Bicycle Adjustment Guide

The purpose of this guide is to have a quick checklist for common bike tasks to jog one's memory especially in the field and/or if those tasks are not performed often enough and it's easy to get rusty. This guide is more for myself (Uncle Erik) in case I need it in the field. This guide assumes prior knowledge of the location of the limit screws, barrel adjusters, and derailleur parts such as derailleur cage, jockey wheels, etc.

There are better guides (look at "derailleur adjustment" videos from Park Tool on YouTube for example) that will do a better job for teaching people that are new to this mechanical discipline.

Rear shifter cable replacement

NOTE: These instructions do not apply to "rapid-rise" derailleurs (but thankfully they are not common))

NOTE: Please note that if you are doing this, it is HIGHLY recommended that you replace the cable housing as well.

Put rear derailleur into smallest cog.
Put front derailleur into the largest chainring. Not necessary now but needed when doing rear derailleur adjustments.
The shifter should now be in a position where internally it has the least amount of cable being fed into it. Leave it like this for the duration of this exercise.
Remove old cable. Easiest way is to cut the cable in an open area (outside its housing) before it gets crimped by the derailleur cable bolt/screw.
Inspect the housing. Look for cracks or sharp angles that will impede shifting; especially the last portion of housing. It is HIGHLY recommended that you also replace the housing when you replace the cable. If a sharp angle is encountered, try to figure out a way to lessen the sharpness of the angle (slightly longer cable housing would be needed at that section).
Run the cable through the housing but do not tighten it yet to derailleur. Tip: Oil last bit of cable before inserting into last part of housing (Tri-flow lube recommended?)
Turn shifter barrel adjuster clockwise all the way then back 3-4 turns (to give you ability to fine-tune later)
Turn derailleur barrel adjuster clockwise to tighten all the way then turn back 3-4 turns (to give you ability to fine-tune later)
Attach cable to derailleur; cable should be taut.
Stretch cable from an open area (without housing). Pull down hard. Loosen derailleur cable bolt and pull any slack you may have created and tighten bolt to reattach cable to derailleur.

Rear derailleur adjustment

TIP: Turning barrel adjuster Clockwise brings the jockey wheels closer to the smallest cog. Opposite for counterclockwise.

Deraileur hanger:

Make sure that derailleur hanger is OK (not bent) before you proceed.

H-limit screw adjustment:

Get to the smallest rear cog and onto the biggest front chainring. Keep clicking on the shifter even past the smallest cog to make sure the shifter is fully actuated (no more clicks left on the shifter). If it doesn't go to the smallest cog, play with the H limit screw and/or barrel adjuster until it does.

In order not to confuse the shift position with the H limit screw setting, turn the barrel adjuster clockwise a couple of turns (keep count of how many turns) to add slack to the cable.

Tighten (clockwise) H limit screw until there is excessive noise from the chain rubbing on the next higher cog. Loosen the H limit screw 1/4 turn at a time until the moment it quiets but no more.

The H limit screw is set. In preparation for indexing adjustments, turn the barrel adjuster counterclockwise the same number of turns you counted earlier, but don't worry about precision for now (that's what the next part is for).

Indexing (barrel adjuster):

If 2 front rings; stay in biggest. If 3 front rings now switch to middle. Start at smallest cog in the rear.

At a normal pedalling cadence, shift one (and only one) index click. If the shift does not happen return shifter to smallest cog gear and turn barrel adjuster one full turn (counterclockwise) at a time until it shifts to the next cog.
NOTE: If the barrel adjuster comes loose, it's because there is too much slack in the cable. Set shifter and derailleur to smallest cog, loosen cable bolt, pull slack from cable, re-tighten. Try shifting again and adjust until it shifts to the next cog.
NOTE: If one click shift 2 sprockets, return shifter and derailleur to smallest cog and turn the barrel adjuster clockwise (and try again) until one click shifts tot he second cog.

On this second cog, now turn counterclockwise until you hear excessive noise or cogs grabbing chain. Loosen (clockwise) 1/4 turn at a time until the moment it quiets but no more. Now go up every cog EXCEPT the largest (that adjustment is done later by adjusting the L limit screw). If any make noise, loosen 1/4 turn until noise stops. Eventually the noise should stop for all the cogs except the largest when you shift up and down (but do not test the largest cog yet).
NOTE: If the shifting towards the smaller cogs is a bit slow, turn barrel another 1/4 turn clockwise.

L limit screw adjustment:

Shift to the second-largest front chainring, and the second-largest rear cog.

Attempt to shift to the largest rear cog. We will then attempt to set the L limit screw too tight then back up 1/4 turn at a time until OK.
If the shift is done successfully, then the L limit screw is not too tight (but it could be too loose). Shift back to the second-largest rear cog and tighten the L screw 1/2 turn clockwise and shift again until symptoms (mentioned in the next line) happen.
If the shift is not happening or slow in shifting, or there is excessive noise after successful shifting, the L limit screw is too tight, which is what we want for now.

Now that the L limit screw is too tight, turn the L limit screw 1/4 turn counterclockwise and try again. Repeat until shifting is smooth with no excessive noise, but no more (otherwise you run the risk of the chain going past the cogs and into the spokes).

Now without pedalling, put additional constant pressure on the shifter (as if you want to shift past the largest cog) and make sure that the derailleur does NOT move further inward when you do that (if it does, then your L limit screw is still too loose and not doing its job to prevent this behaviour).

B screw check:

Go to the smallest chainring; largest cog.

Gap between larger cog's tooth and jockey wheel tooth should be 5-6mm (but consult your manufacturer as there are exceptions). But do not get too hung up on the B screw if shifting happens properly.

Test-ride the bike: If there are issues, adjust barrel adjusters (or possibly limit screws) 1/4 turn.

Front shifter cable replacement

NOTE: Please note that if you are doing this, it is HIGHLY recommended that you replace the cable housing as well.

Change to largest chainring on rear cogs. Change to smallest chainring in front cogs. This should set shifter to smallest number.
Remove old cable (but keep track of which housing goes where and in which orientation; you would either reuse the housing or cut new housing pieces (recommended) to the same size). Do not change shifter position.
Route new shifter cable through shifter and housing until you reach the front derailleur but do not clamp cable to the derailleur's pinch bolt yet.
Check derailleur L screw: the innermost plate of the derailleur has to barely rub the chain. Once you adjusted the L screw to do that, Go back (counterclockwise) a quarter-turn to silence the rub.
Make sure front shifter is still in smallest gear and proceed to turn the barrel adjuster clockwise until it cannot get any closer to the shifter, then pull back 2-3 turns. Re-clamp the cable but when you pull the cable it should be neither loose nor tight.
If the cable is new; pull hard on exposed length of cable. Unclamp cable and pull up any slack that resulted from this, then clamp again.
Move to the "L-limit screw adjustment" part of the "Front derailleur adjustment" section below.

Front derailleur adjustment

TIP: Turning the barrel adjuster clockwise will move the derailleur cage closer inside to the frame.

Height:

2-3 mm between bottom of carriage and teeth of largest chainring.

Rotation:

Carriage plates parallel to largest chainring.

L-limit screw adjustment:

Shift to smallest chain ring. Shift to largest rear cog. Use barrel adjuster on shifter to slacken the cable by turning clockwise 1-2 revolutions. Tighten L screw clockwise until there is chain rub. Loosen L screw until there is no more rub.

Turn barrel adjuster counterclockwise the same amount you turned clockwise earlier. Test shifting from next chainring back to small one. Should not have any delay.
NOTE: If there is delay, loosen L screw 1/4 turn and try the shift again; repeat until you have both the smallest possible gap (between chain plate and derailleur plate) while having no delay in shifting.

H-limit screw adjustment:

Shift to smallest rear cog. Shift to biggest chainring.
NOTE: If it does not shift to the largest cog, look at the H limit screw's contact point with the derailleur, and if there IS room for the screw to move, then the cable must be slack. Tighten by turning the barrel adjuster counterclockwise (if you end unthreading the barrel adjuster all the way, re-thread it all the way except for 3 turns, shift to smallest chainring, then pull the cable taut at the pinch bolt).

Loosen the H limit screw until there is more than 1mm gap between the chain and the derailleur cage when you apply pressure on the shifter (as if you are trying to go past the large chainring).

Tighten H limit screw 1/4 turn at a time until there is roughly a 1mm gap between the chain and the derailleur cage when you apply pressure on the shifter (and while having no delay in shifting).
NOTE: A loose H limit screw can cause the chain to fall off/out past the largest chainring.

Indexing (barrel adjuster; if no barrel adjuster anywhere at the cable, adjust cable manually at pinch bolt):

Shift to biggest chainring and smallest cog.

Intentionally loosen the cable by turning the barrel adjuster clockwise until there is movement in the front derailleur cage when you apply pressure on the shifter (as if you are trying to go past the large chainring).

Once you have movement, turn the barrel adjuster counterclockwise in slight increments until the moment there is no more cage movement when you apply pressure on the shifter.

IMPORTANT: You need to know that there are some gear combinations that are not really meant to be used. For example, largest cog to largest chainring, and smallest cog to smallest chainring. These will normally cause rubbing of the chain with the derailleur cage and should NOT be something that you need to try correcting (attempting to correct for this rub might break shifting in other gears).
Test-ride the bike: If there are issues, adjust barrel adjusters (or possibly limit screws) 1/4 turn.