@Your Name:

Hi Your Name,

Are you asking why they chose those specific numbers or why they are progressive? When it comes to torque, graphite shaft manufacturers can actually control a much wider range of torque compared to steel so it’s not a manufacturing limitation. Design wise, if you’re asking why the numbers are not lower say compared to Attas 7R , the torque at this low range, doesn’t have as much effect on twisting or stability in my opinion and Mamiya probably thought it best to keep the numbers reasonable for feel purposes. The actual stiffness of the shaft and design will take care of the control aspect. Even at that, I think the numbers are quite low on the ATTAS line here which is reflective of the Axiv as well. If you look at some other graphite manufacturers, say for example the i10 from Roddio, their 107g SX flex shaft is 2.3* of torque across the set and this translates into very good feel for a nearly 110g range shaft. Even Quadra’s 100+ gram 100i Pro X Flex has torque ranging from 2.6 to 2.3 and that really translates into great feel.

@anton:
Oh hi Anton (^_^). The progression is a design feature, they could be all made with similar torque if they wanted but progressive torque is pretty common for iron shafts, graphite or steel. There are a couple of reasons for this, one is yes the heads are heavier and the speeds are lower but the lower irons still focus on control and many brands will lower torque for the shorter irons (though as I said earlier at that low number the difference between 2.2 and 1.9 is probably quite minimal). I guess their thinking is that a lower torque shaft can also result in a lower trajectory thus creating heavier spin which is more desired in the short irons. Nippon’s NS Pro 950 Weight Flow uses the same concept in their steel shaft, heavier as they get shorter with decreasing torque. Nippon says this is for stability and direction.

The second reason is higher torque translates into shaft feel ie kick which is not necessarily desired with short irons or wedges where it’s more of a steering or directing of the ball at the pin so to speak. These are just my observations of course. :)