Here I am trying to avoid the softest cow pats at a meeting last year - it's not ALWAYS muddy!
Here's one showing our two types of Group 2 - on the left is a Group 2 roller, and my machine (#7) is a Group 2 Wheels. We only race these in the northern club (NWLMRA) They are not allowed in the southern club (BLMRA) as they come from a commercial rather than a domestic background.
Here's my mate John going for it on his Group 2 roller:
These are what we call group 3's - based on Westwood Lawnbugs and usually with a tecumseh 10 horse lump:
And this is what we call Group 4 - more like what you guys will recognise.
Here's a closer pic of my old group 2 roller so you can see underneath - that's a metal roller underneath with tyre tread bolted to it - it's not what you'd call a smooth ride!! When the track gets rough you feel every little bump - though these are actually a lot lighter to drive than the Group 2 wheels. The Scag (#7) weighs in at something in the region of 140kg without me on it.
Andy