Tuesday, June 24, 2008

Somewhat Complicated Bike Repair - derailleur roller cleaning

Today I became fed-up with the popping my road bike has been doing lately. The slack on the chain would suddenly increases, then decreases, creating a jerking motion. After observing this a few times, I realized that my rear derailleur (or dérailleur) was the cause of this. On a previous ride to Belen, a large amount of bubble gum lodged itself in my rear derailleur, which seems to cause the slack issue.

In case anyone else is having problems similar to these, and doesn't like to pay a bike shop $60 to fix a $100 part, I decided to write a simple post of how to clean the rollers on your rear derailleur. When I started working on bicycles, I wasn't able to find any good resources online teaching people how to fix things. Hopefully this post can help if you want to learn about fixing bikes but aren't quite sure where to begin.

Please continue reading below if you would like to learn how to clean your derailleur rollers in an easy and fun way. Before I performed this repair, I checked to see if my chain had any stuck links. From the limited amount of bike repair I've done, stuck links seem to be a much more common problem that a junked up derailleur. If you want to try and clean your derailleur rollers, it might be a good idea to read this post the entire way through before you begin on anything. If you have any questions, send me a comment and I'll try and clarify.

You will need the following tools to perform this repair:
  • Allen Wrench that fits your derailleur
  • Boiling Water
  • WD-40
  • Tri-Flow or some other grease
  • Clean Rag
Here is a basic diagram of the different parts on a rear derailleur:




Originally From here


Since the bubble gum was kicked up on my derailleur, I decided to clean the two rollers and the casing. My bike has basically the same design as above, with a slightly different casing mechanism. I have a Shimano 105 rear derailleur. The first thing I did was to throw my bike on my Nashbar (r) bike repair stand.



As you can clearly see, the Nashbar brand products are highly reliable (please note the vice grip acting as a handle.) At first, I used to wonder why Nashbar brand tools were so cheap. Now I realize that the low, low cost is due to the fact that everything I bought under that brand broke. I now try and purchase Park brand tools even though they are 2x-3x as expensive. If you do not have a bike repair stand, you can have a friend hold the bike for you while you work, or you can try and balance your bike like this in a chair (not recommended, but this is what I did before I bought a repair stand):



Note how the front fork is wedged into the chair arm, while the other chair arm is wedged under a counter. This is done in order to life the rear wheel off the ground, stabilize the bike and give you access to the rear derailleur with both hands free. You want to be able to spin the pedals to make the rear wheel move without it hitting the ground.

If you don't have a repair stand, and don't feel comfortable putting your bike in the ghetto repair stand, you can perform this repair without one. Simply be careful during the "testing" phase later on.

After my bike was on the repair stand, I thought for a bit about how the different parts were held together. On my bike, a single Allen bolt holds on both rollers. Once I realized that the top and bottom rollers screwed in from opposite directions, I took note of which way each one way attached. Here are some images of how my rollers are held in:


Here is a picture with some clarification in case you're not sure how to spot an Allen bolt.
This view is from looking inside my bike, I needed to work on my top roller reaching through the spokes.


Here is the outside view of the bottom roller.


Another picture of the bottom roller

After securing my bike in my repair stand (or depending on your resources, chair-counter combination) I removed the bottom Allen bolt and carefully placed it someplace I wouldn't loose it. Once the Allen was out, I carefully remove the bottom roller and broke it into it's components. Make sure you are very careful with this step, I was lucky enough not to lose any of the parts despite my somewhat haphazard removal of assembly.



Here are two casing components, an inside sleeve and the roller itself. I did not include the allen bolt in the picture.


The casing components should pop out of the roller pretty easily. For my bike, I had to use a flathead screw driver to carefully pry open the top roller since the parts were safely housed away in a protective bubble gum cocoon. After everything was separated, I sprayed WD40 on everything and scrubbed it down with a rag. This removed a lot of the caked on grime, but didn't cut the bubble gum at all. For that, I placed the parts in boiling water and scrubbed the pieces down when hot. After repeating the boil-scrub cycle for about 7 times, all the gum was cleaned off. I did a final WD40 treatment on the dry pieces, wiped them down, and then put a TINY amount of tri-flow (synthetic grease) on the insides of the part. After reassembling the pieces for an individual roller, I placed the roller back in my derailleur.

Once both rollers were clean, I carefully took off a casing piece that was held on my the rollers and cleaned that as well. The casing wasn't totally necessary for clean chain movement, but I didn't want any little pieces of bubble gum going back into my rollers. Everything that was assessable was rubbed down with a rag.

Probably the most difficult part here, that I somewhat glossed over above, was getting the roller back into the derailleur such that the chain is correctly guided by the roller. In order to accomplish this, I used one hand to hold the roller in place and remove the chain tension from slamming the roller out of place. My other hand was used Turn the Allen bolt. This isn't quite as awkward as it sounds though, once the Allen is into the housing even a little bit, you don't have to stabilize it much leaving your hand free to remove slack from the chain.

After everything is back together, turn your pedals a few times to drive your wheel and send the chain over the newly adjusted derailleur. Using my repair stand makes this test simple and easy. If you did not take my approach of wedging your bike into a chair, I recommend lifting up the rear wheel and using your other hand to spin the pedals. Do not actually ride your bike to test this - if the chain is not correctly running along the rollers you probably will cause some damage riding it.

Look closely at how the chain is moving over the rollers. If it is a smooth motion with the chain being guided by the rollers, that is looking good. Shift through all your rear gears to make sure that's still working. When I performed this repair, I did not have the chain guided by the roller correctly. If everything looks good, take it for a test ride.

Thanks for reading! Depending on how things go, I might make some youtube videos of bike repair. Send me a comment if you think that would be cool. A special thanks to Oleg Semanov for loaning me his nice digital camera to take pictures with for this post.



1 comment:

Anthony Russell said...

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