Hi and thank you for your help.
I am building a CNC Router based off of the CNC Router Parts design using 80/20 extrusion and a rack and pinion drive. The cutting surface will be 4ft by 4ft.

I got some Bosch Rexroth linear rails and bearings (25mm wide rails) but just now figured out that the carriages are the version with no preload.

My question is, what are the consequences of running bearings with no preload? Realistically, I am interested in routing wood and maybe machining a little bit of aluminum but rarely. What kind of problems might I run into compared to medium or high preload bearings?

Thank you for your help