MOCYC and HD Playground. But then, let's be honest, there is a striking relationship between overpriced or substandard ads (lacking basic info from i) Green Book to ii) miles on the clock - I'm guilty of that one myself, except I honestly don't know whether 44397 is the true mileage on a late 1980s bike I'm advertising.
Few or no responses tell me I placed a bad ad or got the price all wrong. Watch how quickly you will get responses on a good ad with an attractive price!
As to the website and traffic, do you want quality or quantity?
GTR is fantastic - but then, are you just here to sell something, without reading any of the trip reports etc.? Your loss!
To me, GTR is like having a beer with a few good friends vs renting a tent for 1000 people and announcing free beer to the unknown crowd.
When I screwed up posting pictures, others stepped in and did it for me. and I'm not telling how much time David FL spent helping this computing Neanderthal. Don't you think the Golden Triangle Rider has better things to do? But then, he cares and his website is leaving all the rest!
There is an equilibrium for your bike. Advertise it well and get the price right and it will sell.