Bicycle Mechanics - How Do You Stop Rear Deraillers From Skipping Gears

hey
i bought a new rear derailler and shifter for an old giant iguana as i cant sell it with a broken one. we put it all on but the rear derailler skip a couple of gears in the middle but is ajusted so it fitts on the top and the bottom cogs. how do i adjust the cogs it the middle.

Did you keep the old wire? If so, perhaps the wire is sticking in its sheath (rust, dirt), making precise gearshifts impossible.
Erling.

How many miles on the chain? How "stretched" is it? Do the rear cogs show any wear? More info, please.

The cable length needs to be adjusted so that the derailleur is in the correct cog to match the index of the shifter. The Hi/Low stops keep the chain from overshooting the "top and bottom cogs" only.

Al

hey
i bought a new rear derailler and shifter for an old giant iguana as i cant sell it with a broken one. we put it all on but the rear derailler skip a couple of gears in the middle but is ajusted so it fitts on the top and the bottom cogs. how do i adjust the cogs it the middle.www.parktool.com repair section has the skinny on deriler adjustment. Start at the beginning with good cable.

yeh
everyone i put a new gear cable in i have a new lx deore derailller and decore shifters, the rear cog may be a bit worn but it looks ok. how do i adjust the hi low shifter so it adjusts the ones in the middle.

Without looking at your bike, my guess is that you have a bent derailleur hanger. That's fairly common and the fact that your old derailleur was broken makes me suspect a bent hanger even more.

Shift into a gear that makes the arm on your derailleur point straight down. Now stand your bike up against something and go around to the back of the bike. From the back, your derailleur arm should point straight down. If it's pointing toward the wheel, bend it back straight (you can probably do it with just your hands) and see how it works.