I am guessing they are cheap bikes from China I hope you have done your homework so many get recalled  plus a lot are down right dangerous .Bikes were featured on a current affair programe a few moths back .

I know of one where the handle bars broke off and the bar went through the little tackers chin.

It was sold at a market but the seller was held responsible .

The fine and cost were high .

Anything you are selling for kids you need to be extra carefull