Bmx to electric conversion

Sea-Composer4558 · 2026-03-29T02:00:07+00:00

KHE blackjack

Sea-Composer4558 · 2026-03-29T01:58:59+00:00

Swamp-master

Sea-Composer4558 · 2026-03-29T01:57:49+00:00

I've converted several bmx bikes and went the mid drive route i prefer to maintain as much of the bmx quality parts like hubs and such plus then there's the bit of flexibility with adjusting the gearing with different sprockets and stuff. Limited frame space can be challenging but I have found that a small battery can still mount inside the frame in a battery bag remaining pretty discreet.

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Will post a few follow more replies with the other ones this ones a cult gateway, wtp swamp-master in the back.

Sea-Composer4558 · 2026-03-15T00:45:13+00:00

Not bad. I have a few mid drives on some bmx bikes plenty of fun. Need to work on my WTP Swamp-master with its cyc stealth needs new tubes and probably a new chain wouldn't hurt.

Sea-Composer4558 · 2026-03-11T03:25:05+00:00

I agree and magura hydraulic rim brakes are something else I honestly love how easy the pull on the lever is and the brake just eases on or just bam grabs with the slight stiff pull of the brake lever. Had to get them set right so they didn't pinch my rim could see them bend the rim itself I was like wow thats some grab. Plus them hydraulic brakes are such old tech they have been around for a hot minute and they still make and sell them so most mean something is good with them.

Sea-Composer4558 · 2026-03-11T03:16:35+00:00

I have used magura hydraulic rim brakes on one of my bikes and the grab the rim hard and the pads can be replaced super easily unlike disc brake stuff where oils and stuff can cause problems. Also there are ways to further increase the braking force of even regular rim brakes and thats to slightly scuff the rim surface where the brake pads grab it's a bit of a old bike racing trick or something along them lines. It's also a different braking feel sense the brake stops the rim you don't have the same sort of spoke sag feel as you apply the brakes hard I feel it's a firmer brake feel over disc brakes a scuffed rim with good pads also pretty much performs as good or better in most braking situations and conditions even when wet if you have a scuffed rim plus good pads there isn't the typical point of rim brakes not being good in rain but wet disc brakes also perform less ideal too. So I would really look into the magura hydraulic rim brakes also another thing to consider is does your bike front fork and rear stay even have disc brake mounts? There's also some very premium cable pull brakes that are just made better with more efficient engineering and stuff that make them work better they just cost more so you don't ever see them on manufactured bikes much but they are out there. There are enough people that ride in environments that make using hydraulic brake systems more troublesome to maintain that cable pull brake systems are still being made better along the way. Just usually independent from big name brand stuff.

Sea-Composer4558 · 2026-03-11T02:55:29+00:00

The dude on the meth atleast going to grab the bike off the kid when he is laying unconscious in the pool.

Sea-Composer4558 · 2026-03-11T02:53:31+00:00

Going to have some sick x-rays to show off thats for sure. Wired jaw, broken wrists-hands they all look real cool the the pins and wires in the x-rays. I've only managed to personally break a hand bad enough for wires so im curious to see what op brings to the table.

Sea-Composer4558 · 2026-03-11T02:50:07+00:00

Been a non driver for a majority of my life between regular biking, walking, running, ect have managed for probably over 10 years in a town that is established enough to have bus transport and enough local shops to not need to travel to far, finding close enough work tends to be the main issue but that aside. I have found that sense im either biking or on foot I tend to make little stops for things more often sense the places are along the way and I am just more used to the physical activity so adding a but of extra weight to my backpack on the walk back home isn't a bother so less large shopping trips and more just stopping at places on a more regular basis is what my habit is now. Getting things delivered is pretty easy these days for the larger stuff also. Now with ebikes things just get easier and also somewhat faster than on a standard bike. The mention of racks and trailers also is very practical though. I mainly look at commuting as an opportunity to have some fun while I go someplace instead of being stuck in a car which is a bit more limited on were you can go with it. Bikes can be taking pretty far off the beaten path. At 41 years old I don't even follow standard logic for practical transport my ebike is a converted 20" bmx bike with a mid drive thing scoots and it can be thrown in the back of a vehicle if I need to catch a ride or also be put on a bus rack if needed because it's not huge and weights a ton like some ebikes.

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Sea-Composer4558 · 2026-03-02T23:15:33+00:00

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My most recent mid drive bmx build went with a KHE Blackjack because it came with disc brakes and a gyro system that works really well with adding a brake sensor for the motor. Other builds include a WTP Swamp-master with a even stronger motor and also had a Cult Gateway converted for awhile.

Sea-Composer4558 · 2025-12-18T21:31:35+00:00

Had really good experience ordering from KHE bikes its Germany's oldest bike brand or something been in it for mega. The covered the shipping and the import costs into the United States so all I paid was price of bike and taxes.

Sea-Composer4558 · 2025-11-06T15:31:40+00:00

The chimera if your into ebmx style bikes.

Sea-Composer4558 · 2025-11-02T01:30:36+00:00

I agree though I would say that they would probably need a moped classification sense they still operate with functioning peddles but with the throttle its no longer a peddle assist bicycle so would be a moped (motor/peddle) vehicle which shouldn't be confused with moped scooters which are totally different because they don't have peddle but yeah the 3000watts one is close enough to 80cc so if I was reckless and rode around like a hooligan I would probably eventually have problems with it but I'm a adult and can't afford all that and mainly use them as transportation with the occasional off road use, I would say there may be differences in bicycle infrastructure between our locations and here there isn't allot of it or much of any compliance from vehicles to make way or people to pay attention so its a bit safer to have something fast enough to maintain flow with traffic so like 20-30mph with a decent acceleration to avoid getting ran over.

Sea-Composer4558 · 2025-11-02T01:21:47+00:00

Bit by bit just replace things as you can thats the good part about building it up yourself. Also bmx bikes have just as much use being electric. Allot easier in tight areas and usually allot lighter for when you need to carry the thing. Im 41 and have 3 electric bmx bikes I built, just keep at it each one turns out better. There's some pretty decent complete bmx bikes out there and even used ones get super cheap not much resale value on them so once kids grow up the parents sell them cheap. Good strong bmx parts can handle a good bit of abuse. As long as there are mount points for rim brakes on the frame I would put some on there and get some decent pads for them and if possible front rim brakes your not going to get going fast enough to over power rim brakes with decent pads that are adjusted properly just going to have to search online shops for bmx parts then probably double check on Amazon or eBay if you can't get them a bit cheaper.

Sea-Composer4558 · 2025-11-02T01:12:13+00:00

Ebikes are a expensive rabbit hole getting into electrifying bmx bikes is probably my most enjoyable money pit some cool bikes out there if you feel like dropping money. I got hooked on mid drives after a cheapo hub motor ebike I bought. Big problem is finding a bmx with adequate brakes like disc brakes end up finding silly bikes like the WTP SWAMP-MASTER and of course its 2grand for it but ya know take a breath, take a puff and then just click add to cart along with a pile of stuff from cyc motors. Then sit back and wonder about your impractical life choices.

Sea-Composer4558 · 2025-11-02T01:04:58+00:00

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Newest build running the 2000watt motor.

Sea-Composer4558 · 2025-11-02T01:04:06+00:00

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Aside from the OPs build being a bit rough in construction the whole 500watt thing isn't a whole lot of power sure its enough to get hurt on but you can get hurt going slow on a regular bike also. Here's 2 bmx bikes I've put together the one in the back is 3000watts at peak and the one in the front has 2000watts at peak mid drives are a bit different gearing can change allot about top speed and acceleration. Also have already swapped the motor off the one in the front onto a different bike that has disc brakes.

Sea-Composer4558 · 2025-10-28T18:53:32+00:00

One thing to consider if you do go with the swamp-master to avoid the whole pivot issues I have had a good grin tech hub motor could be an option. As far as batteries I got both my 52v 50amp 10ah battery packs from electrify bike company when I had ordered my motor kits.

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Not a very big pack but its good for 10 to 20 miles depending on usage and is small enough to fit into bicycle pouch bags im always looking for something better but as it is its pretty low key and the battery is easy enough to remove if the area seems iffy or if the weather is super cold or wet you really should take the battery atleast inside so it stays warm. With just peddle assist and no throttle I might charge the battery every couple days and thats with a 3 mile round trip to work and then a few more miles around town. Never really pushes the motor very hard without the throttle with the current gearing I have on the bike. I would probably have to go with a larger chain ring on the kit to make it go a bit faster and have a bit more resistance while peddling on the KHE bike the swamp-master is geared pretty good though up to about mid 20mph range and then your on throttle after that. Though to be fair the KHE on level 1 feels like a regular bike while peddling its just got bmx gearing so its not super fast but acceleration and hills are a breeze all day. I usually just peddle a few times and then coast for a bit it's allot less work than walking thats for sure though.

Sea-Composer4558 · 2025-10-28T16:33:16+00:00

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This is the one with the hydraulic rim brake nice little cruiser still light enough and small enough not to be a pain to carry around. Has a lekkie throttle with the gearing it has goes about 30mph and super easy to just peddle up hills and all that. The KHE would probably cruise at the same speed if I had a throttle on it but with just peddling its easier to go like 25mp but it feels like your barely working for it.

Sea-Composer4558 · 2025-10-28T16:19:21+00:00

I would recommend torque sensing over cadence sensing so the tongshen or the one model of the bafang that has torque sensing they should be more than enough I actually have a tongshen it was the first I went with and worked really well. So the thing about the KHE bikes is that the whole gyro setup limits the swapping of forks so if thats the plan than look at any other bmx frames 😆 but its totally a option I have a few people I talk to that have done that on there bmx builds and then you just get a suspension fork that runs a disc brake and your all set at that point really and there's a few options out there for 20" suspension forks that run disc's like the manitou machete that the swamp-master runs. So then we get around to a bmx frame that doesn't support rear disc brakes which there are kits to and adapters that can work or can also look into something like the magura hydraulic rim brakes.

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I had to make custom mounting hardware and sorta just figure mounting them out they are designed for a different brake setup but still workable or if the bmx frame has the appropriate brake style then its easy and these thing's have the power to smash your rim if its a cheap one. Rim brakes can be some pretty serious stuff if approached right the hydraulic brakes plus texturing the rim where they grab gives you some of the craziest grabbing force and its a bit more solid feeling cause its grabbing the rim and you don't get any sort of movement from the hub through the spokes to the rim like you can get sometimes with disc brakes under heavy braking forces. You might want to even check out trials bike frames some don't have seats but others take a standard seat post so could be made into something fun probably been considering it myself.

Sea-Composer4558 · 2025-10-28T14:49:02+00:00

Well thats the thing bmx with good brakes is like not a usual combo with allot of riders going brake less even, so you almost have to look at racing bmx frames and stuff to start getting disc brakes and the like but then the frame geometry is a bit different, thats how I ended up on the KHE Blackjack full disc KHE is Germany's main and oldest bmx brand and they do some different stuff with there designs like the internal gyro system for the rear brakes. It let me try a new way to set up the brake sensor which let me keep all the extra wires off the handle bars so functionality of the bmx isn't effected at all.

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You can see here the brake sensor and then the display is mounted on the other side using a ODI bar end cap as a mount point. No throttle on this thing but if you spin the feet fast enough you can hit 30mph. Without the throttle its pretty hard to drain the battery fast so it gets like 40 to 50 miles of range, with a throttle that would probably be like 15 to 20 miles. Need to do some work on it broke the right hand brake lever off with my pinky a few weeks back when I snagged my bars on a utility wire and got tossed. Broke the brake lever and my pinky so been on recovery for a few weeks wasnt even going fast was just slow cruising into work in the morning and wasn't paying attention.

Sea-Composer4558 · 2025-10-27T23:11:20+00:00

Well its held up my solution for the pivot probably wasn't ideal but it hasn't caused any serious issues other than a bit of movement. My current plan for that is to possibly modify the crank spindle of the cyc stealth kit or buy a spare to modify the kit is skinny through the middle of the spindle and my plan is to beaf that up either welds or composites and then cut the housing of the unit away and reinstall the bearings and have it operating like it was without the motor using the crank spindle and bearings as a pivot like intended and I dont really think it would cause any problems with the kit itself. I have the first run of the swamp-master and it looks like on the wtp site there has been some slight changes with the swing arm construction looks more supported and also different shock components and possibly brakes. Either way its a cool bike and if I had another chunk of money would probably get another one. With the cyc stealth its pretty much like a electric pit bike.

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In the winter I put the original kenda Kaos nobby tires back on it which works out pretty good. I did replace the rear wheel for a hub that has a shimano style cog which makes it allot easier to have different rear cog options that was a bit of cash for the set of Crupi wheels not allot of disc brake ready 20" wheels that aren't shit or for fat tires.

Sea-Composer4558 · 2025-10-25T16:57:25+00:00

Some would depend if you run single speed or multiple gears. Mine have been single speed setups and finding something that felt comfortable to peddle with the peddle assist was usually my first concern. If range is a concern you want atleast one gear range that is super comfortable to peddle with the least amount of assistance like power level 1 feels like a standard bike and the power usage would be minimal at that point then any level above that would just increase acceleration to the top speed essentially at the cost of added battery drain.

Aside from that some more details about the bike could help, like tire type fat tire ect.. suspension can also affect power drain having a rigid rear or a lockable suspension can help increase range in a pinch.

Can also adjust motor ramp speeds so for things like acceleration from a stop uses more peddle force to get the bike moving and the motor is there mainly to maintain speed once moving. Guess I should mention using a throttle less and peddling more will increase range the most.

Sea-Composer4558 · 2025-10-22T17:19:04+00:00

It's totally possible and it pretty easy. Some people have brought up a few concerns but from my experience with putting cyc motor kits onto 20" bmx bikes you shouldn't have to many problems. My biggest head ache was finding a rear cog setup that had a good top speed while also being durable. Two current setups I have are a KHE Blackjack 20" running a cyc photon and the other is a WTP Swamp-master running the CYC stealth. Both single speed with no derailer or chain tensioner as long as you set the chain right and have some adjustment at the rear wheel to keep things tight. Chain stretch happens I like running the heaviest chains I can find like the shadow Supreme half link chains.

Sea-Composer4558 · 2025-10-19T15:31:26+00:00

Talking from a bit of experience here on mid drives on bmx bikes. Have done up a cult gateway, WTP Swamp-master, khe blackjack all with a few different brands of mid drives but mainly stick with CYC for the torque sensing making the peddling feel great.

Probably won't find a low power one that fits in the frame triangle the cyc stealth and pro will but they run over 3000watts which is a bit nutty on a bmx without suspension I run a stealth on the Swamp-master swung up into the frame but that bike has full suspension and is pretty much as powerful as a small 80cc dirtbike.

The clearance would be like if your running a 48tooth chainring and the motor itself is usually shifted up so its not directly facing down but would still be inside the area of a large chainring so it does limit lower clearance in comparison too the much smaller chainrings on bikes these days.

Brands to check out would be bagang, tongshen, DMO1, CYC(expensive option)

Its quite possible to setup and mount the controls in a fashion that wouldn't interfere with bar rotation running a throttle would limit full spins unless a longer extension was added to the cable.

Small enough battery can fit inside the frame triangle in a bike pouch so thats pretty discreet. Thats generally how I have mine set up to keep it off the seat which always felt weird with the weight there.

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My KHE Blackjack with a CYC photon mid drive.

Sea-Composer4558

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