FORK TRAVEL AND HEAD ANGLE

[steveO:K]

I am wondering if anyone knows how much fork travel affects head tube angle.

 

Basically I am looking to buy a bike. It is fitted with a reba fork which can be adjusted to either 100 or 120 mm travel. The head tude angle is 71 degrees, which I assume would be applicable to the recommended front fork travel of 100mm. I ,am just curious to know what this head tube angle will change to if i adjust the fork to 120mm.

 

It may be a shot in the dark asking as this might prove difficult to calculate...but was wondering anyway