Installing and Adjusting the Jab Derailleur

Safety

• Safety glasses
• Nitrile gloves (recommended)

Torque and Threadlocker

All fasteners need both. See specs.

Tools

• Bike work stand
• Torque wrench
• Metric hex keys (individual, not a multi-tool)
• T25 Torx
• 7mm open-end wrench
• Cable cutter (cuts cable and housing cleanly)
• Needle nose pliers
• Hanger alignment tool (recommended)

Supplies

• Shift cable and cable end
• Shift housing (if old housing is damaged)
• Blue threadlocker (such as Loctite 242)
• Grease (T hanger only)

If there is an old derailleur on the frame, remove it.

• No need to break the chain if it's intact (remove pulleys instead).
• Check cable & housing for friction.
• Check hanger alignment.

Prepare cage

Lock cage: insert T25 or 4mm hex key in cage lock.

Remove upper pulley.

Remove lower cage spacer.

Prep

Put bike in work stand.
Apply threadlocker to M10 mounting bolt threads.

Attach to hanger

When the M10 mounting bolt is torqued, the joint will be tight with a lot of friction, and the derailleur will not rotate easily. This is as intended.

Route chain

Chain already on bike? Don't break it unless it needs to be longer or shorter.
Route chain over cassette and chainring.

Place chain inside derailleur cage.

Install upper pulley

Install upper pulley.
Check narrow/wide pulley teeth sit in matching narrow/wide chain links.
Turn cranks slowly. No rubbing or clicking.
Noise? Chain may be on upper spacer instead of pulley.

Reinstall lower cage spacer

Apply threadlocker to empty M3 hole in cage, next to lower pulley.
Install lower cage spacer with M3 flat head screw.

Position derailleur

Back B screw lock nut off derailleur.
Back B screw out until it doesn't touch B screw plate. Don't remove it.
Rotate derailleur forward (counterclockwise, viewed from drive side) as far as it goes.

Shift chain to smallest cog.
May need to loosen small-cog limit screw.

Set chain length

Remove tool from cage lock. Let cage tension chain.
Confirm derailleur is still rotated fully forward.
Note: if needed for tension, turn B screw in a few turns at most.

Too long: no chain tension.
Remove 1 pair of links (1 inner + 1 outer). Repeat from Position derailleur.

Too short: cage at an angle to chain (around 30°).
Add 1 pair of links using an extra connecting link, or use a longer chain. Repeat from Position derailleur.

Correct: chain has tension. Cage roughly parallel to lower chain run.
Some chain slightly hidden behind cage arm.

Install cam (if not installed)

Insert tool in cage lock to release chain tension.
Install cam with 2 screws.

Route cable

New shift cable recommended. Replace housing if damaged. Trim housing if needed.
Route cable through shifter and housing. Seat cable head in shifter.

Pull cable end by hand and shift. Should move freely.
Friction? Find and fix it.

Route cable through Jab pulley bracket.
Seat housing and ferrule fully.

Route cable through hole in cam.

Reset barrel adjuster

Clamp cable

Loosen cable pinch screw (T25). Don't remove it.
Washer should rest on screw head, not stick to link.

Pull cable by hand.
Shift to release cable fully (smallest cog position).

Wrap cable about 90° around pinch screw. Pull tight without moving derailleur.
Keep cable behind lip on edge of link, pointing straight back.
Tighten pinch screw to torque spec.

Check for slack between pulley bracket and cam. Slack? Repeat this step.
Coil extra cable. Cut it later.

Check clearance

In order to adjust the B screw, back the B screw lock nut off derailleur.

Turn cranks slowly. Don't force.
Pulley hits cassette? Turn B screw in a few turns until cranks turn freely.

Adjust B gap

Rear suspension: Not compressed.

Shift to 2nd largest cog.

Measure the gap between the tips of the teeth.

Pulley to largest cog (not 2nd largest cog).

This provides space for the chain to shift to larger cogs.

Target 3mm to 8mm. Up to 16mm is OK if it shifts well.

Shift through whole cassette. Pulley must not touch any cog.
B screw in too far? Recheck chain length (6. Set Chain Length).

Lock B screw

Apply threadlocker to B screw where it enters derailleur.
Hold B screw with hex key. Tighten lock nut with 7mm wrench.

Inner limit screw (nearest cassette): small cog limit.
Outer limit screw: large cog limit.

Small cog limit

Shift to smallest cog.
Turn cranks slowly. View pulley from behind.
Adjust small-cog screw: pulley in line with small cog, or 1–2mm outward.
Chain must reach small cog, but not go past it.

Large cog limit

Shift gently to largest cog. A hard shift can drop chain into spokes.
Stop wheel.
Push derailleur linkage toward spokes by hand and hold. Don't push on cage or body.

View from behind.
Adjust large-cog screw: pulley in line with large cog, or up to 1mm outward.

Tune barrel adjuster

Matches shifter clicks to cogs. Key for good shifting.
Location: on shifter (mountain bike) or derailleur (drop bar).
Turn out: tighter cable, toward larger cogs.
Turn in: looser cable, toward smaller cogs.

Shift to smallest cog.
Start by turning barrel adjuster out.
Pedal at normal speed. Shift up one cog at a time. Let chain settle each time.
Shift up and down whole cassette. Note shift speed each way, and any noise.

Slow to larger cogs? Turn barrel adjuster out.
Slow to smaller cogs? Turn barrel adjuster in.
Clicking on a cog? Stay there. View pulley from behind while pedaling slowly.
Pulley off toward smaller cogs? Turn barrel adjuster out.
Pulley off toward larger cogs? Turn barrel adjuster in.
Mountain bike adjusters may need only 1–2 clicks for the final dial in.

Trim cable

Uncoil cable. Route it in either groove on bottom of link, pointing rearward. Both work.

Cut cable about 25mm past link.
Check strands aren't frayed.

Crimp cable end on with needle nose pliers.

Test ride

Remove bike from stand. Test ride.
Small barrel adjustments are normal (bike is under load on the ground).
New cables stretch. Recheck after first 1–2 rides.

Done!