The twist-grip shift itself
Long nose pliers
An adjustable spanner
Some Allen keys (to remove the grip shift from the handlebars)
Step 1: remove the cover of the handlebars
Step 2: insert the Allen key into the grub screw on the grip and loosen it. It comes off very easily. The new grip shift comes with cable, so slip off your cable cap to make it easy to remove, use spanner release the cable in place.
Step 3: pull the cable out of the cover.
Step 4: put the new grip shift on and you loosen the grub screw with the Allen key; just slot grip shift onto the handlebar.
Step 5: put a rubber handle back on the handlebar as well, getting it into position you are comfortable with;
Step 6: tighten up the Allen key again reasonably, don’t over tighten it because you never know how good the grub screws off, you don’t want to cross thread it.
Step 7: Unravel the cable and set it back through the cable guard, poking out the other end. Spread one end into the end of the grip shift while other end goes into a housing on the underside of the bike frame.
Step 8: then you need to thread the cable through the guide on the underside of the frame, and finally back onto the derailleur itself.
Note: Properly lots of stuff out there and the instruction guides as to how to get the tension right on the cable now on the derailleur itself. But the best way is a common sense approach when you shift from first gear to the second and to the third, you will see the derailleur moving across the front gears on the bike so you need to get the cable pretension you are happy with so that when you move to the second gear, the derailleur moves a cable onto the second cog.
Step 10: turn your bike upside down maybe on the table if you’ve got the space. You can turn the wheels and firm it with the derailleur to see whether you got tension on the cable right.
Step 11: put the grip shifter into first gear which is the loosest in terms of tension on the cable. There’s also some adjustment and some fine-tuning that can be done by turning nuts. So we’ll leave that fully in so that we’ve got a maximum amount of adjustment.
Step 12: You are going to take up tension on the cable and simply tighten up the nut on the derailleur with spanners. Then with the left hand, the handlebar and the grip that you need to operate. Slightly off the table, so you can turn it and then turn the wheel round, this won’t break the grip shift.
Step 13: Then see how the derailleur is performing to decide whether it needs some adjustment or not. You can turn the cogs down and tighten up cable a little bit, and then turn the wheel again, and give it another go in third, down first, up to second, back up to third.
Step 14: After all seems to work smoothly, you might then just turn the bike in the right way up and just check the gear shifting when successfully corresponds with the right number on the chip.