I spent a good bit of time thinking about the hitch. My favorite part is using a short piece of automotive heater hose to wrap around the bike seat post. It flexes a little, absorbs small shocks, and attaches and removes quickly with no tools. I like it.
The trailer has a wooden frame with low-speed low-pressure wheels, slightly smaller than wheelbarrow wheels. They roll nicely and absorb minor shocks.
It's all connected by a long piece of black iron pipe, bent to the contours of the rear bike wheel and the bow of the kayak. And the pipe swivels in the frame so everything moves.
- Non-swivel pneumatic casters, 10 inch diameter wheels: http://www.harborfreight.com/10-inch-pneumatic-rigid-caster-38943.html
- Black iron gas pipe, 10 ft length, 3/4 inch diameter: http://www.lowes.com/pd_313570-185-314+34X120_0__?Ntt=313570&UserSearch=313570&productId=3538958&rpp=32
- Automotive heater hose
- Misc timbers, metal, nuts, bolts, nails, fittings, etc.
- A hydraulic pipe bender was helpful: http://www.harborfreight.com/12-ton-hydraulic-pipe-bender-32888.html
- Generic handyman tools: Drills, saws, wrenches, files, etc.
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Step 1: Seat Post Hitch
I designed this hitch to fit around the bike seat post.
- Yaw: The rubber hose allows the hitch to swivel about the seat post as the bike turns left and right.
- Roll: The big bolt and nylock nut allows the hitch to swivel as the bike leans side to side.
- Pitch: The rubber hose and rubber bumper allows a little movement as the bike and trailer move up and down.
Installation and removal:
- Two metal pins hold the rubber hose to the hitch.
- To remove the hitch from the bike, simply remove one pin from the hose, then slide the hose off.
- To install the hitch, slide the hose over hitch, then install pin.
Details in the photos.
Step 2: Pipe
Measure the bike.
Design the length of pipe to accomadate your kayak. I chose to support it at the bow and at 60% of its length.
Design the bends in your pipe to clear the bike wheel and kayak bow. Bend the pipe to fit.
Step 3: Assembly
Cut timbers to fit. Bolt everything together.
Step 4: Cradles
Fabricate and install wooden cradles to support the kayak at its sides, rather than resting on the keel.
Install cradles on the front and rear of the trailer.
Cover the cradles with carpet or other padding to protect the kayak. (not shown)
Step 5: Test Rides
Ensure all nuts, bolts, and pipe fittings are secure.
Attach the hitch to the bike seat post. Install kayaks to the trailer with bungees, straps, etc. Test.
Step 6: Afterthoughts
1. After I built the trailer, I realized it needed a small wheel on the front. Purposes:
- This wheel supports the trailer when not being used, rather than resting on the plywood.
- The wheel makes the trailer easier to move around the driveway with boats on it.
Advice: design your front wheel cleanly from the start.
2. After testing on the bike, I decided pipe was positioned too close to top of the bicycle rear wheel. Rather than bending the pipe, I tied the pipe up to the saddle rails.
Advice: design your pipe to fit the bike correctly!
3. Longer cradles. Right now, most weight of the kayaks is resting on the two rear cradles. Each is only about 6 inches long. I hope shocks from bad bumps or potholes don't damage the kayaks under the cradles. If I were doing it again, I would make them 12 inches long or so.
Advice: make your rear cradles longer.