cugrad said:I am new to biking, and I bought one of those online Dawes bikes (Lighting 1000) b/c I thought it would be a good way to force myself to learn how the components work. Well, so far it has, except for one problem I am having. For reference, this bike using Shimano Sora components, the rear derailleur has a part number of RD-3000 on it. I have consulted the shimano PDF tech files, as well as a few other sources, to no avail.
When on the lowest gear settings (little front gear and big rear gear, right?) the rear derailleur vibrates considerably. Seemingly it is a "vertical" vibration, not lateral. If I pull on the brake cable (which pulls the guide pulley away from the sprocket) just slightly, it relieves the vibration. Clearly, something is trying to hold that guide pulley too close to the sprocket. However, I have toyed with everything and cannot seem to fix it. I would expect the B-tension adjustment screw to fix it, but it appears to have absolutely no effect on anything. 😕 I have also played with the top and low adjustments, as well as the brake cable tension (but just the small tensioner, whatever you call it).
Thanks in advance for any help.
There is a method and order to adjusting the rear derailleur and it works much better to follow a step by step procedure than just tweak here and there. Rather than go through that here, you should check out two online sources that are excellent in talking you through this: www.sheldonbrown.com and www.parktool.com
sheldonbrown.comindex.htmlOpen ↗
parktool.combyregion.aspOpen ↗
Both have sections on derailleur adjustment. Read both before starting and follow the one that makes most sense to you. Both will work fine, just a matter of which one works best with your brain 🙂
I applaud you for wanting to learn how to do this stuff yourself, and it is very doable. Back in the way early days, I completely tore down my first derailleur bike and built it back up using a printed repair manual (Glenn's) and no face to face instruciton... so I know it can be done.
You cann print the instructions from those sites (recommended) If you'd rather have a printed book, one I've seen that looks pretty good (which I bought for a young friend new to road bikes) is by a guy called Zinn.
By the way, it seems you have some nomenclature mixed up. The front brake levers control both braking and shifting, and therefore move two differnt cables depending on how you're moving the lever - squeezing the lever moves the BRAKE cable. Pushing the lever sideways moves the SHIFT (AKA derailleur) cable.
