For most DIY builds, a torque-sensing mid-drive is the best motor if you ride hills, trails or carry loads, because it drives through your gears and fits most standard bottom brackets. A geared rear hub is the better choice for a cheap, flat-terrain commuter. Pick power by legal class first, then match battery voltage.

Prices in this guide are USD as listed on cycmotor.com on October 10, 2026.

The three CYC motors for DIY builds

Each build below uses one of these. Prices are current on cycmotor.com.

CYC Photon 2

Street-legal commuting, gravel and Class 1 trails

750W nominal, 2000W peak, 135 Nm, 3.5 kg

Kit $950 · Photon 2 + A-52 battery $1,338

Shop Photon 2

CYC Photon Pro

Steep off-road climbs, cargo and private land

3000W rated, 4000W peak, 180 Nm, 4.5 kg

Kit $1,098 · Photon Pro + A-52L battery $1,636

Shop Photon Pro

CYC X1 Pro Gen 4

Maximum power off-road builds

6000W peak, dual-stage reduction, X12 controller

Kit $1,250 · X1 Pro 4 + A-65 battery $2,246

Shop X1 Pro 4

Start with your build goal

The motor is the hardest part to change later, so choose it from the job the bike has to do. Four questions settle most builds:

1. Where will you ride: public roads and bike paths, shared trails, or private land?
2. How steep is it, and how much weight (rider plus cargo) will the motor move?
3. What frame are you converting, and what bottom bracket does it use?
4. What is your total budget for motor, battery and electronics?

The legal question comes first. In the US, Class 1, 2 and 3 e-bikes are generally limited to 750W nominal motor power. Class 1 is pedal assist only to 20 mph, Class 2 adds a throttle with a 20 mph limit, and Class 3 is pedal assist to 28 mph. State and local rules vary, and many trail systems allow Class 1 only. Anything above those limits belongs on private land or off-road where it is permitted.

Decision matrix

Motor options for DIY builds

Geared rear hub. The motor sits in the rear wheel. It is the cheapest and simplest kit type: swap the wheel, mount the battery, run the wires. It does not touch the bottom bracket, so it works on frames a mid-drive cannot fit. The trade-off is that it drives the wheel at a fixed ratio, so it has no mechanical advantage on long, steep climbs, and it adds weight at the rear axle.

Direct-drive hub. Same location, no internal gears. It is quiet and has few wearing parts, but it is heavier than a geared hub and suits flat, steady riding more than climbing.

Mid-drive. The motor replaces the bottom bracket and drives the chain. Because it works through your gears, it can stay in an efficient speed range on climbs. This is why mid-drives dominate eMTB and cargo builds. The cost is extra load on the chain and cassette, so drivetrain wear matters more.

Cadence vs torque sensing. A cadence sensor switches power on when the cranks turn. A torque sensor measures how hard you push and scales assist to match, which feels closer to a factory e-bike. Every CYC Photon and X1 platform uses a torque sensor. Many budget mid-drive kits use cadence sensing.

CYC mid-drive specs at a glance

Specs from the CYC product pages. All three are listed in CYC motors.

When a hub kit or a cheaper mid-drive is the better buy

A CYC motor is not the right answer for every build. Be honest with yourself about these cases:

• Flat routes and a tight budget. If your commute is short and flat, a geared hub kit does the job for less money and less install work.
• Frames a mid-drive cannot fit. Frames with proprietary bottom brackets, such as Trek BB90 and BB95 where bearings press directly into the frame, cannot take any mid-drive. A hub kit is the only option.
• Single-speed or internally geared bikes. A mid-drive's main advantage is using your gears. Without a derailleur drivetrain, that advantage shrinks.
• You prefer cadence assist. Some riders like the on/off feel of cadence sensing, and cadence-based mid-drive kits typically cost less. If you value ride feel, serviceability and an open CANBUS battery system less than price, they are a reasonable choice.

Where a CYC mid-drive earns its price is hills, trails, cargo, and builds you plan to keep and service. The Photon 2 drive unit opens with four M5 bolts, and its controller, torque sensor, motor module and first-stage assembly are individually replaceable, according to CYC's Photon 2 engineering notes.

Match the motor to your battery and controller

Voltage has to match. All three CYC motors accept 36 to 72V, and the Photon 2 has no proprietary battery lock-in. CYC's own A-Series packs talk to the drive system over CANBUS and are listed as compatible with all CYC mid-drives.

All three use 21700 cells and ship with a 4A charger and mount. CYC does not publish range figures, and range depends on terrain, rider weight, assist level and how much you pedal. More watt-hours means more range for the same riding. See all packs in CYC batteries and the battery selection guide.

If you use a third-party battery, check three things: nominal voltage inside the motor's range, a BMS rated for the controller's current draw, and a connector you can wire correctly. A pack that cannot deliver the current will cut out under load.

Frame fit: bottom bracket checks

Measure before you buy. Check the shell width (typically 68 to 120mm) and the internal diameter with a caliper. A threaded BSA shell is about 34mm internal, a PressFit BB92 about 41mm, and a PF30 about 46mm.

CYC product pages list BSA 68 to 83mm, BB92, BSA 100mm and BSA 120mm. CYC's FAQ adds PF30, BB30 and T47 through a press-to-thread sleeve. Also check chainstay clearance around the motor housing and that the down tube has room or mounting points for the battery.

Chainline matters on a mid-drive. On the Photon 2, 36T to 50T rings keep a 52mm chainline, and 32T and 34T rings use a 7mm offset. The CYC chainring guide covers ring choice by riding type: smaller rings for climbing, larger rings for road use.

Electronics: display, throttle and brake sensors

CYC drive systems use CANBUS communication. The Intuition Display is a 2.1-inch color IPS screen rated 36 to 72V and IP65, with Bluetooth to the Ride Control app. In the app you set speed and power caps and pedal assist behavior. That is how a Photon 2 is configured to Class 1, 2 or 3 limits.

Add-ons are sold separately in accessories and parts: thumb or twist throttles ($22) for Class 2 builds, and a brake sensor set ($30) that cuts motor power when you brake. Fit brake sensors on every build, legal class or not.

Three example CYC builds with parts lists

Each list shows the bundle (motor plus battery) and the parts most builders add. Kit contents are not fully itemized on the product pages, so the display, chainring and sensor lines are listed separately until CYC confirms what ships in the box. You supply the bike.

Build 1: Street-legal hilly commuter (Class 1, 2 or 3)

Why it works: the Photon 2 is the CYC motor that can be set inside US class limits. A 40T ring sits in CYC's mixed-terrain recommendation. The A-52 keeps weight down for carrying the bike upstairs.

Build 2: Trail eMTB (private land)

The Photon Pro exceeds US class limits, so this build is for private land and off-road areas that allow it. If your local trails are Class 1 only, build the same bike with the Photon 2 + A-52L bundle ($1,488) instead and set it to Class 1. For a real example, read Robert Neal's DIY eMTB build with the CYC Photon on a Banshee Prime V3 frame (first-generation Photon, third-party 52V battery).

Build 3: High-power off-road (private land only)

The HD Drivetrain is $388 for 150, 157 and 177mm rear spacing, which brings the total to $2,860. The X1 Pro 4 uses a two-stage reduction: a pedal-side chainring plus a larger motor chainring. To change the ratio, motor chainrings run $28 to $58. CYC recommends 32T/53T for steep trails and 40T/72T for open, faster terrain. The HD Drivetrain pairs a 5-speed cassette (15 to 30T, chromoly steel and 7075 aluminum) with a reinforced rear hub and Microshift shifter and clutch derailleur, which CYC designed for high-torque mid-drive builds.

This system exceeds every US e-bike class. Ride it only on private land or off-road areas where it is permitted.

Tools and installation

A CYC mid-drive is a bolt-on conversion. CYC describes it as a job a competent home mechanic can do with common tools, and any bike shop or CYC dealer can fit it. Expect to need:

• Crank puller or crank tool for your current cranks
• Bottom bracket tool for your shell standard
• Hex and torque wrenches
• Cable cutters and zip ties for wiring
• Caliper for measuring the shell before ordering

Install order is usually: remove cranks and bottom bracket, fit the motor and spacers, check chainline, mount the battery, route the display, sensor and throttle cables, then set limits in the Ride Control app before the first ride.

Safety and legal configuration

• Set power and speed limits before riding on public roads. Keep a record of the settings.
• Check your state's class rules and any trail-specific limits. Many trail systems are Class 1 only.
• Upgrade brakes to match. A heavier, faster bike needs strong hydraulic discs.
• Fit brake sensors so the motor cuts when you brake.
• Check torque on motor mounting bolts after the first rides.
• Charge with the supplied charger and store packs away from heat.

FAQ

What is the best motor for a DIY electric bike? For hilly, trail or cargo use, a torque-sensing mid-drive such as the CYC Photon 2 (135 N.m, 750W nominal) is the strongest street-legal choice. For flat, low-budget commuting, a geared rear hub kit is simpler and cheaper.

What size motor do I need for an electric bike? For street use in the US, 750W nominal is the legal ceiling for Class 1, 2 and 3. Higher ratings, such as the Photon Pro (3000W rated) or X1 Pro 4 (5000W rated), are for off-road use.

What voltage is best for a DIY e-bike? Match the battery to the motor's range. CYC motors accept 36 to 72V, and CYC's packs are 52V (A-52, A-52L) or 65V (A-65).

Can I use any battery with my e-bike motor? Only if voltage, current rating and connectors match. The Photon 2 has no proprietary battery lock-in, but CYC A-Series packs add CANBUS communication with the display and app.

Is a mid-drive or hub motor better for a DIY build? Mid-drive for hills, trails and cargo, because it works through your gears. Hub motor for flat routes, unusual bottom brackets, single-speed bikes and the lowest budget. See the CYC conversion kit FAQ for fit and legal questions.