ok yeah 1 1/4 is now old and outdated and no-one makes it anymore, but that said it could be the perfect size for trials headtubes. Not to big, not to heavy! It is something that would have to be taken on by the majority of trials manufacturers to make it worthwhile! You actually said 1 1/5 in your origional post But yeah didn't mission come in 1.5 headtube, maybe it could be useful for stronger forks, but the strength benefits would have have to outway the weight gains. Which it probably doesn't!