To Buy or to Rebuild and Upgrade

The price of kids' bikes is not getting any cheaper, if you don't know where to look 😉 A lot of Bikedads and Bikemoms are looking through buy-sell pages and Facebook marketplace to try to save on their kiddo's next size of bike. 

One very popular bike to upgrade is one of the Old Specialized Hotrocks. Fellow BikeDad fan and guest contributor was Luis Ramirez. Below are some tricks and tips if you have decided to go the used route and upgrade a bike for your little shredder.

Words and Pictures by Luis Ramirez

One dad, one kid, zero experience—and one awesome little mountain bike. About 14 months ago, my son pulled me—full send—into mountain biking. At 40, I was learning to ride trails, decode bike jargon, and figure out why my derailleur wouldn’t
shift. He was leading the charge. I was just trying to keep up.

We were both total newbies. But we jumped in, hard. Somewhere along the way, we stumbled onto Seth’s Bike Hacks and the magical
concept of finding used bikes with a solid foundation, something sturdy and well-designed that you could upgrade into a whole new ride. That’s when a light bulb went off: what if, instead of dropping serious cash on a new bike, we built one together? YouTube, a few basic tools, and some weekend wrenching later—suddenly, we were mountain bike builders. Or at least pretending convincingly.

When it came time for him to move up to a 24” bike, we realized that anything lightweight and trail-worthy started at around $1,000. That wasn’t happening. So, we went the DIY route.

Specifically, the 2017 model. It's not flashy, but it's light, strong, affordable, and upgradable. If you’re a parent who wants to build a legit kids’ mountain bike without draining your bank account—or just want a cool project to tackle with your kid—this frame is where it’s at.

Why the Hotrock Rocks
1. Lightweight Aluminum Frame
Strong, trail-ready, and easy for kids to handle.

2. Disc Brake Mounts
Real stopping power for real confidence.

3. Affordable & Easy to Find
Used frames go for $50–100 on marketplaces. That leaves plenty of budget for upgrades—or sparkling waters.

4. Standard Sizing for Components
From forks to seatposts to bottom brackets, the Hotrock plays nice with standard MTB parts. You can easily upgrade or swap in better components over time.

5. Perfect Fit for Growing Riders
The 24” version is great for ages 7–11, depending on height and riding ability. It’s a bike that evolves as your kid does.

We started with a 2017 24” Specialized Hotrock (girls’ model with a lower stand over height). After stripping it down, we sanded and painted it by hand—turning it into a canvas for doodles and creativity. We named the final build Purrgil—a nod to its deep purple-and gold paint job and the space whales from Star Wars that travel through hyperspace. It's fast, wild, and one-of-a-kind... just like my kid.

Here’s what made Purrgil come alive:
 Frame: 2017 24” Specialized Hotrock (Girls’ model)
 Air Fork: Trailcraft TC30 24” w/ 80mm travel
 Brakes: Shimano Deore 6100 hydraulic
 Dropper: FOX Transfer SL 27.2 70mm Factory
 Drivetrain: Microshift Advent 9-speed
o 11-42t cassette
o RD-M6195M-B clutch derailleur
o Trail Trigger Pro shifter
 Wheels: Trek 24” oil slick
 Tires: Maxxis Minion DHF (2.4 front) / Rekon (2.2 rear)
 Weight: 25.3 lbs.

Final Thoughts: Build the Bike, Build the Bond
We didn’t know what we were doing when we started. Honestly, we still don’t know half the time. But that’s kind of the point. You don’t need to be a pro wrench or have a garage full of tools to do a build like this. Just a little time, a willingness to learn, and a shared love for two wheels.

The bike we built isn’t just trail-capable, it’s a one-of-a-kind memory machine. My son got a bike he’s proud of. I got to watch him learn, create, and fall a little more in love with the sport and, consequently, the outdoors. And yeah, I fell in love with it too. Would I do it again? Already am. I picked up a 20” Hotrock to start a build for my laughter. The obsession—and the bonding—continues.

If you’re thinking about building something special for your kid and want to talk parts, tools, or paint ideas—reach out! I’m on Instagram at @quixotear. And don’t forget to check out your local bike co-op. They’re often goldmines for used parts, friendly advice,
and hands-on help—especially for first-time builders. These bikes may not be carbon fibre dream machines, but when you build them together, they ride like something money can’t buy. Purrgil is a head turner.

By Luis Ramirez
Aspiring Bike Papi and Budget-Build Enthusiast