downhill" bike? 
If its those downhill bikes those supermarkets, i wouldn't dare to
take em off-road much less thrash them. the last bike i got from
those supermarts is now in bad condition, twisted front dee,
chainring cover broke off, handlebar misaligned and the wheels are
like potato chips.
Thats why i salute those people going offroad with bikes like
those.
Damn power.