David
Happy New Year to you and all our fellow R/C flyers as well.
The nose gear strut diameter is 4mm. I haven't been able to operate the gear yet, but the quality looks good and strong. Hopefully the electronics will hold up a reasonable amount of flights. I've built roughly eight airplanes, but this is my first pattern plane or retract installation and I'm thoroughly enjoying the quality of the wood and clean cuts.
Here's to a prosperous new year, Cheers!
Dave