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-   -   Stuck chain with EEB (https://www.bikeforums.net/bicycle-mechanics/554481-stuck-chain-eeb.html)

MichaelW 06-22-09 04:03 PM

Stuck chain with EEB
 
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The chain of my Dahon Cadenza 8 came off the chainwheel and got stuck. It was completely inoperable by the roadside so I had to wheel it the final 1 mile home.
http://www.bikeforums.net/images/attach/jpg.gif
The problem is one which many Eccentric Bottom Bracket users should beware. Usually a derailled chain will rest on the standard BB shell and can be re-railled using the front mech and some judicious pedalling.
The EEB has a wider diameter so there is room for the chain to slip between the edge of the shell and the chainset.
Matters are compounded by the Truvativ Isoflow single chainset which uses the same forging as the triple but with the inner bolt holes left un-machined. These small protrusions trap the chain and the only release is to remove the chainset.
Whilst I had the chainset off, I took a file to these small bits of metal, hopefully there is now an escape path for the chain.

If you have an EBB and a chainset with protruding bits you might want to consider filing them down. Take care not to nick the main crank with the file.

operator 06-22-09 05:12 PM

The point of the EBB is so that that you can tension the chain to prevent exactly what it is you experienced. The fact that it occurred means your EBB was never properly adjusted to provide proper chain tension or it lost it's adjustment due to significant chain wear.

The chain should never come off to begin with. If you want to prevent this from happening, install an inner jump stop. The regular cadenza with a dual chainring up front (NOT your model) is even worse in this regard.

This is a user maintenance failure, not a design failure.


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