Originally Posted by
glyphrunner
The handle bars are already moved forward and down as far as they will go.
That's understood. And is why MRT2 suggested putting a new stem on.
As for swapping out the seat, tires, handle bars, etc. wouldn't it just be better to trade this bike in for something new, has those components, and is at the approximate price all these upgrades would already cost?
You only need to swap the seat and tires. This will be a LOT cheaper than buying a new bike! I still wouldn't expect a Navigator to be a speed demon, but you won't lose weight any more effectively on a fast bike than a slow one.
The only questionable advice MRT2 gave you was to switch to clipless pedals. These need special shoes to use which will add a fair amount to his upgrade estimate; I'd put BMX pin pedals on instead and ride in any soft soled shoe or boot you like.
You said that you need to lose weight but you didn't say how heavy you are: the Nav is a good choice for heavy riders as it is strong and the riding position makes minimum demands on core strength and flexibility. I'd spend $100 on a new saddle, pedals and tyres now, then trade to a different bike when your body has adapted to cycling - if at all.