BMX - seat post extension

Got a used bmx bike to ride with my grandaughter My knees don't bend far enuf to bea able to sit on the stock set up could use a source for modified seat post I will not be doing any tricks

Thanks Bill Brophy

I have a bmx that I ride with my grandaughter. I also ride it after dark its easier than getting my road bike gear on plus the town I live in gets less bike friendly after dark.I work with a couple of bmx riders and sometimes I ride with them they do tricks I try a few bunny hops and a few manuals with limited success but I have fun.
Riding bmx has really improved my bike handling skills especially on the mtb . For me it is also more relaxing I ride in the street,on side walks,in parking lots pretty much anywere I feel like going never in a hurry just cruising.I have my seat about fist high although the only time I sit is when I need to duck under something,
when I stop for traffic or take a break.bmx bikes are alot easier to control and peddle when standing.I am 58 years old and bmx is still fun

What size is the current seat post?

I got a 1" diameter Chrome Moly seat post, sold thru Seattle Bike Supply,
so a Red Line brand..

It worked OK with a foot of post exposed.. an old mountain bike I built up as a single speed. I believe Red Line offers a 7/8 OD post also..

OTOH, the 1.25" seat pillar on my folding bike is stronger yet. but its because the ChroMoly tube is bigger OD. so the 7/8, is less strong than the 1" though both the same stuff..

I recall seeing a thick wall aluminum post that is quite tall,
but at 63 i dont remember where or when..

Thanks I'm going to take your advice and try it around town the thought of bunny hops gives me th willies

Twelve inches

You can get a new seatpost up to 450mm long(17 3/4 inches). You just have to know the diameter.