"We got into it pretty seriously, building tracks with lots of jumps," said Lance.
"We were always trying to outdo each other and see who could jump bigger."
In 2013, before Grant was diagnosed, the brothers travelled to North America together.
"We had a great month road-tripping and riding at Whistler Bike Park in Canada," said Grant, who is 41 and a lecturer in philosophy at Lincoln University in Christchurch.
In a positive twist on the situation, Grant's illness has brought the pair even closer.
"Lance's concern was obvious right from the start and he flew down to Christchurch when I was in hospital the first time to support me," said Grant.
"He visited me during a dialysis session to see my new reality. We also spent a long weekend driving around the upper South Island. A lot of that weekend involved talking and reflecting about what it all meant for both of us."
Lance is 38 and moved to Rotorua early in 2007.
"If you are a mountain biker this is the place in New Zealand to live," he said.
"There are over 150km of the best trails in the country in the Whakarewarewa Forest and our mountain bike community is like a big family."
He works at Cyclezone, a local bike shop, and rides as often as possible.
He's ramped up his weekly kilometres in the last couple of months.
"As it sunk in about Grant, I was inspired to use what we are both passionate about to do something positive and help raise money for and awareness of Kidney Health New Zealand," he added.
As Team Kidney, Lance will ride the Solo category at the Gloworm 24 Hours of Nduro from midday January 31 to midday, February 1. He will be taking pledges for each kilometre and lap he covers.
"I'm pretty fit, but I'm taking this very seriously and already doing six-hour training rides. It'll be a big challenge - but nothing like the challenge Grant is facing."
His brother plans to be in Rotorua to cheer him on.
"Lance's support is immensely important to me," Grant said, "I want to be at the side of the trail at the 24 Hours of Nduro."
Two weeks after the Nduro, Lance will be putting his best pedal forward at the annual 10-day Rotorua Bike Festival, which starts on Friday February 13.
"Festival week is a great time to be in town, it's summer and hot and the sun always seem to shine," he said. "There are events you can rock up and ride in and others where you can watch some of the best athletes in the country in action."
One of the events at the 2014 Festival he rode in was Bike Speedway. This is two short straights and two corners, in front of the Rotorua Museum and Art Gallery in Government Gardens.
"I decided to channel Elvis," Lance said with a laugh.
"I might need to get that costume out, again, and hand the crown round for donations."
The Rotorua Singlespeed Society is also supporting his fund-raising efforts.
"One gear mountain biking is very tough and very competitive at the sharp end, with tattoos for the winning man and woman," said Paul Laing from the society.
"However, most people enter for the social side and to dress up in extravagant costumes."
The society has run three previous national championships and the Singlespeed World Championships in 2010. While these events are always light-hearted, there is always a serious side.
"The New Zealand champs are traditionally run on the closest weekend to Anzac Day, with a ride to the dawn service at Ohinemutu on the shores of Lake Rotorua," said Laing.
"With the 100th anniversary of Gallipoli in 2015 we are planning a very special Anzac edition."
The society always makes substantial donations to charity - they gave over $5000 to the Cancer Society in 2013.
"In 2015 we will donate to the RSA and Kidney Health New Zealand," said Laing.
Lance is a committee member of the society.
"He's a mate," Laing added. "And in Rotorua we look after our mates."
For Lance, a big summer of mountain biking in Rotorua has taken on a very special meaning.
He is hoping that he is compatible and can donate a kidney to his brother.
"It gives me hope of returning to a normal life," said Grant.
"Post-transplant, I'll always need to take anti-rejection drugs, and risky activities like downhill mountain biking may be out, but a kidney transplant is my best opportunity to live normally again."
And there will be some health implications for Lance but he is ready for that.
"After the procedure and a short - and probably painful - stay in hospital, the outlook for donors like him is statistically very good," said Grant. "There are always risks, but he should be able to live a largely normal life, including returning to mountain biking."
