Removing a seized-in eccentric from a Thorn Rohloff equipped cycle.
Andy B. September 2006
Because our alloy eccentric is anodised and because the inside of the shell is treated with rust inhibitor (as well as being greased prior to assembly) a seizedin eccentric is a very unlikely occurrence. However, if the bottom bracket is allowed to become submerged and active steps are not taken to drain the water out, it is possible that some oxidation will eventually occur… the longer this process is allowed to continue, before any chain adjustment is attempted, the more possible it becomes that seizure may occur.
The design of our eccentric is deliberately crude and simple but well engineered… this makes seizure unlikely in the first place and enables simple, easily sourced, “tools” to be used upon it if necessary.
If the eccentric will not turn, using the tools provided, the following procedures should be implemented.
 Remove the eccentric bolts from (the underside of) the shell… they are stainless into stainless, so they would need to have long exposure to a strong corrosive agent (sea water) to become seized.
 A light tap with a soft mallet (or lump of wood) onto the centre of the left hand crank, may be enough to free the eccentric, otherwise place a drift (wooden dowel or section of pole/branch or whatever) against the alloy eccentric and attempt to drive the eccentric through the shell by striking it firmly with a mallet (hammer, stone, brick or lump of wood)… the bond (caused by the oxidation of the shell/eccentric) should be broken and the eccentric can then be adjusted. Proceed to step . If this does not work, as it may not, because you will be unable to get a direct blow to the centre of the eccentric, proceed to step  If this procedure has been successful, it is wise to carry out steps , , ,  and , as soon as practicable, afterwards.
 Remove the eccentric bolts from (the underside of) the shell.
 Remove the left hand crank. (You will need the appropriate tool, if you don’t have self-extracting cranks).
 Push the eccentric out or the shell and proceed to steps  and  If the eccentric is seized you will need to follow steps  through to .
 Remove the bottom bracket assembly. (This will involve removing the right hand crank and you will need the appropriate bottom bracket tool).
 Place the largest drift obtainable (as long as it is slightly smaller than the dia of the eccentric, because it will be going through the shell too!) against the eccentric and strike the drift heavily with a weighty object… the eccentric will move… but, if really tight, you may have to prevent the frame from moving during the process (Beware of frame damage). If the eccentric moves but becomes stuck again, strike it (and drift it out from) from the other side (I know from all the development work, when I was determining necessary tolerances, that a tight eccentric has a preference over which side it will most easily drift free from).
 When removed thoroughly clean and re-grease the eccentric, the shell and the threads for the screws. Now is a good time to consider a re-application of a product like “Wax Oyl” to the insides of the frame tubes…don’t forget to remove the seat post too.
 Re-grease threads on screws, then adjust the throw of the eccentric and tighten the screws. (8 10 Newton metres).