Phasor Cycles Ride Review

April 5, 2012

Written by senior editor Eric, April 2012

Most e-bike manufacturers in the United States have resorted to converting existing bicycles rather than going through the expense and difficulty of building their own frame. The Phasor on the other hand, is much more than just a converted bicycle frame. Phasor Cycles is a new electric vehicle company started by two people on a shoe string university grant, and t’is one of the few American companies attempting to build an e-bike from the ground up.

The big difference between this e-bike frame, and a converted bicycle frame, is that the batteries are mounted snugly in the frame in a purpose-built metal enclosure. This not only makes the bike fire safe but also more stable, robust and balanced for hard core off-road riding. Also, this e-bike has a slick look, a rarity amongst thousands of commercially available cheap e-bikes pouring in from China.

By the way, pictures sent from David’s garage work shop prove that this bike is exquisitely hand made in the USA – a rare thing these days but as you can see, this is not your typical “garage build”.


welded frame in an alignment jig

Raw Phasor Cycle #1

Phasor Cycle frame just back from paint shop


David is selling the bike frame pictured above, powder coated and finished in the color of the buyer’s choice. The frame includes all the custom frame components, bearings, and extra-wide bottom bracket spindle…but without the rear suspension, crank set, or pedals for $1,860

The workmanship and attention to detail on this frame cannot be stated with just words. A lot of skilled hand machined artistry goes into this bike. To give you an idea, check out this video of what goes into just building a swing arm for this e-bike:



The big drawback of the Phasor e-bike for most consumers is that you will be required to source and buy all the components yourself, assemble the bike, design your own battery pack and wire all the electrics. If you tried to buy all the bicycle components necessary to complete the Phasor at your local bicyle shop, it would cost you a small fortune.

Thankfully, Google and internet shopping sources to make this somewhat easier and cheaper for a bargain motivated  shopper. But, it is certain that sourcing components for this bike will be a time-consuming and potentially expensive task if you do not shop wisely. Expect to spend many hours researching and comparing which suspension fork to use etc. And we haven’t even considered electric components yet (battery, motor, controller) which is a headache in itself for the inexperienced new e-biker.

The Phasor is essentially a DIY electric bike builders dream, but it could be a nightmare for a novice who is just getting into electric bikes and wants something to ride ASAP. David says that in the future, the Phasor company will offer to build their customers bikes with the components of their choice. We hope that Phasor Cycles will at least provide some kind of a list of suppliers showing where to buy each component that will be needed.

As far as components costs, the bike I tested and rode with – 56V / 20-Ah LiPo  battery pack, BMC-V4T motor, high quality Fox shocks front and rear…David estimates that it would cost $6,000 to build with the price of the frame included.  Lots of money can be saved by buying lesser components (David uses a top of the line  Fox 40 RC2 front fork and DHX rear shock).

You can save even more money by  finding a used downhill mountain bike through Craigslist or Ebay and stripping the components off of it. These days it is not hard to find a top of the line used downhill bike for $1,500 and a decent one for $500.  When you get into the project, you will find many ways that you can save money – less battery, cheaper motor etc. and you can decide for yourself if and where to cut corners. This is a great way to learn firsthand why the e-bike equation is so complex and why it is hard to find a high performance, relatively light weight e-bike with a long range at a cheap price.

The other big drawback to the Phasor e-bike is that there is a lead time. Currently, the wait for your frame to be delivered is up to three months after putting up a 50% deposit. That’s a long time to wait for anything in this day and age.

Lets look at some of the features and specifications of the frame itself:



Features / Specs:

    • Fully TIG-welded Chromoly frame and monopivot swingarm
    • Front suspension compatibility: Uses standard MTB 1-1/8″ steerer tube
    • Clearance for long suspension travel, 26″ wheels (up to 28″ actual tire OD)
    • Large frame enclosure, room for lots of batteries, controller, chargers, wiring, etc.
    • Progressive rear suspension geometry
    • High ground clearance
    • Low, centralized center of gravity
    • Zero offset rear- no dish required
    • 66° Head tube angle
    • 50″ Wheelbase
    • Standover height  ~ 31″ with 8″ travel forks
    • Thick 3/8″ 4130 chromoly dropouts with captive axle retainers

In general this bike has an aggressive stance, like a downhill mountain bike with high forks and low seat. It is designed for stability riding in off-road conditions, and for making big jumps. The bike can handle a pounding, as can be seen in the video at the bottom of this story.

Now lets look at the specifications of the compete e-bike as tested:

      • 56V / 20-Ah, Zippy LiPo (15S4P)
      • BMC V4T Geared hub motor
      • 40A e-bike motor controller
      • 26″ x 3″ wheels with 2.7″ Kenda Nevegal tires
      • Hayes hydraulic disc brakes, 9″ front 8″ rear
      • Weight: 85 lb as shown
      • Fox 40 RC2 8″ travel downhill forks
      • Rear shock Fox DHX  3″ stroke coilover – with 2.7:1 leverage ratio for 8.1″ rear travel 9.5″ eye to eye
      • Cycle analyst


Some explanation is order in terms of the electrical components that David chose. Remember that this bike can be configured in any way that the builder chooses, so all his choices might not be your choices.

20-Ah of 56V battery is a lot of lithium. This is more than twice as much battery as you will find in any available commercial bike. Lithium batteries are generally the most expensive component of an e-bike.  This e-bike with 20-Ah of 56V is over 1000-WH of battery. To give you an idea the Specialized Turbo comes with 350-WH of lithium and the bike costs over $7000. The $12,000 Optibike has 720-WH of battery. The $5,000 Smart e-bike comes with 400-WH of battery etc…However, all those mentioned bikes come with professionally assembled battery packs with battery management systems, and are considered completely fire safe.

David’s bike was designed to fit Hobby King cells and to use a DIY battery assembled by the DIY buyer, so the risk is in the users hands, even though the risk is lessened because of the metal battery enclosure. Assembling the battery pack would be the hardest part a first time DIYer would face building a Phaoer, and should not be taken lightly. According to David, the Phasor is capable of holding double of what he has in it as tested, or up to 40-Ah of 56V,  over 2,200-WH.

Remember this would add to the cost and the weight of the bike significantly. An extra 20-Ah 56 volt of LiPo would weigh around 18 extra pounds, and cost somewhere around an additional $650 to build, not including a battery management system (BMS) which would be a really good idea considering the expensive size of only the stock pack.

Please look to the forums at endless sphere,  if  you are looking to take on building a LiPo pack for the first time, and do all the research you can on that forum since building a LiPo pack is a difficult and possibly a dangerous undertaking. For a primer on selecting a battery read our article here:


bmc v3 hub motor


Phasor cycles have been designed for a rear  hub motor. It could be run with a front hub motor, although traction is a problem when climbing steep off-road terrain with only a front hub set up. If you were an extremist you could run a hub motor on both wheels for all wheel drive (see our article on choosing front or back hub motor).

The BMC is a geared hub motor, weighing only 7.5  pounds and putting out its power more efficiently than a direct drive hub motor. See our comparison by clicking here.  The BMC uses a planetary gear system, making it much more efficient and lighter weight than a direct drive motor, which has no gears. However the BMC is not able to handle the huge powerloads of a direct drive motor, so has a maximum speed of around 40-MPH depending on how it is configured…but at any speed above 30-MPH the user must be careful not to overheat and fry the motor.

The BMC V3 as tested on this bike is a $400 motor. It is among the  most refined hub motors on the market. However, because of its complex nature (having gears and a roller-clutch) it is less reliable than other high performance hub motors on the market (which are heavier). If you can accept a lot of extra weight and drag in the rear wheel, many users will opt to go for a much larger and more powerful direct drive (gearless) hub motor, for example the Crystalite 5304, the same hub motor used in the Stealth Bomber which could easily transform the Phasor into a 50-MPH machine, but it weighs-in at a hefty 25lbs…a lot of weight to have un-suspended in the rear wheel.

Cycle Analyst V2 (V3 available in 20130


David uses a CycleAnalyst by  to contantly gauge the usage of his batteries, and to make sure he does not damage his batteries by going beyond their safe low-voltage point. He is also able to tell how many amp-hours (Ah) he has used, so when he is out trail-riding he doesnt run out of battery and end up pedaling his heavy e-bike home. A CycleAnalyst has become a staple to DIY e-bike builders, and is essential to anyone using a built yourself LiPo pack, especially if that pack does not contain a battery management system. These days most high performance e-bikes are equipped with CycleAnalysts, even many of the factory-built high performance e-bikes such as the Stealth Bomber.


3-inch tires on the  Phasor cycle, compared to 4-inch Surly Pugsley tires


Wheels and tires
The Phasor frame has room for massively wide tires. The bike we tested had 3-inch wide rims, but there was clearance for even wider rims…maybe even 4-inch fat bike rims. This bike tracks really well with the extra wide 3-inch rims we tested. The extra width made a huge difference in the stability of the bike when I test rode it on off-road trails. We at believe in wide tires on electric bikes. See our article on tires by clicking here:

This bike uses high quality bicycle hydraulic brakes with giant rotors. Quality brakes are essential on a bike this powerful, especially considering its weight and capacity to bomb down a hill. Look at our article here on importance of brakes:


Example of the very professional wiring on the Phasor Cycle


This is a small detail that makes a huge difference. But most DIY bikes have exposed wires running across the frame held down with zip-ties and duct-tape…that are very unsightly. Wiring is one of the ugliest features of DIY electric bike, and on a conversion bike it is a hard problem to solve. On the Phasor e-bike, the wires are well hidden and protected within the frame. Same with the gigantic battery which is also hidden within the frame. Because the Phasor Cycle frame is essentially a hollow shell you are  able to run wires within the frame and pop them out wherever you desire (with the help of a drill).

Ride Report
I met David for 15-mile ride through Del Cerro Park, a popular Southern California mountain bike destination on the coastline in Palos Verdes. I must say, it was a nice change of pace to be riding on an e-bike where the battery was so large that getting stranded out on the trail was almost a non-issue. With the type of riding we were doing, the Phasor had a 25-mile range, even though we were riding with a lot of acceleration and speed up and down hills, the type of riding that is not efficient for electrical systems. Having a battery built into the frame so that you don’t have to change packs when one pack runs out etc, was a real nice feature, and there are only a few high performance bikes I have ridden (Stealth Bomber, Optibike) where I had this sensation that I would tire of riding before the bike ran out of battery.

In the last few years I have ridden many DIY full-suspension mountain e-bikes, and I have never been that impressed when it comes to trail riding because of the awkwardly mounted battery pack. When riding the Phasor, the feel of the low mounted battery had a really nice effect. The only other time I have felt this is when riding an expensive Optibike or Stealth Bomber. The weight of the battery becomes a keel that actually makes the bike feel more stable, like a MX-motorcycle, rather than a wobbly e-bike with its weight mounted up high…the kind I am more use to.  The Phasor makes mountain trail riding fun, quiet and smooth…a rare sensation, at least in my experience of e-bike trail riding.

The other big factor of having the batteries mounted inside the frame is I did not feel the jankiness I usually feel when riding a DIY mountain bike with battery on the rear rack. No rattling noises or whats worse, the sound of big dangerous bricks of LiPo thumping around when I go over jumps. As you can see in the below video, this bike can actually take gigantic jumps, and still nothing on the bike makes clunky noises except for the tires hitting the ground and the suspension compressing.

So although I was riding an electric bike that was very similiar (component-wise)  to conversion e-bikes I own and have ridden…because of the purpose built e-bike frame, this bike made for an entirely different kind of experience than what I am used to. The bike handled solid, and I  found myself riding faster on a rough trail than I usually would. For better or for worse, the Phasor inspires confidence when riding fast off-road and tempts you to ride faster. The only other electric bike I have ridden with this kind of stability and solid feeling when riding off-road is the Stealth Bomber (the Optibike was also similar, but lacked this level power):


Phasor Pros vs Bomber

          • Considerably cheaper to build a bike of similar performance
          • Versatility in what components you want to use on bike
          • No choice to opt out of the expensive and heavy V-boxx (7.5lbs)
          • Option to use high density LiPo batteries
          • Easily can be repaired by replacing easily sourced components
          • Owner learns bike inside and out by assembling it
          • Owner can choose any color for frame
          • American made, help the USA!
          • No expensive shipping from overseas
          • Do not to deal with an expensive and complicated v-boxx repair, in case it fails
          • Extremely Rare/special bike


Phaser Cons Vs Bomber

  • Have to source components and assemble bike
  • No company support like Bomber offers.
  • No warranty on components like Bomber offers
  • Have to assemble your own battery pack
  • Potential LiPo fire danger
  • No community of Phasor owners like Stealth google group (Here’s the ES discussion on Phasors)
  • Unproven frame design compared to Bomber
  • Does not have the straight chain line the bomber has.


Read our ride report and review of Stealth Bomber Here.

The Stealth Bomber and Phasor bikes are very similar looking machines, although you can tell by examining pictures that the Phasor is not a clone type rip-off of the Stealth Bomber. The Phasor is completely different geometry-wise and uses a different type swing arm. The idea of both of these bikes is the same, a fully suspended rear hub powered bike designed for off-road riding that can carry a lot of battery…so naturally they do share design characteristics.

The Stealth Bomber is custom-built around a fancy pedal gearing system called the Suntour v-boxx. The 9-speed v-boxx is very unique, and you can’t opt out of it if it happens to break. Since it is very rare, you will have a very hard time replacing it or repairing it if it does fail. The v-boxx also has the disadvantage of being heavy. At 7.5lbs the v-boxx system weighs as much as the BMC motor David is running on his Phasor. However the benefit of the system is that you get all your gearing inside the bottom bracket so you have a perfectly straight chain line without derailleurs.

With the Phasor, as in any hub motor bike, an internal  gear hub shifting system such as an Alfine-8 is out of the question.  So therefore, the only good choice to go with a straight chain-line and without derailleurs on the Phasor would be the Schlumpf planetary crank system which would give you 2-speeds, one very high and very low. This is worthy to mention because Stealth offers a second bike, the Stealth Fighter which uses the Schlumpf instead of the v-boxx.  However, even though it’s not as sexy as a v-boxx or Schlumpf, a derailleur system makes a lot of sense because it is cheap, light weight, easy to have serviced, and easily replaceable.

I have ridden both a Phasor and a Stealth Bomber, and they do indeed ride very similarly. I must admit I am not a hard-core trail rider, and therefore cannot comment on geometry differences, trail riding characteristics etc. They both feel really solid and stable to me. Most of my e-bike riding involves riding on the street, fire roads, and mild off-road…and both bikes are overkill for this type of application, but…the full suspension and low mounted battery is a very nice luxury either way. However for the reasons stated above, if I owned a bike like the Phasor or the Stealth, I would probably get into trail riding more than I do now.

The big difference I see between the two bikes, is David built his bike with the 7.5-lb BMC hub-motor, where as the Stealth has 26-pound Crystalyte hub motor in its rear wheel. Also, David is installing lighter and denser LiPo batteries, while the Stealth Bomber has chosen to use the heavier but fire safer LiFePO4.

Phasor weighs in at 85 pounds. The Stealth is 120 pounds. The Stealth has a higher top speed, and actually accelerates harder on pavement in spite of these extra pounds. However, the Phasor can easily be mounted with the same motor as the Stealth and have the same performance numbers, while still staying 15-20 pounds lighter than the Bomber. Stealth has thrown weight concerns out the window with many of its component choices. For example, its cheaply priced RST-R1 fork is a full 3 pounds heavier than the Fox fork that David is using.

But the worst place to arrange the bikes weight is in the wheels. Unsprung weight in the wheels is a big deal handling wise. So having either a 26-pound Crystalyte 5304 or a 7-pound BMC motor  in your rear wheel is not a good thing, but the BMC is the much lesser of two evils. The 26-pound Crystalyte does feel like a lead barbell when riding the Stealth Bomber. And with the Phasor you could run either motor at no extra charge, since you build and configure the bike yourself.

Which brings us to the biggest advantage of the Stealth Bomber. For those who do not want the hassle of building their own bike, the Stealth Bomber comes in a box, turn-key condition and ready to ride. You have a company customer service rep to answer your technical questions if you have any problems, and the bike even comes with a warranty although shipping the 120-pound Stealth to an approved repair center would be a big expense, and a hassle to say the least. And lets not forget the price of the Stealth, as the one I tested is $12,000 and could cost even more depending on the options you choose.

When you build a bike up yourself like the Phasor you will understand how each component mounts, and if anything breaks you can easily switch it out. So count easy repairs as an advantage to a DIY e-bike like the Phasor. However…you will be on your own with no one to complain to, and most likely will have to eat the cost of the broken part.

Also, when building and researching your build you will really learn the difficulties of the e-bike equation…for example choosing weight over performance, or weight over range…how much the battery costs, how long your battery will last etc.  You will probably find that once you get into it…owning a fast e-bike with a long range that is affordable is a nearly impossible task.

David says the price to build up the Phasor e-bike like the one I rode (complete with top of the line Fox suspension on front and rear) would run around $6,000. It could be done cheaper if you used less expensive suspension components, or even cheaper by buying a used downhill mountain bike off craigslist or ebay (you can buy a top of the line DH bike that’s just a few years old for $2,000, and a decent one for $500) and stripped it of its suspension and components and then sold the bare frame back on ebay. Or, you could even go cheaper by installing less battery or a less powerful / less expensive motor. These are all compromises that can be hard to make, since you can never really know how all your selected parts will perform together until after you have bought them all.

The Phasor when configured correctly (expensively), is similar  to the $12,000 Australian made Stealth Bomber electric bike. However this bike can be built for less than half the price of the Stealth, and since Phasor only sells the frame, the end user has a lot of versatility on which motor, battery, and suspension components to fit the bike with. But as we have stated, that versatility is also a big headache and can be expensive if you don’t research every thing carefully before you buy.

Several years ago, when David was still a college student he was asked why he chose a high performance electric bike as his senior project. He answered “When we saw that no one was really making anything with the performance we sought for at a  price we could afford, we set out to make our own,”

Now, a relatively short time later, David has successfully brought a worthy contender in the world of high performance e-bikes to the commercial market at a more affordable price than anything else offered in a full suspension high performance e-bike. We at wish him the best with his electric bike business venture.

For those interested in purchasing a frame, David is accepting deposits for the first production run scheduled for summer of 2012.



Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.


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