Any question answered...

It's an established weight measurement. In my racing days heavy bikes were always measured in small elephants... 1 heavy bike = 1 small elephant.

Yes, but as The Tester has pointed out, sadly factually incorrect.
Although I don't have the exact figures to hand, let's assume, as the elephant gestation period is two years, that at six months in the womb it could well weigh 25kgs.
Surely then it would be more correct to say. 'The bicycle had the equivalent weight of an elephant of six months in utero'.