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Questions and answers about sports

Sprocket touching the biggest cog no matter B screw…how do I fix?

5 min read

Asked by: Sheri Sharp

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.

Why is my derailleur touching my cassette?

When the spring breaks or wears down, the derailleur becomes “weak”, and the chain pulls it forward too much. In some cases, the derailleur assumes an awkward position causing rubbing against the cassette. If you have a bad derailleur spring, the solution is to replace it or buy a new derailleur.

Does the B screw affect shifting?

So what does happen when the B-Tension adjustment is too far away from the cog? Essentially, it just slows down your shifting. It will still work, but as the derailleur pushes on the chain from the inside, the shift takes place when the chain picks up the tooth on the next cog.

What does B gap do?

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. That distance is your B-gap.

Why is my b screw not working?

If the derailleur is bent, the b-screw may fail to come in contact with the hanger. If that’s the problem, you will have to straighten the derailleur if possible or replace it. If the derailleur isn’t fully tightened to the hanger, the b-screw and the lip of the hanger may not come in contact.

Does the B screw increase chain tension?

The B-screw is not for tensioning the chain, it is for adjusting the clearance between the mech’s guide (top) pulley and the biggest sprocket.

How close should jockey wheel be to cassette?

With the bike in the highest gear, the upper jockey wheel should run just clear of the cassette. Turning clockwise will increase the gap, anti-clockwise will close it. Adjust until there is about 2mm of clearance between the cassette and the upper jockey wheel.

How do you adjust the B screw on a rear derailleur?

Quote from video: And shift the rear derailleur to the biggest cog. I'm gonna start off by backing the B screw all the way out. So I'm gonna do that by turning this counter clockwise.

How do you adjust tension on a derailleur?

Adjust the cable tension

Turning the adjuster anticlockwise increases tension on the cable, bringing the derailleur closer to the wheel. 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.

What size is a Shimano B-screw?

The B-screw is an M4 x . 75 pitch x 12mm length. Looking at a couple older shimano derailleur’s, it appears that the B-screw is also an M4.

How do you calculate B tension?

Quote from video: If you're going to measure your b gap usually use calipers. Or you might have a handy measuring tool in your toolbox.

How do you adjust B screws on a mountain bike?

B-Tension Adjustment

If the guide pulley is rubbing on the sprocket, tighten the B-screw clockwise to increase tension and move the pulley away from the sprocket. If there is a large gap between the pulley and sprocket, loosen the B-screw until the pulley rubs the sprocket, and then tighten it until it just clears.

What is B limit?

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. It is the area where the derailleur cable enters the derailleur and can increase or decrease the cable tension by threading it in and out.

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.

What does a derailleur extender do?

Quote from video: Похожие запросы

Which way do you turn a limit screw?

Turning the screw clockwise, moves the derailleur limit to the left, turning it counter clockwise, moves it to the right. In the end, the sprocket and the upper pulley should be aligned perfectly.

Which way do you turn a high limit screw?

Set the limit screws

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. You want the uppermost jockey wheel to sit directly below the smallest of the sprockets.

How do you set a mixture for a screw?

Turn the screw counterclockwise and clockwise 1/2 a turn from the middle position and listen to the sound of the idle. Set the screw in the position where the engine’s idle sounds most even and smooth to balance the fuel mixture.

How do you adjust a set screw?

Set screws – how tight is tight enough? To tighten new, standard, alloy, cup point set screws, install an allen wrench with the short end in the socket, long end in your hand, and tighten until the wrench bends or twists about 30° (1 hour on a clock face). Then the set screw is as tight as it should be.

How do you fix a misaligned screw hole?

Possible Solutions

  1. Re-Drill the new hole slightly oversize with a larger drill bit. …
  2. Use a rat-tail file or a rotary file, or a grinding tool to enlarge the hole only in the area needed. …
  3. Then there’s the fun one . . . …
  4. If you’re really in a hurry, just use a smaller pin or a bolt with a little smaller diameter.

How do you fix a screw in the wrong place?

Quote from video: And get some toothpicks for this hole right here three ought to do it just place them in the hole. Like that break off the excess.