I only know of two trikes in my area- and one rider has a balance problem due to an illness and the other has a balance problem due to age. No idea how old but he is old.
BUT- the Para-Olympics and we have a rider in the UK that is good. Can't remember his name- but on the Trike he is fantastic. Off the bike and he can only just stand.
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How long was I in the army? Five foot seven.
Spike Milligan