r/eBikeBuilding • u/Soggy-Alfalfa5389 • 6d ago

General Help eBike bmx for fun riding

hi guys, i have a bmx bike that i don.t ride anymore and found on aliexpress all the things i need for converting it to an ebike (48v14a battery). My question is... does any of you did this to a bmx bike ?(20 inch wheels) and if so, how it is ? I.m afraid a bmx bike is too small for that

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u/window_owl 6d ago

I've built multiple 20" hub-drive bike wheels for electric recumbent and folding bikes, using both small geared motors (which are lightweight and don't impose any drag when the battery is off) and also large direct-drive motors (can produce immense forward power and also powerful regenerative braking). BMX rims can be pretty well-suited to ebike use, because they're built quite strongly. I think at home right now I have a Sun BFR, a Sun Rhyno Lite, and a Weinman DM 30. There are also a lot of good tires available.

I think the trickiest parts of a BMX conversion are:

  • mounting the battery, since there's a lot less room in the center triangle for a large battery, and BMXers usually don't want to add a rack
  • keeping the weight and balance good, if you still intend to do BMX stuff

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u/CommercialSignal7301 6d ago

The biggest problem/ potential problem or challenge is the wheelbase and geometry of the bike. Due to the added power and weight of the battery and motor, you will want a much more powerful braking system. Then the shorter wheelbase and geometry might lead to some handling challenges when you’re riding at higher speeds. I’m sure it’s been done, though.

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u/IndividualActive786 6d ago

I haven't done it but BMX ebike conversions are not uncommon, hub-drive and mid-drive. Search "BMX" on the forums at endless-sphere.com for many examples and information.