820mm bb to saddle top… let’s see.
A 20in frame is 508mm.
A 400mm seatpost gives you 300mm extension out of the frame.
A saddle adds about 20-30mm above the clamp on the post.
So that’s 508+300+25=833mm.
So you’re not even at maximum extension on a 20in frame by my reckoning.
Hmm well the 21″ inbread feels better than the 20″ did and not bent a seat post on the 21″ yet unlike the 20″. Not that far from the shffield shop so will come have a sit on one when they’re in. Am open to be proved wrong