Wednesday, March 16, 2011

More Wheel Pics

Here's a top view of the rear wheel installed. That's a 14-28 7 speed freewheel. We might swap that out for something with a higher range later on, but I had this one laying around and it's almost new.
Here is the left steering arm. The brake caliper mounts on top of the two towers. Yeah, I know, the spiral in the center of the brake rotors points the wrong way - the wheels are installed backwards, but that will get fixed when we take it apart again.
And the right is shown here. The caliper mounts underneath this one on similar towers.
Here is the right side again from underneath. The king pins are tilted in 20 deg, and back 15 deg. This setup gives me about 1.5" of trail and center point steering. I was shooting for a little less trail, but the bottom of the king pin prevents me from moving the axle farther forward. Another option would be to weld the steering arms to the bottom of the king pins, but I really want this to be easy to repair years from now.
I ordered some rod ends from McMaster-Carr to use in the steering linkage. At around $2.25 each, this was much better than trying to scrounge up a set of suitable rod ends like I did for my red bike. That only used 2, and it didn't mater what size they were. Here I need symmetry, so all 4 need to be the same (and I added a couple extra for future use since shipping was the same).



Steering Arms

With the steering arms completed, #1 son was anxious to try painting them. Here, he's priming them.

The black semi-gloss we are using for everything that isn't going to be green is drying here.

Here are the wheels. The hubs and rims are black, with the green spokes. They look awesome in real life.

And here they are installed (temporarily). I put the back wheel on while my favorite son installed the steering arms and front wheels.

With the wheels bungy corded to prevent them from flipping back and bending the brake rotors, we can start laying out the seat. It will be non-adjustable, similar to the way a Catrike seat is hard-pointed to the frame.


Saturday, March 12, 2011

Hubs Completed

Since the wheels for the front of the trike originally had coaster brakes, I needed to adapt them for a rotor. To make an adapter, I cut a donut from 1/8" thick steel, and drilled holes to match the rotors that I got as part of a complete kit from Bike Nashbar. I welded the donuts onto the hub flange that used to hold a sprocket.

I reused parts from the old wheels to build up the axles, then assembled them into the hubs.
Here's the outside of the completed wheel.
And the inside, or the brake side, of the wheel.


Tuesday, March 08, 2011

Trike Steering Knuckles

Time to set up the front end. Keep in mind that this is the first time I've undertaken this, and I'm no pro. If you know a better way of doing this (short of learning a real cad/cam program), I'd love your input. I propped up the trike frame with a box and set the front tires in place. Shooting for about 1.5" of trail, I took a few pictures to refer to for alignment, and started fabricating the steering knuckles.

I started by cutting some tapered pieces to fit the tapered square of the "bottom brackets" that I'm using as king pins. these came from some 1.25" square tube scraps. I like working with this stuff because it's easy to cut and weld, and it's pretty strong.
Then I clamped the pieces onto the bottom bracket spindle (leaving room at the end to draw them up with the capture bolt, and welded up the joints.
With these parts completed, I used more square tube scraps and a few clamps to adjust the position of the pieces relative to each other in order to get the right angles for my steering and welded it all together. The idea here is to add everything that needs to be added, like brake mounts, and steering arms, then trim away everything extra. Crude but, hopefully, effective.
After drilling axle holes, I installed the wheels and built mounts for the disc brake calipers. Following a test fit on the trike, I added stud for the steering tie rod to connect to, on the wheel side of the trailing arm. To establish a wild stab at ackerman steering, I used a spreadsheet that I downloaded (in the links on the right of this page). The only real guess work was where in blazes to start my measurements from. In theory, one would measure everything from the king pin, but that goes out the window when the king pin is tilted aft and in to obtain center-point (or near to it) steering.

Again, I spent the better part of an afternoon looking at other trikes on the internet. I determined that some of the most respected trikes must be using the point where the tire meets the road as their reference point, so that's what I did. My steering arms will connect just inside and behind the brake rotors. Then I cut off all the extra material on my steering knuckles to lighten them up a little.