Trike #2

Frame

     This frame was made out of 1" square box tube steel, with 1/16" walls.  I wanted to try to reduce the weight and simplify the construction by standardizing the tube size.  I experimented with a more adjustable seat and triangulating the rear end for stiffness.  Due to the thinner wall of the tubing, I also added the "truss" on the boom to ty to eliminate boom flex.  The boom is super solid now and I might extend the boom another 1" to 18" from the center of the pedal crank to the cross member but I don't want there to be too much tail wagging at higher pedal RPMs though.

     Initially I built the front end to accommodate these small 6" wheels as they were all I had at the time.  The wheel bearings were pretty low grade though and have zero tolerance for lateral loading so after the first test drive, the bearings and their housings were toast and I went to the 20" wheels with 14mm axles.

As a result, the caster is steeper than I would have liked and it makes the steering a little heavy and at speed, it's more sensitive than I would like now that the 20" wheels are on it.  The front wheels also have about 5 degrees camber to them as well which is an unintended result of upgrading to the 20" wheels.

     I added a front derailler post to this one, as well as a short stub to mount my U-shaped bike lock.  Water bottle holders can be mounted wherever I choose later using self tapping screws as I wasn't really interested in adding carrier bosses after messing around with cable guides and cable housing guides.  I welded a small piece of tubing to the left rear to stick the safety flag in as opposed to using the one that came with it which needed to be bolted and unbolted.  With mine, it just drops in and the wind resistance on the flag keeps it in place inside the small 4" tube.

     I initially added the front chain guide pulley just in front of and below the cross member which meant the chain was routed under the cross member.  On the test ride, I discovered that the torque from pedalling and the torque from the chain trying to straighten itself out put a HUGE load on the cross member as they were both trying to force the boom down.  To rectify this, I moved the pulley back under the front of the seat and now the power side of the chain runs over the front cross member so now, pushing on the pedals forces the boom down while the torque from the chain tries to pull the boom back up.  As I also reinforced the boom, the boom flex issue has been solved - there is NO flex.  The pulley is made out of an old roller blade wheel and the small metal U strap is to keep the chain from dropping too far out of the pulley slot.  I used green 5/8" garden hose for the return side of the chain until I locate some nice, small black hose to replace it.

Seat

     The original seat was made out of some old ¾" stainless steel tubing and red canvas.  It was pretty comfortable but it was too big and too complicated to make.

I wanted something easier to build and a little smaller, so I made the new one and used blue nylon mesh.  The new seat is smaller, lighter, and took about ¼ the time to build.  There are a couple mods I want to do to the next one to make it a little smaller, and easier still to build.  The fact that the front and top ends of the side seat rails hasn't affected the stability or comfort of the seat either.  The original bottom supports were about ½" too short so you could occaisionally feel it through the seat material.  I added about ¾" to them and the problem has been solved.  The seat back is about 20" long and the seat bottom is about 12".  The total side rail length is 39" and it's 16" wide.

     When I made the bike, I wanted to have 12" of seat adjustment (via 12 holes spaced 1" apart) and planned to have the seat around the 2nd last hole for me at 6' 2".  As it turned out, my measurements were off and I need to have the seat at the 4th or 5th hole from the front to be comfortable.

     You can also see where I added some extra height to the middle of the 1/8" mild steel piece that connects the seat sides to the seat mount.  You can also see some actual good use of my $20 pair of roller blades too. :)

Wheels

     The rear wheel is standard 26" wheel with a 6 speed cassette on it.  The front wheels are heavy duty 20" wheels with 48 spokes and 14mm axles - same ones as on the first bike.  Top speed is pretty good with the big rear wheel when I use the 49 tooth chain wheel.

Misc Hardware

     The brakes, levers and deraillers were all salvaged parts.  The only store bought items were the front wheels and tires.  The front brakes are much easier to pull than the dual rear brakes on the first bike due to the length and routing of the cables.  The rear derailler cable was also fairly sticky initially, but with some heavy oil heated up and poured down the cable, it has gotten much better.  The handle bars are made from ¾" EMT and were bent to wrap around your legs and hips to minimize the turning radius.  Aside from the wheels, one Allen wrench will take all the Allen head screws out as I tried to keep them all the same size for simplicity.

Specs:

Modifications:

• added fenders to all 3 wheels.  Made from pieces of scrap 7075 AL.  Definitely more effort than I intended and next time I'll simply buy plastic ones and try to mod them instead.  Should be much easier.

• added mounts for a child seat and a trailer to the rear end.  Child seat mounted . . .

Trailer hitched . . .

Next time . . .

• I want to get a smaller profiled, smoother tread rear tire for it.  It's very easy to get to top speed on it but I can feel the drag from the knobby rear tire and the hum is pretty loud too. :)
• bike is too heavy.  Will simplify the frame and make it lower, narrower and hopefully shorter to try to reduce the weight.
• bike is too wide.  I will try to keep the next one as close to 30" as I can so I can get it in and out of doors and gates easier.
• bike seat is pretty comfortable, but I want to narrow it by an inch, shorten the front by an inch, shorten the back by 2", lengthen the front seat support by ½" and move it forward an inch, and move the back seat support down 1 or 2".
• mount the seat adjustment rails further forward so it fits shorter people easier.  This trike is too long for people close to 5' tall and the extra 6" behind the seat is wasted space.
• I want to use a single post to adjust the seat angle instead of using 2 small ones as it should be easier to use and build.

More bike details when more bikes are built :)