John 'Zac' Brennan

7years All Star
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!
I've Ridden 219.5 mi My goal is 500 mi
My Rankings
  • National: 315th
  • State: 8th in CO
  • My Team: 6th
I've raised $3,102 My goal is $4,000 Donate Now

I'm Riding For

Kahleesi

Kahleesi

Kahleesi ride your cool bike! Have fun❤️

My Story

3 Sep 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 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
  • 220 mi Ridden
    $3,102 Raised
    2026
7years
3,363 mi
Ridden
$23,880
Raised

My Challenge

  • 20.4 mi ride - Into the sunset - Wednesday, September 16, 2026
    Logged this ride 7 hours ago
  • 25.3 mi ride - Bartholomew Lane - Monday, September 14, 2026
    Logged this ride 1 day ago
  • Saturday, September 12 ride
    13 Sep 2026

    27 mile loop from our campsite through area mountains. Windy! Elevation gain of 2,041 feet. Scenic.

    Saturday, September 12 ride
    Posted 4 days ago
  • 27.0 mi ride - Clark loop - Saturday, September 12, 2026
    Logged this ride 4 days ago
  • 19.6 mi ride - Columbine - Friday, September 11, 2026
    Logged this ride 4 days ago
  • 27.2 mi ride - Bartholomew lane+ - Thursday, September 10, 2026
    Logged this ride 4 days ago
  • 5.0 mi ride - Flat tire - Thursday, September 3, 2026
    Logged this ride 4 days ago
  • $2,500 raised to fight kids' cancer!

    I just raised $2,500 to fight kids' cancer and achieved SUPERHERO LEVEL in the challenge! Thank you so much for your support.

    Posted 6 days ago
  • 33.0 mi ride - Home-Mt. Harris Canyon -Downtown Steamboat Springs-Home - Thursday, September 3, 2026
    Logged this ride 13 days ago
  • 20.0 mi ride - Twilight Time - Wednesday, September 2, 2026
    Logged this ride 14 days ago

My Sponsors

  • Kick Cancer's Butt Day matched donation
    “Here's your matched donation from a group of wonderful Children's Cancer Research Fund supporters. THANK YOU so much for your awesome efforts to kick cancer's butt!”
    $450.02
    Received this donation 7 days ago
    John 'Zac' Brennan
    John
    “Thank you.”
  • Pat O’Leary
    “Cancer Sucks! Thanks for riding to support the Children’s Cancer Research Fund. ♥️”
    $207
    Received this donation 2 days ago
    John 'Zac' Brennan
    John
    “Thank you Little Dear☮️❤️”
  • Christopher Flanagan
    $103.50
    Received this donation 37 days ago
    John 'Zac' Brennan
    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 Please share my link with friends and family!”
  • Donald Carluccio
    $103.50
    Received this donation 8 days ago
    John 'Zac' Brennan
    John
    “Thank you Judy and Don☮️❤️”
  • Anonymous
    $103.50
    Received this donation 7 days ago
    John 'Zac' Brennan
    John
    “Thank you ☮️❤️”
  • Greg Krallman
    “Go gettem Zac , I think it’s awesome that you do this every fall .”
    $103.50
    Received this donation 25 days ago
    John 'Zac' Brennan
    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”
  • Jeff and Gloria Halliday
    “Thank you, Zac, for taking on such a critical problem. Your annual commitment to fight cancer goes a long way to putting an end to a terrible threat. Bravo!”
    $103.50
    Received this donation 10 hours ago
  • Joe Huselton
    “Come out of your driveway slower”
    $103.50
    Received this donation 7 days ago
    John 'Zac' Brennan
    John
    “I’m making up for lost time. Thank you Joe for your generous support!! Zac”
  • 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 26 days ago
    John 'Zac' Brennan
    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.”
  • Mike & Cindy Ruzicka
    “Thanks for doing this, Zac!”
    $103.50
    Received this donation 27 days ago
    John 'Zac' Brennan
    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! Please share my link with friends and family! ☮️❤️”
  • Rob Dilldine
    “Zac, I'm very proud of you. Peddle on my Friend!”
    $103.50
    Received this donation 27 days ago
    John 'Zac' Brennan
    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.☮️❤️ Please share my link with friends and family!”
  • Rob Wilmoth
    “Atta Boy Zac! Thanks for your efforts. Rob”
    $103.50
    Received this donation 8 days ago
    John 'Zac' Brennan
    John
    “Thank you Rob☮️❤️”
  • TBH Plumbing & Heating
    “How about delivering some material while you're out on your rides? That burn some miles! 😂😂”
    $103.50
    Received this donation 6 days ago
    John 'Zac' Brennan
    John
    “Thank you Tucker for your generous donation. AND the job offer. Unfortunately you can’t afford me😎”
  • TIMOTHY ANDERSON
    “Keep peddling you beast. Thx for fighting kids cancer.”
    $103.50
    Received this donation 16 hours ago
    John 'Zac' Brennan
    John
    “Tim and Laura, thank you for your help. The boundary waters are forming up at Pearl Lake. But you know, we need the rain. It makes it difficult to get motivated to go ride. But I shall endeavor to persevere.”
  • Tom Raushenbush
    “Make it happen Zac. Enjoyed fishing with you!”
    $103.50
    Received this donation 7 days ago
    John 'Zac' Brennan
    John
    “Thank you Tom. I’m out on a ride now. It’s a beautiful day in the neighborhood.☮️❤️”
  • Wayne and Lisa Adamo
    $103.50
    Received this donation 8 days ago
    John 'Zac' Brennan
    John
    “Thank you Wayne and Lisa☮️❤️”
  • Zachary Schaefer
    $103.50
    Received this donation 1 day ago
    John 'Zac' Brennan
    John
    “Thank you Zach for your support. We’re camping up at Pearl Lake north of town. For 2 weeks total. Part of which (2.5 days) I was attending a men’s cancer retreat 4 hours away. No riding while there. Now I’m playing catch up. Between thunderstorms and heavy winds, it will be a challenge to hit my 500+ mile goal. I’m confident that will be reached.”
  • Facebook Fundraiser Donation
    $103
    Received this donation 17 days ago
    John 'Zac' Brennan
    John
    “Thank you for your help! Please share my link with friends and family.”
  • 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 32 days ago
    John 'Zac' Brennan
    John
    “Thank you Dr. Tom! Please share my link with friends and family!”
  • Alison Carroll
    “Proud of you for keeping this up! Love you and sending hugs from Southern California!”
    $51.75
    Received this donation 16 days ago
    John 'Zac' Brennan
    John
    “Thank you Alison! I’m going out for a ride shortly. Please share my link with your friends and family! ☮️❤️”
Donate Now