Introduction: Recumbent Trike
I have designed this recumbent trike as a cheap introduction into recumbent cycling.
I did not walk to spend $1000 on a commercial trike.
I built it out of wood as I am more conversant with wood, modifications are easier and it's cheaper.
I can then weld up in Alu once it's proven.
My aim was to do it under €100 which I think I have.
Step 1: Donor Bikes.
I used a couple of donor bikes.
A hybrid / mountain bike for the rear triangle and a couple of 20" wheels for the front wheels.
Use an alloy frame if you want to weld up the rear triangle to to an alloy beam later on.
You can use the rear triangle brake to get you started.
The 20" wheel brakes can be kept for the front brakes.
Keep the bottom bracket Chain set and front and rear mechs too along with shifters and brake levers. In fact don't Chuck anything out it might come in handy!
Step 2: Cutting Up.
Cutting up your rear triangle is daunting yet fulfilling espcually if like me it was a decent specialized frame.
I cut it at the end of the top tube next to the seat post.
The downtube I cut 3"/75mm up from the bottom bracket.
This meant I had a stub to support the beam.
I left on two tabs which I could screw into the beam.
Step 3: Cross Member.
I decided on 3x2 cls as it's cheap and similar dimensions to 60 x 30mm alu section.
If I were building in wood for good I would use full section 3x2 for increased strength and stiffness.
I cut up the cross member at 32"/ 800mm wide as I wanted a wider wheel base.
Feel free to narrow down to 28" if you desire.
The front boom is 24"/600m.
The main piece is 36" /750mm long.
I used scrap 1/2 ply 8"/200mm square gussets to strengthen. I later sculpted them so they would not catch on my calves.
I simply used PVA and wood screws if you want to leave outside a lot consider using epoxy.
Step 4: Grafting to the Rear Triangle.
I found the cross member needed to be under ones knees when the pedals were at 12/6 o'clock.
When I was happy I drilled a 32mm hole at the angle of the seat tube.
I then used a speedy hoist hanger round the back of the seat post to reinforce the joint.
The reminant of the down tube was screwed into the underneath of the beam.
Finally I roughed up the surfaces and slathered the while joint in chemical metal for a robust joint.
Step 5: Steering Arms.
I used 6" /150mm 30 x 5mm plate x4 for the lugs as I could then weld to the Alu section in the future.
I drilled 8mm holes 1" 3" and 5" in from end.
I cut the arms out of a scrap 10"/250mm 3x2.
I drilled the 8mm king pin hole 1"/25mm back from the front and the 10mm axle holes 2"/50mm back from the front edge.
Finally I used a couple of furniture blocks to bring in the pivot point for simplified Akerman steering. These will be replaced with Alu L section in future.
Step 6: Bottom Bracket Assembly
I soon realised that the bottom bracket would be best served as a separate assembly rather than built into the front boom.
I used a Bb30 to threaded adaptor approx $20.
Using a spare piece of cls 10" 250mm long. I drilled a 40mm hole just above the edge.
I then cut it through the middle of the hole leaving the majority of the material in the clamp above.
I used 10mm bolts at 6" centers.
I bedded in the adaptor with chemical metal.
Step 7: Drive Train.
Seeing that I had a sram gripshift spare, I used it linked up to a mid level rear mech. If using a Larger 30+ cassette the use a long arm mech.
The cable run is short and completely in the outer sleeve.
I used 15mm plastic central heating pipe to guide my top chain under the seat it works well. I used two pipe clips to retain.
I needed 2.5 lengths of chain.
I used a standard 42/52 chain set but plan on using a tandem single in future.
To use a double or triple you will need a tube above the chain set on which to mount the front mech.
Step 8: Seat
The seat is some scrap 3/8"/ 9mm ply 16" 400mm square. I used 30mm alloy angle to joint but you could use a triangle of timber.
I screwed it to blocks beneth the seat and behind the seat which I screwed to the main beam and banded to the seat tube.
I plan of covering the seat with foam and some old cycling jerseys for fun!
Step 9: Brakes
- Brakes I am currently using a single rear v brake but plan on using front brakes soon, attached to a hammer headed steering arm with caliper brakes outboard and steering linkage inboard.
I used a flat handlebar for the steering which works well.