Jamie Cox will set off from St Matha’s Hill, Surrey, on Saturday, April 30 and cycle down the Downs Link to Truleigh Hill before travelling across the South Downs Way.
He will be finishing his journey in Eastbourne later that day.
The challenge is being undertaken to raise money for The Fire Fighters Charity in memory of two well-loved and much-missed colleagues – Mark Butler, who died after suffering from leukaemia, and Simon Constable, who died having suffered a stroke in 2019.
Mark and Simon had served a combined total of 66 years in the fire service.
Speaking of his charity challenge, Jamie said: “As we mark the third anniversaries of Mark and Simon’s passings, I am hoping to raise £250 for a charity that provides support for both serving and former firefighters, as well as their families.
“I regularly ride off-road on my mountain bike but nowhere near the distance of over 100km in a day which is what I’ll be doing.
“The weather forecast is set to be warm and dry, which will make the ride less slippery on the hills, but it may make the climbs of Truleigh Hill, Firle Beacon, Wilmington Hill and going on to Jevington that little bit harder in the heat.
“Mountain biking is very different to road cycling technically, with the average speed being less, especially when its muddy, so we are grateful we have a dry week leading up to the event.”
Jamie will be joined on the day by Horsham Green Watch manager Al Green, who will help set the pace, while friends and family will be joining them along the way to provide encouragement.
Jamie added: “Three years on from losing Simon and Mark, they are still both very much in all of our thoughts. This one is for them.”
The Fire Fighters Charity support the mental, physical and social needs of all serving and retired members of the UK’s fire family.
It provides thousands of people with personalised support every year.
The charity was formed during the Second World War as a way to support families during the Blitz.
You can support the fundraising efforts by visiting www.justgiving.com/fundraising/markandsimon22.