DERAILLEUR ADJUSTMENT


want to state upfront that if you don’t know what you are doing when it comes to adjusting a derailleur (front or rear) don’t attempt it as you will likely make things worse. That being said, it is not necessarily a difficult thing to learn. Here are some resources to help:

http://sheldonbrown.com/derailer-adjustment.html

http://www.williambenedict.com/bikes/derailleurs.html

There are gobs of other sources available online about this subject. From my own personal experiences I don’t buy into everything I read about this as far as the instructions they give. I have found that what seems to work on a bicycle may not always work as well on a trike … strange as that may sound. Every time without fail that I have had a “professional mechanic” adjust my rear derailleur I have had to redo it myself as their work never lasted long before problems developed. It usually did good to last thru the day. The way I go about this I learned a few years ago and I have found that it works quite well and remains working for a very long time. So without further ado here is how I recommend adjusting the derailleurs.

Keep in mind that a derailleur moves the chain from the smallest sprocket onto the largest sprocket … that is to say that with no tension on the shifting cable the chain will be (should be) on the smallest sprocket. As the cable is tightened (by rotating the twist shifter or moving the shift lever) the derailleur will move the chain over onto larger sprockets.

The first thing one should check the rear derailleur itself … making sure it is straight, not bent out of position. The area of the frame where the rear derailleur bolts onto (known as the derailleur hanger) is made to bend (or even break off) to protect the rear derailleur from being damaged. Sometimes the derailleur still gets damaged anyway. Oftentimes the mounting area can be straightened. I have straightened them just with my bare hands taking a hold of the derailleur to use as leverage. Of course, one needs to be careful not to bend the derailleur in the process. The main reason I have done it this way is because I was out riding at the time and didn’t have the “special tools” needed to work on this. Sometimes it was someone else’s bike or trike I was working on trying to get them going again. This brings me to another point … namely if something happens where you can’t pedal normally and easily stop pedaling immediately and don’t try to push hard on the pedals forcing the crank to turn. By doing this you can cause serious damage back there with the rear derailleur and derailleur hanger. This and getting a tree limb or something such kicked up into the works back there are probably the two main causes of damage.

I have also used tools I rigged up. There is a tool made for this which one can purchase. However, I have found that with a 20 inch rear wheel and fenders it is quite difficult and impractical to use if if not impossible. If you have a “good eye” and know what you are doing you can accomplish this task just looking at things. Sometimes the derailleur hanger won’t straighten sufficiently and needs to be replaced. As stated, they are designed to bend or even break off so they are easy to replace. Depending upon where the hanger got bent it may be easy to straighten. If it bent thru the threaded hole I would strongly advice replacing it as it isn’t practical to try to salvage  the threads.

Here is what the Catrike derailleur hanger looks like:

Catrike derailleur hanger

Other brands look similar. If you look up images of a derailleur hanger you will find that they make what seems like a blue million of them … all different from the other.

And here is what the tool used to straighten a bent derailleur hanger looks like:

rear derailleur straightening tool

And here is a picture of a bent derailleur hanger:

SANYO DIGITAL CAMERA

Of course, this is a minor bend.  A bike or trike can usually still be ridden with this sort of damage until such time as it can be worked on.

Here is a picture of a really bad bend which has moved the derailleur right over into the spokes of the rear wheel so that it can’t be ridden.

rear derailleur and hanger badlly bent

Keep in mind that this is shown being done on a bicycle and not a tadpole trike. It is easier to do on a bike which has a much larger diameter wheel (unless you have a 26 inch or 700 rear wheel) and nothing much in the way than a trike with a 20 inch wheel and oftentimes some stuff in the way.

Once the alignment of the rear derailleur is checked out and is determined not to be bent you can proceed on to the next step which is determining if the derailleur is properly aligned at the extreme travel between the smallest and largest sprockets (cogs). The sprockets should be perfectly lined up vertically with each other.

rear derailleur alignment with cogs

This alignment needs to be done before any other adjustment is attempted.

Note – I am sure there will be people who don’t agree with what I am sharing here. That’s okay, but I really am not interested in hearing/reading comments about it since I have seen the results of doing it other ways. I paid out good money to have someone do it their “other ways” and wasted my money as I had to redo it myself.

To make this adjustment the shifting cable ideally should be completely disconnected from the derailleur. In the high gear position (smallest sprocket or cog for those who insist on being technical) the adjustment is quite easy to do since the spring(s) in the rear derailleur move and keep the derailleur over on that side. Adjusting it on the opposite side is a little more involved and difficult since you are fighting the spring(s) to move the derailleur over and hold it there … but it can be done. I just pull the derailleur over by hand the same as the cable does. Once you have this vertical alignment done you can proceed to the next adjustment which is the actual shifting.

Before doing any adjustment for the shifting there are some prerequisites:

1) be sure that the shifting cable is still detached from the rear derailleur

2) turn in any shifting cable barrel adjusters all the way in and then back them out about 3/4 of a  turn

3) shift the shifter into high gear position

4) the chain needs to be on the smallest sprocket of the crankset (front sprockets where the pedals are)

5) the chain should already be on the smallest sprocket on the rear but make sure it is

6) make sure the shifting cable is seated all the way into the ferrules all thru its run (shifter, rear derailleur and any other place which might apply)

With all these things done you are ready to continue …

1) take all the slack out of the shifting cable by pulling it (with your fingers only) tightly down at the rear derailleur and then tighten the clamp down on the cable to hold it with the slack removed

Note: If you have help available this next part is much easier to do with their assistance since a tadpole trike’s chain run is much longer than a bicycle’s. I don’t think a gorrilla has arms long enough to reach the pedals and have their face back by the rear cassette (sprockets) so they can see what is happening.

By following these instructions above the shifting should work fairly well as is. However, it may need slight tweaking to dial it in so pedaling and shifting is required. You can make minor adjustments by turning a barrel adjuster on the shifting cable. You shouldn’t have to turn it very far either way. Usually, if anything is needed, making the cable slightly tighter is the answer. Getting it truly dialed in usually is best accomplished while riding it and seated.

Here is the rear derailleur nomenclature:

rear derailleur nomenclature

That should be it for the rear derailleur. The front derailleur is usually much simpler and not as sensitive as the rear derailleur. Here is a video explaining how:

There is one adjustment I have not mentioned as of yet. It is the “B-Tension”  or angle adjustment screw. Basically you should adjust the B-tension screw so that the pulley on the rear derailleur is as close to the largest cog on the cassette as possible without dragging. On a bicycle the angle of the chain coming onto the rear cogs is different than it is on my tadpole trikes. Because of this the appearance of the chain as it wraps part way around the sprocket varies from what is seen on a bicycle. In the drawing below notice how much more of an angle on the trike compared to the bike. I point this out because one can’t go by what they say about this adjustment for bicycles since a tadpole trike is different. Basically speaking in either case, bike or trike, the chain wraps approximately half way around the sprockets. The B tension adjustment should reflect this and still have about 5 to 7 mm or about .2 to .27 inches gap ( just over 3/16 to about 17/64 inch).

b tension adjustment angle

Park Tools says:

“For derailleurs with a spring in the upper pivot, begin by shifting to the innermost rear cog, which is the largest cog. View the upper pulley relative to the largest cog. If the pulley is rubbing against this cog, tighten the B-screw to increase upper pivot spring tension, which pulls the pulley back and away from the cog. If there is a large gap between the upper pulley and cog, loosen the screw. To find a good setting, loosen the B-screw until the upper pulley begins to rub, then tighten the screw to get clearance.”

B tension adjustment

To be most honest and upfront with you it is this adjustment I have struggled with the most … not being sure of what I am doing and the end result. All I know is I am not having any trouble with the shifting.

Here is one set of instructions I just found:

With the chain shifted to the largest rear sprocket turn the crank (pedal the trike) and open up the B tension screw until you hear a rattling noise and the rear derailleur starts to vibrate. Then tighten the B tension screw until you hear no rattling.  They say that the jockey pulley of the rear derailleur should be as close as possible to the large rear cog without making any noise.

This is how I go about adjusting my derailleurs and it works great for me. I have tried to talk to mechanics about this and they just pay no attention to me and continue on doing things the way they always do.  They may get away with it on bicycles, but it sure doesn’t work on my trike. That’s why I usually don’t let them adjust my derailleurs anymore. I tell them it shifts fine as is … please don’t touch it!

MISC TIDBITS:

Lubrication –

The derailleurs should occasionally be lubricated as they have several moving parts … all of which need a drop of oil applied periodically. This will ensure that they move freely and function properly.

Today’s cables (shifting and brake) are said to be pre-stretched and pre-lubricated. That means that supposedly readjustment should not be necessary due to the cable stretching after use. And “they” say that cables should not be lubricated … not ever. You won’t go to jail if you do and I have done it myself on occasion and it was helpful. I have had moisture get inside of the cable housing and in the winter time the cable froze up and caused problems.

“Cable Adjustment
The cable tension adjuster defines how far up or down the derailleur moves. Step back so you can see the chain and sprocket alignment, and then through the gears in both directions, first shifting up two and down one, and then down two and up one. The chain should look centered on each sprocket. If it is rubbing on a larger gear it means there is too much tension on the cable. Loosen the tension by turning the adjuster clockwise. If it wants to jump down to a smaller gear it needs more tension. Increase the tension by turning the adjuster counter-clockwise.
You can also use sound to check the adjustment. There is always a base-level of noise that can be heard in every gear. This noise will increase in a slightly different way depending on which way the tension is out of adjustment. If there is too much tension you will hear a metallic rubbing sound, but if there is too little tension you will hear a clicking noise as the chain tries to jump to a smaller sprocket. There is usually a cable tension adjuster on your shift lever. With practice you will be able to make small cable tension adjustments while you are riding.”  (from the Sheldon Brown website)

Here are the original instructions I came across several years ago. I don’t remember what website I found it on so I can not give credit here for it.

“Adjusting your derailleur

One of the main problems that I find on every single bike that comes through my shop is that the derailleurs are out of adjustement. The derailleur is that thing in the front and back of the chain drive that “derails” the chain into it’s proper place. Now, don’t bother fidling with the thing as it is, let’s start fresh.

FIRST: Unscrew the cables from their attachement on the derailleurs. Bring the shifters back to their dead position, that’s when there is no pull on the cable and make sure that all the cable housing adjustment screws on the shifters and/or derailleurs are screwed back in to their original position(more on that later).

SECOND: Now with everything deconnected, turn the pedals and the chain should come to rest in the last position gear on the outside of the wheel and at the first one closest to the frame on the chain ring. That’s because the system works by pulling on the devices with the cable. If you are not at the last gear on the wheel and the first one at the chain ring, you have already found a problem. You have two screws on every derailleur, one to adjust the last gear: “H” and one to adjust the first gear “L”. This is the same on every derailleur, adjust that screw by going clockwise to move the derailleur in and counterclockwise to move it out. Careful, in the rear one you could end up with the chain in between the wheel and the frame, go slowly.

THIRD: Now that your derailleurs are adjusted properly at their last position gear, reinstall the cable. Make sure there is no slack in the cable. Now turn the pedals and click in the first position for the rear derailleur, it should go into the next available gear. Not doing that? Don’t worry, remember that adjustement screw on the cable housing? Now start to unscrew it slowly while turning the pedals. This will strech the cable a little bit at a time. Unscrew it until the chain goes into the next available gear,”click” that’s it, you’re done. Now shift until you have pulled the cable all the way to first gear. If it goes there, you’re good. If not,one of two things have happened. Booboo one is that the chain won’t go into first, simply unscrew “L” slowly until it does while keeping tension on the cable with the shifter. Booboo two, the chain is now between the gear and the spokes of the wheel. Carefully remove the chain and set it on the first gear and screw “L” to block the derailleur from going forward.”

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About Steve Newbauer

I have a few current blogs (tadpolerider1, navysight, and truthtoponder) so I am keeping busy. I hope you the reader will find these blogs interesting and enjoy your time here. Feel free to email me at stevenewbauer at outlook.com

Posted on July 11, 2014, in maintenance/repair, tadpole trikes, videos and tagged , , , . Bookmark the permalink. Comments Off on DERAILLEUR ADJUSTMENT.

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