Tires pressure /average speed
 

Does higher/lower tire pressure effect the average speed on the cyclometer?

no

Citations needed for why you answer "no."

Of course it does. Inflated higher, the tire is slightly larger in circumference.

That's what i had in mind as well,i only weight 127 lbs,my tires max pressure is 100 lbs,i been riding for over 1K miles with 75 lbs front and 80 lbs rear, now i have dropped down even more, 63 front and 70 rear,tires are Bontrage race lite 700X32 Nebula.I am doing this just for a softer ride,if it will slow me down in speed,i don't ride over curb or any rought stuffs, i have to tolerate the loss.

It won't because even though the tire deforms on the ground more with less pressure, you're still dealing with a similar amount of rubber going around. The thick tread on the bottoms of tires won't stretch like the sides will. It has been something tested out with cars extensively and the effect is so minute that the inherent inaccuracy of your cyclometer is a greater factor.

I guess on some super cheap warn out tires there might be, but on anything decent I don't think you'll see much at all.

EDIT: If you have nothing to do for a day, it could be easily tested at home. It would be interesting to see the results for different types of tires.

Do you want to find out? All it takes is a friend, a piece of chalk, a tir pump and a wall. Inflate the rear tire to max. pressure. Using the wall to support yourself while putting much of your weight on the rear wheel. Have your friend place a chalk mark on the ground using the valve stem as the reference. Go forward one revolution and place another chalk mark. Lower the pressure as much as you dare. Then using the same first mark repeat the process. A one inch difference is about 1 %.

You will feel more resistance to pedalling, but the distance/speed will be negligable, though measureable very slightly. Comfort? Will be softer riding.

On rough trails softer mountain bike tires actually roll faster than hard tires. the harder tire transfers more upward motion where as the softer tire deforms and allows energy to go forward.

Yer right, Mr Helicopter Pilot..... But, he's riding on road, just looking for smoother/softer to accomodate a physical condition....

Phil I know better than to argue with you:d LoL

It's the modern world, I can be two places at once and jack both posts.

If you follow the instructions for a roll out test rather than just pluggin in generic numbers, most instruction books will suggest that you apply pressure to the front end while doing the rollout test. Must be a reason for it! Seems that it is affected by pressure one way or another:D

The more weight on an axle, the more the sidewall flexes. The more the sidewall flexes then the smaller the wheel radius. So the smaller the wheel the more revolutions per mile.

I wouldn't have presented it that way, if I didn't consider you a friend ....... LOL