ak08820

Hello

I need to replace the front derailleur cable on my trusty MGX S20 bike. The shifter is a grip shifter and it has the lettering TB-PRO on the grip and shifter and model # is S220.
I am unable to find any service info on this shifter or instructions to replace the cable.
It has a grey colored ring on the outer side which is a "force adjuster" to lighten or tighten the grip shift action. The outer rubber covering can be pulled but does not show the head of the cable anywhere. There is a Phillips screw holding a what looks like a cover on the cable guide but when I remove the screw, the cover does not easily come off.
There are 2 Allen screws locking it on the handlebar.

As it looks like all plastic, I don't want to risk breaking any parts using incorrect dis-assemble procedure.

Wonder if anyone has any info on this shifter and how to correctly replace the cable.

Thanks in advance!

Andrew R Stewart 

I have run across a rotating grip shifter on big box bikes that has no access to the cable for replacement. I believe that the OP has the same. After I replaced the complete shifter with a SRAM MRX I broke apart the old one and found an assembly which was "one way", not meant to allow cable replacement. Andy.

ak08820

After removing the fixed part of the grip, the head of the cable was visible under the rotating grip and was easy to replace the cable. The stamping indicated a German design patent, too. It did not have the traditional little metal clip but there was a larger plastic piece retaining the cable head. The helical movement to move the cable was across the rotating part of the grip (about 2") instead of the usual shorter path.

So, I was able to replace the cable. Still waiting for a response from Pacific Cycle Co. that owns Mongoose/MGX. Will see what they say.