top pull road front mech
One way to save weight is using a road front mech on a MTB. Especially when running a 2x9 drive train. One of the downsides is that roadmechs are only available in down pull versions (cable coming from underneath the mech), however many MTBs have a top pull cable routing.
I started of with a old Shimano Ultegra mech and decided to modify it to a top pull mech. The conversions consist of turning around the front part of the parallellogramme. To do this the mech is first separated by loosening the two 3mm hex bolts.
Then the rear part of the bushing is carefully filed away so that it can be removed with a punch. The front part ca now be detached from the cage.
Then the front side of the part is filed down and a recess is filed in the part to clear the back part (see pics).
The front part is then reinstalled with in reverse sense. The bushing is punched back into place (securing is by tapping the open part of the bushing with a conical punch). The 3mm hex bolts are put back in place. I drilled out th bolts to save additional weight. The mech can be mounted on the bike.
This is my first attempt and prototype. Further steps: polish surface, bolt tuning (al & ti), finding a light clamp, test it in the field.
If all works ok I will see if I can do the same with a Dura Ace and source a light carbon fibre collar.
weight after modification: 109g including collar