Clayton Newman from Leyland and his brother Blake, who lives in Southport, will be riding up to 80 miles a day through France and Spain to reach their childhood holiday destination of L'Estartit on the Costa Brava.
There they will be scattering the ashes of their dad Bill who died aged from dementia aged 83 in November 2020, and they hope to raise £5,000 to help people affected by the condition along the way.
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Due to coronavirus restrictions, the family were not allowed to see Bill in the lead up to his death.
Clayton, 44, who has a flooring business, said: "So many people have been in a similar situation and my brother and I wanted to do something to help, but didn't know what.
"After dad died we were talking about holidays we used to do as kids and I just said a throwaway comment about riding to L’Estartit, and it started from there."
Despite not having ridden together since they were 11 and 13, the brothers have committed to the journey, setting aside up to 12 days for the experience.
They will do it on “basic” road bikes and have had limited opportunity to train - the furthest they’ve ridden is 40 miles.
Clayton, a dad-of-two, said: "We're both working family men and I'd love to say that we've been on the treadmill, doing weights, and have done loads of practice, but we haven't.
"We can only really go on practice runs when the weather is good, and we've only got basic bikes, but we are committed and we will finish it."
Clayton has been inspired by Eddie Izzard's 27 marathons in 27 days for Sport Relief.
He said: "To me, that was an everyday bloke trying to put something in to make a difference. Seeing him go through the pain barrier has really inspired me.”
The men will set off on May 5, getting a ferry to Dieppe in France, and cycling from there.
They will be supported by Clayton's father-in-law, Leslie Alker, driving behind them, carrying essential equipment and helping with logistics.
They have been supplied with water, energy drinks and energy bars by staff at Tesco in Leyland, and already friends and family have donated almost half of their £5,000 target.
Clayton said: "We've been in a pandemic for two years and so we're not trying to raise a huge amount, but something realistic. I'm funding the entire trip myself, so every penny that is donated will go to a good cause.
"It's our little way of doing something good, and if we can help just one family, or care home staff who have sacrificied so much during the pandemic to look after people like my dad, then I will be happy."
Clayton and Blake say they are interested in potentially helping to create an open space at Cedar Grange car home in Southport where their dad was cared for, so that families have an outdoor place to meet.
Clayton is not using a donation site as he doesn't want a percentage of donations to be lost to administration costs.