18 or 20 inch, advice needed

[Gary72]

My little one is getting rapidly more lanky, only 7 but seems to be outgrowing his 16inch bike. Not sure if to get him a complete 18 like the Hoffman, he has the 16 Hoffman now. Or get a 18inch TT FRAME for 20 inch wheels and swap the frame out as he gets bigger. I do have a AERO REFLEX frame set in the shed, light weight about 5 1/2 lbs, but I was going to build that with Tuffs for myself. There are some short frames about
 

[lazychubs]

gary they used to do a hoffman 18/20
and joe stupps had a small 20"frame fly somit or other

[Bob_Acid]

I'm in the same boat atm. The 20 is just too big and the 16 too small. I'm going to get him an 18 and flog his Haro 16