ADVr does not have any paid memberships as far as I know. Where does that figure come from?

Yes, Rally Raid has very effectively leveraged social media and forums to market its products. I definitely see your point there. And, it has built its reputation by word of mouth, which is, in my opinion, the best way to build any business. My initial reaction to your comment about kicking some money back to HUBB is in disagreement. Forums offer a free platform to congregate and chat, so giving something for free and then expecting something in return doesn't sit right with me. But, on the other hand, I can understand your perspective about showing some gratitude. I will have to say that comparatively, HUBB is a very very small community of regulars, which is why I come and go (for long periods). I categorize this site more as a place for travelers that are really reaching out there into the corners of the globe. So, I come by, scan a few subforums and then usually head over to ADV for a bigger contributing audience.

While it's great to see some of the really exotic travelers post here, from an economic standpoint, I feel that Rally Raid would not get much ROI here. The marketplace (potential client base) over at ADV has a much bigger audience and RR has invested in the CB500X forum to really target their market. Jenny's posts over on that Honda forum are all short novels. She really caters to those guys (and gals).

Right, nothing is paid, money comes from donations. When I say "commercial", I mean they now accept ads, which despite super lucrative offers over the years, Baldy, ADV site owner, rejected all until recently. I'm talking multi million dollar offers and all sorts of partnership offers as well.

HUBB and Grant and Susan nearly always took ad revenue. ADV Rider is most ALL USA members, HUBB is UK and Canada based but very diverse, with travelers world wide posting here. Very different.

Figures on ADV Rider membership are based on what is listed somewhere on the ADV Rider forum.
But even if they show a high membership number, you have to figure only a portion are current, active members. Same on all forums. So I guess-ti-mate between 50 and 100K active members on ADV Rider.