okay so is there some simple rule of thumb about this then? I have always worked on the impression that you should have the ball of both feet comfortably on the floor when sitting in the saddle. Am I miles out, and could this explain my knee pains and why I am so slow on the hills. I feel a light bulb moment coming on.
Cheers
The saddle height should not ever have anything to do with how easily or not you can reach the floor with the balls of your feet. This is a VERY rough guide. The saddle height is determined by the amount of leg extension you have when the pedal is at the bottom of it's stroke with the crank inline with the seat tube (I hope that makes sense!!)
With your foot as close to horizontal (level) as you can determine, you should have a small amount of bend at the knee without feeling any tightness behind the knee or a need to lift your heel up/point your toes down. Once you have established the ideal height then make a note of the measurement from centre of Bottom Bracket to top of saddle along the seat tube. This can then be transferred to other bikes or after maintenance. Please note that different crank lengths will alter the saddle height. For example if you decide to fit longer cranks, i.e. 175mm instead of 170mm then you will need to LOWER the saddle by the same amount as the pedal spindle will be further down at the bottom of the pedal stroke.
The reason I say that it has nothing to do with reaching the floor is that if you then transferred this measurement onto your mountain bike, you will be much higher off the floor as an MTB has a higher bottom bracket to give better ground clearance.
Sorry to waffle on a bit but this is possibly THE most important measurement setting on your bike.
Once you have found your setting, go out and ride a bit and you may find that with improved suppleness and flexibility that you can in fact raise it slightly after a while.
Hope this is of some help to you.
Graham