Stealth Electric Bikes - the test ride.
remf
The Stealth Bomber is a bike I've wanted to try since it appeared. The website proclaims 'Bikes on Steroids' and the YouTube videos present an awesome picture. But it was only a picture. That was until yesterday when I was finally able to see, feel and ride not only the Bomber but also the Fighter. Melbourne, Australia is the home of John Karambalis, the force behind Stealth Electric Bikes. Melbourne is a great place to ride and John, it turns out, is a gentleman and scholar of all things two-wheeled. His factory is a bike fanatics dream with all sorts of projects in the works.
Let me say from the start that both the Bomber and Fighter are not only on steroids, it's an exotic variety of electro steroidal injection that goes into them. It bulks them up and gives them power like Usain Bolt on some performance enhancing drug from the future - without even coming close to working up a sweat. As such, this puts them both in a weight and power category above and beyond anything else electric that I've tried. I thought that I'd be comparing them to the Opti, my only clear terms of reference, but they are such different machines it quickly became apparent that comparisons would mean little.
The test ride was in beautiful wilderness parkland, the perfect setting to put them through their paces on flat, winding single track. I started out on the Fighter. Easy to manoeuvre, especially given a flick of the twist, the power to weight ratio is the first thing you feel. Power is 2kW for it's 35kg mass. It comes with a 2-speed Schlumpf BB drive or a 16-speed derailleur setup as an option. Standard also are 6 Pot Hydraulic 203mm front and rear brakes (8 Pot is an upgrade option), 160mm RST Storm Air front and 200mm DNM 3-way coil / air shock on the rear. Over rocks and log jumps, given a twist of the throttle it effortlessly leaped and bounded while negotiating tree branches with surprising agility. It's mass just seems to disappear. A little flick and it was gone with the wind. The 2-speed is an easy, set and forget arrangement, unless you want low range, kick your shoe on the axle button. I'm used to needing to switch gears a lot on the Opti, not so on the Fighter. It has ample power to cope with your requirements across the range. That amount of power and low weight come at a cost somewhere and that is it's 15-20 km range with it's 10 Ah battery. For the sort of riding we did, this would be ample as long as you're able to transport the bike to your riding venue. Lifting it is easy, so no problem there. Maximum speed on the flat was around 55-60 kph and it gets there really quickly. A matter of a few seconds and you're cruising at high speed.
It was now time for the Bomber. It's a fearsome, gnarly beast. Weighing in at 57kg with 3kW on tap, it's not for the meek. Riding a sub 30kg bike every day, it was a steep learning curve on the really fast ride that John took me on. The learning curve took a momentary elastic form, sliding on loose rock, misjudging the weight and momentum and ended up with the Bomber on top of my leg increasing the degree of bloody gravel rash on my right leg. A few seconds to bend the crank back a millimetre or two and I was back. Now this was fun. Sliding it around and jumping something with this much bulk and mass is an adrenaline fuelled workout. The standard RST 203mm front fork and 250mm DNM 4-Way rear coil / air shock soaked everything up while the 6 Pot 203mm front and rear brakes pulled this behemoth up very effectively. Options are 8 Pot brakes and White Brothers Groove 200 fork. The V-Boxx 9-speed makes this a more familiar setup for me, more control over your input yet vastly different to the Opti. Like all hub motors, it obviously doesn't drive through the transmission so the effect of shifting gears is only noticeable at the pedals, not on the throttle. Range on the Bomber is 30+ km at high speed between 60 and 80 kph. Slow it down with one of three power settings, pedal and you'll go considerably further. The battery capacity on the Bomber is 20 Ah.
Both bikes are silent. An attribute that is very desirable but also a reason for caution. It's an amazing feeling flying through the wilderness in complete silence yet when nobody or nothing can hear you coming, you need to be extra vigilant. Another impressive attribute is it's ease of internal access. The LiFePO4 battery is going to take years of abuse, when it's time to replace it, just pop the cover off. Couldn't be any easier. Same with the controller, easy to get to and replace should something go wrong. Any wiring issue that may occur over time can be fixed in minutes. Not that this would be a problem. Both bikes are built to last, to take a beating and not miss a beat. They are downhill tough, virtually unbreakable with the possible exception of riding through deep water, not particularly advisable with any electric bike. The monocoque frames exhibit a forward looking design philosophy. The challenges producing a bike with this kind of durability and power are many. John has succeeded without going anywhere near 5 digits on the price tag. He's working on new developments with a simple upgrade path from current models. It's all Plug & Play simplicity.
It's clear that running a big powerful hub motor at 72V has it's pluses and minuses. The brute power means less range than you might expect from another bike and a lot more weight in the form of unsprung mass in the rear wheel. Not that it's at all noticeable. My preconception was that a heavy hub motor would compromise the ride. Not so. For a big, heavy bike, it is supremely balanced. Jumps that would be impossible on any other bike are a breeze. A lot of attention has gone into tuning the excellent suspension, combined with the sheer thrill of massive and silent power, presents a winning combination in my mind. Something that will really appeal to the electro rev-head like myself. They're available in high torque or high speed setups, giving you a choice depending on your preference according to your riding conditions. It's also clear where their names come from, the angular flat panels reminiscent of the early stealth aircraft designs of their namesakes. Are these bikes really stealthy? According to John, nobody has paid any negative attention. After riding it, I'd say it is very stealthy, no noise, no pollution, no damage. With sensible riding, it'll fly under the radar. In the wrong hands, someone's going to get hurt.
Given the extreme specs of these bikes and the build-up to finally getting to ride them, I've been wondering for a while what my final impression would be. Well, I needn't have wondered. The specs don't lie. They are truly extreme bikes, more at home off-road in the hands of a motorbike rider than a cyclist yet able to be mastered by a skilled bike rider in a matter of hours riding technical off-road trails or much sooner if you stick to the smooth stuff. These are magnificent, desirable machines that will, no doubt, last the distance.
cakey
A huge thankyou , that looks awesome . One question is it an
assist pedal ie you can still get a work out at low revs or is it more
of an mx bike with pedals .
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cakey
hoping they may streamline it a bit loks a bit mx ish .
remf
low setting at low revs, you'll get plenty of workout & greater
range. On medium or high setting with more throttle, in 9th gear
you'll still be putting power to the ground through the cranks. Or you
can just forget the pedals & gears if you want. While I didn't climb
any mountains, there was no problem climbing anything I rode in
technical uphill bits at low speed. I don't think there'd be a much of
a problem climbing mountains either.
The Fighter is streamlined compared to the Bomber. More streamlining
may be possible on the Bomber, I'd speak to John.
Also there are now Stealth dealers in the Netherlands, Germany &
elsewhere. You should try one :P
deerfencer1
Thanks for the great great review--well done man!
The Fighter sounds more like my cup of tay--if I had the trails to do
it justice. It sounds both more powerful and lighter than my Denali
36V e-moto, due no doubt to the lithium factor (the Denali is run off
of (3) 14Ah lead Genesis Odysseys) and the 72V motor. What would you
say is the average running time off a fresh charge ridden moderately
aggressively? Minutes/hours to recharge? What kind of warranty on the
batts and drivetrain. The other major difference between the Fighter
and the Denali is the pedals--I have pegs on mine but would have much
preferred to be able to pedal assist.
LH
remf
me.
The Fighter is nimble & fast...average run time is 30 min - 1hr
depending on the rider... more if you back off and pedal more of
course.
Recharge is about 3.5 hrs for da Bomber and 2 hrs for the Fighter. 12
months warranty on the batteries, motor & controller.
You could buy 2 batteries & always have one charged up! So easy to
swap you could almost ride continuously! Actually if you got 3
batteries, you could go 24/7!
Bike_on
I have seen very few reviews as good as yours. Informative, specific,
witty, fun! Great job.
I read this yesterday and just wanted to stew on your many positive
comments and digest a bit. I do have a couple comments and questions.
1. The Power. A 2kw and 3kw offering from a stock OEM is the first of
its kind. I look directly at the battery. 72V, twice the voltage,
twice the power over E+ and Opti. For the Bomber to run at 3kw, the
controller is drawing 40A, wow! A battery of 20Ahrs, 72V, 40A (2C)
continuous, a 3.5 hr recharge (about 6A, 1/3 C rate) The Fighter @
2kw, 72V, 10Ahr, ~27A (2.7C).
Comment: I hope they are running on nano LiFEPO, which are rated for
5C and do not drop too much V at 2-3C.
2. Opti Comparison
You stated:I thought that I'd be comparing them to the Opti, my only
NO <<
This review is not about the Opti, but from a double Opti owner, you
are going to have to releave more about that in time.
Both bikes are full suspension bikes with similiar center of gravity
designs, good disk brakes.
Both bikes are NOW claimed to have excellent handling. Opti has
reguarly been said to be smooth and stable, nimble.
Both have a reputation of being rugged and taking a beating.
So they do compare, but the Opti is lighter (55lb vs 78lb) and 1/2 the
power.
Question: What matters to me in this comparison is Cakey's point,
Does it really help at all to put pressure on the pedals and spin?
You did mention riding in low assist mode, where I would expect your
legs to feel it more.
Bomber: The power, the weight - No offense, but it sounds like a MX
dirt bike with pedals. That's ok, but how can that mass really be
pedalled, especially off road? With that much "fun" power, it is sort
of torture to make yourself go slow.
Anyway - mucho appreciated. More later on gearing, etc.
Dan
deerfencer1
Dan,
Some good points, and I concur re your doubts about the efficacy of
pedals on a bike as heavy as the Bomber. The reason I favor the
Stealth is that at 78 lbs it's still within the power e-bike category
and I can see it being a complete blast as a serious duty XC bike.
Re remf's observation about comparisons between the Stealth and the
Opti being meaningless, I think I get his gist, having ridden both an
Opti (albeit very briefly) and my Denali e-moto which, while pedaless,
is similar in many ways to the Stealth construction-wise. Basically
these bikes (Stealth and Denali) are built on very heavy duty downhill-
type frames with full pro-grade suspension meant for gobbling up rough
terrain and keeping the rider in control. While both COULD be ridden
as street bikes with a simple tire change, this would be akin to
buying a Hummer for highway commuting--it just doesn't make a lot of
sense.
My larger point is that e-motos like the ones we're discussing are
really semi-dedicated offroad beasts, and while Optis can and have
been ridden over moderately difficult terrain, I seriously doubt you'd
even attempt trails that these other bikes can eat for breakfast
(though a few pro-level mtb riders may give it a go). They are indeed
very different animals, and what I found with my Denali is that the
extra weight actually helps a LOT with maintaining stability in very
unstable conditions--which may be part of what remf is hinting at
here. Simply put, the bike in general stays planted, with superb rear
traction, especially if you're a heavier rider.
LH
remf
I knew someone was going to try to coax a more direct comparison to
the Opti. I should have known it was going to be you asking the tough,
probing questions :p
The Fighter may be compared in some ways. Not so the Bomber. In this
post, I'll concentrate on the Fighter though Larry's comments are
already spot on. I'll comment more on the Bomber later.
> So they do compare, but the Opti is lighter (55lb vs 78lb) and 1/2 the power.
substantial premium albeit offset by the equivalent power of another
MBB. Yes they have similar geometry & both are built to very high
standards, seriously tough & durable machines. They really begin to
differ in their range & available power and therefore each bike's role
& function diverge, in my mind. The extra weight & power of the
Fighter, while not helpful on a commute, allow you to do things off-
road that you wouldn't attempt on the Opti, as Larry points out.
Another major difference is the transmission. The Fighter is available
with a 16-speed derailleur setup, though the bike I tried had the
Schlumpf 2-speed high/low range kickshift. So on tight, technical
trails you'd leave it in low range then as it straightens out just
kick it into high gear. Or you can just leave it in high, throttle
maxed from stationary. *YES* you're still getting pedal input all the
way up to 40mph. Pedal input makes a big difference, improving your
power to weight ratio by 30 or 40% and it's this particular ratio that
makes it accelerate like nothing else I've tried. Low gear is good for
speeds up to 15mph while high is good up to 40mph.
The other metric which accounts for the Fighter's acceleration it's is
available torque. I don't know what it is on either bike, just that
the Fighter has much, much more.
Bottom line, I'd be very happy to have both the Opti & the Fighter
side by side in my garage. The Opti as the fast, long-range cruiser &
the Fighter as the muscle machine.
remf
remf
the lowest gear is going up a hill with a flat battery. Under full
power and at top speed, you can still keep up with the motor
effectively at 50mph.
An illustration, a pro sprint cyclist can put out about 3kW through
his legs. Lets say that we could probably do half of that (1.5kW) for
short bursts...perhaps 5-10 seconds...with a few seconds break in
between.
Because power = torque x rpm, input via the cranks means that you're
putting a massive amount of torque through the cranks for those short
bursts.
So when you're pedalling all out, accelerating out of corners, the
Fighter can get an additional 75% power increase (2kW + ~1.5kW for a
total of 3.5kW), mostly in the form of torque (where you need it most)
for the few seconds until you reach the next corner and have to back
off again. You need to back off because your speed is so high after
5-10 seconds of full throttle and pedalling hard.
The increase that you gain from the Bomber is more like 50%...(3kW +
~1.5kW for a total of around 4.5kW) - 50% more than you would have if
you didn't have pedals.
cakey
what was johns take on the range of the bomber with pedaling
at say 80 -90 cad . I am a bit sceptical with all that power, of its
range .
Jerome Daoust
What is the range on motor alone at 20 mph (flat smooth ground, no
wind).
I know, it will require discipline not to go faster.
remf
On my ride on the Bomber, I covered 11km of bush trails, giving it
plenty of throttle I used 7 Ah. That's about 30km or 20 miles for
20Ah. This is probably the minimum range that you would expect from a
full charge.
According to John, if you're were on straighter & smoother terrain
with more pedal input, the range would stretch to 40km or 25 miles.
Ease up on the throttle and you'll see more than 50km or 30 miles. In
fact here's a post from an owner:
"Yeah, actually I ride it a lot. I like the overall package, which is
well suspended, stealthy and quiet. I went out yesterday and found
another wooded trail system by riding some golf cart paths to their
end.
...
My ride yesterday was 35.57 miles, 15.85 Ah, 33.1 Wh/mi. I would have
had a range of about 43 miles keeping the same riding pattern. I rode
a bit more aggressive than usual, average 22 mph on streets, maybe 5
miles of 38 mph street, 3 miles of sand, then the rest some smooth
trails and twice through a dirt construction zone.
…
The range on fast rolling surfaces is very good. It's the sand that
really sucks up the power, and that's usually when I have to start
paying attention. Range only starts becoming a problem if you are in
conditions which bog down the motor, such as where the bike just
sticks into the ground and needs 2kW just to roll."
http://www.advrider.com/forums/showthread.php?t=466490&page=7
remf
For the Fighter at half of maximum speed, my guess is more than 20
miles @ 20mph, depending on pedal input. Also John can lower the cell
LVC & get more range, sacrificing some cycles on the LiFePO4's.
remf
htfiles
Great review REMF! I've been lucky enough to ride four different
Stealth bikes on 3 occasions in Melbourne, Sydney and most recently in
Canberra at the UCI MTB World Championships. One pre-production bike
(Silent Guerilla, similar to the Bomber), two Bombers and the new
Fighter. I haven't ridden the Opti bike but everything else you've
said sits well with my experiences.
Here's two HD clips from a Sydney based Stealth Bomber owner:
http://www.youtube.com/watch?v=h41Q3-xOcgk
http://www.youtube.com/watch?v=H9U5s2L3w1E
(click the "HQ or HD" button to watch in full resolution)
One comment I'd like to add is that with the Stealth Bomber, the
pedals really add to the experience. Even if the bikes had 10kW, I'd
still want the pedals (and it would still be more DH then MX, IMO).
They add an enjoyable dimension to the ride, especially if you're
already a cyclist and used to pedaling as part of the bike handling.
From a power and energy perspective if you can add 150W of mechanical
power on the flat, that's a significant contribution when riding at
less then ~40km/h and can significantly increase range. From a stop or
a steep hill, pedal input can meaningfully reduce peak current drawn
by the motor. See here:
http://tidalforce.googlegroups.com/web/Track-Cyclists-6s-sprint-torque-power.JPG
Cheers,
htfiles
remf
You're VERY fortunate to have ridden the Stealths so much. I rode them
for an hour or so and I just wanted to keep going. The hardest part is
deciding which one would suit me better. Both of them open up a whole
new dimension on dirt: massive silent power and much lighter than MX,
taking you places not possible on anything else I've seen.
Interesting about the pedals, while not as integral to power
requirements as the Opti, on the Stealths they're not just movable
pegs, they really do add considerably to torque & balance. That extra
150W is very noticeable on the Opti, but surprisingly also on both the
Stealths, especially the Fighter.
Thanks for the links to the videos, they are really well made,
beautifully shot & demonstrate the abilities of the Bomber very
nicely.
On Oct 27, 11:16 am, htfiles <htfi...@gmail.com> wrote:
> Hi all,
>
> Great review REMF! I've been lucky enough to ride four different
> Stealth bikes on 3 occasions in Melbourne, Sydney and most recently in
> Canberra at the UCI MTB World Championships. One pre-production bike
> (Silent Guerilla, similar to the Bomber), two Bombers and the new
> Fighter. I haven't ridden the Opti bike but everything else you've
> said sits well with my experiences.
>
>
> One comment I'd like to add is that with the Stealth Bomber, the
> pedals really add to the experience. Even if the bikes had 10kW, I'd
> still want the pedals (and it would still be more DH then MX, IMO).
> They add an enjoyable dimension to the ride, especially if you're
> already a cyclist and used to pedaling as part of the bike handling.
>
> From a power and energy perspective if you can add 150W of mechanical
> power on the flat, that's a significant contribution when riding at
> less then ~40km/h and can significantly increase range. From a stop or
> a steep hill, pedal input can meaningfully reduce peak current drawn
deerfencer1
second remf's and your own observation that human pedaling, no matter
how feeble, adds to the overall enjoyment of the ride.
I sorely missed this capability with my Denali e-dirt bike, which has
sat in my garage like a forlorn orphan for the past 5-7 years.
Why? Lack of local trails that could do it justice. OTOH my TF S750X
has close to 8K miles on it, and almost every ride is a revelation.
Bottom line: Power to the pedal!
LH
On Oct 27, 6:51 pm, remf <optibi...@gmail.com> wrote:
> Hi ht,
>
> You're VERY fortunate to have ridden the Stealths so much. I rode them
> for an hour or so and I just wanted to keep going. The hardest part is
> deciding which one would suit me better. Both of them open up a whole
> new dimension on dirt: massive silent power and much lighter than MX,
> taking you places not possible on anything else I've seen.
>
> Interesting about the pedals, while not as integral to power
> requirements as the Opti, on the Stealths they're not just movable
> pegs, they really do add considerably to torque & balance. That extra
> 150W is very noticeable on the Opti, but surprisingly also on both the
> Stealths, especially the Fighter.
>
> Thanks for the links to the videos, they are really well made,
> beautifully shot & demonstrate the abilities of the Bomber very
> nicely.
>
> On Oct 27, 11:16 am, htfiles <htfi...@gmail.com> wrote:
>
> > Hi all,
>
> > Great review REMF! I've been lucky enough to ride four different
> > Stealth bikes on 3 occasions in Melbourne, Sydney and most recently in
> > Canberra at the UCI MTB World Championships. One pre-production bike
> > (Silent Guerilla, similar to the Bomber), two Bombers and the new
> > Fighter. I haven't ridden the Opti bike but everything else you've
> > said sits well with my experiences.
>
cakey
htfiles
bikes are designed with CAD & FEA but I know he built a whole heap of
prototypes to dial in the geo, suspension behaviour and frame
construction.
Of course it means he gets to ride and torture everything which would
be fun! He has former DH racers and moto champs putting the bikes
through their paces as well.
Cheers!
Bike_on
Questions for Remf:
Which has a lower center of gravity,the Opti or the Stealth? The Opti
MBB and Battery are pretty low in the frame. Not sure how the stealth
compares, or if it matters.??.
Also, who makes the stealth's motor?
Drive train:
When I rode the E+, I found the independent drive train of the pedals
and motor to be refreshing to the legs. I could over gear or
undergear apart from the motor load to assist. Do you find this true
when riding the stealths? Which is easier to ride off road? :
Shifting gears and throttling the Opti, or shifting (when you want)
and throttling the stealth?
Dan
>
> - Show quoted text -
remf
I wouldn't compare the Bomber to the Opti at all. The only remote
resemblance is the V-Boxx which you shift somewhat like the Rohloff.
As far as the Fighter, the Opti would definitely have the lower COG
and is more agile & manoeuvrable. The Fighter, with all that power &
only high & low range to choose from, regardless of weight, is also a
totally different bike to the Opti. It can jump stuff you'd have to go
around on the Opti. The range of the Opti in Fast mode is more than
double that of the Fighter with 10 Ah of LiFePO4's. One possibility
I've discussed with John is using high end LiPo's in the Fighter,
increasing it's range over 40%.
The motors are *amped* up Crystalytes.
As far as which one is easier to ride off road - that's a really
complex question to answer. I guess it depends on what your used to,
how skilled you are & how technical the off-road is. I definitely
didn't find the Stealths more difficult to ride just that they are
uniquely different. Others will say the Opti is much easier while an
MX rider would probably be more comfortable on the Bomber.
remf
about it so much. Simple high & low gear kick shift which is totally
independent of that grunty motor. You spend less time shifting & more
time cranking.
deerfencer1
offroad e-bikes (and which remf briefly echoed in one of his first
posts), in my experience proximity to trails is very important unless
you don't mind schlepping the bike via car on a heavy-duty carrier or
small trailer. Range is limited enough at 10Ah, which is close to what
my Denali had, to not be able to afford sacrificing half that power to
get to the offroad riding site and back.
Also, these bikes from a visual standpoint are much more obviously NOT
like your average pedal bike than your typical e-bike, making them a
lot more visible to the authorities if ridden on the open road.
In my case I could only find a handful of semi-legal trails/parks
within a short ride of my house, and longer, more challenging trails
meant a drive/schlep to the site, requiring twice the time as my
average e-ride (with half the saddle time). I found I much prefer to
roll out of my driveway on the bike, and that my TFX in the end was
much more personally rewarding (read fun) to ride. (But note my Denali
had pegs, not pedals, so part of my indifference towards the bike
stemmed from the passive, non-pedaling characteristic of the ride.)
In the end 20-30 minutes of offroad fun just didn't hold a candle to
1-2 hours of blacktop cruising on my Tidalforce, especially given the
aerobic benefits of the latter. IMO these e-dirt bikes are in general
best left to the younger daredevils and technical offroad riders, and
I'm sure the downhill mtb crowd would have a ball on them.
At 55 I'm finding I much prefer smooth blacktop, swooping curves, and
gently rolling terrain to rocks, roots, and body jolts--still a roadie
at heart I guess.
My larger point is that these bikes are not neary as practical or
versatile as an
Opti, TF, or E+, so those looking for a one e-bike that does all
should probably cross these off their list--unless they live in the
outback.
LH
Jerome Daoust
Bike_on
Just to add to your comments:
Isn't one of the failsafe modus-operandi of an ebike the ability to
pedal home, in the event of an e-failure, without any major
difficulty? I know the Bomber will not qualify for that, maybe the
Fighter could? With battery capacity about 1/10th the energy of a
gallon of gas, efficient use of the juice is premo for all conditions
in order for electric drive to effectively comopete with the 50cc
market and above.
On a 0-100%, how do you rate the Bomber/Fighter as a MX/bicycle
machine: 50/50 and 40/60?
Dan
remf
You can pedal both the Fighter & the Bomber home in Low/1st
gear...it's just a lot more work than the Opti, I'm guessing that both
the Fighter & Bomber would be easier to pedal without power than a TFX
or E+ since they both freewheel?
I rate these bikes very highly as off-road machines...more than 90%.
The only thing I'd want is extra range - and that's being worked on.
As far as the MX/bike thing...they're not MX, not even close...both
being much lighter. Yet with all that power, they still seem, to me,
to be e-bikes because you're still using the pedals a lot.