ReCYCLE - Electrical bike with durable circular plastic parts

In ReCYCLE we focused on creating durable circular plastic parts for the use of electric bikes, pushing the boundaries of innovation in sustainable engineering thermoplastics.

In short:

Demonstrated that key e‑bike parts can be made from high‑quality recycled plastics.
Developed a toolbox for circular design, including guidelines for disassembly and material selection.
Created a decay model to predict long‑term performance of recycled thermoplastics Acrylonitrile Butadiene Styrene (ABS) and polycarbonate (PC).

The challenge: recycling and repurposing of materials

As demand for electric bikes continues to grow, so does the need to ensure their production aligns with the European Union’s and the Dutch government’s sustainability goals. The aim is to achieve a circular economy for plastics by 2030 and 2050, but current practices fall short of this. Specifically, we need to change our approach to engineering thermoplastics and create a closed loop that allows for the recycling and repurposing of materials, thereby reducing their carbon footprint.

ReCYCLE: creating circular electric bike parts

The project focused on five electric bike parts:

Chain case
Electromotor cover
Battery cover
Coat protector
Head tube plate

For each bike part, a staged circularity approach was adopted. This started with the simplest solution of ‘dropping in’ 100% recyclate into the part and ended with the most complex and costly solution of completely redesigning the part and creating a new injection mould. After each stage, it was assessed whether the part met the required specifications. If so, the subsequent stages were not executed. If not, the next stages were carried out until success was achieved. Activities included:

Defining part requirements.
Translating these into R‑ETP material specifications.
Running injection moulding trials with R-ETP.
Improving the recycled materials in activity.
Optimizing part design to accommodate R-ETP.
Complete part redesign and a new mould
Testing to determine how many lifecycles the parts can bear and the development of a decay model.
Determining life‑cycle impact of the R-ETP solutions and calculating carbon footprints.

Results

1. Validated circular bike parts using R‑ETP

Full sets of technical requirements were established and validated using prototype parts. These include mechanical performance, aesthetic quality, assembly properties, weathering resistance, chemical resistance, and CO₂‑performance.

2. Clear overview of R‑ETP availability

The project mapped the availability of recycled engineering plastics in the Netherlands and the EU. Findings include:

PCR‑ABS is widely available.
PCR‑PA6, PCR‑TPE, and PCR‑PC exist but remain limited.
Some materials, such as PCR‑ASA, are not available.
Most recyclates must be sourced outside the Netherlands.

Because availability drives scalability, additional polymers were tested to widen application potential.

3. Circular material choices for each bike part

The project achieved successful circular versions of all five parts:

Part	Virgin material	Circular R‑ETP solution
Chain case	ABS black	PCR‑ABS black
Electromotor cover	PA6 black	PCR‑ABS black
Battery cover	PC black	High‑impact PCR‑ABS
Coat protector	PC transparent	PCR‑PET transparent or PCR‑PC
Head tube plate	ASA + TPE	2K: PCR‑ABS + PCR‑TPE / 1K: PCR‑ABS black + silver PCR‑ABS

Notably, using PCR‑ABS for both the chain case and motor cover enables disposal as a mono‑stream, simplifying recycling.

4. Toolbox for circular engineering plastics

The project created a practical design toolbox that includes:

Material selection guidance
Design-for-circularity and design-for-disassembly rules
Lessons learned from material trials
A process-flow diagram for developing circular components

5. Decay model for recycled ABS and PC

A new test protocol simulated realistic mechanical recycling combined with accelerated aging.

Key findings:

ABS and PC show predictable declines in impact strength after one recycling step.
Other mechanical properties remain largely stable.
ABS degrades significantly less than PC.
Aging behaviour of post-consumer recycled materials closely mirrors that of virgin materials.
Without downgrading, maintaining performance requires impact modification and colour correction.

6. Multiple possible recycling loops

If downgrading is allowed, the materials can be reused many times:

ABS: 5–14 cycles
PC: 2–4 cycles

7. Significant CO₂‑reduction based on LCA

Switching to R‑ETP leads to strong climate benefits:

–68% CO₂‑eq for the battery case
–55% CO₂‑eq for the motor cover
–55% CO₂‑eq for the coat protector

Reductions in acidification and particulate matter were also achieved, except where long transport distances increased particulate emissions — underlining the importance of local recycling capacity.

This is a project of the Circular Plastics Initiative, co-founded by ISPT and DPI.