Kalkhoff Sahel Impulse 8 Review

2015 Kalkhoff Sahel Impulse 8 Electric Bike Review 1
2015 Kalkhoff Sahel Impulse 8
2015 Kalkhoff Sahel Impulse 8 Impulse 2 Mid Drive Motor
2015 Kalkhoff Sahel Impulse 8 Locking Removable Battery Pack
2015 Kalkhoff Sahel Impulse 8 Backlit Lcd Display Panel
2015 Kalkhoff Sahel Impulse 8 Adjustable Kickstand
2015 Kalkhoff Sahel Impulse 8 Dynamo Hub Lights Fenders
2015 Kalkhoff Sahel Impulse 8 Impulse 2 Battery Pack
2015 Kalkhoff Sahel Impulse 8 Internally Geared Hub
2015 Kalkhoff Sahel Impulse 8 Rack Pannier Blockers
2015 Kalkhoff Sahel Impulse 8 Rear View
2015 Kalkhoff Sahel Impulse 8 Selle Royal Saddle
2015 Kalkhoff Sahel Impulse 8 Under View Of Motor
2015 Kalkhoff Sahel Impulse 8 Ebike
2015 Kalkhoff Sahel Impulse 8 Step Thru
2015 Kalkhoff Sahel Impulse 8 Electric Bike Review 1
2015 Kalkhoff Sahel Impulse 8
2015 Kalkhoff Sahel Impulse 8 Impulse 2 Mid Drive Motor
2015 Kalkhoff Sahel Impulse 8 Locking Removable Battery Pack
2015 Kalkhoff Sahel Impulse 8 Backlit Lcd Display Panel
2015 Kalkhoff Sahel Impulse 8 Adjustable Kickstand
2015 Kalkhoff Sahel Impulse 8 Dynamo Hub Lights Fenders
2015 Kalkhoff Sahel Impulse 8 Impulse 2 Battery Pack
2015 Kalkhoff Sahel Impulse 8 Internally Geared Hub
2015 Kalkhoff Sahel Impulse 8 Rack Pannier Blockers
2015 Kalkhoff Sahel Impulse 8 Rear View
2015 Kalkhoff Sahel Impulse 8 Selle Royal Saddle
2015 Kalkhoff Sahel Impulse 8 Under View Of Motor
2015 Kalkhoff Sahel Impulse 8 Ebike
2015 Kalkhoff Sahel Impulse 8 Step Thru

Summary

  • An extremely capable, thoughtfully engineered and moderately comfortable commuting or touring style electric bike
  • This ebike seems to have everything from dynamo powered LED lights with safety "standing mode" to full length fenders, a chain guard, a quality rack, comfortable saddle, ergonomic grips, mini suspension and a removable battery pack
  • Excellent 50+ mile range, generous two year warranty, four frame sizes and two frame styles, display is not removable, brake levers do not include motor inhibitor and may fight the motor at times, quick release on front wheel only

Video Review

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Introduction

Make:

Kalkhoff

Model:

Sahel Impulse 8

Price:

$3,799 USD

Body Position:

Upright, Forward

Suggested Use:

Urban, Commuting, Touring

Electric Bike Class:

Pedal Assist (Class 1)
Learn more about Ebike classes

Warranty:

2 Year Comprehensive

Availability:

United States

Model Year:

2015

Bicycle Details

Total Weight:

50 lbs (22.67 kg)

Battery Weight:

5.4 lbs (2.44 kg)

Motor Weight:

6.8 lbs (3.08 kg)

Frame Material:

Aluminum Alloy

Frame Sizes:

18.1 in (45.97 cm)19.7 in (50.03 cm)21.7 in (55.11 cm)23.6 in (59.94 cm)

Geometry Measurements:

Wave S Seat Tube 460 (mm), Wave M Seat Tube 500 (mm), Wave L Seat Tube 550 (mm), Diamant M Seat Tube 500 (mm), Diamant L Seat Tube 550 (mm), Diamant XL Seat Tube 600 (mm)

Frame Types:

Step-Thru, High-Step

Frame Colors:

Metallic Gray with Silver Accents

Frame Fork Details:

Urban Headshock with Rigid Alloy Fork

Attachment Points:

Rear Rack Bosses, Fender Bosses, Two Bottle Cage Mounts (Seat Tube and Downtube)

Gearing Details:

8 Speed 1x8 Shimano Nexus, Internally Geared Hub

Shifter Details:

Shimano Revo Grip Twist

Cranks:

Kalkhoff

Pedals:

Aluminum Alloy with Rubber Tread

Stem:

Concept SL, Adjustable Angle

Handlebar:

Concept Metro Style, Gull Wing

Brake Details:

Magura HS11 Hydraulic Rim Brakes, Magura HS11 Levers

Grips:

Ergon Rubber Ergonomic

Saddle:

Selle Royal Nuvola

Seat Post:

Concept SL

Seat Post Length:

350 mm

Seat Post Diameter:

31.6 mm

Rims:

Rodi Scorpion, With Eyelets

Tire Brand:

Schwalbe Energizer Life, 700 x 38c

Wheel Sizes:

28 in (71.12cm)

Tire Details:

Reflective Sidewall Stripes

Tube Details:

Schrader Valve with Presta Valve Adapter

Accessories:

Single Side Adjustable Kickstand, Shimano 3N31 Dynamo Hub in Front Powering Integrated LED Lights, Headlight: AXA Echo 30, LED with parking light, Backlight: LED integrated in rack with parking light, Carrier: Slim 2-leg aluminum alloy, Plastic Chain Protector, Large Bell on Left Bar

Other:

Locking Removable Battery Pack

Electronic Details

Motor Brand:

Impulse 2.0

Motor Type:

Mid-Mounted Geared Motor
Learn more about Ebike motors

Motor Nominal Output:

250 watts

Motor Torque:

70 Newton meters

Battery Brand:

Impulse 2.0

Battery Voltage:

37 volts

Battery Amp Hours:

11.6 ah

Battery Watt Hours:

429.2 wh

Battery Chemistry:

Lithium-ion

Charge Time:

4 hours

Estimated Min Range:

50 miles (80 km)

Estimated Max Range:

85 miles (137 km)

Display Type:

Fixed, Monochrome Compact Backlit LCD with Adjustable Angle by Impulse

Readouts:

Speed, Battery Status, Trip Distance, Odometer, Drive Mode (Eco, Sport, Power), Walk Assist (Hold the + Button)

Display Accessories:

Backlit Independent Button Pad Near Left Grip

Drive Mode:

Advanced Pedal Assist (Measures Wheel Speed, Cadence and Pedal Torque)

Top Speed:

20 mph (32 kph)

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Written Review

This review is for the 2015 Sahel i8 from Kalkhoff. It’s fairly similar to the 2014 version but offers a more sophisticated LCD display panel with multiple readouts and comes with a head shock to smooth out the ride.

Kalkhoff is a leading electric bike manufacturer in Germany known for producing premium, purpose built products. The Impulse 8 is one of their sportier models, offering great frame balance and ride efficiency like the others but shaving some weight by keeping accessories streamlined. Examples of this include the excluded cafe lock, excluded pump, excluded seat post shock and more minimal head shock (verses a full sized suspension fork) compared to the Impulse 8 HS. It’s still feature rich and quite capable as a commuter or touring bike, the range is incredible thanks to the nearly-430 watt hour Lithium-ion battery and efficient 250 watt Impulse 2.0 mid-drive motor. The Impulse 8 comes in two frame styles (step-thru and high-step) and three sizes of each for achieving a great fit, the stem is also adjustable for an aggressive forward body position or more relaxed upright ride. At just under $4,000 this is basically a car replacement ebike. It should perform well in rain or shine given the full length fenders and medium sized hybrid tires. I love that it includes a complete set of reflectors and reflective tire strips but the LED lights take visibility one step further. These are dynamo powered so they’ll work no matter how full your main battery is and the rear light has a built in “stand mode” which keeps it active for a few minutes after you park the bike as an added precaution.

The motor driving the Sahel i8 is a 250 watt mid-drive Impulse 2.0 offering 70 Newton meters of torque. While there’s no true throttle mode (just a slow walk mode) the bike is fun and responsive in one of three pedal assist settings. I didn’t struggle at all to climb with this bike even in higher gears (I tested gear 6 going up a long hill in the video review above). The motor control system measures rear wheel speed, pedal cadence and pedal torque to activate and power the bike. It’s responsive and smooth though not as instantaneous as the Bosch system. It is perhaps quieter however and the shift sensing technology felt a bit smoother. I especially like the chain guard surrounding the front sprocket and the smaller profile of the Impulse 8 motor which nearly disappears at the bottom bracket. Both rider and motor benefit from he Shimano Nexus eight speed internally geared hub at the rear. It’s clean and elegant, though perhaps heavier than a traditional cassette (this ebike measured at 50 pounds total). Because it doesn’t require a traditional derailleur the chain is kept short, tight and secure. The one complaint I do have about this drive system is that the front wheel offers quick release but the rear does not which complicates flat tire fixes on the go and means you’ll have to carry some tools or get an aftermarket skewer.

The battery powering the Kalkhoff Sahel Impulse 8 offers an impressive 37 volts of power and 11.6 amp hours of capacity. That’s enough for up to 85 miles on the lowest level of assist thanks to the efficient centerdrive motor. The pack is one of the best I’ve seen in terms of design because it stays out of your way, keeps weight low and centered on the frame, is protected by the frame in case of tips, has a sturdy locking core, an integrated LED battery level indicator and it can be charged on or off the bike. If you used the bike to commute to work you could easily bring the battery inside for safer storage even if you weren’t topping it off. The integrated handle is comfortable and sturdy, helping to reduce the potential for drops which could damage the plastic casing. To maximize the life of the pack, I recommend storing it a cool dry place while keeping the charge level between 20% and 80% at all times. Even though the battery casing itself is rectangular and not fully integrated into the tubing of the frame, I think it blends in more than some of the bottle-shaped batteries on other electric bikes I’ve tried. The silver/gray paint is a nice touch that’s highlighted several places across the frame. Mounting the battery is very easy thanks to a pivot system that helps to line up pins (it mounts from the side) and the rear fender protects the electronics well from water and mud. There’s no extra controller box and all of the wires are run through the frame tubing… it’s just beautiful.

Activating and adjusting the drive systems on the Sahel Impulse Eight is very intuitive, probably one of the simplest I’ve seen while still delivering advanced drive modes. Once the battery is charged and mounted you just press the power button on the input pad which is mounted very close to the left grip. I love that both the LCD display and button pad are backlit… The LCD panel is not removable but it is small, sturdy and adjustable in terms of angle (to help reduce glare). As it powers up, the display says “Hello” and then quickly switches to show your speed, battery level (with 10 increments), drive mode (Eco, Sport, Power) and a trip/odometer. You can easily change between mph and kilometers by holding the select button and you can reset the trip meter by holding the minus button. I found myself riding in Power mode for the tests and noticed that this bike requires a bit more torque to activate the motor which means you get more of a workout than some other ebikes. I imagine that helps to extend range and possibly contributes to the quieter operation of the motor. There is also a walk mode which can be activated by holding the plus button for a few seconds, this can be useful if you’re heading up a hill pushing the bike instead of riding it.

With a two year warranty and support from one of Europe’s largest conglomerates, Pon Holdings (owner of Derby Cycle, Gazelle and Cervelo), the Sahel 8 is a pricy but truly capable machine. I was very impressed with the actively designed Selle Royal saddle and head shock – as someone who prefers more suspension than less. There are lighter bikes out there but few with this level of utility and full accessory lineup. Even the bell is designed to be easy and intuitive to use. I absolutely love the two bottle cage mounts on the high-step version and wish they would have included at least one on the step-thru and I did notice that while stopped and using the brakes, if I pushed down on the pedals (for stability) the motor would sometimes activate. The good news is, the Magura HS11 hydraulic rim brakes are very powerful and easy to use so it’s not a huge issue. While this isn’t a race bike, the way everything is so tightly integrated (wires, rear LED light, fenders and kickstand) it just feels fast. The bike is balanced, easy to maneuver and professional looking. It would perform well in most urban environments and hold its own out on the open road.

Pros:

  • The high-step “diamont” version of the Sahel 8 offers two mounting points for adding bottle cages (one on the seat tube and one on the downtube)
  • The Selle Royal gel-saddle is very comfortable but not too wide or thick so it’s great for active pedaling (no chaffed thighs) and the head-shock suspension does cushion the ride as well making it more comfortable when traveling long distances
  • Excellent battery design… low and center on the frame, locking but key is not required to be left in when riding, convenient charge port with cover, sturdy handle for easier carrying, built in LED power level indicator
  • Internally geared eight speed hub stays cleaner and requires less maintenance than a traditionally derailleur and cassette, it does weigh a bit more but it also keeps the chain shorter which avoids clanking and chips on the chain stay or dropped chains
  • Great all-weather features including full length fenders (that protect you, the rack and the battery) as well as a chain guard to keep your pants clean
  • Professionally run cables go through the frame which reduces snags, the bike comes in four sizes and includes an adjustable angle stem for really dialing in fit
  • Extremely responsive drive system measures rear wheel speed, pedal cadence and pedal torque for quick motor activation and cutoff
  • Proprietary shift detection system works with cassettes or geared hubs and functioned very well during my ride test – no mashing or banging
  • Good weight distribution with motor and battery mounted near-center on the frame, the battery stays out of the way for easy stand-over
  • Light weight charger only weighs 1.5 lbs and runs cool and quiet, will easily fit into a bag for extending trips – charging at the office etc.
  • Dynamo hub powered LED lights function whether the battery is charged or not and the lights are well mounted and sturdy, reflective tire sidewall stripes and standard plastic reflectors enhance the bike’s visual footprint
  • Comfortable gel saddle is narrow enough to support active pedaling without chafing thighs but also softens bumpy terrain, feels really good and compliments the premium Ergon ergonomic grips and mini neck-shock mounted at the top of the fork
  • Hydraulic rim brakes are unique but offer excellent stopping power and are easy to activate smoothly without much effort
  • LCD display panel is backlit and swivels to reduce glare, it feels solid and is small enough to stay out of the way but the readouts are clear and well executed, rubberized button pad is also backlit and easy to reach without taking left hand off the grip
  • Rear rack uses standard gauge tubing which will work with the widest range of panniers including many clip-on systems, it connects to the fender for reduced rattling and includes a nice spring latch for small light weight items

Cons:

  • The step-thru “wave” frame style does not include any bottle cage mounting points but the high-step “diamont” has two, it would be nice if they both had these
  • The smaller 250 watt motor is capable and efficient but requires more rider input than some other electric bikes with larger motors, I noticed that I got a better workout with this bike
  • Magura HS11 Brake levers do not offer motor cutoff, I’ve noticed that while stopped it is possible to accidentally activate the motor by pushing the pedals for stability
  • It would be nice if the rear wheel offered quick release like the front wheel for performing trail maintenance and flat fixes more easily

Resources:

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Comments (2) YouTube Comments

Bruce
3 years ago

I just LOVE this bike! Got mine in time for a daily commute to jury duty, and have a hundred miles on it now, in weather ranging from perfect to rainy over San Francisco hills. Thank you Court, for pointing out that the diamont frame has water bottle lugs — I got that frame style and am happy to have my Abus folding lock on the seat post tube and a water bottle on the down tube. With the fenders, rack and chain guard that are included, this completes the perfect setup for an immensely practical and fun bike (and I added a mirror on the handlebar end).

But mostly I have to say, it’s just BEAUTIFUL! Every tiny detail of the design is thought out, and I really could hardly improve on it at all. It just has that form-follows-function beauty. The handling is exquisite: low and centered weight and high quality tires. The center-drive with very well-done control takes the hills and is smooth and intuitive, blending all the grace of a bicycle with the efficiency of a 50+ mile range and near-silent operation. I’ll be riding the 30 miles to my daughter’s farm on this, far beyond my initial expectations for an electric bike.

At first I wondered about the dynamo lights, but I see now why they’re a good choice — always on, no batteries to keep charged, and they brighten and flash as you slow down providing essentially a brake light. They’re required in the EU and I see the logic of that choice. Thank you again Court, for helping me make the decision after test riding ten different e-bikes and poring over your amazing site! As an electric car driver (2011 Chevy Volt, number 800 in the nation), I’m as excited now about e-bikes as about e-cars and LED lighting. It gives me great hope. Ride on!

  Reply
Court
3 years ago

Hi Bruce! Great writeup, so glad to hear EBR helped you learn about the model you chose and it’s nice to get an in-depth perspective from you on the LED lights, I also think the dynamo power and flashing feature is cool. Europe is producing amazing products but I love that we get higher power and speed in the US ;)

  Reply

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