Kalkhoff Agattu C11 - Electric Bike Magazine

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Kalkhoff
Agattu C11
Impulse Premium
8 Electric Bike Issue 5
With Kalkhoff’s new Impulse crank drive and
Shimano’s latest 11-speed hub gear, is this latest
£2495 incarnation of the Agattu the best yet?

German brand Kalkhoff have
had an Agattu in their e-bike
line-up for several years;
until 2012 they were powered
by Panasonic crank drive motors
with, as technology developed, ever
increasing battery capacity. This year,
though, Kalkhoff launched their own
‘Impulse’ drive system, with the aim
of addressing some of the perceived
shortcomings of the Panasonic: its
lack of a speed sensor (so it has to
cut out at a particular pedalling
rate, equivalent to 15.5 mph in top
gear), its power profi le (designed for
stricter Japanese regulations) and its
lack of fl exibility (no re-programming
possible). The new Impulse drive
addresses all of these, and adds on-bike
charging (the Panasonic battery had to
be removed for charging), the option
of an informative handlebar display,
and (especially for mainland Europe)
the ability to be combined with a
coaster (back pedal) brake. It also adds
a ‘push assist’ function for low-speed
assistance without pedalling.
Our bike, supplied by Kalkhoff’s UK
importers 50cycles, is the top of the
range Impulse model, complete with
11-speed Shimano hub gear, the large
display and full 540 Wh battery (36V,
15 Ah), promising a range of “up to
120 km/75 miles”. Three frame sizes
are available across diamond frame
and step-through versions: ours was a
medium with cross-bar.
Some of the fi rst Impulse bikes
were supplied with an earlier version
of the control software: ours came
pre-installed with the latest update
giving, they say, improved hill-climbing
performance. If further software
updates are needed and no dealer is
nearby, importers 50cycles can post out
a small device for customers to do the
update at home.
A battery life of 1100 charging cycles
is claimed for the 540 Wh battery,
suggesting a life of over three years in
everyday use, although the warranty
period for both bike and battery is two
years.
50cycles have two bases themselves
(in Loughborough and London) but
there is also a network of six further
dealers selling Kalkhoff bikes, plus
around 70 ‘owner demonstrators’
around the country who are willing to
offer potential buyers test rides (not
necessarily of this model, of course).
Contact 50cycles or see their website for
all of the details.
Specification
Weight overall (inc batteries):
25.15 kg
Battery weight: 2.94 kg
Bike only weight: 22.21 kg
Charger weight: 0.76 kg
(inc. mains cable). ‘Dock’: 1.1 kg
Battery type: Li-Ion
Battery capacity: 540 Watt
hours (15Ah 36V).
Gearing: 11-speed Shimano
Alfi ne hub gear. 36T ring (I think
– hard to count), 21T sprocket.
Ratios 24-100".
Brakes: Magura HS-33 hydraulic
rim brakes front and rear.
Lighting: front LED, rear LED
Other accessories fi tted: bell,
mudguards, carrier rack, stand.
Price: £2495
» ON THE BIKE
The C11 is equipped with a fairly high
end set of cycle components on its
alloy frame. The Shimano 11-speed hub
gear is their newest model, promising
a wider gear range than the commoner
8-speed version, but still with the low
maintenance of fully enclosed gears.
It’s controlled by a ‘trigger’ type shifter,
with separate levers for up and down
shifting, nicely placed below the bars
so you don’t have to release your grip to
change gear.
ON TEST: Kalkhoff Agattu C11 ON Impulse TEST: Ezee Premium Torq
BELOW: The Magura HS33
hydraulic brakes are
smooth and powerful.
Note also the AXA frame
lock, which uses the same
keys as the battery.
The brakes are one of my favourite
systems, Magura hydraulic rim
brakes. I use these on several of my
own bikes and they’ve proved truly
low-maintenance over several years,
retaining a silky smooth feel long
after even the best cable brakes would
be starting to stick. Replacing brake
blocks is very easy too – just snap
the old ones out and the new ones in.
Thumbs up from me.
Everything else is good too, so I
won’t spend too long detailing the rest
of the parts. On instead to the Impulse
system! It nestles neatly between
seatpost and rear mudguard, with a
curve to the battery pack to maximise
its use of space. The motor itself is
built in around the bottom bracket,
and it all sits within the ‘visual
envelope’ of the plastic chainguard.
The battery removal system is
very similar to the Panasonic’s: once
unlocked it just swivels out, and
replacement simply involves seating
the base and clicking the top back
in. It’s fast and easy, and cleverly the
battery keys (two provided) also fi t
the frame lock. This puts a steel bar
between the spokes of the rear wheel
to immobilise the bike, a good way to
Issue 5 Electric Bike 9

+ON TEST
prevent opportunistic theft (but no
substitute for locking it to something
substantial).
From the motor unit a short wire
runs to the wheel rotation sensor,
which detects a magnet attached to
a spoke on the rear wheel. The rest of
the wiring runs up inside the frame to
the headset area before emerging to
run to the handlebar units.
Right next to your hand is the
control console, with the on-off button
and power level up and down switches
(three levels plus ‘off’). The ‘set’
button between them scrolls through
the display modes on the LCD display
at the centre of the handlebars, and
if you hold it down for a few second
it brings up a menu system offering
options including language choice,
units, wheel circumference settings
and many more.
The ‘lump’ you’ll see just below the
console is a bell, very conveniently
sited, and nestling behind that is
the button for push assist – an aid to
walking with the bike, helping you
push it up ramps, for example. The bell
does get in the way of using it a bit, but
it’s a function I rarely felt the need for.
A separate hub dynamo in the front
wheel powers the lights, which are
top quality LED units front and rear.
A switch on the front light controls
them, or just set it to ‘sensor’ mode
and they’ll operate automatically.
Finally, the bikes comes with a twopart
charger, so that you can top up
the battery either on the bike or away
from it (if you have no power point
where you park the bike). The charger
looks rather like a black version of a
10 Electric Bike Issue 5
ABOVE LEFT: The large
battery pack curves
around the rear wheel
(with a mudguard in
between to keep it
clean).
TOP CENTRE: The speed
sensor detects the
passing of a magnet
attached to one of the
spokes on the rear wheel.
ABOVE: The control
buttons are in easy reach
of your left hand, as is
the bell.
ABOVE RIGHT: Quality
forks and LED lights.
HIGH POINTS:
Good quality bike bits
Comfortable ride
Crank drive works well,
especially on hills
Big battery and range
LOW POINTS:
Not silent
‘Soft start’ may not suit
everyone
GOOD FOR:
Those wanting to
cover longer distances
between charges
Anyone with steep hills
to get up
Riders who don’t mind
always having to pedal
Well budgeted cyclists
looking for a quality
e-bike
Available from:
50Cycles and their
dealers: Tel 0333
900 5050 or see
www.50cycles.com
Mac Mini computer for some reason,
and it should charge from empty in
around three hours: quite fast for such
a large battery. To charge away from
the bike, the charger cable plugs into
a ‘dock’ onto which you can place the
battery, just as you would have done
for the previous Panasonic system.
» ON THE ROAD
Even with just a medium frame and
with the stem set at a fairly moderate
angle, the swept-back bars give a fairly
sedate, upright riding position. This
takes the weight off your wrists and
eases the bend of your back, at the
cost perhaps of rather more resistance
into a headwind. A cycle dealer
would have no problem making a few
alterations if you want something
more sporty.
It was also good to find that the
C11’s suspension seatpost worked
well, moving responsively as the rear
wheel hit bumps. The front suspension
too responded well. It has a lockout
function but I didn’t feel much need to
use it even on longish hills.
The brakes were superb, among
the smoothest and most powerful
I’ve tried. Perhaps the smoothness
was down to brand new rims and
brake blocks, but still impressive. The
levers have a lovely feel and not much
pressure is required for stopping.
Overall, the bike aspects were really
good, with a stable, rattle-free ride and
components which really operated well.
I’ll touch on the gears in a moment.
With the electrics turned on,
the LED display comes to life (it
remembers the power setting you
were using when you last switched
it off) and you’re ready to set off.
It did surprise me that the power
assist didn’t start immediately
when you start pedalling, as it does
with most crank motors. Instead, it
seems to ramp over a half rotation
or so. Kalkhoff say that this ‘soft
start’ system makes setting off more
predictable, with no chance of ‘pedal
kick’ if you rest a foot on the pedals
while stationary. True, but I did
miss the instant power assist when
setting off – that first pedal stroke is
exactly when you need full assist most,
especially on hill starts.
After that, though, the power
assist works in true torque sensor
fashion: the harder you pedal the
more it assists. And it does this very
well, without any uneven pulsing, and
however fast you choose to spin the
pedals. As your pedalling speed rises
so does the noise level – if you move
your feet only gently, it’s very low and
quiet, rising to a more urgent buzz if
you really spin them round.
Setting off from lights, this freedom
to pedal as fast as you like is very
welcome: it frees you from needing to
shift up gears for those first few yards.
That’s particularly useful on this
model, as there’s an interplay between
the drive system and hub gear here
which has both positive and negative
consequences. The Shimano 11-speed
hub shifts really well, and it’s even
easy to click through several gears at
a time, whether you’re at a standstill
or moving.
But what it won’t do is shift while
under load: it lets you change gear
at the handlebars, but then the
mechanism within the gear won’t
actually implement the shift until the
load going through the transmission
drops to a ‘safe’ (for the gear internals)
level. This should work really well to
prolong the life of the hub gear, but it
does mean that it’s very hard to shift
(especially into higher gears) without
easing off on the pedals to make the
change happen. And that easing off
also leads to the power assist cutting
out, then ramping up again before
it kicks in again at full power. So as
you’re going up through the gears,
power assistance is ‘punctuated’ each
time by the gear change. It’s not a
problem at all once you’re used to it,
just a quirk you quickly adapt to.
As you speed up, the tail off as it
comes to the legal cut-off speed of 25

km/h (15.5 mph) is very gentle indeed
– in fact it’s often still giving a tiny bit
of power (according to the display) as
you go through 17 mph. You’ll need to
be in one of the higher assist modes to
get there – in ‘eco’ it tails off around
14 mph, and feels noticeably less eager.
Up hills the power level feels
good, and with just moderate effort
in your pedalling it will take you up
even the steepest hills, as long as
you’ve selected a reasonably suitable
gear. One of the display modes is of
instantaneous power assist level, and
it’s interesting to see this reach four
or more bars out of its five as the
power assist works harder to help
you up. Other display modes include
trip and total distances, average
speeds, and one purporting to show
how much CO2 emission you’ve saved
compared to travel by car.
More usefully, your road speed is
always displayed, as is battery status
and an estimate of the range remaining.
On our demo bike this started at 48
miles with a full charge, and this
reduced pretty much in line with my
actual mileage over the following
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BELOW: The display
console is large and clear.
It’s mounted solidly
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ON TEST: Kalkhoff Agattu C11 ON Impulse TEST: Ezee Premium Torq
days. I think it’s always calculated on
the basis of the assist being in ‘power’
mode (its highest setting) as selecting
the presumably more economical ‘sport’
or ‘eco’ modes didn’t affect the figure.
Strangely, though, with around 14
miles to go the range remaining figure
plummeted suddenly to two – but it
continued to work for around another
ten anyway. I couldn’t find details of
how the figure is calculated, but it must
always be an estimate at best. And it’s
good that it was under, rather than
over estimating.
If you’re relatively economical in
your riding the claimed 75 miles range
on a charge should be achievable,
barring major hills. The bike rides well
enough without the assist, although
the weight is noticeable. Certainly
it’s no great sacrifice to switch off
the assist on the flat and downhills if
you’re trying to save power.
» SUMMARY
The Agattu C11 is a strong showcase
for the new Impulse drive, and the
bicycle aspects all perform well. In
almost every riding situation the
electric assist is also excellent, with
plenty of power to add to your own
pedalling, and an excellent display.
My only niggles are the noninstant
start of the assist as you set
off, and the somewhat erratic range
readout, although in fairness it’s
probably near impossible to make
any such figure truly accurate. I
suppose I should also count as a
niggle that it’s not silent, although
it’s very much at the same modest
noise level of other crank drives.
Overall though, a highly impressive
machine with substantial range, a
strong company behind it and with
the mechanical aspects a pleasure
to use. You’re paying for this quality,
admittedly, with the £2495 purchase
price, but if that budget’s in your
ballpark I’d recommend trying it out
and making your own judgement as
to the value: an expensive bike you
really enjoy using will always be a
better buy in my book than a bargain
which reminds you of its cheapness
on every ride.
Peter Eland
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