After setting off from the Princess Mary Stadium in Cleckheaton the mixed-ability cyclists will arrive in Buxton in Derbyshire later on Wednesday.
They are set to reach London on Sunday, July 27.
Tracy Vause is taking part in the ride for the first time after watching the race set off in recent years.
“I cannot actually believe that we are going from Cleckheaton to London; we know it is really hilly on day one so there is not really the shock there.
“I know it is going to be a challenge and you have got to really dig deep”
Ms Vause, from Gomersal, said the group would support each other through the challenge.
“It is not a race, there is not a prize for being first so I am really looking forward to it”.