The 39-year-old from Edgware set off on 20 July with an ambitious goal of cycling the entire 1,600-mile Wild Atlantic Way in just 20 days.
Along the way, she hopes to raise vital funds for The Brain Tumour Charity, which supports families affected by brain tumours, funds pioneering research and campaigns for better treatment and care.
Sarah's determination comes from a deeply personal place.
Rachel De Groen was just 19 when she was diagnosed with what was later identified as a diffuse midline glioma, an aggressive and incurable brain tumour. Doctors initially gave her only three months to live, but Rachel defied expectations and survived for another 15 months.
Those extra months became precious time for the entire family.
Rachel, the youngest of seven siblings, was known for her gentle nature and her love of children, art, fashion, butterflies and the colour pink. Her nieces and nephews adored spending time with her because she would happily sit on the floor playing games with them for hours.
One of the most striking aspects of Rachel's illness was how subtly it began. Rather than headaches or balance problems, the earliest warning signs were changes in her personality. She gradually withdrew from family, struggled with her mental health and became increasingly unwell before doctors finally discovered the tumour.
The diagnosis devastated the family, but instead of allowing despair to take over, they resolved to make every remaining day count. Birthdays became treasured occasions, family outings were organised whenever Rachel felt well enough, and even her brother brought forward his wedding so she could be there.
Sarah told That's Health that experience completely changed how she viewed life.
She explains that when someone you love is dying, everyday worries suddenly become insignificant. It taught her to value every moment and inspired her to take on endurance challenges in Rachel's memory.
Having previously completed the famous Land's End to John O'Groats cycle ride, Sarah is now tackling the even greater elevation and distance of Ireland's Wild Atlantic Way. She hopes to complete the challenge on 12 August, marking the anniversary of Rachel's diagnosis.
As well as remembering her sister, Sarah hopes her journey will raise awareness of brain tumours and the urgent need for more research into better treatments.
Her message is both simple and powerful: life is precious, every day is a gift, and by supporting research today, more families may be spared the heartbreak that hers experienced.
Anyone wishing to support Sarah's remarkable fundraising challenge can donate through her JustGiving page and follow her story as she cycles around one of Europe's most dramatic coastlines.






