21. How to Adjust Cantilever Brakes
Adjust brake levers, re-surface pads, set cable tension and center cantilever style brakes.
In today's tutorial I'll demonstrate how to adjust cantilever style brakes. I will cover linear pull, or V-brakes in a future tutorial. For this job you'll usually need a 5mm allen key, a 10mm open-end wrench, a strip of sandpaper, and an optional cable puller.
The first step is to set up your brake levers. Start by loosening the clamp and then align the levers so that they match the angle of your arms when you're riding. Once the angle is set, tighten the clamp.
If you have smaller hands and your levers are hard to reach, you can set them closer by tightening the reach adjustment screw on the inside of most levers.
Before you begin, you should also check to make sure your wheel is properly centered in the frame, as this will affect the position of your brake pads. Make sure the axle is securely fastened all the way up in your dropouts. If the wheel is still off-center you may need to check the dish, which is further explained in the previous wheel truing tutorial.
Now loosen the tightening bolt on your brake arm and tighten the lever's barrel adjuster all the way.
Loosen and then remove both brake pads from their mounting posts and inspect both their surfaces to make sure they are not too worn. If you see any metal poking through the pad surface, you'll need to replace them. If the pads are in good shape, it's a good idea to resurface them using some sandpaper.
With the pads removed, adjust the brake cable until both brake arms are parallel straight up and down, and then tighten. Using a cable puller makes brake cable adjustments a lot easier.
Now reinstall the brake pads and align them so the pad face is flat against the rim. Then tighten the pad so that it’s snug, but still loose enough to move around.
Take a look from the side to make sure the pad is in line with the rim's brake surface, and not touching the tire or hanging off the bottom of the rim. If you can't avoid one or the other happening, your pads may be too wide for your rim, and you'll have to find some narrower pads.
Cantilever brake pads should be set so that the front of the pad touches the rim before the rear when you pull the brakes. This is called 'toe-in', and it prevents squealing when you use them. It's a bit tricky to set up, so you may have to re-tighten the pads several times before it is correct.
For proper toe-in adjustment, there should be a gap of a few millimeters at the rear of the pad when the front is touching the rim. Park Tools recommends temporarily wrapping a rubber band around the back end of the pad to help set the spacing. Don't forget to remove it when you're done adjusting the pads.
Some bikes like mine have a link unit that sets the straddle wire position for you. If you're using a carrier style with a pinch bolt, make sure the carrier is tightened as low as possible, while still providing enough clearance for your crossover cable, tire and fenders.
Now adjust the cable tension on the brake arm by pulling the cable through the pinch bolt and tightening. You'll have to play with this adjustment until your brakes feel good. I like to have mine set so that the pads hit the rim when my lever is pulled about 1/4 of the way.
Make sure both pads now have equal clearance, and are not rubbing against the rim.
For minor centering adjustments, there is usually a screw on the left brake arm that sets the spring tension on one side. Tighten this clockwise to pull the pad away from the rim, and counter-clockwise to set the right pad closer to the rim.