Home Cruzbike S40 eBike

Cruzbike S40 eBike

Nothing beats a good bike project. Let’s go! Note: This bike is for sale!

Overview Cruzbike S40 Ebike

The Cruzbike S40 Ebike is built on the Cruzbike S40 frame, a short-wheelbase high riding recumbent, a 500 watt (peak 1056 watt) motor, a 48 volt 20.8 Ah battery, disc brakes, SRAM components, Schwalbe Marathon Plus tires with custom battery bracket, custom controller bracket, and a custom torq arm. The bike is 2-wheel drive, the front wheel human is powered and the rear wheel is motorized. It was designed specifically for the Horrible Hundred bike event in Clermont Florida. If Florida was a pancake, the Horrible Hundred crosses over about 20 large blueberries.

Cruzbike S40 Frame

Cruzbike’s are known for high performance and comfort. High performance comes from a relaxed recumbent position, low aerodynamic profile and the biomechanics of front wheel drive. You can check the crazy list of records here.

Components & Specifications

FrameCruzbike S40 Frame
Accessory stubOrigin 8 Perfect place for a light or camera
BatteryLG Li-ion 48V, 20.8 Ah
Battery cradleCustom aluminum
Bottom bracketSRAM Bottom Bracket GPX Team 73/68
Brake lever - leftSRAM Apex 1 Left Break Lever
Brake lever - rightSRAM Apex 1 Double Tap Right Break Lever
Brake setTRP Spyre Allow Mechanical Brake Set
CassetteSRAM Nx Pg-1130 11-42 Speed Cassette
ChainSRAM PCX1 11 Speed Chain
Controller bracketCustom aluminum
CranksetSRAM Apex 1 Crankset
Kill switchIt’s big and red, and accessible
Motor36V 500W rear hub brushless motor
Rear derailleurSRAM Apex 1x11 Long Cage Rear Derailleur
Sling PackCarry tools, tubes, cell phone, snacks, etc.
Thumb throttleCustom thumb throttle bracket
Torq armCustom aluminum
Weight54.2 lbs, 24.5 kg, with full complement of tubes, tools and bottles

Got a camera or headlamp? Mount it here.

LG Bare Cell Battery

Loaded with capability, 998 watt hours at 48 volts, the battery also has significant liabilities. It is massively heavy at 11.3 lbs, more than half the weight of common road bikes made today.

Not only is it big, it is expensive. It cost more than the ebike conversion kit.

In the flatlands of Florida, the biggest factor is not weight but is aerodynamics, followed by rolling resistance. Just the same, the bike and rider will be challenged to complete the Horrible 100 including its 1377 feet of elevation change.


  • Li-ion Battery pack is made of 2900mAh LG Cells
  • Combination 13S8P
  • Charge Limited Voltage 54.6V
  • Discharge Limited Voltage 39V
  • Charge current 2A
  • Charging Mode CC/AC
  • AC Input 100-240V 50/60 Hz
  • Cycle Life 1000 cycles
  • Charging Time 4.5 hours
  • Battery 11.3 lbs, 5.13 kg

The location and construction of the battery bracket was a major design focus. The concern was that over time the aluminum attachments would fail due to the weight and shock of a heavy battery relentlessly pulling on the bike frame. The design has a rectangular bracket enclosing the battery and six separate attachment points to the frame to distribute the load. The main attachment point shares the attachments with the controller. This bracket provides both vertical support and horizontal support to keep the battery from swaying front to back and side to side.

Like most road bikes, the CruzBike S40 does not have front or rear shocks with the only shock absorption being the slightly oversized Schwalbe Marathon Plus tires. Pumped up to 90 psi (6 bar), these tires require 22.6 watts to roll a load of 92.5 lb (42 kg) at 18 mph (29 kph). Just considering rolling resistance and ignoring wind resistance, elevation change, mechanical chain resistance, etc., this battery at 22.8 Ah, discharged at 39 V, use 811 Wh should last 35.8 hours. It appears this is far more battery than we need, and this is without pedaling!

Controller & Custom Bracket

The controller is fairly light weight requiring only a modest bracket design to secure it in place. The bracket uses a pair of aluminum L-channels;

The motor cable was just long enough to fit in a natural place without the need for an extension cable.

Note the covered plug, this is how you charge the battery. The kit comes with a brick style battery charger.

500 Watt Geared Motor & Torq Arm

Given the bike is built for endurance and comfort, the selection of a 500 watt motor fits the bill. See the section The section About Power covers the topic in detail, but know the subject can get complex. A 36 volt motor 500 watt motor that is powered by a 48 volt battery will generate more than 500 watts of power.

Note the custom torq arm. The kit came with a short stainless steel torq arm and a band clamp. I figured the band clamp would scratch the paint so I fabricated an aluminum torq arm that bolts nicely into the chainstay islet.

About Power

The Myth of Ebike Wattage A “watt” is a unit of power, named for Scottish Engineer James Watt.

The number of watts used by an electric motor at any moment equal the voltage supplied by a battery multiplied by the current flowing from the battery to the motor. So an ebike motor connected to a 24V battery being supplied with 10 amps of current would be powered at 24*10=240 watts.

A 500 watt electric bicycle conversion kit may be listed as a 500 watt kit, yet a closer inspection could show that the kit comes with a 48V battery and a 20 amp peak controller. The math shows us that this kit is in fact capable of putting out 48V x 20A=960 watts, essentially a 1,000 watt kit. What might have initially appeared to be too weak (advertised as 500 watts) is actually an approximately 1,000 watt peak kit.

A 48 volt battery with a 22 amps consumes a peak 1056 watts.

This says that our 500 watt motor is capable of putting out twice that for short periods of time.

From Wikipedia On firm, flat ground, a 70 kg (150 lb) person requires about 60 watts [5] to walk at 5 km/h (3.1 mph). That same person on a bicycle, on the same ground, with the same power output, can travel at 15 km/h (9.3 mph) using an ordinary bicycle,[6] so in these conditions the energy expenditure of cycling is one-third that of walking.

From Mapawatt The world 1 hour cycling record for Master Men (35-39) was able to average 302 watts.

As you can see, the best human efforts at producing power over the course of an hour on a bicycle are around 300-400 Watts. To put this in perspective, when my AC is running full blast my house can consume about 4,000 Watts or 4 kW. I would need over 10 of the best cyclists in the world attached to bicycle generators to power my house when it is consuming this much power!

TRP Spyre Alloy Mechanical Road Disc Brakes

These are nice low-maintenance brakes. The large 160 mm rotors give the brakes the leverage they need to stop quickly with even control.

Additional Handlebar Controls

The 3-button switch controls the bike on-off state, sets different pedal-assist modes and allows user configuration of the motor controller. See the second on S830LCD Display & Configuration for details.

User can operate the thumb throttle with both hands or just just the right hand, while maintaining access to one or both brake levers.

Tire Selection & Rolling Resistance

The website at Bicycle Rolling Resistance.com are leaders in testing the rolling efficiency and puncture resistance of modern bicycle tires.

In selecting a tire, there is a balance between the lightest tire possible while still having low rolling resistance, strong puncture resistance while also considering price.

What is the most important factor to you? Puncture resistance is important for everyone, but perhaps gets special attention for the longer rides and touring in general. If you are more geared for the fast Saturday ride, when you know the course is clear of glass and debris, the weight and rolling resistance might be more important.

The rolling resistance test and the puncture tests are excellent, but it seems like there is room for improvement. Looking at the test process I don’t see where they can’t assess mass and acceleration, i.e., rotational momentum. Lighter tires and wheels win when it comes to accelerating to cruising speed from a stop or accelerate from a slower speed (i.e. accelerating out of a turn). It would be a real plus if Bicycle Rolling Resistance.com could produce a measurement of watts to accelerate from zero to cruising speed.

It would be a real plus if Bicycle Rolling Resistance.com could produce a measurement of watts to accelerate from zero to cruising speed.

Rolling Resistance Test Results (Speed: 29 kmh / 18 mph, Load: 42.5 kg) URL

Inner Tube used, Conti Tour 28 (170 gr butyl)

ModelMarathon (GreenGuard)Marathon PlusMarathon Racer
Rolling Resistance 90 psi / 6 bar18.8 Watts22.6 Watts20.9 Watts
Rolling Resistance 75 psi / 5 bar19.6 Watts23.6 Watts22.6 Watts
Rolling Resistance 60 psi / 4 bar21.3 Watts25.5 Watts24.6 Watts
Rolling Resistance 45 psi / 3 bar23.8 Watts28.9 Watts28.8 Watts
Rolling Resistance 30 psi / 2 bar30.6 Watts36.6 Watts38.3 Watts
CRR 90 psi / 6 bar0.005640.006770.00626
CRR 75 psi / 5 bar0.005880.007070.00677
CRR 60 psi / 4 bar0.006380.007640.00737
CRR 45 psi / 3 bar0.007130.008660.00863
CRR 30 psi / 2 bar0.009170.010970.01148
Spin Up VideoYouTubeYouTubeNo Video

For the puncture test, higher is better. A score of 10 takes twice as much force to push a 1 mm stick needle into the tire as a score of 5.

BrandModelWidthWeightRR 60 psiPuncture TestRating
VittoriaCorsa Speed o-TLR23mm225g10.98/55/5
ContinentalGrand Prix 5000 TL25mm295g11.610/65/5
ContinentalGrand Prix TT25mm195g13.98/45/5
SchwalbeMarathon Almotion40mm629g17.113/55/5
SchwalbeMarathon Plus34mm898g25.513/55/5
ContinentalSport Contact II37mm479g20.615/54/5

After some assessment, I chose to use Schwalbe Marathon Plus tires in a 700x35c size.

WheelInside WidthOutside Width
Front17.4 mm23.2 mm
Rear18.8 mm24.8 mm

Schwalbe Marathon Plus tires in a 700x35c size

I wanted a larger tire to provide a smoother ride and chose durability over speed, i.e, to have a heavier tire with thicker tread over a lighter tread with thinner tread. The table above is with tires inflated to 60 PSI. When inflating tires to 90 PSI the difference between the Parathon Plus and tires about half this weight is a little more than 2 watts. For me, the additional durability was worth the 2 extra watts required to move down the road.

One small task is to remove the small rubber nubs from each tire as these will introduce a small amount of aerodynamic drag. Use your fingers or small needle nose plyers. Technically these are called vent spews and are an artifact from the manufacturing process. More information here.

S830 LCD Display & Configuration

The eBike controller is configured from the S830 LCD display.

Enter settings mode
* Power up the unit using a long press on the center button.
* Long press up and down buttons to change a parameter value and advance
to the next parameter.
* Use the center button to advance to the next parameter.

To edit parameter P03.
1. Long press the center button to power up the unit.
2. Long press the up and down buttons to enter settings mode.
3. Shrt press the center button twice to advance to P03.
4. Short press the up and down buttons to change the parameter.
5. Short press the center button to save changed parameter.
P01:3Backlight Brightness (1: darkest; 3: brightest)
P02:1Mileage Unit (0: KM; 1: MILE)
P03:36Voltage Class: 24V /36V / 48V
P04:10Hibernation Time (0: never, other figures refer to the hibernation time), Unit: Minute
P05:1 09Power Gear – 0/3 Gear Mode: Gear, 1/5 Gear Mode: Gear, P05 means how many assist grades you want from the motor.
P06:29.0Wheel Diameter Unit: inch Precision: 0.1
P07:86Magnet Steel Number for Speed Test Range: 1-100, Set magnet number P07 to 47 if it’s direct drive motor and if the motor is geared then it should be set to 86.
P08:50Speed Limit Range: 0-50km/h, parameter 50 indicates no speed limit.
P09:1Zero / Non-zero Start Setting: 0: Zero Start, 1: Non-zero Start
P10:2Drive Mode: 0 Pedal Assist only, 1 Throttle only, 2 Pedal Assist and Throttle
P11:2Uncertain. If you know what this does let me know.
P12:3Assist Power Intensity Range: 0-5, P12 means pedal assist sensitivity, from 0 to 5 shows how sensitive you want your pedal assist.
P13:8Power Magnet Steel Number. For eBikeling set it to 8.
P16:8ODO Zero-Out: Long press the upper key for 5 seconds and ODO will zero out.

This Bike is For Sale

It has been a fun project but is time to clear out the barn a bit and make room for future projects. I have four other bikes and can only ride one at a time.

Before moving forward, unless it is not obvious, this bike is not for everyone. Some young teens might be OK with this bike but a bike like this is more complicated than a standard bike. A motorized bike of this caliber could get someone in trouble or even killed.

If you already have experience with a Cruzbike then you are good to go, but if not there is a learning curve to a front wheel drive bike. Some new riders get the hang of it in 15 minutes while other riders may need to experience as many as 100 miles before feeling totally comfortable.

The price for this bike is $5,650.00. This works out to the current cost of a Cruzbike S40 at $4,650, plus $1,000.00 for the ebike upgrade kit, plus a few parts. And you get my design and labor for free. Yes, even today these batteries are still over $500 and the Ebikeling kit is $399.

So how would buying this bike work? There are a couple of options. If you are in the Central Florida area, contact me and we can make arrangements for your to see it and ride it. Like Disney, Universal Studios or Kennedy Space Center? This is not too far and you would have another excuse to travel this way.

For payment, I can provide you with PayPal information, a Bitcoin or Etherium public key, or you could snailmail me a check and we can wait for it to clear before moving ahead.

If you are not in Central Florida then you could arrange for an inspection with a bike shop. We could also talk via Zoom, phone or some other way.

As for shipping, it will be between you and a bike shop and a shipper. We can pick a bike shop of your choosing, and for a small fee they will box the bike for you and you can schedule shipping with a company like Bike Flights. I have used them a couple of times and they are cost effective with good service.

Contact me, thanks! [email protected]

This post is licensed under CC BY 4.0 by the author.