When Rachel woke up one morning with blurred vision, she was frightened to know what the future would hold.
A visit to A&E and several GP appointments followed, until finally, she was diagnosed with optic neuritis (inflammation of the optic nerve) - also an indicator of multiple sclerosis.
Uncertain if her eyesight would improve, Rachel was determined to see her MS as an obstacle, and not a limitation.
Her friend Roz persuaded her to enter Ride London and will be acting as her guide over the course. Raising money for the MS Society is a huge motivator for Rachel to cross the finish line with her friend.
The Ride London event takes place over three days from 28 to 30 July. You can find details of the BBC's live coverage of the event here, while the BBC Sport website will feature live text commentary of the Ride London 100 and 46 races and the men's elite London-Surrey Classic from 09:00 BST on Sunday.
And if you're inspired to try cycling yourself, check out our Get Inspired guide.