Hey Thomas,
I'm stumped on this one. Your inner link count looks good (358) as well as external link profile to that page. Here are a few suggestions:
1. Add exact keyword to
2. Add exact keyword to
3. Review Google Pagespeed insights data: https://developers.google.com/speed/pagespeed/insights/?url=https%3A%2F%2Fwattbike.com%2Fgb%2Fproduct%2Fatom
4. Review the schema structure on product pages: https://search.google.com/structured-data/testing-tool#url=https%3A%2F%2Fwattbike.com%2Fgb%2Fproduct%2Fatom
5. Review 404 errors in Search Console
You normally don't see this type of drop unless there's a bigger issue going on related to the entire site. I hope that helps!