John 'Zac' Brennan

Cancer is the biggest killer of kids from disease in the USA, 38 children die every week. Please donate now and support my challenge to fight kids' cancer!

Donate Now

I've Ridden 0.0 mi My goal is 500 mi

My Rankings

National: 241st
State: 7th in CO
My Team: 4th

I've raised $825 My goal is $1,000 Donate Now

I'm Riding For

Kahleesi

Kahleesi ride your cool bike! Have fun❤️

My Story

16 Aug 2026

This September 2026 I am taking part in the Great Cycle Challenge to fight kids' cancer!

Cancer research funding has been recently defunded by the current administration in Washington. Now, more than ever the children née our help.

Why? Because right now, cancer is the biggest killer of children from disease in the United States. Over 15,700 children are diagnosed every year, and sadly, 38 children die of cancer every week. Kids should be living life, not fighting for it.

So I am raising funds through my challenge to help these kids and support Children's Cancer Research Fund to allow them to continue their work to develop lifesaving treatments and find a cure for childhood cancer.

Please support me by making a donation to give these kids the brighter futures they deserve. I'm also riding for myself. In Vietnam in the Army I was exposed to Agent Orange herbicide and now at 76, have Stage IV metastatic prostate cancer.

Your support will change little lives.....and mine too!

Thank you.

John Zac Brennan

My Legacy

Here's my personal impact over 7 years to fight kids' cancer and save little lives.

514 mi Ridden

$2,077 Raised

2020
465 mi Ridden

$1,695 Raised

2021
519 mi Ridden

$2,266 Raised

2022
546 mi Ridden

$6,000 Raised

2023
565 mi Ridden

$4,500 Raised

2024
534 mi Ridden

$4,240 Raised

2025
Ridden

$825 Raised

2026

3,144 mi

Ridden

$21,603

Raised

My Challenge

26.8 mi ride - Random South of town - Sunday, August 23, 2026

Logged this ride 2 days ago
$500 raised to fight kids' cancer!

I just raised $500 to fight kids' cancer and achieved GUARDIAN LEVEL in the challenge! Thank you so much for your support.

Posted 4 days ago
$250 raised to fight kids' cancer!

I just raised $250 to fight kids' cancer and achieved PROTECTOR LEVEL in the challenge! Thank you so much for your support.

Posted 9 days ago
$100 raised to fight kids' cancer!

I just raised $100 to fight kids' cancer and achieved DEFENDER LEVEL in the challenge! Thank you so much for your support.

Posted 35 days ago

My Sponsors

Christopher Flanagan
$103.50
Received this donation 14 days ago

John

“Chris, Thank you for your support. I’m gearing up for next month’s Ride. Been riding when the heat relents. A few mornings and evenings. My legs are good ,it’s the smoke that’s reduced my normal ride levels this Spring/Summer. I’m coming to Junction Monday afternoon, August 24th. Oral surgeon follow up visit Tuesday am. I would like to get together. Dinner Monday? Brunch Tuesday? Lemme know”

Chris, Thank you for your support. I’m gearing up for next month’s Ride. Been riding when the heat relents. A few mornings and evenings. My legs are good ,it’s the smoke that’s reduced my normal ride levels this Spring/Summer. I’m coming to Junction Monday afternoon, August 24th. Oral surgeon follow up visit Tuesday am. I would like to get together. Dinner Monday? Brunch Tuesday? Lemme know
Greg Krallman

“Go gettem Zac , I think it’s awesome that you do this every fall .”
$103.50
Received this donation 2 days ago

John

“Thank you, Greg! You know the value of support that we can give each other. Whether you’re on the giving or the receiving end of it, it’s vital that we continue to help each other out. These little children fighting their cancers need all the support, help and love that we can give them. Research is critical. Please share my ride at https://greatcyclechallenge.com/Riders/JohnBrennan”

Thank you, Greg! You know the value of support that we can give each other. Whether you’re on the giving or the receiving end of it, it’s vital that we continue to help each other out. These little children fighting their cancers need all the support, help and love that we can give them. Research is critical. Please share my ride at https://greatcyclechallenge.com/Riders/JohnBrennan
Lura Briscoe

“Way to go Zach! Thank you for being there for Jeff! Lots of love and big hearts! Lura”
$103.50
Received this donation 3 days ago

John

“Lura, Thank you so very much! This Cycle Challenge is fun for me, except when it’s hot!! The small amount of suffering I feel from the heat is nothing compared to what these little children go through with their cancer treatments. Please share my ride with your family and friends. ☮️❤️❤️ I miss Jeff.”

Lura, Thank you so very much! This Cycle Challenge is fun for me, except when it’s hot!! The small amount of suffering I feel from the heat is nothing compared to what these little children go through with their cancer treatments. Please share my ride with your family and friends. ☮️❤️❤️ I miss Jeff.
Mike & Cindy Ruzicka

“Thanks for doing this, Zac!”
$103.50
Received this donation 5 days ago

John

“Mike&Cindy, thank you for your support. The kids and their families also thank you. The monies we raise support children’s cancer research. We need to keep the scientists working. We need to eliminate all cancers, especially children’s cancers!”

Mike&Cindy, thank you for your support. The kids and their families also thank you. The monies we raise support children’s cancer research. We need to keep the scientists working. We need to eliminate all cancers, especially children’s cancers!
Rob Dilldine

“Zac, I'm very proud of you. Peddle on my Friend!”
$103.50
Received this donation 4 days ago

John

“Hey Rob, thanks for your kind support. These children need all the help we can give them to fight these terrible cancers. The researchers need funding, and this is where we come in. I’m gonna go for a ride shortly. Take care buddy.☮️❤️”

Hey Rob, thanks for your kind support. These children need all the help we can give them to fight these terrible cancers. The researchers need funding, and this is where we come in. I’m gonna go for a ride shortly. Take care buddy.☮️❤️
Tom Schreiber

“Tom, Thank you for your kind donation. The heat has broken and I’m pumped to ride and raise bucks for the kids. My miles don’t officially count until September 1st. Then my initial goal is 200 mil for a start. Typically it ends up over 500 miles. This is my 7th year of participating. I’m stoked!!”
$100
Received this donation 9 days ago

John
Christy Browning
$51.75
Received this donation 3 days ago

John

“Thank you very much, Christy! You and I depend upon each other. These children struck by cancer certainly depend on all of us. Research funds are a critical component of our lives. If Washington won’t do it; then it is simply up to us to take care of these children ☮️❤️”

Thank you very much, Christy! You and I depend upon each other. These children struck by cancer certainly depend on all of us. Research funds are a critical component of our lives. If Washington won’t do it; then it is simply up to us to take care of these children ☮️❤️
Mike Fitzpatrick

“Go Zac”
$51.75
Received this donation 5 days ago

John

“Thank you Mike! You make a difference! I appreciate your ongoing support buddy!”

Thank you Mike! You make a difference! I appreciate your ongoing support buddy!
John 'Zac' Brennan

“Time to kick off my fundraising efforts! I’m down for $100 to get things started.”
$103.50
Received this donation 35 days ago

John