Got a new Tour II directly from TerraTrike in January of 2013 and have a few hundred miles on it. Yesterday I was about to air up the tires, picked up the front to rotate the valve to a convenient location, and noticed that the wheel was flopping around a bit. On closer inspection I found that the top bolt on the kingpin had backed way out. I took the kingpin out and found that not only was the top bolt loose, but the bottom bolt had also backed out a bit and I was able to unscrew it easily with my fingers. Both bolts had blue thread lock applied, but it didn't matter. I was able to easily screw the bolts all the way into and out of the king pin with my fingers. I'm glad that I noticed the issue before the top bolt backed out all the way, allowing the king pin to drop out the bottom while riding, which would allow the wheel to come off and possibly do great damage to me and the trike.
Today I cleaned up all the threads on the kingpin bolts and kingpins. I applied Locktite Red (strong) thread locker to the bolts on top of the kingpins and tightened them like crazy, then I applied Locktite Blue (medium) to the bottom bolts and tightened them for proper steering feel. I figure that if any bolts loosen while riding then it will be the bottom bolts. Even if they drop out, the top bolts should still hold the kingpins in place so the wheel would be less likely to fall off.
What I would like to see instead of the current configuration is a step bolt and Nylock nut. Or even an old school castle nut and safety wire. Loosing a kingpin at speed could be devastating. If I ever detect loosening again, then I'm going the step bolt route.
While I was at it I decided to check and adjust the alignment. The trike has always seemed rather unstable to me at speeds of 20 to 25 MPH, and checking the alignment has been on my list. I have no trouble at speed when not pedaling, but if I try to pedal downhill, then I wiggle all over the place. It feels like I'm riding a rubber bike. At first I thought it was pedal steer, the flexing of the frame while I pedaled, or maybe I was pulling on the steering while pedaling. However, I have ruled both of those causes out. The trike starts to wiggle at speed even if I'm pedaling in a really low gear while going down a hill, with only my finger tips on the bars. It appears that it's the shifting of my weight while pedaling that causes me to wiggle side to side at speed.
I did some quick measurements before starting but didn't look too close. I believe that the trike as delivered to me from TerraTrike was near neutral, but possibly a little toed out. I watched the TerraTrike video on how to align your trike, and took note that neutral alignment is for an average weight rider. Once the rider sits on the trike, the alignment should change to 1/8th inch toed in due to frame flex. An "average weight" rider's weight was not specified, but I will assume average to be around 170 pounds. My take away from the video is that no matter what the weight, the trike should be toed in 1/8 inch with the rider sitting in the seat.
With the knowledge from the video in hand, and knowing that I'm probably heavier than the average rider (245 lbs), I figured that I might need to toe the unweighted trike out a bit. I figured that maybe 1/16 of an inch would be good. However, I found it maddening to get the trike aligned. First issue was that when tightening the lock nuts on the tie rods, the tie rod would turn and change the alignment. I messed with it for a while and was able to minimize the change, but it would be far easier to adjust if there was at least a flat spot on the tie rod to hold while tightening the nuts. The bigger issue was that alignment numbers were not making sense. The ratio between the front and back measurements wasn't always the same. What I found is that the center line on my Schwalbe Marithon Plus tires could not be trusted to be right in the middle. Depending on how the wheel was turned, I could get different measurements. I compensated for the issue by making the tires near the valve stem with a Sharpie, and rotating that spot to the front or back while measuring to take variances of the tire out of the equation. This greatly reduced the variances in my measurements.
After getting the trike setup with 1/16 inch toe out, I sat on the trike and had my wife do some measurements. What I found is that even my weight of 245 pounds, which I consider to be higher than the average rider, did not cause a 1/8 inch deflection of the alignment as sated in the TerraTrike alignment video. In fact, even with neutral alignment, my weight will not even cause a 1/16 inch toe in.
My trike is set to as close to neutral as I can get it, which is maybe one millimeter off, and I'll see how it goes once the rain stops. If the trike still wiggles at speed, then I'll try greater toe in just for fun. I'm not sure what's causing my "riding a rubber trike" feeling at speed, but playing with alignment and tire pressure are on my list of things to try in an attempt to minimize it.
Anybody else been down this road and have some relevant advise?