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  1. The new DH Jab is here!

Jab Installation Checklist

Categories

Compatibility

Derailleur
  • The Jab derailleur is compatible with most 1x drivetrain components found on 12 speed and 11 speed mountain and gravel bikes.
  • The Jab will not work with 2x or 3x drivetrains.
  • Refer to our drivetrain compatibility chart for a full summary of compatible drivetrains.
Shifter & Cassette
  • The cam on the Jab derailleur is like a key that pairs a shifter and cassette.
  • Refer to our drivetrain compatibility chart for cam selection details.
Chain Length and Type
  • Make sure you start with more than enough chain links. The chain length is critical for good shifting, proper B gap adjustment, and proper chain meshing.
  • The chain needs to be compatible with the cassette and chainring.
  • The Jab is compatible with nearly all 12 speed and 11 speed chains.
Hanger / Dropout
  • The Jab derailleur with standard mount will fit any frame.
  • The Jab derailleur with the UDH stiffener plate will fit any UDH frame that has a SRAM UDH hanger.
  • Some non-SRAM UDH hangers might not fit properly due to alternate dimensions of the bolts.
  • The Jab derailleur with T-Type mount will fit any UDH frame. It comes with its own hanger.
Chainstay Length
  • This is the distance from the bottom bracket to the rear wheel axle.
  • Longer is better for good chain meshing (low noise and low friction).
  • If the chainstay length is too short, the lower pulley of the derailleur might not mesh well. Also check Chain Line in Alignment below.

Clean & Lubricate / Eliminate Friction

Chain
  • Keep your chain cleaned and lubricated.
  • Always lubricate your chain after cleaning it.
  • While you clean, place a clean rag over your brake caliper and rotor to prevent oil from spraying onto them.
Cassette
  • Brush the gunk off the cassette regularly.
  • While you brush, cover the brake rotor with a clean rag to prevent oil from spraying onto it.
Chainring
  • Clean the gunk off the teeth of the chainring periodically.
Bottom Bracket
  • Brush grit off the bottom bracket seals periodically.
  • If the cranks do not spin freely with no chain attached, you may need to rebuild or replace your bottom bracket.
Rear Wheel Hub
  • Make sure your hub rotates freely.
  • Make sure your freehub ratchets freely. It should never drive the chain when the wheel is freewheeling.
  • It is wise to clean and re-grease the freehub when the cassette is removed.
Cable and Housing
  • Check for cable and housing friction by shifting with no derailleur attached to the cable.
  • Replace if there is any noticeable friction.
  • Note that some cables are 1.25mm diameter and others are 1.10mm. The cable must be compatible with the housing.
Derailleur Pulleys
  • Periodically remove, clean, and re-grease the derailleur pulley bearings.
  • Packing the dust shields with grease will make the bearings last a long time.
Derailleur Links
  • The Jab ball bearing link pivots are outstanding at eliminating friction.
  • If you have a Jab with bushing pivots, we recommend to update to the ball bearing links. Email support@madronecycles.com for details.
Derailleur Cage
  • Rotate the cage by hand to make sure the only friction source is the clutch.

Alignment

Hanger
  • Ensure your hanger is aligned. This requires a hanger alignment tool.
  • It is wise to check new hanger alignment even if they are brand new.
Chain Line
  • Make sure your chain line matches the manufacturer specifications. The chainring offset should be set for the rear hub and cassette combination.
Derailleur
  • A bend in one or more parts of the derailleur will hurt shift quality.
  • It is usually hard to see slight bends.
  • Contact us if you need help checking for bends.

Install

Cage Lock
  • Use a 4mm hex or T25
Remove Upper Pulley & Lower Spacer
  • No need to break the chain if its intact.
Mount Derailleur
  • Jabs with standard mounts have one bolt to tighten.
  • Jabs with stiffener plates have 2 bolts to tighten. One is the the derailleur mounting bolt and the other is the hanger attachment bolt (often left hand thread).
  • After installing, rotate the derailleur counter clockwise to ensure the B screw plate is contacting the dropout.
Route & Pinch Cable
  • Make sure the cable housing ferrules are seated properly.
  • The chain should be in the small cog.
  • The shifter should be at the correct shift for the small cog.
  • Make sure the limit screw for the small cog is roughly adjusted.
  • Pull all of the slack out of the cable.
  • Pull the cable to the rear and make sure it is routed as desired.
  • Pinch it with the screw with no slack.
Chain in Cage
  • Make sure the chain is routed over the top of the cassette.
  • With the upper pulley and lower cage spacer removed, place the chain in the cage.
Install Upper Pulley & Lower Spacer
  • Install the upper pulley.
  • Make sure the wide teeth of each pulley are meshed with the wide links of the chain.
  • Install the lower cage spacer.

Chain Length / Adjust B Gap

B Screw Out
  • Back the B screw out until it has no effect on the derailleur position.
  • Do not remove the B screw.
  • Rotate the derailleur counter clockwise to ensure the parts are all contacting each other correctly.
  • It also has a jam nut. This needs to be loose during adjustment, and then tightened after adjustment is complete.
Chain on Small Cog
  • Make sure the chain is on the smallest cog.
  • Make sure the chain is meshed properly with all teeth it is contacting.
Chain Length (not too short)
  • The chain should have as many links as possible without having chain slack.
  • It should not be rubbing on the upper cage spacer.
  • View the chain and derailleur cage. The chain should be hidden behind the cage.
  • Break the chain only after you are sure the length is good.
  • When in doubt, break it too long because removing links is better than adding them.
Adjust B Gap
  • After breaking the chain to the proper number of links, adjust the B gap.
  • Shift to the 2nd largest cog.
  • The tips of the pulley teeth should be 3mm to 8mm from the tips of the teeth of the largest cassette cog.

Final Adjustments

Limit Screws
  • The outer limit screw controls the limit at the large cog.
  • Set the large cog limit so it can complete a shift to the large cog without limiting the shifter motion. However, do not allow the chain to shift over the cog into the spokes.
  • The inner limit screw controls the limit at the small cog.
  • Set the small cog limit so it can complete a shift to the small cog.
Barrel Adjustment
  • Adjust after the cable is pinched in the approximate position.
  • Set the barrel adjustment so there is no unusual noise in any gear.
  • Fine tune the barrel adjustment so the shifts up are the same speed and ease and the shifts down.
  • Finalize the barrel adjustment while riding the bike (it can be slightly different between the work stand and riding).