Dieses Fahrrad ist das Meinige

aber es ist "Dieses" und nicht "Das"

I don't want to criticize but I reviewed all german sentences by SeeVogel and I noticed that the quality is poor and the translations seldom fully match the other languages...

Yes, you're right sacredceltic, his sentences should be reviewed. I think we need you xtofu80 as you speak both, German and Japanese, to take a look on his sentences, most of them are translated from Japanese...

On this sentence: yes, "Dieses Fahrrad gehört mir." is best.

I wasn't criticising anybody but "work". I happened to look at most of his/her translations and they're mostly inaccurate. I wasn't taking exception with him/her or targeting his/her translations. I happened to review hundreds, including yours, MUIRIEL, etc...because I was looking for good translations from German into French and English. And I noticed these were the worst matchings with these languages.

Sorry for leaving my sentences behind such a long time.
Critics are welcome. I adopted them because I thought the translation was good.
"Das Meinige" is for "mono"
この自転車は私のです　"Das Fahrrad gehört mir"
I think the mono implies a more personal "have" than just "gehört mir".
If you can accept this; more than one translation for japanese sentences are always possible.
And also I still use "das Meinige";
Or make a deal and say "Das Fahrrad ist meins." which is really common spoken german.

Dieses Fahrad wäre aber sono

Ähem... ist schon korrekt aber:
kono = das hier (bei mir)
sono = das dort (bei dir)
Vielleicht deshalb auch "Das Meinige" weil ich dabei
an ein Fahrrad denke, das ich bei mir, an meiner Seite habe.

Meinige → meinige

Meinige und meinige = gleichwertig nach alt/neu Rechtschreibung

Hier ist es aber nicht substantiviert, sondern bezieht sich auf das vorangehende Substantiv „Fahrrad“.