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 V-brake setup/tuning guide

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kam0t3
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PostSubject: V-brake setup/tuning guide   Fri May 30, 2008 4:28 pm

malamang marami na sa atin ang nakabasa nito. pero post ko pa rin.
medyo mahaba lng. Enjoy!

from: Trials-Online.com FAQ

==========================================================
Many times I hear from noobs and experienced riders alike that they have problems getting brakes to lock. This, it seems, is one of the most common problems encountered in biketrials. Since most of us come from other forms of biking, usually mountain biking, we end up with a V-brake equipped "starter" bike. The exception would be discs and HS33, of course, but as far as rim brakes go, we're pretty much running V's. The reason so many people have problems locking their V-brakes up is not what is often blamed. "My brakes are teh poo!!!" is the common thing that's said. In reality, your brakes are not poo. Even the most low end brakes can be set up to work for trials. Brake system quality really does begin to matter when a rider gets into higher levels of riding, but for beginner/intermediate level riders, just about any V-brake on the planet can be made to work, some better than others, but nearly all can achieve reasonable lockup with one finger.

Before we begin, I will give you an example. I am anything but your average trials rider. I weight 250lbs and I ride with a lot of BMX influence. BMX riding is quite a bit different than trials in the fact that BMX responds well to what I like to describe as "Angry Gorilla" style. Basically pure power riding, getting things done by brute force. My size, power and aggressiveness make me among the biggest and angriest gorillas you'll ever see on a bike. Everything on my bike is built up so tuff that it can survive a direct hit by a 10 mile wide asteroid. When it all ends, there will be cockroaches and my bike left standing.

So, what brings my big nutty self to an instant stop when I need to hit an edge and not loop out? The answer may surprise you. I run a set of old Tektro OEM brakes that came on a low end '01 GT XC bike. After a year my back brake is still perfectly functional and I get a good solid positive lock. My front brake of the same type finally died when I stripped out the brake cable retaining bolt hole while doing a fork swap, and I was forced to put on a set of Wal-Mart quality brakes of approximately '98 vinatge. The levers I use are OEM Tektro off the low end GT. "What? How does that work?" you wonder? Setup: it's all in the setup.
The Setup

The cool (and oftentimes frustrating) thing about V-brakes is that they have a lot of latitude for adjustment and tuning to suit different riding conditions. There are several things that can be adjusted to completely change the braking characteristics of a set of brakes. Since most of us start trials on our XC bikes, let's look at the typical XC setup.
XC brake setup

Most XC bikes are set up to use 2 finger braking and to have good modulation. Both things that are detrimental to trials. On XC bikes, a 23" wide flat bar is the norm. After putting grips and shift levers on a narrow bar, there's not a whole lot of room left for brakes. This is one of the big advantages of running a wide trials bar. I found on the standard 23" bar that comes on nearly every XC bike the brakes can only be moved in towards the stem slightly. Also for XC, we want good modulation, and we DON'T want brakelock. Brakelock on singletrack means skidding and skidding on trails is bad. Brakelock up front is REALLY bad for obvious reasons. To achieve good modulation the brake pads are set up with the nose (the part of the pad pointing backwards against the rotation direction) of the brake pad "toed in" to the rim. This is done for several reasons. First, it prevents squeal and brake noise. Secondly, the nose hitting first provides light braking and as you squeeze harder the braking increases as the pad flexes and more of it's surface contacts the rim. This is where all that modulation comes from. Third, the toed-in nose serves to clear mud, dirt, dust, water, bear poo, or whatever you run over off the rim before it gets trapped under the brake pad. Some pads have little extended nose pieces called "scrapers" that aid in water and mud removal. Add this to the 2 finger setup which reduces leverage (explanation of leverage comes later) and makes you have to pull real hard to lock. This setup works great on XC, lets you apply "enough" braking at any point, and prevents you from accidentally skidding or pitching yourself over the bars. For trials though, this is a setup far from adequate.
Trials brake setup

Okay, time for the "fun" part, trials, YAY!!! Trials is the opposite of XC when it comes to brake performance. Unless you're manualing modulation is essentially a bad thing. You want some modulation up front but in the back, you really want to achieve a brake that works like an on/off switch. To visualize why, picture landing a gap to rear on a skinny with brakes that modulate well. OUCH!

Hopefully by now you also found out that wide bars are essential for trials success, and here's where it can actually affect your braking, lever position. Good braking begins at your fingertips, literally. Brake levers that are out of position even slightly can cause brake perfomance to suffer drastically. This is one of the most important aspects overall of good brake performance. For trials, you want to use one finger braking. Your index finger should interface with the brake lever between the first and second knuckle (I will refer to this hereafter as the interface zone) and your middle finger should remain securely wrapped around the grip. Lever placement is critical for achieving this. The lever should be positioned so that with your wrists in neutral riding position you just comfortably rest your interface zone on the brake lever. The levers should be far enough inward of the grips so that your index finger must reach inward to grab the brake. The middle finger knuckle should not be under any part of the brake lever tip when the brakes are applied. When the lever is brought all the way down to the bar there should be a slight gap between your index and middle finger to ensure clearance of the end of the lever. Any further outward and you're set up improperly for 1 finger braking. The idea of this is that even if you try, you can't reach the lever with both fingers without moving your hands inward. Only wide bars allow the brakes to be adjusted properly in this way, and that is why trials bars have the rise and sweep well inward of the ends. This will feel strange at first, but ride it and get used to using one finger and your braking will improve by this alone. THIS IS VERY IMPORTANT and is the basis for all trials moves.

Next in importance of braking is the brake pads. This is where a majority of the adjustment takes place. V-brake pads can be adjusted to virtually any angle of contact and be toed in and out. For trials, it's fairly simple. You want the pads to strike the rim completely flat, as flat as possible. No toe in, no angled up or down, just all the brake surface hitting at the same time. This won't give good modulation and may make some noise. Deal with it, those are trials noises. Ride with 'em long enough and the noises will be "normal", and brakes that don't make noise will feel wrong. What this will do is cause all of the brake pad surface to engage the rim braking surface simultaneously and provide maximum friction between the two all at once, rather than the progressive increase that toed in pads provide. The easiest way to do this is to loosen the brake pads with a 5mm hex key, and with the key still inserted long end first into the hex head, position the pad and squeeze the brakes just so the pad contacts the rim surface. Do this on a true part of the rim with no dents to ensure accuracy. Use the hex wrench to wiggle and move the brake pad into position. You want to get it as low as possible on the rim, towards the hub. The reason for this is simple. As you move the pad towards the brakearm pivot point leverage increases. Remember leverage from back at the brake lever adjustment? Well, here's the other side of it. By moving the levers inward you are causing your index finger interface zone to contact the outermost possible part of the lever, providing maximum mechanical efficiency. If it helps to visualize it think of this in the same way a longer crankarm works. It's mechanical advantage. Now, at the brake pad we do the same thing in reverse. We want "torque" to be increased there, so we move towards the pivot instead of away. The pad moves less distance now but does so with more force. In my experience I found that this is the best place for tuning, and can make the difference between locking and slipping. Just make sure you don't set the pads so they miss the braking surface. Do both sides like this and tighten each up as you hold the brakes locked where you want the pads. When you look at the brakes you should see that both brake pad posts are alinged across from each other when the brakes are applied and that the pad contact area is flush in all directions with the rim... If they're not, fix 'em. THIS IS CRITICAL. The pads must be the same on each side, one high and one low pad will cause the rim to twist slightly, not enough to damage the rim, but enought to make your brakes ineffective for trials.

After the levers are positioned properly and your brake pads are adjusted, make sure your brake arms both move an equal distance when the brakes are applied. If one arm doesn't move and just stays on the rim while the other moves a long way, check for any place the cable may be interfering such as being tied off too far back on the toptube and not allowing enough cable for flex. If this is not the case, there are adjustment screws for spring tension on most brakearms. Tighten the screw on the side that is too close to the rim, 1/4 turn at a time, and work the brakes several times to see if they both spring back equally. Reapeat until you get it right. If the screw does not allow enough adjustment you may need to change the position of the spring engagemet on the frame or fork. There are usually 3 holes in the frame/fork where the spring end can go. Try a tighter position and loosen the screw. Also, on older brakes the springs can become bent and require straightening. This is simple, just bend them back slightly with your fingers and a pair of pliers so they are straight where they run up the brakearm to the spring catch.

That covers the adjustment part of the brakes. There are other things you can do to increase braking. One thing you can do is use tar. Be warned though, tar is an on/off switch. Your brakes will either be locked or unlocked no matter how fast or slow you will be going. Don't tar if you want any modulation at all. Don't tar your front if you plan to ride anywhere except on trials obstacles. Rims can also be ground, and better brake pads can be selected. Ceramic rims are also available that have a ceramic coating which increases friction.

Something that anyone with enough ambition can do to improve braking is scuffing your rims. To do this, get yourself a green scotchbrite pad. This is the green scrubby thing you use to wash dishes, the thing attached to the yellow sponge in your kitchen. Scotchbrite can be bought in the hardware store for about $1 a sheet. Make sure you get 3M brand green, as this is the grit that you want for the scuff. I've seen other brands that were green and had different grit, they were either too coarse or too fine. Use the 3M one cause the green color is a standard abrasiveness. Take your tire off the rim and begin by scrubbing the braking surface in the direction of the spokes, radially. Use water to help with the initial cleaning and rinse away the grime till you got a dull/shiny surface. Do both braking surfaces entirely and be sure you scrub radially or you will lose some braking effectiveness. Put it all back together, double check your brake adjustment and go ride.

If you followed the instructions above you will have maximized your V-brake effectiveness. Keep in mind a good set of pads makes a world of difference over the black hard rubber pads that come on most low to mid end XC bikes.

The rest of the adjustment is done simply for rider perference. Adjust the cable length and barrel adjuster on the levers to achieve brakelock in a comfortable hand position. Some brake levers have a leverage adjustment, on Avid it's called the speed dial, Shimano calls it the power-something-or-other, but it basically changes the "gear ratio" between the lever and the arms. Adjust these till they feel right and you get good lock. Tektros even have this as a 2 position adjuster. On the leverblade where the cable end clevis is (the thing that holds the brake cable on the lever) there is a slot with 2 positions, C and V. C is for older centerpull cantelever brakes and V is for V-brakes. Try the C position even though you have V-brakes. The C position provides more power but at lack of feel. Some riders like this position others hate it, and vice versa. Remeber when you make this change it will affect how far the cable is pulled and will require a cable adjustment on the brakearm.

Well, that's about it for V-brakes. A brake booster may help, good cables are always a help, but mostly it comes from proper setup. It helps to think of your brakes as a kind of drivetrain. All the leverage stuff can be likened to changing gears. The C and V positions are like the front chainrings and the brake pad position on the arm is like your rear gears. Pick a "gear" that works AND is comfortable. Also, give yourself time to build up a strong index finger for braking. Because you're going from 2 finger braking to one finger braking, you'll be working your finger pretty hard. Back when you were using 2 fingers your middle finger was doing all the "heavy lifting" and your index finger was just there cause there's nowhere else to put it. Now that you swap fingers it will take time to develop that muscle and also the skill of using one finger to control the brakes. Don't give up. If it helps you, try and hold your middle finger down with your thumb from around the grip to train yourself not to lift that finger and reach for brakes.

Happy Trialsin' Peace

V-brake setup guide written by Al Signore
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kam0t3
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PostSubject: Re: V-brake setup/tuning guide   Fri May 30, 2008 4:30 pm

nga pla heres the link : http://www.trials-online.com/trials-faq-included.php
if you wanna read the entire doc.
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zteg43
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PostSubject: Re: V-brake setup/tuning guide   Sat May 31, 2008 12:15 am

nice find!Smile
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PostSubject: Re: V-brake setup/tuning guide   Sat May 31, 2008 12:43 am

ang haba

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PostSubject: Re: V-brake setup/tuning guide   Sat May 31, 2008 1:32 am

punta nalang kayo k benjo panalo mag setup ng brake ang mamang yan hehehe....
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chi
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PostSubject: Re: V-brake setup/tuning guide   Sat May 31, 2008 11:59 am

ako im using Old School Shimano XTs rear Vbrake w/ serfas all weather pads & Shimano cable/housing so far so good walang brake problem issues. makapit naman sa Tire tap.
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kris1134
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PostSubject: Re: V-brake setup/tuning guide   Sat Jul 26, 2008 7:24 pm

may nalaman lng ako, kung kayo ay may v brake tapos malapad ang rim nyo, mapapansin nyo na masyadong malaki ang buka ng v brake nyo..

tip ko ay kalasin nyo ung sa may brake shoe nyo at pagbaligtarin ang spacer. ung medyo makapal ay ililipat nyo sa labas. un lng
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PostSubject: Re: V-brake setup/tuning guide   Wed Aug 06, 2008 12:33 am

kris1134 wrote:
may nalaman lng ako, kung kayo ay may v brake tapos malapad ang rim nyo, mapapansin nyo na masyadong malaki ang buka ng v brake nyo..

tip ko ay kalasin nyo ung sa may brake shoe nyo at pagbaligtarin ang spacer. ung medyo makapal ay ililipat nyo sa labas. un lng

bro salamat sa mungkahi mo na to... na solve mo ang problema ko lumiit nga ang buka ng brakes ko salamat ng marami bro... mukhang pwede na ako uli mag shorts ah hehehe sana hindi na ito sumabit sa shorts...

salamat talaga... cheers

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PostSubject: Re: V-brake setup/tuning guide   Wed Aug 06, 2008 3:39 pm

ah kaya ba madalas kayo naka pants??? naiinitan kasi ako tingnan kayo e. haha. yown pala yown!!!
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PostSubject: Re: V-brake setup/tuning guide   Sat Aug 09, 2008 12:15 am

zteg43 wrote:
ah kaya ba madalas kayo naka pants??? naiinitan kasi ako tingnan kayo e. haha. yown pala yown!!!

ilang beses nako muntik patayin ng shorts brads....

-habang nag pupumilit mag manual sa EDSA pumasok yung saddle sa shorts ko...

-isang nightride yun tali sa gilid ng shorts ko kinain ng gulong st bumuhol sa preno...

-yun preno tuwing naka shortsgumagasgas sa gilid ng tuhod ko di mo alam mamya sugat sugat ka na pala hindi mo nararamdaman...

-minsan kinailangan ko mag bail sa dulo ng pedal kick drop, ayun tinorno ng saddle yun pwet ko at binutas yun short kasi sumabit na naman at di naka eject...

-pasa pasa ang mga binti pagkatapos mag practice ng pivots...


naiinggit nga ako kela tzard at benjo tuwing nakikita ko sila naka shorts kasi ang presko sa yagbols men kapag naka shorts ka....


siguro para hindi sumabit yun "pekpek shorts" siguro ang kailangan ala basketball shorts nun era ni jaworski brads...

peace jawo!!!

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PostSubject: Re: V-brake setup/tuning guide   Sat Aug 09, 2008 3:34 pm

3/4 pwede dyan Joolz pero iba pa din ang maong. Protektado sa gasgas - gasgas
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PostSubject: Re: V-brake setup/tuning guide   Sun Aug 10, 2008 1:41 am

tumpak ka jan brads iba parin ang maong hehehe

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PostSubject: Re: V-brake setup/tuning guide   Sun Aug 10, 2008 12:34 pm

hehe. ang init! asim sa singit!
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PostSubject: Re: V-brake setup/tuning guide   Sun Aug 10, 2008 2:43 pm

hehe, syempre ako ligo agad pagkatapos ng ride eversince.
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PostSubject: Re: V-brake setup/tuning guide   Mon Aug 11, 2008 12:24 pm

Shorts:

Merong lumabas na shorts na may tali ang bottom knee part, napag usapan namin ito ni Benjo dati kasi parehas kami naka ganon. yon ang pwede sa vbrakes, hindi sasabit itali lang.
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PostSubject: Re: V-brake setup/tuning guide   Mon Aug 11, 2008 1:58 pm

Meron ako nyan, may bilog na garter at clip sa baba ng tuhod panalo ito pang vees.
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PostSubject: Re: V-brake setup/tuning guide   Mon Aug 11, 2008 3:12 pm

ganyan gamit ko dati na shorts pang bike.
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PostSubject: Re: V-brake setup/tuning guide   Mon Aug 11, 2008 11:07 pm

ganyan din yung kinain ng gulong ko hehehe peace...

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PostSubject: Re: V-brake setup/tuning guide   Tue Aug 12, 2008 12:12 pm

joolz wrote:
ganyan din yung kinain ng gulong ko hehehe peace...

hehe. siguro nga mag pants ka na lang Laughing
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PostSubject: Re: V-brake setup/tuning guide   Wed Aug 13, 2008 10:16 am

hahaha..joolz baka mahaba ang tali nung sa iyo hehehe

gamit ko maong na shorts..hirap lang labhan kasi light color.naghahanap ako ng mga cargo shorts para may bulsa din

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