The BIG Gravel Grind presented by Subaru of Sarnia is an annual gravel cycling event held in Thedford, Ontario, organized by the Bluewater Cycling Organization (BCO). Established in 2024 in memory of Jamie Hastings, a beloved Sarnia community member and cycling advocate, the event has quickly become a highlight for cyclists in Lambton County and beyond. The event is designed to foster community spirit, promote healthy living, and support local charities, with proceeds benefiting organizations such as the Women's Interval Home and Weir Active.

Participants can choose from four distinct routes—20 km, 40 km, 60 km, and 80 km—each showcasing the picturesque gravel roads and rural landscapes of the region. The event is non-competitive and emphasizes a social, inclusive atmosphere, making it accessible to riders of all skill levels. With amenities like fuel stations, a signature event jersey, and a post-ride meal and entertainment, the BIG Gravel Grind offers a memorable and rewarding experience for all involved.

The BIG Gravel Grind routes primarily traverse well-maintained gravel roads with occasional paved sections. The terrain is generally flat to gently rolling, making it suitable for a wide range of cyclists. The 20 km route is almost entirely flat, ideal for beginners or those seeking a leisurely ride. The longer routes (40 km, 60 km, and 80 km) introduce more rolling hills, providing a moderate challenge without significant elevation gain. Surfaces are predominantly smooth gravel, with some sections offering a slightly rougher texture, ensuring a classic gravel riding experience. Multiple fuel stations are strategically placed along each route to keep riders hydrated and energized.

- Four route options: 20 km, 40 km, 60 km, and 80 km
- Scenic gravel roads and rural landscapes of Lambton County
- Multiple fuel and refreshment stations along each route
- Signature event jersey for all participants
- Post-ride meal and entertainment included
- Non-competitive, social atmosphere
- Supports local charities and community organizations