California man buys $2,000 motor to stick on $20 bike so he could see what happens
Published on Aug 02, 2025 at 9:05 PM (UTC+4)
by Molly Davidson
Last updated on Jul 31, 2025 at 1:52 PM (UTC+4)
Edited by
Tom Wood
A DIY e-bike experiment started with a $20 BMX and ended with pure street chaos.
Sur Ronster scored the bargain-bin bike on Facebook Marketplace – a wobbly relic with one brake, a chain, and tires that sort of held air.
Then he bolted on a $2,000 CYC X1 Pro Gen 4 mid-drive motor and paired it with a hulking A65 battery, just to see if the universe would allow such madness.
Spoiler: it worked… kind of. The results were equal parts genius and disaster.
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The $2,000 motor vs. the $20 bike
YouTuber Sur Ronster’s experiment started with a junk BMX and the most powerful e-bike mid-drive kit you can buy – 6,000 watts of illegal fun.
That’s roughly eight times the legal street limit and about the same punch as a small dirt bike.
The DIY e-bike build wasn’t plug-and-play.
BMX bottom brackets don’t fit standard kits, so he rolled over to Tim at Mayhem Racing, who custom-cut steel spacers and welded everything into place.
A new chain, some tension tweaks, and a janky-but-functional wiring job later, the Franken-bike was alive.
When he finally hit the throttle, the BMX launched like a rocket… and immediately reminded him that $20 brakes don’t stop 6,000 watts of bad idea.
He skidded, smoked, and eventually hurt his ankle in the process – all while cackling through the sketchiest ride of his life.
The end result?
Possibly the fastest $20 bike ever built, now packing more power than most entry-level e-motorcycles.
Not one DIY e-bike, but two
Of course, one bike wasn’t enough.
After nearly breaking himself (and the BMX), Sur Ronster stepped up to a Throne Dime pedal bike – finally giving the monster motor a frame that could almost handle it.
This time he went full send, hitting 35-40mph and joining a city ride-out like it was nothing.
He swapped throttles mid-build, dodged a couple of wipeouts, and kept pushing the kit to its absolute limit.
But the soul of the chaos was still that $20 BMX – the wobbly little frame that somehow survived 6,000 watts of pure chaos
And if bikes could talk, that one would probably beg for early retirement.
Subscribe to Sur Ronster’s YouTube channel for more DIY content, or watch the video below:
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Molly Davidson is a Junior Content Writer at Supercar Blondie. Based in Melbourne, she holds a double Bachelor’s degree in Arts/Law from Swinburne University and a Master’s of Writing and Publishing from RMIT. Molly has contributed to a range of magazines and journals, developing a strong interest in lifestyle and car news content. When she’s not writing, she’s spending quality time with her rescue English staffy, Boof.
