Trying and Failing to Reach Schloss Charlottenburg by Bike

It's almost exactly 24 hours later and I'm sitting once again on the terrace outside the Hamburger Bahnhof Museum.
I now know where the bike trail called Mauerweg, or Berlin Wall Way, on the opposite side of this canal goes.

From where I'm sitting it is maybe 1km actually following the location of the Berlin Wall, but it soon leaves the wall behind and becomes a meandering shared pedestrian/bike path following something called the Berlin Spandauer Shifffahrtskanal mainly along something called Nordufer. If you follow Nordufer you get to Spandauer. I rode the path past a large swimming lake with a beach, a sports stadium, several live aboard canal barges, several Berliners fishing, having surreptitious bankside BBQs, tossing a frisbee into the green water for a golden retriever to fetch, sunbathing on blankets on a day of overcast, wind and bursts of hot sun. There's also a fair amount of litter, overgrown bushes in need of a severe pruning, tagged walls and a persistent whiff of sewer, always the delight of riding in old urban places.
I got to tour something called "kolonies" which are entire communities of small cottages, on tiny plots of land that include vegetable gardens, rose arbors, wood fireplaces, garden gnomes and immaculately pruned fruit trees, all neatly fenced from the neighbor by chain link fences. These must be the Berliners idea of a summer house in the country The one I rode through is called Napoleon, but there are many others marked on my TI map..
I saw no signposts at all for Charlottenburg, which I'd expected to be a major cyclist destination. Instead I followed signs to Jungfernheide which dumped me in a neighborhood of immigrant apartment blocks with a nice view of bombers taking off from the Berlin-Tegel airport.
The bike surface is everything from smooth road to sand, frost heaves, tree roots, cobbles of all sizes, temporaty asphalt surfaces leading to construction sites, and red tiles, often uneven that are the official bike path but often too narrow for 2 cyclists to comfortably pass each other without dismounting.
I can tell this route must be a long distance radweg because from time to time I've seen pairs of touring cyclists trying to pedal their loaded bikes along this path.
I did tour the Gedenkstatte Berliner Mauer, a new Berlin Wall museum memorial, which I'd found after having breakfast in the Kollwitz Platz neighborhood. Kollwitz is pretty much dead center for the hipster gentrifying area of Prenzlauer Berg, where I went looking for a decent meal at a reasonable price. Unless you're willing to live on curry wursts from a street vendor, I've decided that in Berlin, as in all of Germany, it's impossible to eat decently without paying too much.
I've been eating a lot of sausage flavoured potato soup and ordering still expensive salads off the side dish part of menus. It's a very fat and salt laden culinary style here.
It's a shame I can't cook my own meals in the youth hostels where I stay. That's what I do when I travel in New Zealand and Australia.