Grant Hutchinson, the drummer with Frightened Rabbit, will pedal through five British cities this May in aid of the Cystinosis Foundation UK.
The massive bike ride is inspired by his brother Neil's daughter Morven, who suffers from the condition.
Morven was diagnosed with the rare illness at birth and the three-year-old now has to consume a cocktail of drugs every few hours, including during the night.
The condition causes impaired growth and kidney problems and has a particularly drastic affect on young children. At the moment there is no cure.
Grant, whose brother Scott is the Frightened Rabbit front man, wants to help the toddler.
He said: "We are a very close-knit family, and as soon as I found out about this I wanted to help.
"This is a tough challenge, but it's also a fun one, so hopefully people will support us."
Neil, who also has another one-year-old daughter named Ailish, is a trustee member of the Cystinosis Foundation.
He added: "I immediately identified with the charity as a way of helping Morven and others with the condition and so set about raising money."
Frightened Rabbit has a strong fan base in Glasgow, and sold out two dates at the O2 Academy last November.
The band is looking for help from its Glasgow fans.
The aim is to raise around £100,000, that will go towards research for those with the genetic condition.
Drummer Grant said: "There are lots of ways people can help. The main way would obviously be to donate money to the cause.
"Also, if there are any keen cyclists out there who want to help with training, or have a good route they like to do, then please let me know and we can get out together.
"It's always easier having other people with you to encourage you up those hills."
Although Grant admits that cycling is not something the brothers have always enjoyed.
He said: "Our Dad is a very keen cyclist and it was something he tried to pass on to us but, for me, it always felt like more of a chore than anything.
"In my head it's going to be a great 12 days of sitting on a bike chatting to friends in the sun. Edinburgh to London is all down hill, right?"