I have to disagree to what you say about vibration, incomfortable riding position and lack of wind protection etc. Big singles are said to vibrate the most and I have now owned 3 different of those, a Dr 650, a Dominator 650 and a Tenere 660. Although they do vibrate a little - it has never bothered me to an extent its a real problem. A 250 of which I have experience with the Crf250L and a Klx 250 do not vibrate at all compared to 650s singles. Actually the bike I have owned that vibrated most was the Transalp 600 which was a heavy bike of 195 kilos dry and with V-twin engine. So to say that small bikes vibrate more doesnt make sence at all to me.

Most smaller bikes that I have experience with are taller and have wheels of 21 and 18 and actually many of the biggest so called adventure bikes are lower and comes with 19/17 wheels. Thus I cant find much compliance in what you say about this subject and reality.
Wind protection and such - well its what you put on your bike and what equipement you fit. There might be more choises for wind protection for bigger bikes - thats a point but personally I often prefers less protection. High windscreens twnd to give buffeting issues and are thus uncomfortable. Often better results if you cut off 10 cm on the windscreen.

I see that in a later post you complane about a bike that had problems reaching 120 km/h. Well - if your ideas about adventure riding is to ride on roads that one can ride in + 120 km/h and on bikes that can easily pass that speed when loaded up - we might have a totally different idea about adventure riding. I recently rode from northern Europe to Australia with many detours and approx. 80 k kms and I can count one hand the times I rode in 120 km/h or more and I can probably count in two hands the roads and stretches this were possible. In most of the world roads riding in 120 km an hour is not possible. And certainly not interesting....its the winding back roads, gravel roads, mountain roads etc that are interesting. Not a boring straight forward highway/freeway/motorway.

And when you say dont let the size of a bike dictate where you go I cannot do anything else that smile - because the size of the bike WILL dictate where you are able to go. Thats a fact....

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In the end everything will be fine. If its not fine its not the end....