Already love your acoustic bike but crave that electric boost? A conversion kit turns almost any bicycle into an e-bike for a fraction of the cost of a new ride—if you choose a kit that’s legal where you ride. This guide shows you exactly where to buy compliant e-bike conversion kits in 2025, what certifications to look for, and how to avoid expensive regulatory missteps.

What Makes an E-Bike Conversion Kit “Legal”?

U.S. Requirements

1. Motor power ≤ 750 W (federal Consumer Product Safety Commission definition).

2. Top assisted speed ≤ 20 mph (Class 1 & 2) or ≤ 28 mph with pedal assist only (Class 3).

3. UL 2849 certification for the complete electrical system—many retailers now advertise this clearly.

4. Operable pedals must remain on the bike.

Trunk Rack Laws for Transporting Your E-Bike

EU & UK Requirements

• Motor ≤ 250 W and pedal-assist cut-off at 25 km/h.

• EN 15194 compliance label.

• Throttles above 6 km/h typically illegal without registration.

Pro tip: Always check local state or provincial rules—New York City, for example, enforces a strict 20 mph limit even on Class 3 kits.

Top Places to Buy Legal E-Bike Conversion Kits

1. Grin Technologies (ebikes.ca) – Vancouver, Canada

• Why they’re trusted: Publish independent dyno tests and only sell UL-compliant batteries.

• Best for: Tech-savvy riders who want modular options (hub, mid-drive, or the well-known All-Axle hub).

• Shipping: Worldwide; U.S. orders clear customs with pre-paid duties.

2. BafangUSA Direct – Monrovia, California

• What you’ll find: Full BBS mid-drive kits (250 W, 500 W, 750 W) all with U.S.-legal firmware.

• Why buy here: Domestic warranty support and UL-listed batteries assembled in California.

3. Swytch – London, UK (Ships Worldwide)

• Highlight: Featherweight 250 W front-hub kit that snaps on/off with a quick-release power pack.

• Compliance: Certified to EN 15194 (EU) and CPSC wattage limits for U.S. customers.

• Caveat: Pre-order model—lead times can stretch to 8–12 weeks.

4. Ebikeling – Illinois, USA

• Products: Budget-friendly hub-motor kits (350 W–750 W) with or without batteries.

• Certification: Recently added UL 2849 batteries; verify listing number before you buy.

• Ideal for: DIYers upgrading older commuters.

5. Luna Cycle – El Segundo, California

• Focus: Enthusiast-grade BBSHD (1 000 W) and BBS02 (750 W) kits.

• Legality tip: The 1 000 W option is off-road-only in many states; opt for the 750 W BBS02 to stay street-legal.

• Perk: In-house battery spot-welding and optional UL-listing.

Buying on Amazon or eBay: Safe or Sketchy?

Marketplace listings can save a few dollars but often skip safety certifications. Before clicking “Buy Now”:

1. Search the UL database for the battery’s file number.

2. Read wattage carefully—many listings hide a 1 000 W motor under “48 V” wording.

3. Check return policy; some sellers ship from overseas with no practical warranty.

If the ad copy looks vague (“high-speed motor,” no mention of wattage or UL), keep scrolling.

Mid-Drive vs. Hub-Drive Kits: Which Is Easier to Keep Legal?

Mid-drives can push speeds beyond Class 3 if you fit a large chainring, so choose gearing wisely.

How to Verify a Kit’s Compliance Before Purchase

1. Locate the motor sticker or spec sheet—ensure ≤ 750 W (U.S.) or ≤ 250 W (EU).

2. Confirm UL 2849 or EN 15194 listing for the entire system, not just the cells.

3. Ask the retailer for a controller programming screenshot showing speed limit settings.

4. Read rider forums (ES, Reddit r/ebikes) for real-world police encounters.

Tips for Smooth Installation & Registration (Where Required)

• Keep photos of the build—handy proof if authorities question your setup.

• Label visible wiring with heat-shrink tags noting voltage and fuse ratings.

• If local DMV requires inspection, print the kit’s compliance certificate and bring the box.

Key Takeaways

• Stick with reputable retailers that advertise UL or EN certification.

• 750 W/20–28 mph is the legal ceiling for U.S. streets; 250 W/25 km/h in most of Europe.

• Verify specs before buying—marketplace deals without paperwork can void insurance or lead to fines.

• Choose the kit (hub vs. mid) that meets both your terrain needs and local laws to ride worry-free.

Frequently Asked Questions

Q: What’s the safest motor power to stay street-legal in the U.S.?
A: A 500 W or 750 W kit with a 20 mph (Class 2) or 28 mph (Class 3) cap keeps you compliant in all 50 states.*

Q: Do I need to register my converted e-bike?
A: Most states treat compliant e-bikes like bicycles—no registration. Hawaii, Alaska, and some EU countries may require a simple permit.*

Q: Are throttle-only kits legal?
A: Yes, if limited to 20 mph and 750 W (Class 2). Pedal-assist-only kits can go up to 28 mph (Class 3).*

Q: Can I install a kit myself without voiding my bike’s warranty?
A: Check with the bike brand—many void frame warranties if you add a motor. Steel or chromoly frames handle conversion stress best.*

Q: How long does a conversion take for a beginner?
A: Hub-drive kits: about 2 hours with basic tools. Mid-drives: 3–4 hours and a bottom-bracket tool set.*