Upgrading And Modding The Sondors Electric Fatbike On A Shoestring Bud - E Smart Way

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Upgrading And Modding The Sondors Electric Fatbike On A Shoestring Budget

Posted by Tom Lee on

So you plunked down your cash for a chance to get your hands on the Storm Electric Fatbike from the Indiegogo campaign. I would start budgeting you money for upgrades now, because I can guarantee you will want to upgrade this bike in pretty short order. The bike is pretty heavy and the motor and battery are pretty small.


Storm Ebike – A dirt cheap platform ripe for upgrades

UpdateL Lunacycle.com has created a huge area on their website for tons of upgrades for the Sondor’s ebike that are all way cheaper than you’re going to find anywhere else. Click here and have you’re wife’s credit card ready. She’s going to love it!



There are going to be two mandatory upgrades for every Storm fatbike. The saddle and the tubes. I have yet to see any fatbike ship from China with tubes that are a reasonable weight. Swapping out the Seatpost/Seat and Tubes should save you at least 3 pounds maybe 4. Instructions on swapping tubes can be found here. If there are rubber rim strips I suggest pulling them out and replacing them with nylon. What kind of seat should you get? Everyone’s butt is different. Your best bet is to support your local bike shop and show up and try a few out. If it’s uncomfortable to sit on for 5 minutes, it is going to be really uncomfortable in the long run. When you find a seat that works for you buy a bunch of them so you have a lifetime supply. The one I settled on was the Amp found here for a mere 240 grams/$26 and I bought 5 of them about 10 years ago so now I have a lifetime supply. The chances of your ass being shaped anything like mine are slim to none as I am 6’10” tall and have zero fat on my rump. Find what works for you, buy a couple of them. Be aware that cheap seats tend to be heavy and the rails will often bend from stress when single-track trail-riding.

Update: I’ve test ridden this bike (review here) and can say with some certainty that this bike will never make a good trail machine. Build Duh Banana Bike instead.

It's all about finding the right saddle.

It’s all about finding the right saddle.

If the Storm ships with a steel seat post then you should get an aluminum one. If you are tall like I am you will need to get a 400mm or longer as this is a small frame and it doesn’t look like we get to pick sizes. If you’re under 6′ you can get by with a 350mm one.

The best weight to cost ratio in the market right now.

The best weight to cost ratio in the market right now. Vee-Rubber Missions.

The 2nd easiest way to save weight is the tires. A list of fatbike tire weights are listed here. As far as I know the Vee-Rubber Mission has the best weight/cost ratio of them all. Origins8 are a bit cheaper but very heavy. You can get the Vee-Rubber Missions for $50 a tire shipped at Bikes Direct right here which is the cheapest I’ve seen (except on Fleabay). These tires are pretty crappy in deep powder, but decent on the road and hard-packed sand. Be aware that these tires still weigh in at ~1430grams so weigh the tires that come with the Storm first and find out how much you’re going to be saving first. If you don’t have a scale I recommend getting a ‘luggage scale’ from ebay. You can get them for about $5 and are incredibly useful when weighing bikes and tires and all sorts of other things that are a pain to weigh with a postage scale.


There are three components to your power system that matter, the battery, the controller and the motor. Your system will produce the amount of power that the weakest component will allow. This means if you increase your battery you’ll have more range but not more power, as you are still limited by the controller and the motor. If you upgrade the controller but nothing else you’ll stress the battery and the BMS will shut it down (of if you’re running Lipo without BMS you could get some nice fireworks). Your motor will also burn out. If you upgrade the motor but nothing else then you are essentially carrying around more weight that does nothing for you. So what order do I upgrade because I’m cheap and I have a tiny budget for this ebike? Battery first, then motor and controller together.

The BMS on a Duct Tape Battery.

The BMS on a Duct Tape Battery with a bad cell I have to trace down and fix myself.

When your battery dies, which it will, you will have to make a choice about whether to buy another battery or upgrade the one you have. I strongly recommend the latter approach. Even though you won’t get more power from your battery, you will get more range. When upgrading the battery you will have to decide whether to get a 36v system or a 48v system. The problem with getting a 48v system is that you risk burning out the motor and controller and voiding your non-existent warranty. That being said controllers are cheap (although good ones are not) and motors can usually be over volted and over amped (just a little bit for little motors but a lot on the 10+ pounders). The rule of thumb is that if you want higher top speed add volts to the system, if you want more power add more amps to the system.

If you want to stay with a 36v system you can install a snap-in replacement for the sondors ebike battery for $311 from Lunacycles made with top-quality grade-A cells located here. This battery will add 54% to the range of your bike and also supports a 25 Amp continuous draw which is far more than what the stock Sondors controller uses (about 8 amps). You can easily swap out the controller and get a lot more hill climbing power out of that beefy rear motor.


I’ve been over-volting this bike for months without any issues even with the original controller. For all it’s short comings the torque sensing on this bike is pretty awesome.

I have a 24v Giant twist which I upgraded with a 36v 10Ah battery. It got a lot more usable and fun with a lot more power and so far I’ve not had any problems. Does this mean that you can do it too with impunity on the Storm? Maybe, maybe not. If you’re planning on upgrading the controller and motor anyway then might as well try it. Destroying cheap Chinese electronics is fun, I’ve destroyed lots of stuff. Just don’t go crying back to the vendor begging for free replacements when you are driving it at higher volts & amps than its nominal power rating.

Geared Hub Motor upgrades

When you can’t stand the uphill pedaling anymore and absolutely have to upgrade you motor what one should you choose? The first decision you should make is whether to get a Direct Drive, Geared hub or Mid-drive system. Direct Drive is out unless you want to get a 15lb monster. Anything less and you will be disappointed with its performance on the hills. If you want something for the streets get a Geared hub, if you want to ride trails get a mid-drive system. There is more discussion on this here.

The new Fat-Mac motors, the only real option for a fat-bike hub mounted motor

The newest Fat-Mac motors, the only real option for a fat-bike hub mounted motor

For Geared hubs the only one I recommend is the FATMac from Paul at em3ev.com . This motor just came out and isn’t even on his website yet, but there is one in the mail coming to me as we speak. It should work with drop-outs between 170-185mm. I’ll be testing the 12T (high torque winding) unit and posting the results here in the coming weeks. I’ll update this page as I know more. The 12T should be used for trail riding, the 10T may be preferable on a street machine to get a higher top speed (at the cost of torque). Be aware that fatbike tires are NOT designed to be used at speeds higher than 20 mph. With a tube you will get enough heat from the friction between the tube and the tire to melt the inside of the tire if you try to go over 20mph on a regular basis with these tires. Get a lightweight scooter tire if you want to go 30-40mph and expect to get harassed by the cops from time to time because, oh yeah … it’s illegal.

Yes, but is it legal?

Yes, but is it legal?

To mount a new hubmotor onto the existing rear rim you will need different length spokes. In order to figure out the right length spokes you will need to use the Sapim spoke calculator with the parameters set on Paul’s website here.  Paul sells 13Gauge high quality sapim spokes custom cut to any length. Be aware that the nipples and threads on these spokes are very hard to come by in the US. Save yourself a lot of trouble and order a few extra. Mounting a rim on hub motor is not for the faint of heart, you can save some heartache and stress by taking it to your local bike shop and having them do it for about $50. Your first 4 or 5 wheel builds will be pretty bad, after that it gets better.

Overpowering Motors

All ebike motors have a nominal voltage rating. This is the amount of power they can take continuously without burning out. It’s a little misleading though because if you apply 500 watts on a steep hill with a full load on a 500 watt motor for 20+ minutes chances are that you will fry the motor. As an ebiker and a modder your enemy is heat. When there is too much load on the motor and it is spinning too slowly all the power you are dumping into the motor is still going into the motor, but the energy that is not being used because you’re going to darn slow is shed off in waste heat. This waste heat quickly builds up and you can end up melting your windings, phase wires hall sensors etc. Direct drive motors shed heat much better because the motor casing is right next to the windings. On a geared hub motor your motor is hidden inside the casing and there is gears and a clutch separating it from the cooler outside air. Geared hubs have a hard time shedding heat compared Direct Drive.

Heat is the #1 cause of premature death in all hub motors

Heat is the #1 cause of premature death in all hub motors

Luckily the FatMac comes upgraded with a thermal sensor built into it that works well with the Cycle Analyst (about $125+shipping) from Grin Tech. The CA can limit the watts dumped into the motor as the temp increases then shut down entirely if the heat buildup becomes too much. Alternatively if you’re a cheapskate like me you can just hook up a $5 aquarium thermometer and watch the heat yourself and cut the power back when the heat builds up too high. If you want to install a thermal sensor on your existing Storm geared hub but don’t want to try to take it apart to install the sensor (it’s a pain) you can actually carefully drill out the opposite side of the axle and slide a temp probe into the axle on that side. You’ll need a drill press and don’t go too far or you’ll get yourself into trouble. You want to drill far enough to just go past where the hub meets the axle and no farther. If your hub is not held in place properly the drill will ‘drift’ and come out the side of the axle.


Geared hub guts

Generally the heavier the motor is, the more likely that you can increase the watts without frying the motor. A 1000 watt rated 15lb hub motor can probably take 2000 watts but a 250 watt hub motor that weighs 3 lbs will likely only be able to take about 350 watts before frying (if that). The best motor for overwatting in my opinion is the FatMac from EM3EV. With upgraded phase wires you should be able to pump 2000 watts (for a short time) into this 8lb motor even though it is only rated for 500/1000watts.

There is a great article on hot-rodding hub motors done by the really smart people at electricbike.com here. I stole almost everything in this article from them but it’s OK because now I’m giving them credit for it..

Torque Arm

If you want to put a hub motor that doesn’t totally suck on this bike you’ll have to start thinking about a torque arm. If you’re running over 1000 watts (I would do 2000 watts on a hub motor with thermal sensing/shutoff and a 3 way switch to set the amps at 25/33/40) then you should put a torque arm on the rear. I like it when stuff breaks and I think it’s really funny so I wouldn’t do it, but you should. Dr Bass from ES makes a Torque Arm that epoxy’s onto the frame which looks much cooler than the v4 TA from Grin found here. Nothing impresses the ladies like a couple of hose clamps on the chain-stay.

The king of the mid-drive systems

The king of the mid-drive systems – the BBS02

Mid Drive upgrades

For mid drive the only factory built units I recommend is the BBS02 or BBSHD. The lightning rods kit is totally awesome and comes with a 100mm bracket as a standard option, but could be a little too much power for those of you just starting out (wow, that should sell a few units, “it’s too powerful for a sissy like you…”). The BBS02 with a 32T ring in the front and a 22T or bigger gear in the rear should give you enough torque to easily climb stairs with this bike. A post on how to convert the Storm to the ultimate Singletrack 2WD bike is located here. You will have to permanently modify the bottom bracket to do so and you will never be able to mount a standard crank on the bike again. You almost certainly will need an offset crank for the non-drive side as well. If you are building a street bike you can keep the 42T chainwheel that comes with the BBS02, if you want to build it for trail riding you will want a Steel 32T chainwheel and a BCD104 adapter. Truative makes the cheapest chainring I’ve been able to find for about $12 on Fleabay. Search for “TruVativ Trushift 32t 104mm Steel Chainring” to find it or something like it. I have not been able to find a front ring that fits on a BCD104 adapter that is smaller than 32T. Be aware that some of the cheaper BBS02 chainring adapters you may have to grind down a bit to keep the chain from hitting the adapter. On a 34T the chain will never hit. Regular Steel is better than stainless steel which is MUCH better than aluminum or alloy on a mid-drive system. I am all for saving weight, but steel is best for the drivetrain on mid-drives.

Only 2 weeks of use on a mid drive unit with an alloy chainring

Only 2 weeks of use on a mid drive unit with an alloy chainring. I could pick my teeth with these gears they are so worn down.

Connecting it all together

Make sure to push it all the way into the plastic housing till it clicks.

Make sure to push it all the way into the plastic housing till it clicks.

Most motors and batteries come stock with the banana connectors, I always replace them with Anderson Power Pole connectors. You can buy them bulk on ebay (connector pros) for about $.50 each and crimpers are around $30. They are worth every penny. They have a sacrificial ‘tongue’ that takes the bulk of the damage from the spark that forms every time you hook up your battery. The battery is always on and there is no easy way to have a switch hooked up to it that won’t burn out eventually from the sparking so your best bet is the Powerpole connectors. If you need to connect stuff with extra wire use 12 gauge speaker wire available online or at your hardware store. I recommend getting 2 cord Black/Red color combo so you don’t swap them around accidentally. Get the 45 Amp version not the aluminum 30 Amp ones.

Who do I buy from?

For Chinese prices and American service then look no father than Luna Cycles. You won’t find cheaper batteries and Eric also owns electricbike.com which is an incredibly valuable source for ebike information. My favorite offering of his is the Monster Pack Extreme which puts out a whopping 6000 Watts continuous and 10,000 watts burst.

After ignoring all advice from the folks at Endless-Sphere I have spent well over $10,000 on shady Chinese vendors to save a few hundred dollars. In the end I got burned 3 times and had about $1500 worth of stuff fail that really shouldn’t have. I’m not going to go into detail of who these vendors were or how they burned me, all I’m going to say is that there has been only one Chinese vendor who has been honest and forthright in all my dealings with him. When parts show up missing, he ships them out right away. When he overcharged me (accidentally) he refunded the money and apologized. That vendor is Paul at em3ev.com and at this time I can recommend no one else to buy batteries/BBS02/FatMac in China from. His stuff is not cheap, and the shipping costs will give you sticker shock but the stuff works. He supplies chargers that have settings to charge to only 90% of capacity (which greatly increases the packs lifespan). He uses top quality cells and stands by his work. He also builds triangle packs which are the perfect place to mount the batteries. So take a gamble on ebay or wherever you want to get your packs from, but with Lithium batteries you get what you pay for and there is a lot of crap out there getting peddled as gold.

The Canadian company Grin Tech created the Cycle Analyst and have been extremely important in the eBike community. They have tons of cool products like the Cycle Analyst, Cycle Satiator and Torque Sensing Ebike kits. My partner in crime, Larry Clarkburg from Boxy Bikes here in Ithaca buys thousands of dollars of stuff from them. We can highly recommend them as well.

Edward Lyen mods controllers out of his shop in CA. He is the place to go for high power Ebike controllers custom modded with more powerful mosfets that can take a whole lot of power. His website is here and redirects to ES threads about his controllers. If you want a controller to work with your motor it is often preferable to buy the motor and controller as a pair thus guaranteeing that the connectors will be plug and play not plug and pray.


When buying from HK make sure to leave the browser open on the item you want for about 10 minutes and go do something else. You’ll get a ‘special one time offer’ that will help you save even more money. It’s not that special and its not a one time offer, so don’t stress, it will always come back if you wait long enough.

If you want bare battery packs without a BMS then look no farther than Hobbyking. Although ebike geeks often use Lipos (Zippy Flightmax is a favorite) they can explode when overcharged or if discharged too quickly. For normal people Lifepo4 is a much safer chemistry to deal with. Also be aware if you are building more than a 1P pack it can get tricky hooking them together because if the voltages are not almost identical (within about .02V) you can get a huge surge through the wires as the cells try to equalize and that can make the batteries explode. If you want to build a 12S2P pack (12 Cells in Series with another 12 cells in Parallel to the first set) I recommend going with 2 smaller 2P packs. For example you can hook two 6S2P packs together in Series to get one 12P2P pack which is much safer than connecting 2 12S packs together in Parallel to make a 12S2P pack. There is a significant voltage difference between the Lipo (3.7v nom) and Lifepo4 (3.0-3.3v nom) chemistry so do the math before you build a pack to get the number of cells right for the power-level you want to create. Before you do ANYTHING with Lipo batteries get an account on Endless-sphere and read the wiki here. If you don’t understand what you are reading keep reading till you do understand it. If you can’t seem to understand it no matter how much you read then just buy a pre-made pack with a BMS. For real. No joke.

There are other preferred vendors on this 11 page thread of Endless Sphere but do some research before you buy. A lot of people get burned on ebay, Alibaba and Aliexpress from Chinese vendors. They don’t speak English and most of the time you are trying to communicate with Emails pumped through google translate. I honestly don’t think they MEAN to rip westerners off, it’s more like they don’t understand why we think we deserve support when we are buying these products with such little markup. It’s a different culture in China than in the US around product support. You can read more about how I survived a month in China for $50 in my travel blog here.

With a little cash and elbow grease your cheap looking Storm can look like this

With a little cash and some elbow grease your cheap looking Storm can look like this. Dude, where’s my frame?

Be prepared for stuff to break, on average I can ride about 2 hours a day for a week single-track in 6-8 inches of snow before I destroy something on my bike. Luckily I have 6 electric fat-bikes currently in circulation (with more on the way) and I always seem to be able to cobble one of them together so I can ride the next day. I’m really hard on my gear, but the nature of this stuff is that it breaks and you have to fix it yourself.

It’s fun, trust me.

Ride on.




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