It had been many years since my last metric century.
Almost did one last year on the Platte River / Highline Canal / Cherry Cr loop.
I've done two this year.
First was a loop from my house NW to I25 & Big Dry Cr trail.
SW to Standley Lake
W to Little Dry Cr Trail & W to Highway 93.
S to Clear Cr trail in Golden
E to Platte River Trail
NE to Spratt Lake & Grange Hall Trail
N to some local trails & a little detour to finish off the 100K.
Two weeks ago I biked down to the Platte River trail - S to Littleton & Prince St.
& back up to Niver Cr trail to my work - 8 hours on my feet before heading home to complete the 100KM ride.
(Had to run an errand & didn't want to pay for the gas!)
Now If I could get rid of about 50 pounds, it would make things a lot easier...
I would probably need a downhill route to average 15.5 MPH.
Usually more like 11 MPH average on my MTB