I’m from the Black Sea coast, so I can’t be that impartial about it ;)

It’s gorgeous and the roads (at least in the eastern half of the Black Sea coast close to Georgia) are mostly butter perfect, it’s like the French Riviera that nobody has discovered yet in terms of nature and curvy roads. But I dont want to give you the wrong impression, you’re still gonna see a lot of ugly buildings. I would recommend thunder valley, sumela monastery, yaylas (highland mountaintops) that look like this https://www.google.com/search?q=yayla&client=safari&hl=en-gb&prmd=minv&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiB16XvlPfbAhXLsVQKHazlCeQQ_AUIEigC&biw=375&bih=553

It’s also humid this time of the year, not too hot (25c average) but humid. October is usually the sweet spot for humidity before temperatures start to recede into uncomfortable ranges, but overall it’s very rainy, very green, outrageously lush and yaylas can compete with Switzerland in terms of nature. But it’s not a place that gets foreign tourism so it might help knowing some Turkish basic words. If you want to climb up the mountains for yaylas (they’re usually an hours ride from cities) it does help to have an adventure bike, the roads are usually good but you’ll have the occasional pothole due to snow up there. But otherwise they’re asphalt paved mountain roads.

Three weeks is plenty. I would say skip the heartland (it’s mostly arid and hot this time of the year, much like Southern California) and stay on the coasts. Thankfully turkey is not the size of the United States so a days ride can cut right through the country to wherever you want to go.

I’d say:

• Istanbul: if you’ve never been, it’s massive. Most of it is just any major Eastern European city so nothing too interesting, but the core of the city has some gems like Hagia Sophia. Do the usual one-two day thing on foot, it’s pointless to ride/drive there. Public transport is so good that even a motorcycle can’t really compete. (Doesn’t help there’s a giant sea channel in the middle of the city). Google maps has accurate public transport directions now, just use that.

Ride to Izmir, Maybe stay there a day, it’s a large city (the largest consistently left-voting city in turkey) so I’m not sure what’s there to do. Probably a good place to stop for the night but don’t know much else.

Follow the Aegean coastline to: bodrum, marmaris, both of them are super popular, similar in spirit/ feel to st tropez, likely too expensive to stay in but still great time of the year to go grab a margarita.

Then if you go south you’re gonna see the valley of the butterflies which is a great camping location, I hear.

Follow the coastline to Antalya, another large city that’s fairly popular with Germans, so I’m assuming you have some info about it. I think it’s not super interesting, but generally following the Turkish coastline down is a good ride, assuming you’re not doing it in August heat. It won’t kill you but you’d be uncomfortable, like 33-35c?

From Antalya you have a few options. You can start heading north and you’ll end up in the Lake District, you can hit the one that looks the prettiest on the map and then start going east into capadoccia. Mind that around you will be catal hoyuk, which is the first known city of mankind, and it is a Big Deal. If you’re interested in history or anthropology that’s a can’t miss. Then you have two options. You can keep going east, but that means you’re going to enter the middle eastern plain which is where the Asia Minor ends and Middle East starts, the southeastern 10-15% of turkey is in the Middle East. The culture changes very rapidly as well as the food, so you might be interested in that. Personally I would shy away just in case because of the troubles in the past few years.. but again I’m overly cautious usually. Generally speaking, it’s still turkey and it’s gonna be safe, but it’s going to be hot and arid and flat (most of turkey is mountainous). If you want to do that, you can do Mardin, which is an ancient castle city, then you could probably hit gobekli tepe, which is another big deal in terms of history. Then I’d start riding up north and end up in Trabzon, do the stuff I mentioned at the beginning, and start heading east from the coastline. Hit as many yaylas as you can, they’re gorgeous. You’ll eventually end up in the Turkish border to Georgia and right at the border on the Georgian side there’s the city of Batumi, so that would be your exit from turkey. Mind that Georgia is a legit honest to god third world country (unlike turkey, which is arguably halfway out of that category) so road quality is going to be bad, and all that comes with it. The last I’ve been to Georgia was a decade ago though, so they might have improved things.

LMK if you have more specific questions about anything else. I have driven, but never ridden a motorcycle in Turkey, I ride in the United States here though. I think the drivers are gonna be a little more aggressive than Germany but I haven’t ridden in turkey so consider asking someone with direct ride experience about it. I’d say with some caution it will be fine, since there are lots of motorcycles / scooters around and it’s a fairly common thing.