The Slingshot — Flex-Frame Mountain Bike

For sale is my personal 1997 Slingshot, one of the strangest production mountain bikes ever made. It has no down tube. Where the frame’s strongest tube should be, there’s a steel cable, a coil spring, and a flexing composite link, and the whole front end actually moves. It looks like it shouldn’t work. Then you ride it, and it’s the smoothest ’90s mountain bike you’ve ever felt.

In its day this was genuinely high-end, built for cross-country racing. It’s the actual red Slingshot from the videos. I pulled it out of my attic, brought it all the way back, and got it dialed. Now it’s looking for a new rider.

Wait, a cable and a spring?

Yep. In the early 1980s, a Michigan inventor named Mark Groendal cracked the down tube on a mini-bike and noticed it rode better over the bumps. So he built a bicycle around the idea. Ditch the rigid down tube, run a stainless-steel cable under tension, add a coil spring and a flexing composite “flex board,” and let the whole front triangle move. Slingshot called it “The Flexible Bicycle.” Back then, this was suspension, and it worked. The slogan said it best: “Don’t knock it till you’ve tried it.”

(Quick timeline, just so the record’s straight: the design dates to the early ’80s. This particular bike is a 1997 build, right around 30 years old now.)

Where the down tube should be: a steel cable, under tension, doing the job.

The part that doesn’t exist anymore

Here’s the catch, and it’s the whole reason you almost never see a Slingshot in rideable condition. The piece that holds the front of the bike to the back is a “dog bone link,” a flat plate of G10 Garolite, a fiberglass composite engineered to flex. Over millions of flexes and a few decades, those original links fatigue and turn brittle, and you can’t buy a new one anymore. That’s exactly why this bike sat in my attic for years.

So I made one. I fought the original out of the frame, reverse-engineered it, and had a new link machined from the correct G10 Garolite, in the exact original shape. It’s serviceable, not epoxied in like the old race bikes, and the steel cable beside it caps how far the frame can flex, so there’s no chance of it letting go on the trail. Better still, it ships with a spare machined link, plus the 3D-printed prototypes and the original link as labeled souvenirs. You’ll never be grounded by the one part that grounds every other Slingshot.

That’s what makes this the ultimate collector Slingshot. It’s not a wall-hanger. It’s genuinely, safely rideable, arguably more trustworthy now than the day it left the factory.

It ships with a spare machined link, plus the prototypes and the original as labeled souvenirs.

This exact bike

It came to me remarkably original and clean, and I’ve since gone right through it. The elastomer fork is fully serviced and plush, it wears new brake pads, and the worn pads and the missing self-extracting crank cap have been sorted. Expect honest cosmetic scratches, since it’s a 30-year-old bike that gets ridden, but it rolls, shifts, stops, and flexes exactly as it should. Full specs, measurements, and what’s in the box are in the Specifications and What’s Included tabs below.

Cleaned up, fully serviced, and ready for someone who’ll actually ride it.

On the trail it’s the smoothest ’90s mountain bike I’ve ridden. The serviced fork is plush, it climbs beautifully with barely any pedal bob, and the flex frame does this magic thing where it just takes the edge off everything. It’s only 25 pounds. It rips. That’s the whole point.

Why it’s for sale

I build and resurrect a lot of bikes for videos, and I can’t keep them all. I’ve simply run out of room. So a few are heading to new homes through Berm Peak Bikes, and whatever they bring goes straight back into more dumb, fun projects. I’m not in this to make money on a bicycle. I just want it ridden by someone who’ll appreciate it, so it’ll leave here personally packed by me.

And if you’re not buying, thanks for geeking out over a 30-year-old bike held together with a cable, a spring, and a fiberglass dog bone. That’s exactly the kind of weird I’m here for. Don’t knock it till you’ve tried it.