va7db

Hi From Vancouver CanadaHi, Newbe here.....I have questions about the Shimano SG7R40 Internal Gear Hub.
I recently purchased one off a fellow who assured me it worked..... :-) I cannot understand how the handlebar cable mechanism activates the selected gears, there is no mechanical connection I can see because the cable attachment at the hub end simply rotates a square toothed gear......the problem is that this gear doesn’t seem to rotate Anything on the shaft ? It doesn’t have a cam or any means of pushing on the shaft either?
I checked a later model 11 speed hub on a friends bike and it has a definite spring tension to return the cable to the handlebar selector......mine doesn’t have any such springy feeling? Any Info / links appreciated before I go crazy :-)
Dave

Dan Burkhart 

Are you missing the cassette joint assembly?

va7db

Thanks Dan, In the video you can clearly see that there is no springy action to return the cable when pulled by the handlebar control unit.....how the heck does that cable get back ? My other confusion is that the square toothed gear that he seats the cable end assembly onto just rotates around the axle, I can’t see anyway it can change the gears inside the hub ? Have watched many video’s and no-one explains either of those points. :-(

Dan Burkhart 

If the cassette joint is properly seated, the cable anchor properly set, and cable ends fully seated, it should spring return to first gear. The cassette joint engages a toothed ring that rotates about the axle to actuate the internal shift mechanism. If everything is properly installed and adjusted, and the cassette joint does not return to it's low normal position, something is wrong inside the hub.
In reviewing your question, I'm wondering if you think the entire cassette joint is supposed to rotate. The part that the cable housing enters is held in position, while the part that the cable anchor attaches to rotates in relation to it when the shift cable is actuated. I hope that is what the confusion is.