Mountain bike front derailleur debugging, mountain bike speed adjustment method

1. Confirm that the rear wheel is correctly installed
If the rear wheel is disassembled and re-installed, if the gear shift is inaccurate, in addition to the deformation of the transmission or the lug caused by the collision during the transportation, it is more common for novices that the rear wheel is not installed correctly, resulting in To one side, or the quick release is not firmly pressed. After opening the quick release, hook both ends of the quick release with the index fingers of both hands, put your thumbs against the frame hooks, slightly raise the body and hit the ground, confirm that the hub axle does enter the hooks, and then re-press the quick release .
2. Confirm the life of the chain and clean the transmission system
The chain will be elongated and worn after a long time. Continued use will accelerate the wear and tear of the flywheel, gears and rear variable guide wheel. Therefore, regular use of chain gauges to confirm whether the chain length is still within the allowable range of extension is one of the important maintenance tasks. After that, start with cleaning the flywheel. You can choose to remove it and wipe it or use it with a long-haired stiff brush with detergent. The rear variable guide wheel is another focus of cleaning. If you haven’t noticed this part of maintenance for a long time, sticky chain oil Thick sludge will accumulate on the guide wheel, which is also one of the common causes of unsmooth gear shifting.
3. Change the lifting lugs after correction
When the rear derailleur reaches the maximum flywheel position, there is almost less than 5 mm of distance from the rear wheel wire. As long as the lugs swing inward, plus the sum of the deformations when pedaling hard, it may cause the rear derailleur to be involved. Among the rear wheels, if the lifting lugs of the lighter ones break and become skewed, the rear wheels of the heavy ones are damaged and the rear wheel is reimbursed, even causing a car accident.
4. Reset the tension adjustment button of the variable speed cable to zero
In order to strive for a larger space for adjusting the tension of the transmission cable, the knob must be rotated to the end in a clockwise square line before replacing the new cable. When the inner cable is not replaced, the screw out range should be within 2~3 teeth. If it exceeds, reset the knob to zero, loosen the inner cable fixing screw and tighten it again before adjusting.
5. Adjust the upper and lower limit screws
The L and H screws respectively limit the upper and lower ranges of the transmission. Exceeding this range may cause the chain to break away from the flywheel, resulting in scratches on the frame or wheel wires, or even the rear derailleur being caught in the rear wheels.
When adjusting the H screw, retract the gear to the position of the smallest flywheel, and change the front derailleur to the position of the big plate, and confirm whether the smallest flywheel is in line with the rear variable guide wheel. Then turn the pedal with your right hand, buckle the post-change body with your left index finger, push the post-change link with your thumb, and release the chain after going up to gears 3 and 4 to confirm whether the chain can return to the minimum gear. If it falls out of the flywheel range, Turn the H screw clockwise. If it is not possible to return to the minimum gear, turn the H screw counterclockwise and continue to rotate the pedal until the chain can return to the next minimum gear and there is no abnormal sound.
When adjusting the L screw, turn the pedal to retract the front gear to the small gear position, and manually push the rear derailleur to the position of the largest flywheel. If the chain falls between the flywheel and the wire, or the rear guide plate hits the wire, Rotate the L screw clockwise until the chain does not fall down; if the chain cannot smoothly reach the position of the largest sprocket, turn the L screw counterclockwise until the chain can smoothly reach the largest sprocket position.
6. Install a new insider line
In addition to the difference in smoothness that can be felt by the touch of the inner cable, the naked eye can also judge whether the surface woven by countless fine threads has been ground. These details will cause the shifting feel after completion. Compliance, if the wire surface is coated with Teflon or the like, there is no need to put butter on the installation process.
7. Tighten the gap between the line pipes
After the inner cable is installed, it must be confirmed that the gap between the variable speed outer tube and the thread stop bolt is minimized, otherwise the inner cable tension must be adjusted again after using it for a long time. The method of the egg is to hold the rear derailleur firmly with one hand to prevent it from moving when in the minimum gear, and force the shifting gear lever with the other hand to use the power of the inner cable to tighten the gaps between the lines and tubes. After tightening, try to pull the uncovered variable speed inner cable. If the tension is too loose, loosen the inner cable fixing screw and re-tighten it.
8. Adjust the B screw
The purpose of the B screw is to adjust the distance between the guide wheel and the flywheel when it is adjusted to the maximum flywheel gear. Under the premise of not allowing the two to contact and produce abnormal noise, the closer the guide wheel and the flywheel, the better the transmission efficiency. Take the specifications of SHIMANO and SRAM as an example, the minimum value of this distance is 6mm, which can be confirmed with a 6mm Allen key. Screw in clockwise, the farther the distance between the guide wheel and the flywheel, and vice versa, the closer.
9. Adjust the tension of the transmission line
Next, start to rotate the pedal and move the shift lever one by one to observe the movement of the rear derailleur. Each gear will stay for at least three seconds. If the upshift speed is too slow, turn the tension adjustment knob counterclockwise; if downshifting If the speed is not smooth or the speed is too slow, turn the tension adjustment knob clockwise until the balance point of the forward and backward gear speed is obtained.
10. Take-up end
Cut off the excess wire tail at a position about 3 cm behind the fixing screw of the variable speed inner cable. Subjectively, this length is more beautiful and there is enough space to use it if you need to loosen the fixing screw in the future. When cutting the thread, it is best to hold the end to be kept with one hand to avoid the inner cable from splitting. Then use the built-in function of the wire cutter or any handy tool to press the end sleeve tightly.