Hi all,
Seeing this thread for the first time. I’m adding some comments, mostly from memory, or otherwise noted of where I/we need to look to find out more.
There’s a little more detail to that (see IUF Rulebook), something about additional support devices. It basically clarifies that the single wheel is the only point of contact with the ground.
In the past, the GWR has indicated that they prefer taking their guidance from the IUF when available. Some things aren’t covered by IUF rules, such as tall unicycle records. Not sure if the Guinness people are still committed to this, but I think they would still prefer to be, so they can aim any criticism at us.
I think you will find at least one: I believe Cathy Fox (of the Paul Fox Unicycle Club, Marion, Ohio) was listed with the 100 mile record in or around 1979. She did it along with Floyd Crandall, who was the fastest Track racer at the time. She was on a Tom Miller Big Wheel (probably 40") but Floyd had a wooden wagon wheel unicycle that probably weighed about 25 kg or more, and couldn’t keep up. If anyone has Guinness Books dating back to 1980 or so they can confirm or deny this. I used to have a 1982 copy, but it might be in a box if I didn’t get rid of it (can’t find it now). Edit: I see you have her listed farther down the page, along with Takayuki. Oh well, I included some additional details below, so I’ll leave that content in there. 
As for Guinness putting restrictions/requirements on records, again they would prefer to get this information from the IUF if available. This later lead to the IUF World Records Committee creating lots of rules for record-setting. These can make doing record attempts more difficult and expensive, but also will lend an element of clarity and consistency for current and future records. Those rules also apply to Track racing (not recently covered by Guinness); the Track for Unicon 21 did not meet those requirements so IUF records could not be set there. I don’t believe the track we used was the one originally intended; that one may have been affected by construction.
But remember, the Guinness Book of World Records is not as an exhaustive collection of all known; it’s still got to compete in the book market so the editors pick and choose what records will be included from year to year. Some records come and go over the years, such as the 100m sprint, which was covered from 1980 with Floyd Crandall, at least into the 90s with Peter Rosendahl.
Woah, just looked at the Guiness World Records website; their approach has changed a lot! They’ve monetized it in a big way, while making it much easier for people to use it as a publicity tool!
But no online collection of records (unless I missed something), which means they still have to prioritize book sales when editing the thing.
[quote=“Wikipedia”]…in fact, it is almost impossible to ride a unicycle in a velodrome.[/quote]In case you haven’t tried this: Things Not To Do on a Unicycle Sorry about the decrepit state of my ancient website, it is one of the things I hope to “finally get to” in retirement.
[quote=“Wikipedia”] However, it was not until several years later that the one-hour record was beaten with a 36” unicycle.[/quote]Note that before the Coker was available, a 100 mile Guinness record had been set with a 42/43" pneumatic-tired (made from a commercial rickshaw wheel; very heavy!). This was Takayuki Koike’s record, set in 1987, supposedly with zero dismounts. But the effect of the Coker on the world of long distance unicycling cannot be overstated. They were very affordable, and held up remarkably well considering their modest specs. I still have one hanging in my garage that’s ready to go.
)… I’ll start by uploading one that belongs to me, just to see.