Magna bikes are intended for transportation, not off road use. That being said, they are decent bikes for the intended price range of 75 - 100 dollars. A Magna Invader sells for around 90 dollars new and about half of that used.
what ever size fits them for their intended uses.
Yes you can use a motor cross helmet for bmx riding i actually recommend it but that's my opinion
in terms of modern bmx the logest that people use today is either 21" or 24" top tube
Use cow manure
freestyle, dirt, street
it matters what you are going to use it for
10W-40W best for magna's in Australia semi-synthetic
to have equal rights
use unknown weapons and technology
BMX bike ramps are usually made out of material such as chrome or aluminum. They have to be durable enough for multiple people to use them at the same time.
you cant skate you can only use a bmx bike