Installing and Adjusting the Jab Derailleur

Mounting

Apply thread locking compound to the M10 threads on the mounting bolt of the Jab.

Variant

If you have the Jab with the UDH stiffener or T stiffener:

Thread the M10 mounting bolt into the hanger but do not tighten it yet.

Ensure the B screw plate is positioned correctly on the hanger.

Place the hanger (with derailleur attached) in the frame as shown.

You do not need the M17 ring washer when using either of the 2 Madrone stiffener plates. It won't fit and is unnecessary with a stiffener plate.

If you have the T Hanger, apply grease to the threads of the M17 bolt for the T hanger. The M17 bolt has a reverse (left hand) thread direction. If you have a UDH hanger, follow the manufacturers directions for thread preparation and torque.

Tighten the hanger bolt and M10 derailleur mounting bolt iteratively until both reach their torque specs. 

Variant

If you have the Jab with standard mount:

Install the derailleur hanger into the frame as per the manufacturer’s instructions.

Ensure you have a straight derailleur hanger. We recommend using a hanger alignment tool, even if you have a new hanger. This will verify that it is aligned.

Start the threads of the M10 mounting bolt into the hanger.

Ensure the B screw plate is positioned correctly on the hanger.

Tighten the M10 mounting bolt.

Set the cage lock with a tool.

Remove the lower cage spacer.

Chain Length

If the chain is already on your bike, there is no need to break the connecting link. You can route the chain through the derailleur by removing the upper pulley and lower cage spacer.

Route the chain over the cassette and over the chain ring.

Place the chain inside the derailleur cage.

Install the upper pulley.

Make sure the narrow/wide teeth of the upper and lower pulley are engaged with the chain in the narrow/wide links.

Slowly rotate the cranks to make sure the chain does not rub, click, or have trouble meshing on the pulleys. 

If there is noise, the chain might be routed over the upper spacer instead of the upper pulley.

Make sure the lock nut of the B screw is not contacting the derailleur. Thread it out if it is.

Back the B screw out until it is not contacting the B screw plate. There is no need to remove it from the derailleur though. This is an important part of determining the optimal chain length.

Rotate the derailleur forward (counter clock wise) as far as it will go. This is an important part of determining the optimal chain length.

Remove the tool from the cage lock, and allow the cage to put tension on the chain. Again, make sure the derailleur is rotated all the way forward (counter clockwise).

Important: Ideally the B screw will be backed out completely. However, if you need to turn it in a few turns to get chain tension, that is OK, but do not thread it in more than a few turns to achieve chain tension.

Chain too long: If the chain does not have tension, the chain is too long. Remove 1 pair of links (one outer and one inner) and repeat the previous steps.

Chain length good: The cage should apply tension to the chain. At the same time, the cage should be roughly parallel to the bottom run of chain.

Chain too short: The cage will apply tension to the chain, but the cage and chain will not be parallel. For example, they might be at roughly 30 degrees to each other. Most modern chains are not intended to add links, so you can use an alternate chain, or use additional connecting link to add links to increase the chain length. Start by adding 1 pair of links (one outer and one inner) and repeat the previous steps.

Install Shift Cable

Install the cam using 2 screws.

You will probably need a new shift cable, and you might need a new shift housing. Damaged housing will hurt shift quality. You may also need to trim the length of your previous shift housing.

Route the cable through your shifter and shift housing. Make sure the head of the cable is seated properly in the shifter. 

With your hand, apply tension to the end of the cable (after it exits the end of the housing) and shift.

You should not feel any significant friction. If you do, locate the source of the friction and resolve it.

Route the cable through the Jab pulley bracket.

Make sure the housing and ferrule are fully seated. If they are not, you will need to repeat this step later during adjustment.

Route the cable through the hole on the cam.

Variant

If you have a mountain bike shifter:

On the shifter, screw the barrel adjuster all the way in.

Variant

If you have a drop shifter (on a gravel bike or road bike with drop bars):

On the derailleur, screw the barrel adjuster and locking nut all the way in.

Loosen the cable pinch screw with a T25 torx driver, but do not remove it.

Pull tension on the cable with your hand, and shift so the cable is let out all the way. This shift position is for the smallest cog on the cassette.

Wrap the cable about 90 degrees around the cable pinch screw, and pull it tight, without moving the derailleur linkage up the cassette.

The cable should not protrude over the outside edge of the link, or it will get pinched. It should go straight rearward and stay tucked behind the small lip on the edge of the link.

Tighten the cable pinch screw down. 

There are 2 places to route the cable. You can use either one.

Visually check to make sure the cable does not have too much slack in the area between the cable pulley bracket and the cam. If there is slack, repeat the previous steps.

If your cable has excess length, you can coil it so it holds itself in a circle. You will cut it to length later.

B Screw Adjustment

The B adjustment controls how close/far the upper derailleur pulley is from the cassette. This adjustment is important for good shifting quality.

Make sure the lock nut on the B screw is not contacting the derailleur. Thread it out if it is.

Make sure the derailleur is rotated as far forward (counter clock wise) as it will go until the B screw is contacting the B screw plate positively. The mounting bolt holds the derailleur tight, so sometimes the chain tension will not pull it forward. If you adjust the B screw and the derailleur is not rotated forward, it will re-adjust itself when you ride it.

Turn the cranks slowly to see if there is enough B adjustment to shift, but do not force the drivetrain to move or spin. If there is too little B adjustment, the pulley will contact the cassette and make noise while pedaling. If this happens, thread the B screw in a few turns to give it enough clearance to shift.

Once is is possible to pedal the drivetrain, shift the chain to the 2nd largest cog on the cassette.

If you have rear suspension, it is OK to make the B adjustment in the uncompressed position, because we were extra careful above during the chain length steps, and are starting with little to no B screw adjustment.

View the upper derailleur pulley from the side and see how close it is to the teeth of the largest cog. 

Adjust the B screw so that the tips of the teeth of the pulley and large cog have the smallest gap you can achieve, without having the teeth overlap.

Not enough gap: Teeth overlap. This will case the derailleur to rub when you shift to larger cogs, hinder shift performance, and make chain meshing noises.

Ideal gap: The gap between the tips of the teeth is between about 3mm to 8mm. 

Good: The gap between the tips of the teeth is between about 8mm to 12mm.

Large but OK: The gap between the tips of the teeth is between about 12mm to 16mm. 

If the B screw itself needs to be threaded in too far to get the gap in the right range, review the chain length section above. If there are still issues, check to make sure you have the right cage length.

The B adjustment gap is important, but achieving good shifting can result in different settings depending on the drivetrain configuration so if you are a little outside the range listed above, that is OK. What matters most is that the derailleur shifts well.

Generally the gap will increase with larger cassette cogs, so shift through the entire cassette to make sure none of the smaller cogs have contact with the upper pulley.

You will finalize and lock the B screw adjustment later.

Limit Screw Adjustment

There are 2 limit screws. They control how far the derailleur can move at each end of the cassette. The screw nearest to the cassette controls the limit at the small cog. The screw furthest from the cassette controls the limit at the big cog.

Make sure the chain is on the small cog.

Pedal the cranks slowly, and observe the derailleur pulley from behind.

Adjust the limit screw (for the small cog) so that the derailleur pulley is approximately in line with the small cog on the cassette, or perhaps 1mm to 2mm outward. 

The limit screw should not be set to prevent the chain from reaching the small cog from the next larger one. It should also not allow the chain to move off the outside of the small cog.

Shift the derailleur to the largest cog, taking care not to shift too aggressively into the largest cog. This will help avoid shifting the chain over the cassette, and into the spokes of the wheel.

Make sure the wheel is not rotating.

With your hand, squeeze the linkage of the derailleur to push it as far toward the spokes as it will go. Do not apply leverage to the cage or main body of the derailleur.

Keep squeezing the derailleur with your hand until the limit screw adjustment is done.

Observe the derailleur from behind.

Adjust the limit screw (for the large cog) so that the derailleur pulley is approximately in line with the small cog on the cassette, or perhaps 1mm outward.

You will finalize the limit screw adjustments later.

Barrel Adjuster

Now that the B screw and limit screws are approximately adjusted, you can adjust the barrel adjuster. This adjustment is critical for good shift quality. 

The barrel adjustment matches up the clicks in the shifter with the cogs on the cassette. It is a knob that can be found on the cable housing near the shifter (on mountain bikes) or on the derailleur (on gravel or road bikes). Rotating the barrel adjuster one direction or the other makes the housing longer or shorter, which moves the derailleur slightly up or down the cassette.

Start by shifting to the smallest cog.

If you followed the steps above, you will likely need to start by rotating the barrel adjuster counter clockwise (as if you are looking at it from the direction that the cable housing enters it).

This will tighten the cable a little bit, and pull the derailleur in the direction of the larger cogs.

Both barrel adjuster types are shown in these 2 images.

Pedal at a normal cadence, and shift the derailleur from the small cog up to the next larger cog, one shift at a time, and let the chain fully arrive at the cog.

Continue this process up and down the cassette, and note the speed that it shifts up, and down, and whether any cogs have unusual noises. 

If the derailleur is slower moving to a larger cog, make the housing longer (by turning the adjuster counter clock wise). Do the opposite if the derailleur is slower moving to smaller cogs.

If the derailleur is clicking in a cog or having trouble meshing in a cog, leave it in that cog, observe the cassette from behind while slowly pedaling, and identify which direction the upper derailleur pulley is off.

If the pulley is biased toward smaller cogs, make the housing longer (by turning the adjuster counter clock wise). Do the opposite if the pulley is biased toward the larger cogs.

Sometimes MTB barrel adjusters requires as little as 1 or 2 clicks to reach correct adjustment.

If you have a Jab derailleur with a barrel adjuster on the derailleur, use the finger lock nut to lock the adjuster in place after the adjustment is dialed in.

Final Steps

Repeat the B screw adjustment steps to finalize or verify that the B screw adjustment is set properly, and the shift quality is good.

Repeat the limit screw adjustment steps to finalize or verify that they are set properly, and do not prevent the derailleur from moving to the large or small cog, and also do not allow the derailleur to move the chain off the outside of the cassette at either end.

Ride the bike to verify that the shifting is good while being ridden.

Shift through all gears one at a time, note the speed of making shifts, and listen for sounds.

Ensure the bike can shift while climbing too.

Do not pedal or ride too slow when the chain is on the smaller cogs, since the shifting will be delayed. Ride as if you would ride normally.

It is not uncommon for the barrel adjuster to require small adjustment for riding on the ground because the wheel and frame are loaded, unlike when they are in a work stand.

Also, new cables will stretch after they are initially installed, so you will probably need to repeat the barrel adjustment after the first 1-2 rides.

Mount the bike back in the stand.

Apply threadlocking compound to the B screw right where it enters the derailleur.

Tighten B screw lock nut with a 7mm open end wrench while holding the B screw in place with a hex key. This will ensure that the adjustment does not change while riding.

Apply threadlocking compound to the remaining M3 hole in the cage next to the lower pulley.

Install the M3 flat head screw and cage spacer.

Un-coil the shift cable and route it in one of the 2 grooves on the bottom of the link. It will point to the rear of the bike.

Cut the shift cable about 25mm from the link, or to your preference.

Make sure the strands of the cable are not frayed.

Optional, but recommended: Drip a couple drops of CA glue (super glue) on the tip of the cut cable so it wicks in and helps prevent the strands from fraying.

Crimp a cable end on the tip of the cable. 

There are 2 places to route the cable on the bottom of the derailleur. 

Both work great - you can pick the one that you prefer.