Shimano Nexus 7 Hub SG-7C18 Lock Ring Problem

I had a flat on my rear wheel. My bicycle is equipped with Shimano Nexus SG-7C18 7-speed coaster brake and in order to change a tube you need to remove both the chain and the internal Nexus 7 hub cassette joint.

Shimano Nexus 7 hub cassette joint and lock ring

Shimano Nexus 7 hub cassette joint (39) and lock ring (13)

That part seemed easy to do, but the trouble came when I tried to reinstall the Shimano Nexus 7 hub cassette joint with cable and lock ring. Even when hub twist shifter was set to speed 1 as advised and had the matching yellow arrows (shifter cassette joint) and dots (lock ring) properly positioned, lock ring wouldn’t lock by turning. It seemed as there wasn’t enough space between the ring and the cassette joint as the lock ring locks in grooves behind the casing.

After I took the bicycle to a mechanic, he told me he had a hard time locking the lock ring, too. His advise was to put shifter in position (speed) 1, put the cassette joint on the hub, use your fingers to open (tension) the cassette joint as wide as possible and this creates enough space for the lock ring to be locked. I hope I won’t have to repeat this procedure as it seems overly complicated. One would expect better from Shimano.

Complete list of Shimano Nexus 7 internal hub parts as well as installation instructions are available as PDF files directly from Shimano website.

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July 30, 2012 at 13:02 :: Filed under Rants :: Permalink [*] ::

Comments:

I struggled just like you at first until I read the proper alignement sequence in the shimano tech doc: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Nexus/CoasterHub/SI-7C26C-EN_v1_m56577569830605809.pdf

Author Guillaume, 21:04 January 15, 2013


I have tried to follow the manual you posted then but it didn’t work for me.

Author Daniel, 11:49 January 22, 2013


One must unleash the wire to be able to move the locker and the ring below (which is supposed to be locked !).
It was not possible to properly fasten the locker until I unleashed the wired!
Then it worked out just fine. – Thanks to Guilaume who provided the PDF-Link.
guyhofmann (Germany

Author guyhofmann, 21:04 April 23, 2013


you can come to bikekitchen with things like this. We like to dismantle everything

Author tom, 15:12 May 13, 2013


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