Tuesday, February 5, 2008

How to adjusting the rear derailleur

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This blog entry will discus how to adjust the rear derailleur. No amount of adjustment will compensate for damaged equipment, be it a bent derailleur, derailleur hanger, bent or worn-out cog, chain etc. So I assume all is in good shape.

If you’re installing the derailleur for the first time there are some basic steps.
Once you have installed the derailleur on the bike, without the cable installed vertically align the top wheel of the derailleur with your smallest rear cog gear. You do this by adjusting the travel limiting screw on your derailleur labeled with a (H). Adjust the screw as needed to align the gear and derailleur.

Make sure your shifting pod is in the correct position for the high gear and you have adjusted the cable adjustment screw in all the way. Install your cable on the derailleur as normal making sure to pull the cable tight before tightening down the cable.
Check to make sure there is no slack in the cable. If there is, retighten the cable.

Once you have all the play removed form your cable, using the shifter pod select the lowest gear or where the derailleur is in the position to align with the largest gear on the cog. Make sure the top derailleur wheel is vertically aligned with the large gear. Now test to insure the derailleur doesn’t go past the largest gear and will not come in contact with the spokes. You can do this by pushing on the shifter or tying to push the derailleur closer to the wheel using you hand. If the derailleur goes too far or will not reach the sprocket adjust screw labeled (L) as needed. It is very important that the derailleur does not come in contact with the wheel in any way.

Now shift back to the highest gear (small cog) and install the chain. It is much easier to install the chain when it is in the highest gear. Also make sure to thread the chain correctly through the derailleur cage. Once the chain is installed make sure it peddles smooth and the chain doesn’t try to jump.

Now shift the derailleur into the lowest gear (largest cog) again. Check to ensure the top derailleur wheel is vertically lined up with the largest gear and if all looks good make sure the chain it runs smooth on the large sprocket. Once you have accomplished that, try shifting to second gear, making sure the chain drops as expected. If all looks good cycle through the gears as normal making sure the bike goes through all the gears as expected.

Now you can fine tune the derailleur; shift the drivetrain to the lowest gear (large cog) again and carefully shift it to the fourth or fifth gear. Now check to make sure the top derailleur wheel is vertically lined up with the selected gear. Adjust your derailleur by adjusting the tension on the cable. The chain should run about 1mm - 1.5 mm away from the next larger gear.

After you have taken the time to adjust the derailleur properly, and if the bike doesn’t shift correctly you most likely have other drivetrain issue and need to have it looked at by a professional mechanic.

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1 comment:

trickyrider said...

There are lots of different types of gears and gear mechanism fitted to bicycles. The most popular type is the front and rear derailleur system. 1. Set up bicycle in repair stand 2. Shift drive train into fastest rear gear 3. Release brake mechanism,Remove both wheels 4. Clean entire bicycle 5. Check over wheels 6. Replace wheels in dropouts 7. Adjust derailleur. http://www.bikecyclingreviews.com/adjust_rear_gear_html.html