Normally I'd suggest let it go after twenty years, but some things can be a bit different. If the sentimental value of this bike is that strong, I'd suggest trying to get it back. As mentioned upthread, the current owner probably has no idea of the bike's history. Just taking it will only perpetuate the cycle of crime and apathy towards cycling, which is shit. However, if you think that you'd be happy to pay to own it again and it would be worth it, make an offer to the owner. I'm generally against the principle of paying to get back stuff that was stolen from you but sometimes there are exceptions and this might be one of them.
Normally I'd suggest let it go after twenty years, but some things can be a bit different. If the sentimental value of this bike is that strong, I'd suggest trying to get it back. As mentioned upthread, the current owner probably has no idea of the bike's history. Just taking it will only perpetuate the cycle of crime and apathy towards cycling, which is shit. However, if you think that you'd be happy to pay to own it again and it would be worth it, make an offer to the owner. I'm generally against the principle of paying to get back stuff that was stolen from you but sometimes there are exceptions and this might be one of them.