From Henderson continue south on 93, merge with 169 to the LeSeuer exit. Cross the river, then right on N 2nd st, then right on Ferry to Main. Continue down Main Cty 36. Continue on 36 through Ottawa township to cty 23, then continue on 23 to hwy 99 into St. Peter.
This is a really nice backroad route to St. Peter. It follows the Minnesota River, takes you through Ottawa and past a frack sand mining operation. Get off your bike, climb the dirt wall just short of Ottawa and take a look! They actually sold a section of cty 109 to the mining company. Scenery is river valley, bluffs, nice curving road, elevation changes. There's even a trout stream hidden at the south end of the Ottawa State wildlife Mgmt Area. Nice Sunday drive - no need to stop at Henderson.
Road is usually in pretty good shape. It's rarely boring, not terribly technical but a nice, winding country road with elevation changes, good curves, good sightlines and little traffic.
This is not really a stretch that requires amenities. There are no gas stations between Le Seuer and St. Peter, but it's also only 30 miles.