Adjusting Direct-pull Cantilever Bicycle Brakes ("V-Brakes ®")
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by Sheldon "Direct Pull" Brown
revised by John "Leverage" Allen
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vbrake

About Rim Brakes

Direct-pull brakes are a type of cantilever rim brake. In connection with this article, please read the lead article about rim brakes. It covers, among other things,

Most brake problems result from excessive friction or poor installation of the cables, not poor setup, or poor quality brakes. Also see the article on cables for information on cable selection and adjustment of brake cables and brake levers.

Direct-pull vs Traditional Cantilever Brakes

Traditional cantilever brakes used two cables, a main cable running down the centerline of the bike, and a second, "transverse" cable connecting the cantilever units on each side of the wheel. The main cable would pull upward on the middle of the transverse cable, causing the cantilever units to rotate inward.

The "direct pull" cantilever, also commonly known under its Shimano trademark name "V-Brake" is a simpler design, using only a single cable. The cable housing connects to one arm, and the inner cable runs across the top of the tire to the opposite arm. When the brake is applied, the housing pushes on one cantilever while the inner cable pulls the other.

Since the cable runs straight across the top of the tire, direct pull cantis need longer arms to get the cable high enough to clear the tire. This increases the mechanical advantage of the system, requiring the use of special matching brake levers.

Direct-pull brakes also avoid a serious risk. If the main cable of a traditional cantilever brake fails, the transverse cable can snag on a knobby tire and lock the wheel. If the front wheel, the rider will pitch forward. A direct-pull brake only stops working if the cable parts. Your bicycle has two brakes -- right?

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Quick Release

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Normal Position
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Boot Pulled Away
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Noodle Unhooked

For wheel removal, the noodle may be unhooked from the arm link. This will allow the brake shoes to open up wide enough to clear even a fat tire. First, pull the boot away from the end of the noodle. Then squeeze the brake arms together with one hand while unhooking the lower end of the noodle from the keyhole-shaped slot in the arm link.

Make sure to hook the brake back up immediately after you re-install the wheel!

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Direct-pull Brake Adjustment

First, remove the arms from the studs, and make sure the studs are free of rust. Coat the studs liberally with grease (this is VERY important!)

Install the arms with them at their maximum spread and tighten the bolts that hold them to the frame. This is how you set the springs.

Shoe adjustment is covered in the article about rim brakes, but there are a few special things about direct-pull brakes:

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Centering

When the brake is released, the brake shoes retract away from the rim. Ideally, the shoes on both sides should back off by the same amount. If they don't, the brake is not properly centered. In extreme cases, one of the shoes may not retract, and may rub on the rim even when the brake is not being applied.

If a brake appears off-center, check first that the wheel is installed straight in the frame/fork. If the wheel is crooked, and you maladjust the brake to compensate, you are creating two problems where there was only one before.

Spring Adjustment

If your wheels are centered, and your brakes are not, and, if the pivots are properly lubricated and free-moving, the brake shoes should be centered. If they are not, you probably need to adjust the spring tension on one or both of the cantilevers.

Some brake bosses have more than one hole for the end of the spring, to allow a rough adumstment of spring tension. Generally, the hole which provides more tension should be used with a narrower rim. Make sure that both brake arms use matching holes.

Most direct-pull cantilevers have a fine adjustment for spring tension. The adjustment will be a small screw with the head facing outward to the side of the bike. The screw is generally located near the bottom of the cantilever, below the pivot point. Sometimes it works with a Phillips screwdriver; other times, a small Allen wrench may be needed.

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Tightening this screw tightens the spring, so you want to tighten the spring of whichever arm is too close to the rim. This will make it spring back farther.

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Parallel-Push Linkage

v-type brake
Older Shimano's XTR and XT V-Brakes feature a special parallelogram linkage. This serves two purposes:

Unfortunately, the extra pivots considerably complicate the mechanism, and this has caused maintenance problems and excessive squeal in practice.

Reader Paul Rintoule has sent in some advice on maintenance of parallel-push brakes:

Shimano parallel-push V-brake tune-up kits have all but dried up so I fixed my squealing XT parallel-push V-brakes by adding disc brake rotor washers to tighten up the parallel-push pivot cage. This works the same as the tune-up kit did.

  1. Firstly, buy some disk brake rotor spacer/washers from a bike shop and super glue from the local supermarket, hardware store etc..
  2. Remove the brake arms from the bike using a 5mm Allen key.
  3. On your workbench, remove the brake pads.
  4. Using a utility knife, peel off the silver stickers from the ends of the parallel-push cage pivot.
  5. Take a photo of a parallel-push cage to remember the order of existing spacer and spring.
  6. Remove the 2mm Allen set screw from each brake arm. You now can push out the parallel-push cage pivot.
  7. Give the parts a wipe clean.
  8. Now reassemble the brake arms and parallel-push cages including adding one or more rotor spacers between the brake arm and the parallel-push pivot cage to take up most of the slack. You want each pivot cage still to turn freely on its pivot without binding.
  9. Replace the 2mm Allen set screw in each brake arm using blue threadlock compound.
  10. Degrease the silver main pivot stickers and the ends of the main pivot using solvent and a cotton swab (Q-Tip).
  11. Clean the brake pads with using solvent and sandpaper and then reattach.
  12. Clean the wheel rims using solvent and sandpaper/fine steel wool.
  13. Reattach the silver main pivot stickers using a small amount of super glue around their perimeter. When glue has set (10 or 20 seconds) reattach the brake arms to your bike, remembering to use blue threadlock compound on the main pivot bolts.

You have now removed the slack that causes severe squealing.

  

Brake Levers for Direct-pull Cantilevers

Direct-pull cantilevers have double the mechanical advantage compared with traditional brakes, so they require special brake levers. Direct-pull brake levers pull the cable twice as far, half as hard. The lower mechanical advantage of the lever compensates for the higher mechanical advantage of the brake arms. It is not generally safe to mix and match levers/cables between direct-pull and other types for this reason.

Drop-bar Levers

To make a brake lever with low enough mechanical advantage for direct-pull cantilevers, the cable must run twice as far from the lever's pivot point. This is easy enough to do with levers for straight/upright handlebars. Levers for drop handlebars are harder to configure for direct-pull brakes, and currently, there are only a couple of drop-bar levers made that are compatible, the. At present (2018) there are several drop-bar brake levers designed to work with direct-pull cantilevers: the Dia Compe 287V, Cane Creek SCR-5V "Æro" levers, Tektro RL520 and perhaps others. Due to the nature of drop-bar levers, it is not so easy to make a suitable lever that can be operated both from the drops and from the hoods.

Most newer drop bar bikes are have Ergo or STI brake/shifter units as original equipment. Direct-pull cantis are not compatible with these. Other types of shifters may of course be used, along with the special brake levers. In any case many cyclists prefer bar-end shifters. These are simpler and less expensive than brake-lever shifters, and give an indication of what sprocket is in use: brake-lever shifters return to the same position after every shift.

Drop-bar Workarounds

If you want to use Ergo or STI brifters with direct-pull cantis, there are two workarounds available: QBP Travel Agent

Neither of these systems is ideal, and neither is really any better than traditional center-pull cantilevers.

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Compatibility

Note the differing levers and pivot stud positions.

Cantilever Brake Compatibility/Interchangeability
Cantilever
Type
Frame
Pivot Studs
Levers Cable Routing
Direct Pull
V-Brake ®
Below the Rim Long Pull
Low Tension
Cable comes in from the side.

Lower housing stop is part of the cantilever

Traditional
Center Pull
Standard
Short Pull
High Tension
Cable runs down the bicycle's center line.

Lower rear housing stop on frame,
either special braze-on ,
or mounted to the seatpost bolt.

Front housing stop on headset ,
fork or handlebar stem .

U-Brake
Cantilever
Above the Rim
Roller-Cam
Cantilever

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