For all you who have been following my experiment, welcome back!
To all that are just catching up here is where I stand. I am building a 69er out of a single speed frame that is set for 26″ wheels. The bike is built with tires, wheels and misc parts I had in my shop. (Click links to learn about all the parts.) The first build is with a RockShox Reba 29er set at 100mm of travel.

After checking tire and air pressure, I set off to tool around in the back of my neighborhood where they are building new houses. After a mile I turned around. I felt like I was on a cruiser bike with front suspension. The Reba at 100mm of travel quickly came off and on went the original Surly 1×1 fork. The tire clearance is slim, but the 29er front wheel fits with no rubbing.

Back on the bike. It handled much better, much like the 1×1 originally with a 100mm of travel with the 26″ front wheel. (The bike is designed for 80mm of suspension.) I’m now left playing with air pressure on the front and rear since I no longer have such a plush ride.

Another ride in the morning, I’ll plan to get a few rides on this fork before the next write up.

The first photo is with the Reba fork set at 100mm. The second is with the original 1×1 fork. See how much closer the wheel is to the downtube?