A standard road bike (700 x 23mm) has a diameter of 668mm (334mm radius), and a bottom bracket drop of 78mm, and 172.5mm cranks.
So 334-78-172.5 = 83.5mm = 3.2in which is much higher than your numbers...
My road bike has approximately 3.5in which is consistent.

1.75in seems very low, are you measuring correctly (pedal level)?
What type of pedals?

The front fork being bottomed out isn't particularly surprising. It's probably a standard coil fork designed for a ~200 lbs rider not a tandem. What is the model of fork.