[Joe Johnson]

From all the data I have done and seen, Mu of a material on carpet can easily get over 1.

It is my understanding that Team 60 did some comparitive tests form the various rubber conveyor materials available from McMaster.com. I am going from memory, but I believe they the soft rubber cross hatch stuff came out best at 1.3 or something like that.

We used a similar McMaster tread for wheels in 2002. It has similar Mu values (1.2-1.3).

Rubber, knobby pneumatic tires seem to be about the same mu on carpet from our experience last year, especially if you ran the tires with low pressure.

If pneumatic tires are allowed again next year (and I don't see why they wouldn't be), I will recommend that we use them again next year. They are a good balance of high grip and easy to use, make and maintain.

I am especially fond of the "mountain board' tires we had last year -- they were a dream to bolt a sprocket to -- drill 4 holes, use 4 1/4-20 bolts with an equal amount of spacers and VIOLA! your done.

As to the specific mu value, a lot goes into it. What I do know is that the folks in my freshman physics class were not telling the whole truth with that simple F<mu*N business. It is a good place to start, but the story is a lot more complex than that.

Joe J.