For the last couple of years, I've been riding an early '90s vintage Specialized Hardrock, which I've fitted up with fat road tires, fenders, Wald folding baskets, a stem extender and trekking bars (to give an upright ride). I've noticed that the bike has always been more fatiguing to ride than any other bike I can remember riding, but I thought it was just me, because I was so much heavier than when I used to ride a lot. Today I decided to make the experiment of trying to ride with no hands, which is something I always used to do.
I couldn't do it. The bike won't track straight unless I'm holding the bars. Is this something common to MTB geometry, or should I suspect some other issues that I might be able to correct? I've found that the bike actually seems more stable when it's loaded up with 20-30 lbs of groceries.