Rear derailleur adjustment screws
5 min read
Asked by: James Stafford
What screws to use to adjust derailleur?
Your derailleur has two limit screws. For the outer limit, you adjust the H-Screw, so your chain does not fall between the cog and the dropout and for the inner limit, you turn the L-Screw, keeping the chain from derailing towards the spokes.
What are the three screws on a rear derailleur?
Derailleur Limit Screws (H-screw and L-screw) Rear derailleurs “derail” or shove the chain off of one sprocket and move it to another. The upper derailleur pulley (called the “guide pulley”) pushes the chain to the next sprocket. A proper gear adjustment aligns the guide pulley under the sprocket.
Which are the H and L limit screws?
Limit screws are typically labeled as H and L for high and low limit—high limit sets the position for your highest gear (aka smallest cog/sprocket on the cassette) and low limit for your lowest gear (largest cog, which is closest to your spokes).
What does the B screw do on a rear derailleur?
The B-gap or B-tension screw is located at the very back of your derailleur. It pushes against a tab on your frame’s derailleur hanger, allowing you to adjust the distance between your rear derailleur’s top pulley and the cassette.
What size are derailleur limit screws?
Specifically, M4 x around 18 mm.
What does H and L mean on a derailleur?
You need to adjust the high (H) and low (L) limit screws on the derailleur. Viewed from behind the bike, the H screw limits how far the derailleur can move to the right, while the L screw limits how far the derailleur can move to the left.
What does the H screw do?
The H screw dictates how far towards the frame the derailleur can move (the higher limit). Turning it clockwise moves the jockey wheel closer to the spokes, counter clockwise, closer to the frame.
Which way do you turn an H screw?
If the chain does not shift to the smallest cog, it is likely being stopped either by the limit screw, or cable setting. First turn the H-limit screw count-clockwise a few turns.
How do you adjust a Shimano rear derailleur?
Quote from video: The derailleur down into the small cog. Once we do that we're going to turn the barrel adjuster all the way in so that we have room to adjust it. After adjusting the cable position at the anchor.
Do limit screws affect shifting?
Cable tension and limit setting
In the simplest of terms, sluggish upshifts can be caused by too little cable tension; while slow downshifts could be too much tension. Limit screws set the extremes for which a derailleur can travel. Too often people wrongly play with these screws when shifting goes bad.
What does the low limit screw do?
The lower limit screw sets the maximum distance the derailleur can shift in the lower gears. The B-limit screw sets the distance the upper jockey wheel sits from the cogs. (B) Barrell adjuster – This is an adjustment device on the back of most derailleurs.
How do you set a limit B screw?
Quote from video: If the B screw is too loose it will Rumble as we ride. If the B screw is too tight this gap will be very large and the shifting will be sloppy to set the screw we must turn it.
Should you adjust the front or rear derailleur first?
In a nutshell, adjust the front derailleur first, then the rear. Show activity on this post. If the derailers just need minor tweaking (they are basically in adjustment but are “not quite right”) then you adjust the one that is obviously wrong, check the overall adjustment again, then again adjust what needs adjusting.
What size is B screw?
The B-screw is an M4 x . 75 pitch x 12mm length.
What are limit screws?
The main purpose for the limit screw is to prevent the chain from going into the spokes or into the frame. Tightening the H-limit screw restricts the limit as shown. The goal is to dial it in as close as possible to the inward cog, as shown in the previous photo.
How do you adjust the limit on a B screw?
Quote from video: Help out the little fellow by first pulling the derailleur body back make the adjustments that you want and then put the derailleur back in its normal. Position.
How do I adjust the tension on my derailleur?
Adjust the cable tension
Clockwise decreases the tension, moving it back towards the frame. If the chain seems hesitant to shift up, increase the cable tension by turning the barrel adjuster anticlockwise. If it skips over a gear, turn the adjuster clockwise to decrease the tension.
Which way do you turn an H screw?
If the chain does not shift to the smallest cog, it is likely being stopped either by the limit screw, or cable setting. First turn the H-limit screw count-clockwise a few turns.
How do you adjust a Shimano derailleur?
Quote from video: The derailleur down into the small cog. Once we do that we're going to turn the barrel adjuster all the way in so that we have room to adjust it. After adjusting the cable position at the anchor.
Should you adjust the front or rear derailleur first?
In a nutshell, adjust the front derailleur first, then the rear. Show activity on this post. If the derailers just need minor tweaking (they are basically in adjustment but are “not quite right”) then you adjust the one that is obviously wrong, check the overall adjustment again, then again adjust what needs adjusting.
How do you adjust a Shimano 7 speed rear derailleur?
Quote from video: So the first thing you want to do is take your 9 millimeter socket. You go ahead and loosen the cable. It's always the first. Step.