Because the m980 is 10speed, it is designed for a 42t outer ring, the 9speed is based around a 44t ring.
brilliant info ..... I guess I should have twigged after trying to use a 10 spd SLX front mech.
so it is m970 I need.
Shimano XTR Front Mech E-Type 9sp M970 Specifications :
Model No. FD-M970-E
Rear Speeds: 9
Front SIS :Yes
Chain Ring : Triple/Double
Top Swing Link : Yes
E-type BB Mount : Aluminum
BB Plate :Aluminum
Outer Link Material/Finish : Steel/Painted Inner Link Material/Finish : Aluminum/Painted
Chain Guide Material/Finish : Aluminum/ Nickel Plated