this. ! oncehad a near)accident as a result* ! was riding an unfamiliar bike that was set up left)front,even though ! am used to right)front. ! came to an intersection, a car cut me off, !instinctively grabbed with my right hand. Since this was the rear brake, ! was only

barely able to stop in time9

! will add one further reason for preferring the right)front setup* %ost people are righthanded. ! think we can all agree that the front brake re(uires more skill than the reartherefore, it should be assigned to the more skillful hand.

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