BionX SL 350 Review

Bionx Sl 350 Electric Bike Conversion Kit 1
Bionx Sl 350 Surly Neck Romancer Pug
Bionx Sl 350 Surly Conversion
Xtracycle Edgerunner Bionx 350 48v Battery
Xtracycle Edgerunner Bionx 350 Display Panel
Xtracycle Edgerunner Bionx 350 Disc Brake
Bionx Sl 350 Motor Internals
Bionx Sl 350 Electric Bike Conversion Kit 1
Bionx Sl 350 Surly Neck Romancer Pug
Bionx Sl 350 Surly Conversion
Xtracycle Edgerunner Bionx 350 48v Battery
Xtracycle Edgerunner Bionx 350 Display Panel
Xtracycle Edgerunner Bionx 350 Disc Brake
Bionx Sl 350 Motor Internals


  • Top of the line kit, 350 watt motor is ~2.5 lbs lighter than the older PL 350 model, includes advanced security features
  • Available in two designs to fit most bikes: mount to down tube or integrated into a rear carry rack
  • Increased torque output with 48 volt XL battery, the strongest BionX makes
  • Versatile drive system offers throttle mode, pedal assist or regen mode in addition to regenerative braking

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Video Review

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SL 350


$1,999 USD

Suggested Use:

Neighborhood, Commuting, Urban

Electric Bike Class:

Throttle on Demand (Class 2)
Learn more about Ebike classes


2 Year Covering Manufacturer Defects (1,000 Charge Cycles)


United States, Canada

Model Year:


Bicycle Details

Total Weight:

16.1 lbs (7.3 kg) (Optional Rear Rack Configuration 18.9 lbs)

Motor Weight:

9.5 lbs (4.3 kg)

Wheel Sizes:

20 in (50.8cm)26 in (66.04cm)28 in (71.12cm)


Optional Black or Silver Rim and Spokes, Battery Comes in Mid-Frame or Rear-Rack Configuration, Rear-Rack Battery Has an Integrated LED Light, System Locks Motor if Display is Removed

Electronic Details

Motor Brand:


Motor Type:

Rear-Mounted Gearless Direct Drive Hub
Learn more about Ebike motors

Motor Nominal Output:

350 watts

Battery Voltage:

48 volts

Battery Amp Hours:

8.8 ah

Battery Watt Hours:

422.4 wh

Battery Chemistry:


Charge Time:

4 hours

Estimated Min Range:

45 miles (72 km)

Estimated Max Range:

65 miles (105 km)

Display Type:

Removable Backlit Monochrome LCD


4 Proportional Assist and Generate Modes, Lighting Controls, Battery Voltage, Trip Distance, Odometer, Chronometer, Average Speed, Clock

Display Accessories:

Independent Button Pad

Drive Mode:

Torque Sensing Pedal Assist, Trigger Throttle

Top Speed:

20 mph (32 kph)

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Written Review

The BionX SL “Super Light” 350 takes the proven, solid performance of the long-lived PL 350 and makes the motor 2.5 pounds lighter while upgrading the 37 volt battery to 48 volts for increased power, awesome! This is one of the highest quality, most feature rich electric bike conversion kits you can buy. It comes with throttle mode, four levels of pedal assist, regenerative “negative mode” and regenerative braking. Instead of using pedelec sensors to track rider input, it uses torque sensors built right into the hub motor making it less jerky and easier to install on the bike. Everything about this kit is high quality, and that’s why it costs about as much as a fully built electric bike.

Now that you know the up side, here’s the down side. BionX kits like this have to be installed onto a bike you already own. That’s a negative because it is time consuming, requires tools or further spend to have a bike shop do it for you. Sure, you probably already know this, it is an electric bike “kit” after all. But unlike some other electric bike kits, BionX systems take more finessing because they replace the entire rear wheel of a bike and that means you have to deal with the derailleur and chain rings. The other tricky bit is adjusting the brake lever system which controls regenerative braking in addition to normal “stop” braking.

Most full electric bikes come with Tektro brake levers that have sensors preinstalled. They tell the motor to shut off whenever you pull the brakes, or they tell the regen system to kick in. That’s also what the sensor does on a BionX kit except it isn’t built into the brake lever. You have to mount it yourself on the outside of the brake lever making it more exposed and ultimately vulnerable. It also means you can only mount the sensor to one brake lever, not both like most fully integrated bikes. The other negative about this and the rest of the BionX kits is that the power cables going from the battery pack to the hub motor and the computer and brake sensor to the battery pack aren’t integrated into the bike frame. It’s a bit less aesthetically pleasing, but it’s not the end of the world and wireless kits are just around the corner.

Back to the good stuff! The motor on the SL 350 kit is really the center piece. It’s an upgraded design from what is offered in the PL 350 kit and weighs 2.5lbs less. It’s brushless and gearless so it coasts silently and last longer than other geared hub motors. It also looks great, having seen the cutaway demo at Interbike myself and feeling the light weight of the motor when it was off the bike, it’s an amazing piece of technology. This light weight design combined with the 48v XL battery pack offers the kind of power that heavier riders will appreciate. It would also suit heavier mountain bike conversions well) and perform better in steep, off road environments.

BionX kits are perfect for people who already have bikes they love and just want to add electric assist. Whether your bike is a recumbent, folding or super light full suspension carbon mountain bike, this kit will take it to the high end of the ebike spectrum for $2K. The computer console has been designed to help you protect your very expensive bike and has two built in security features. If the LCD computer is removed from the bike the motor locks by engaging the highest torque regeneration setting. Also, the console comes with a password built in so even if it’s on the bike, a thief won’t be able to turn it on. With all of this said, if the SL is just too expensive and you’re willing to sacrifice a bit in terms of weight and power, you can spend ~$500 less and pick from one of the PL 350 options.

When choosing between the DT or RR version of this kit, take into consideration the mounting options given your frame and the weight distribution you care most about. I am always a fan of the down tube “mid-frame” battery mounting design because it distributes weight more evenly across the frame from front to rear. This makes the bike easier to pick up and carry, mount on car racks and handle when riding by avoiding tail slide-outs but it also takes the spot where you would otherwise put a water bottle cage. The rear rack by comparison, leaves the bike rear-heavy but provides a great space for hanging panniers or putting a saddle bag. The rear rack design weighs more than the down tube but for some bikes it may be the only option. The first picture below shows the DT (down tube) option with the gray triangle pack and the second picture shows the RR (rear rack) option which mounts to a metal rack. If you choose the second option make sure your bike has threaded braze-on eyelets for mounting a rack.

Note that some users have successfully drilled their own mounting holes for the down tube battery kit but that can compromise the structural integrity of the bike or may not be an option at all with carbon frames. Both battery designs are lockable and the rear rack design has a built in tail light for safety.

Depending on your bike setup, this kit is available with three wheel diameter options including 20″, 26″ or 700c which is equivalent to 29″. The rims themselves are available in silver or black spoke options to match your setup which is nice. Whichever version of this kit you decide on you’ll be getting technology that is feature rich and high quality backed by a solid brand.


  • Lightweight, redesigned hub motor is 2.5lbs lighter and more stylish than PL 350
  • Battery pack offers extra power at 48 volts, great for climbing hills or supporting heavier riders
  • Works with almost any bike, including those with smaller diameters like folding bikes and recumbents
  • Both battery configurations lock to the frame for security and can be charged on or off of the bike
  • Hub motor runs smooth and quiet (gearless and hubless) and has built in torque sensing and regenerative braking
  • Rear-wheel hub motor exerts force onto the part of the frame that is designed to handle it vs. front hub designs, great if you mount to a bike with a front shock
  • Works with disc brake setups as well as v-brakes


  • The amp hours of the 48 volt pack are 8.8 vs. 9.6 on the highest end PL kit meaning it won’t go quite as far. Still, 8.8 is much better than the low end 6.4 amp hour PL kit from BionX
  • Installation is a bit complicated, time consuming or expensive if you hire it done
  • With kits like this the wires and cables aren’t integrated into the frame vs. buying a pre-built ebike that might look a little nicer
  • Trade offs in how you mount the battery: rear rack is heavier and unbalanced, mid mount takes water bottle spot
  • This kit alone costs as much as a high end, fully assembled electric bike
  • Throttle and computer may not mount as easily to road bikes with drop handle bars due to shape and size of tubes and grip tape
  • The rear rack battery design includes a built in light but in many cases you still have to get your own front light vs. an integrated solution feeding from one battery source
  • This kit is only compatible with 135 mm axle size so check your mountain bikes carefully or bikes with thru axles


More BionX Reviews

BionX D-500 Review

  • MSRP: $2,499
  • MODEL YEAR: 2015, 2016

Top of the line 500 watt electric bike kit with a focus on acceleration and low end torque for climbing. Unique center-spoked design for improved comfort and wheel durability, narrow casing accommodates a larger cassette…...

BionX S-350 Review

  • MSRP: $2,099
  • MODEL YEAR: 2014, 2015

Versatile electric bike conversion set with four levels of assist, four levels of regen and throttle mode. Available with five battery pack configurations including two rear mount and three downtube mounted...

BionX P-350 Review

  • MSRP: $1,799
  • MODEL YEAR: 2014, 2015

A more affordable, less powerful electric drive kit from BionX with rear-mount battery design only. G2 console offers four levels of assist, four levels of regen and throttle mode with…...

BionX PL 350 Review

  • MSRP: $1,499
  • MODEL YEAR: 2013

A line of three 350 watt, 37 volt electric bike conversion kits. Available in mid-frame or rear rack styles to fit just about any bike...

BionX PL 250 Review

  • MSRP: $1,199
  • MODEL YEAR: 2013

One of the lightest electric bike conversion kits available anywhere, just 7.3kg (16.1 lbs). Mounts to water bottle eyelets on downtube of, distributes weight evenly front to rear...

5 years ago

I installed the BionX 350XL 48V on a Raliegh 5.2- 27 SPD. Mountain Bike . I have over 3000 mi. of riding pleasure on this bike. My best millage is 49 mi. on one charge Utilizing the right mix of bike gearing and electric assist with re-gen whilst pedaling. Thumb throttle when necessary utilizing mostly plus mode to 4 to start and down assist to plus 2 average speed 12.5 MPH. Re-gen minus 1 except when going down a steep or long downhill grades then a higher re-gen -3 or 4 slow the bike down to 20 mph. Love to watch the battery bar accumulate energy on the plus side during re-gen thus increasing range. So I know I could achieve 60 plus miles in range under ideal weather conditions less than 5 mph headwind. My total cost of the bike with bells and whistles less than $2,600.00. ADVANTAGE I ride a bike that fits Me. Instead of riding a bike I have to fit into. Thanks Team BionX

E.Lynn Leaverton
2 years ago

I had a sl 350 ht rr installed on my Rambler tadpole in 2013 and have ridden well over 6000 miles by January 2016.. My best power mileage was 52 miles Westbound on Idaho’s Trail of the Coeur da Alene. The motor has been strong and dependable. The only problem I had was a battery that would not take a charge which was in warranty and replaced quickly by Gary at NWrecumbent Cycles in Post Falls. You meet the nicest people on the bike trails in the Pacific Nortwest.

2 years ago

Awesome! Sounds like you’ve had a great experience. Thanks for sharing the excellent service by NWrecumbent Cycles, they sound like a great shop :)


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1 day ago

It cost me about $140 to have a bare hub motor (Bafang) shipped from China, and $60 of that was for the shipping. It would be over $250 with a wheel, so I just buy better spokes and a rim and lace them myself. Unless it's proprietary like Bionx, hub motors are interchangeable.

A reseller/importer like Juiced can get those replacements for far less, but they gotta make their margins, and so does a bike shop, so a replacement could be spendy.

Bosch and Yamaha mid drives ...I would expect to be double spendy.

I might have around 2200 miles on my ebikes in 2.5 years of ownership. Three bafang motors, and several unknown names. I don't abuse them, and haven't any failures with the motor or electronics. More importantly, the batteries seem to behave.

1 week ago


1 week ago

Some nice cargo ebikes there, a friend just ordered a Riese & Muller Packster 60 and from what I've read it can be a true car replacement. I'd be wary of getting a Bionx converted cargo bike because they have gone into receivership and used a proprietary system so batteries and parts may be hard to get in future. To be fair the 2018 Rad Power bikes use a custom battery case which can't be swapped out for a generic replacement but at least those can be with new cells unlike a Bionx battery.

2 weeks ago

The ebike situation is like the wild west or the early days of motorcycling, it seems everyone and their dog is building an e bike. I have a BionX system and there is no way i was ever going to pay the price they wanted for a replacement battery. It did work well and continues to work well but I foresee a HD500 wall ornament on my garage wall at some point in the future. Grin technologies is looking like they will be getting my money next time

Go Time Electric Bikes
2 weeks ago

Yes we hope so...It is a great system

2 weeks ago

Interesting; I thought, A2B was a trademark of UltraMotor. Then it seems as Ultra Motor ran into bankruptcy, their business was taken over by TDCM. The firmware used by UltraMotor made me the impression to be a legacy of the BionX firmware. In the beginning, Stromer used such firmware.

So, a non-Stromer replacement motor could work with the Stromer display unit (because the 36V battery is free accessible). Does this fit with your experiences?

86 and still kicking
2 weeks ago

Will do, we sell both Ohm and Elby and would just hate to see this tech disappear. Not sure how many folks have ridden the D500 system but the smoothness, power, diagnostic and configuration capability, and durability of the system is top tier tech.

My feeling is that someone will step in to purchase certain assets and maintain production of these motors.

2 weeks ago

Hi 86,
If you or your contacts hear anymore re a possible Bionx-Boinx bailout could you please keep the forums posted
I know a few Bionx owners who will be relived if the rumours are substantiated

86 and still kicking
2 weeks ago

Bionx Europe is still up and running and we expect the Bionx tech to be purchased and continue. My contacts at Elby (another Bionx bike) seem to know something we do not as they are business as usual.

2 weeks ago

Uh-Ohm ; BionX filed for bankruptcy !

Ravi Kempaiah
2 weeks ago

One of the documents noted... BionX owes $21 Million...
That is some massive debt to be resolved.

Richard Challis
3 years ago

Does anyone have a dead SL 350 battery. The control board in my wife's battery has corroded but the batteries are still fine.. Bionx will not sell me a new controller . . . I have to but a new battery and throw away all those lithium cells . . . not very environmentally responsible !

4 years ago

Recently my friends and I have been going out on night rides. We usually roll 3 deep (2 and a 500w Between the 3 of us we are pumping over 2000 lumens from our combined flashlights on the trails. Needless to say its a pretty bright ride. Here's a quick video I made from my iPhone last night. Still saving for my garmin camera :) Thanks again for the heads up James.

Just after I made this video, we came up to a concession road that intersects the bike path. Out of nowhere red and blue flashing lights appear. We all stop, because the cop who stopped us, blocked the bike path. As soon as he got out of his vehicle, the three of us turned our lights off.

With a dumbfounded look on the cops face, He told us he had been chasing us for 20 mins down the parallel concession rds to the trail. He was shocked that we were just bikes. He then said you guys were really ripping it up out there have a safe ride. Then we were on our way again :)

I love electric biking.

4 years ago

Hey Mike! Welcome to the forum, that's a beautiful bike there... I know the feeling and concern about converting a nice regular bicycle to electric. Some of the kits that I've reviewed are easily removable, like the and, but others like the almost become permanent because they mount in the rear wheel.

I love the option of pedal assist and throttle but you'll pay extra for that and have to do some screwing around to get it setup vs. plug and play on the simpler kits. Here's a of the ebike kits I've reviewed. The is pretty sweet and can go on the front or rear wheel (front would make it easier to swap in and out so you could do regular riding).

One of the best resources I know of for getting tips and advice on creating your own electric bike is a forum called Some of the guys there are interested in performance modding (where you get a higher top speed and more power than is legal) but they're all really smart and might be able to help you out!

Maybe a couple more people will chime in here to help you as well, let me know if you have any questions about the kits I've got listed and definitely share what you end up with! I'd love to hear how it goes and see some pictures of the finished product :D

murat dogusan
2 years ago

price of this kit?

Steve Birks
3 years ago

Wow I would love one of those be ideal for our twin grand children one day - one day !!!
3 years ago

I agree Steve, very cool use of technology and lots of versatility with the different add-ons. Xtracycle announced a new version of their EdgeRunner at Interbike last month which uses the Bosch mid-drive and is even more powerful and efficient. Very cool stuff... compatible with the same great accessories. Review coming soon!

Anthony Lobino
4 years ago

I've got a Big Dummy and I'm looking into the 350 HT kits but I'm unsure whether or not the spending an extra $500-600 from 36 volt to 48 volt is worth it; what are your thoughts? Would I be able to buy a 48 volt battery later on and use it with my 36 volt kit?
4 years ago

I believe you can upgrade to 48 volt packs and they will work with older 36 volt motors. From what I've gathered, all of the new BionX systems run 48 volt packs which improves efficiency and of course power. If you do get an older kit, check how old it is because batteries slowly lose their full capacity just sitting on the shelf.  $500 to $600 is quite a bit extra and I'm not sure how much you may or may not need the additional power, I've had good luck with the older 36 volt systems and BionX offers good support if you buy through a local dealer. Hope this helps!

Joe G.P.
4 years ago

that's the quietest electric motor i've seen you review.
Also i heard one of cheap electric bikes a few days ago, sounded like he was dragging a 2by4 behind him
4 years ago

Yeah, this thing is so quiet... Really impressed with the setup. Climbs well, has regen, mounts to the downtube. Good stuff all around and the Xtracycle is a neat platform :)

Torian Allen
4 years ago

+Electric Bike Review, are there any other electric velomobiles's out there worth testing? 

Torian Allen
4 years ago

Ok, perfect! Thank you!
4 years ago

Hi Torian (cool name btw) this is one of my favorites but Yuba also has one called the elMundo and you can see a few other recumbent/cargo style ebikes here

4 years ago

Please do a review of the iZip Express Electric Bike w/ the 750watt motor. Thx
4 years ago

Great request... It's on my list but I just haven't seen it in the wild! There was one at Currie's headquarters a few months back but it was being repaired. I'm not sure if they even sell it anymore?