Gear and Brake Cable Replacement

Question: When replacing cables for front and rear derailleur, what position should your H and L screws be?  All the way up or down perhaps half way??  Same for brake cables adjuster.
Jack.

Hi Jack,

If you are changing the gear cable on either the front or rear derailleur mechanism you shouldn’t touch the adjusting screws. These are to stop the chain falling off either the inside or the outside of the sprockets at the back or the chain set at the front. If it’s only a cable change the screws should still be in the correct position, if you need to adjust them then it most easily done before you fit the cable, this you do by pushing the rear derailleur in with your one hand while turning the pedals with the other.

If the chain comes off on the wheel side you need to screw in the L screw until it sits on the sprocket comfortably and if it comes off the small sprocket then you need to screw in the H screw. Then of course if they don’t go far enough you have to let the screws out.

The front gear mechanism is the same; you shouldn’t need to do anything with the adjusting screws if it worked well before. If you do need to adjust them then this is easier with the cable attached, the same procedure as the rear, if the chain comes off the inside then screw the screw in and on the outside then it’s the other screw. The lever does not stop the chain coming off the sprockets, inside or out.

Push in and out

When putting a new brake cable you should wind the cable adjuster nearly fully down because as the cable stretches, as new cable do, you will need to take up the slack with the adjuster possibly out on the road when you don’t have the tools or the time. I said nearly all the way down because when you fit a new cable you tend to pull it fractionally too tight and might need to slacken it until the cable stretches. After you fit brake cables pull the brakes on, very hard a few times to bed the cable in and to stretch it a little, always check your brakes before you go on a ride.

Good luck, the best way to learn to be your own mechanic is by doing it.