# Axlow V1 Recumbent Trike - Concept-Level Design

Date: 2026-06-08

Status: Concept design for expert review. Not a production drawing.

## 1. Design Intent

Axlow V1 is a locally manufacturable tadpole recumbent trike. The first prototype should prove ride position, steering, braking, chain routing, and manufacturability before advanced features such as folding, electric assist, belt drive, or custom internal gear hubs are added.

Core idea:

- Comfortable low recumbent riding position
- Two front steering wheels, one rear driven wheel
- Side steering handles
- Front crank boom
- Long chain drive to rear wheel
- Mild steel tubular chassis for prototype
- Bought-out bicycle drivetrain and brake components for V0/V1
- Designed for SolidWorks refinement and local fabrication

## 2. Preliminary Geometry

| Parameter | Concept Target | Review Notes |
| --- | --- | --- |
| Overall length | 1850-2050 mm | Depends on boom adjustment and rear wheel size |
| Overall width | 820-880 mm | Must pass doorway/gate constraints if needed |
| Front track width | 760-820 mm center-to-center | Wider improves stability but increases bulk |
| Wheelbase | 1200-1350 mm | Front axle line to rear axle |
| Seat base height | 300-380 mm | Lower is stable but harder for some riders to enter |
| Seat back angle | 42-50 degrees from ground | Adjustable preferred |
| Bottom bracket height | 430-520 mm | Slightly above seat base for recumbent efficiency |
| Ground clearance | 120-150 mm | Practical for Indian uneven surfaces |
| Front wheel size | 20 inch | Commercially common for tadpole trikes |
| Rear wheel size | 26 inch preferred | 20 inch alternate |
| Crank boom adjustment | 180-250 mm | For different rider heights |
| Turning circle | Under 5 m target | Must be tested physically |
| Rider capacity | 100-120 kg | To be validated structurally |
| Prototype weight | 30-38 kg | Mild steel prototype target |

## 3. Frame Concept

Suggested frame members:

- Main spine tube from front boom receiver to rear fork/triangle
- Front cross-member carrying left/right steering knuckles
- Rear fork or rear triangle supporting driven rear wheel
- Seat base supports tied into main spine
- Seat back supports tied into rear frame
- Boom receiver tube for adjustable crank boom
- Gussets at front cross-member and seat load points
- Idler bracket near seat/front spine area

Preliminary material:

- Main spine: 50 x 50 x 2.5 mm rectangular mild steel tube, or 50 mm OD round tube with 2.5-3 mm wall
- Front cross-member: 40 x 40 x 2.5 mm rectangular tube, or 40 mm OD round tube
- Seat frame: 22-28 mm OD tube, 1.6-2 mm wall
- Brackets/gussets: 3-5 mm mild steel plate
- Boom: telescoping tube pair with clamp bolts and anti-rotation feature

## 4. Steering Concept

Recommended system:

- Side steering handles mounted beside the rider
- Link rods from handles to steering arms on front knuckles
- Ackermann-style geometry using angled steering arms
- Mechanical stops to prevent oversteer and heel/wheel interference
- Toe adjustment through threaded rod ends

Preliminary targets:

| Parameter | Concept Target |
| --- | --- |
| Caster | 8-12 degrees |
| Camber | 0 to -2 degrees |
| Toe-in | 1-3 mm total |
| Steering lock | Limited by interference and rollover risk |

## 5. Drivetrain Concept

Recommended Prototype 0 drivetrain:

- Standard bicycle crankset at front boom
- 1x8, 1x9, or 3x7 drivetrain
- Long chain running along main spine to rear wheel
- One power-side idler near the front/seat transition
- Return chain guided through low-friction chain tube
- Rear derailleur and cassette/freewheel
- Chain guards near rider hands, seat, and clothing contact zones

## 6. Braking And Safety

Recommended Prototype 0 braking:

- Dual front mechanical disc brakes
- Separate or linked brake lever to be reviewed
- Rear parking brake if simple to add
- Brake cable routing along front cross-member and steering handles

Critical checks:

- Rider can enter and exit safely
- Pedals do not interfere with front wheels during turn
- Heels clear the front cross-member and tyres
- Hands do not contact wheels, steering rods, or chain
- Chain is guarded near clothing and skin
- Brake levers are reachable and intuitive
- Seat supports lower back well
- Visibility flag mount is included
- Reflector/light mounts are included

## 7. Manufacturing Strategy

Make in-house:

- Main frame
- Boom receiver and adjustable boom
- Front cross-member
- Steering brackets and linkages
- Seat frame
- Idler brackets
- Cable tabs and guard mounts
- Custom spacers/bushes
- Prototype jigs

Buy out initially:

- Wheels
- Tyres/tubes
- Hubs
- Crankset
- Bottom bracket
- Chain
- Cassette/freewheel
- Derailleur and shifter
- Disc brake calipers/rotors/levers
- Cables/housings
- Rod ends if available
- Seat mesh/fabric/padding
- Grips

## 8. Prototype Test Plan

Static checks:

- Frame alignment
- Front toe measurement
- Steering range and interference
- Brake cable movement through full steering range
- Chain line and chain tube rubbing
- Seat flex and mount flex

Low-speed tests:

- Straight tracking
- Tight turn both directions
- Braking with both front brakes
- Braking with one side only
- Start from standstill in low gear
- Slope start if practical
- Rider entry/exit

## 9. Key Risks

| Risk | Why It Matters | Early Mitigation |
| --- | --- | --- |
| Poor steering geometry | Tire scrub, instability, unsafe handling | Model Ackermann and add toe adjustment |
| Brake imbalance | Pulls trike during braking | Test linked vs independent braking |
| Chain routing complexity | Noise, derailment, rider contact | Use idlers, chain tubes, and guards |
| Seat discomfort | Product fails despite good mechanics | Prototype adjustable seat early |
| Excess weight | Hard to sell and transport | Accept in V0, reduce in V1 |
| Low visibility | Road safety issue | Add flag and light mounts |
| Cost creep | Hard to commercialize | Use bought-out parts first |