Rider Triangle and Reach Study for an Electric Motorcycle

The problem

Electric motorcycles often move the battery into the space a rider's knees and feet would use, so the rider triangle needs care. A poor triangle gives wrist pain, a cramped knee or a rider who cannot reach the ground. Many student projects pick a seat height by eye rather than by measured joint angles for a range of riders.

Objectives

• Build a parametric 2D rider manikin from published anthropometric data.
• Lay out handlebar, seat and footpeg positions around the battery and frame.
• Measure knee, hip, elbow and trunk angles for small and large riders and compare them with comfort ranges.
• Recommend adjustable ranges and report the trade-offs.

What you need

Key concepts

Rider triangle

The triangle formed by the grip, the seat contact point and the footpeg. Its shape sets the rider's posture.

Percentile rider

A rider whose body dimension sits at a given percentile of a population. Designs are usually checked for a small and a large rider to cover most users.

Joint-angle comfort range

Published studies give ranges of knee, hip, elbow and trunk angles that riders find comfortable for a riding style. They are guides, not fixed limits.

Blocks in SOLIDWORKS

Sketch blocks act like rigid links that can rotate about points, so a 2D manikin can be posed while keeping segment lengths fixed.

Step-by-step guide

1. 1

   Define the vehicle and riders

   Write the brief for an example commuter electric motorcycle: wheelbase about 1350 mm, an example 3 kWh battery between the frame rails, seat height target of 780–800 mm. From a published Indian anthropometric source, tabulate stature, thigh, lower leg, upper arm, forearm and trunk lengths for an example 5th-percentile female and 95th-percentile male. State the source and any conversions you make.

   Checkpoint: A requirements table and an anthropometric table with a stated source for each value.

2. 2

   Build the vehicle layout

   In a layout part, sketch the ground line, wheel centres, steering axis and the battery and motor envelopes as rectangles from the brief. Add the seat surface line, the handlebar grip point and the footpeg point as sketch points with dimensions linked to global variables. Keep everything in one side-view sketch so changes propagate. Add a front view sketch for seat width and peg width.

   Checkpoint: Changing a global variable moves the grip, seat or peg point and the sketch stays fully defined.

3. 3

   Build a parametric manikin

   Create sketch blocks for foot, lower leg, thigh, trunk, upper arm, forearm and head, with pivot points at ankle, knee, hip, shoulder, elbow and neck. Drive block lengths from a design table that holds both rider percentiles. Insert the blocks into the layout and constrain the hip to the seat point, the hand to the grip point and the ball of the foot to the peg point, leaving the joints free to find a pose.

   Checkpoint: The manikin solves for both rider sizes without over-defining the sketch and every segment length matches the table.

4. 4

   Add riding-style configurations

   Create configurations for commuter upright and sport-touring positions by changing grip height, grip reach and peg position in the design table. Combine them with the rider configurations so you have four cases. Add a trunk-angle constraint for each style if the sketch needs one to solve. Keep a table of every input value so results can be reproduced. Name each configuration clearly, such as P05-Commuter, so drawings and result tables refer to the same case.

   Checkpoint: Four configurations rebuild without errors and each shows a plausible rider pose on screen.

5. 5

   Measure joint angles

   Add reference angle dimensions at the knee, hip, elbow, shoulder and trunk-to-vertical in each configuration, and read wrist extension from the grip angle. Export the values to Excel through the design table or by recording them. Compare each angle with published comfort ranges for that riding style and colour the cells that fall outside. Note that comfort ranges vary between studies, so cite the one you use.

   Checkpoint: A table of joint angles for all four cases, with out-of-range values marked and the comfort source cited.

6. 6

   Check ground reach and knee clearance

   Add a stopped-rider configuration where the manikin moves its foot from the peg to the ground. Measure whether the small rider can reach the ground with the ball of the foot, using the seat width at the front from the front-view sketch. Check that the large rider's knee clears the battery and tank envelope with a stated margin. Repeat after any layout change.

   Checkpoint: The small rider reaches the ground with at least the ball of the foot and the large rider's knee clears the envelopes by the stated margin.

7. 7

   Iterate the triangle

   Change grip, seat and peg positions to bring angles into range for both riders, while respecting the battery and frame envelopes. Try one or two adjustable features, such as a two-position handlebar riser or adjustable pegs, and measure how much they help. Record each iteration in a table with the input change and the angle results. Stop when further changes trade one rider's comfort for the other's.

   Checkpoint: An iteration log showing a final triangle that keeps most angles in range for both riders, with the remaining trade-offs explained.

8. 8

   Model physical parts

   Model simple parts for the handlebar riser, seat base outline and footpeg brackets at the final positions, and place them in an assembly with the frame and battery envelopes. Run Interference Detection between the parts, envelopes and the large-rider manikin extruded as thin bodies. Make a dimensioned layout drawing of the rider triangle with tolerances for adjustment ranges. Keep adjustable parts at their mid position for the drawing and show the end positions as alternate position views.

   Checkpoint: Interference Detection passes and the layout drawing shows the final grip, seat and peg points with adjustment ranges.

9. 9

   Report the study

   Write up the anthropometric source, manikin method, configurations, angle tables, ground-reach and knee checks and the iteration history. Discuss the limits of a 2D sketch manikin: no soft-tissue compression, no dynamic loads and simplified joints. Recommend a physical check with a seating buck and a few riders as the next step. Include images of the manikin in each configuration. Add the design table as an appendix so the exact values behind every pose can be checked.

   Checkpoint: A report with tables and images that another student could use to reproduce the final triangle.

Testing & validation

• Manikin segment lengths match the stated anthropometric source.
• Joint angles compared with a cited comfort range for every case.
• Ground-reach and knee-clearance checks for both riders.
• Interference Detection passes for the final layout.

Expected results

A parametric rider-triangle layout with a reusable manikin, joint-angle tables for two riders and two riding styles, and a recommended triangle with adjustment ranges.

Take it further

• Build a simple adjustable seating buck and measure real riders.
• Extend the manikin to 3D with assembly mates and angle limits.
• Add a pillion and check the pillion triangle and grab-rail reach.

Viva and review questions

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