- all on disc calliper are 5mm (+ a 2mm nub to stop the 5mm inside pad adjuster moving)
1) Turn the bike upside-down. Undo the rear axle bolts which will loosen the chain. Then slip the chain off the front sprocket (where the crank/pedals are). This is done by pushing the chain outwards and back-pedalling the crank. Then remove the back wheel.
2) wind the disc onto the thread on the wheel/hub, opposite side to the driver. This is self tightening due to thread direction when brakes are applied, tighten as much as you can by hand then once brakes are installed ensure you brake rolling forwards a few times to fully tighten - this will prevent the disc from coming loose if you roll backwards with the brakes on.
3) attach the calliper to the frame mount on the inside as shown. Put the larger eye bolt in (larger piece inside, hex facing out). First check the female piece doesn’t protrude through the hole - this will prevent it being tightened fully - fix as new paragraph below. Otherwise wind in to hold in place but don’t fully tighten so you can position for the smaller stabiliser bolt. Put this in and tighten up completely.
If there is still movement of the mount on the frame, or you cannot fully tighten e.g. the bolt spins in the frame - this will be due to the eye bolt being fractionally too long (occasionally happens due to a thickness variance in some frame coatings). You can fix this by undoing the eyebolt, and rubbing the edge of female/larger side of the eyebolt on metal suitable sand paper for approx 30 seconds (this sits closest to wheel).
Then fully tighten the larger eye bolt to secure mount in place. Note on the back of the calliper there is a hex to adjust the brake pad in as it wears.
4) Undo the cable clamp so the break pads are as far apart as possible.
5) Put the wheel and chain back on, sitting the disc inside the calliper - with the new disc unit you’ll have to sit the wheel low and push against the tyre a little to get it past. Ensure the chain is the correct tension and the wheel is aligned centre (crank should turn freely, but chain shouldn’t sag or come off easily without force). You can use the small drill holes on the frame stays to help centre the wheel. Once the wheel is on correctly you can adjust and tighten the calliper.
6) Align the calliper on the disc. Once you have the brake on the frame and wheel installed, hold the brake on/closed using the lever-arm. Semi-tighten the 5mm front adjustment bolt only (top of the brake unit) and then release the brake. If you look down the disc the unit should be hard against the fixed side closest to wheel, but if it has a little clearance already you can just tighten both. If not, you should then be able to push the rear of the unit in a fraction to give enough clearance on the disc. Keep it as close as possible to the fixed/wheel side pad without touching, lightly tighten down the rear bolt then spin wheel to check.
If it does touch and any adjustment is needed - loosen them off again and repeat. The adjuster bolts should be tight once done.
CABLE / LEVER:
7) Put the lever onto the handle bar right hand side (when viewed from riders position), be careful to get the bolt aligned correctly in the hole, gently wind in. The lever is made from aluminium to keep weight down, caution - it can thread against the harder steel bolt.
6) On the lever, align the barrel adjusters so the openings line up as pictured below. Insert the cable into the lever as shown, pull down through the opening you’ve made then wind the adjusters in so they are tight against the lever. This allows adjustment if the cable begins to stretch over time. The small allen bolt you can see (has blue thread lock showing) can be wound in to adjust the lever inwards for small hands.
7) Insert the the cable into the disc calliper as shown below, and through the clamp bolt on the arm. Pull the cable so the brake lever on the handlebars holds together, you don’t have to pull it too tight, just so the cable and tube seat correctly at both the lever and calliper ends.
Then push the calliper lever as shown in the two shots below so the pads are nearly touching the disc (hold the cable with other hand so it slides up the cable instead of pushing it back up the tube), and tighten the cable clamp.
If the brakes aren't tight enough, loosen the cable clamp again and push lever a little further forward with your thumb, re-tighten. Vice versa if it’s too tight and grabs the disc when brakes aren’t applied, let it slide back a fraction. Tighten, and you’re done!
If needed any minor adjustments can be done at the adjuster (end of cable tube where it sits in the calliper) - but try get it adjusted at the calliper first so you have room to adjust in the future as the cable stretches over time.