Tern HSD S+ Folding Electric Bike

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Enormously useful yet surprisingly small—the Tern HSD S+ folding electric bike is shorter than a standard bicycle, yet carries a whole lot of cargo, while offering a ride so easy, it shifts itself.


  • Next-generation Bosch® Performance Line motor with Intuvia display delivers pedal assist up to 20 mph, helping you carry groceries and tackle steep hills, without the sweat
  • enviolo AUTOMATiQ shifter and Sport 380 internally geared rear hub offer effortless, stepless automatic shifting across a wide gear ratio range of 380%
  • Perfect for longer rides, the Bosch PowerPack 500 battery offers a range of up to 74 mi., depending on conditions and assist settings
  • Custom Suntour suspension fork smooths out rough roads with 70mm of travel
  • Cane Creek® Thudbuster ST suspension seatpost offers additional comfort without sacrificing performance or control; tunable to match your weight and riding preferences
  • Magura® MT4 hydraulic disc brakes deliver consistent, powerful braking, even in wet conditions
  • Gates Carbon Drive® CDX belt lasts more than twice as long as a typical chain and works without lubrication, meaning no greasy, dirty buildup to get on your hands or clothes
  • ABUS® keyed-alike frame lock offers light security for quick stops and can be matched to use the same keys as a higher-security ABUS lock (not included)
  • Fits riders from 4'11" to 6'5" (150 to 195 cm)
  • Fits one Thule® Yepp Maxi, Yepp Nexxt Maxi or Bobike® GO Maxi child seat—no adapters needed (child seats not included)
  • Specs and images are subject to change


This e-bike comes with Coast to Coast Support, which includes:
  • 1 year of free adjustments (see more below)
  • In-store bike assembly
  • Pickup in store or curbside
  • Bike experts available at 170+ bike shops
REI Co-op Members get more:
  • An additional year of free adjustments on e-bikes
  • 20% off shop services
  • Free tubes with purchase of flat tire repair (Co-op Cycles brand tubes only; tube must be installed at time of purchase)
More about our free adjustments:
New bikes go through a normal break-in period, after which they should be readjusted. All electric bicycles sold at REI include free adjustments for the defined period (one year after purchase date for non-members, or two years for REI Co-op Members)—as many times as you need. Included: derailleur and brake adjustments, lateral wheel truing, hub and headset bearing adjustments, tire inflation, chain lubrication and e-bike firmware updates. Not included: replacement or installation of new components or accessories, any other services. Call your local REI Co-op Bike Shop for more information.

UL2849 certified
View the Tern HSD Product LineView all Tern Electric Cargo Bikes

Technical Specs

Best Use

Urban Cycling

E-Bike Classification

Class 1: pedal assist up to 20 mph


Bosch Performance Line (Gen 3)

Motor Type


Motor Torque (Nm)


Battery Type

Lithium Ion

Battery Capacity (Wh)

500 watt hours

Battery Removable


Charge Time (hrs)

2.5-4.5 hours

Pedal Assist Range

32-74 miles


6061 aluminum





Bike Suspension

Front Suspension


Suntour custom for Tern

Fork Travel

70 millimeters


Tern HSD custom

Bottom Bracket

Motor integrated


enviolo AUTOMATiQ

Rear Cogs

Gates CDX, precision CNC machined cog

Internally Geared


Brake Type

Hydraulic Disc Brake


Magura MT-4 hydraulic disc

Brake Levers

Magura hydraulic


Tern Atlas H, Cargo

Front Hub

Novatec, thru axle, sealed bearings

Rear Hub

enviolo Sport 380

Wheel Size

20 inches


Schwalbe Big Ben 20 x 2.2 in. (55-406mm), RaceGuard Puncture Protection

Tire Width

2.2 inches

Handlebar Shape

Flat Bar


Tern Sweep, 6061-AL, Tern Andros Adapted


Tern Physis 3D with Andros Stem

Seat Post

Cane Creek Thudbuster ST, Tern Telescope, 34.9/30.9mm


Tern HSD


Urban platform with nonslip surface, sealed bearings


Tern Flux Pro Taper, 1.5 in., angular contact bearings


Gates Carbon Drive CDX Belt

Belt Drive



58 lbs. 11.2 oz.

Bike Weight

Bike weight is based on median size, as sold, or the average of two median sizes.



Size Chart

One Size
Height Range4'11''-6'5''

How we measure bikes

  1. Standover Height Standover Height is a measurement from the ground to the top of the top tube, measured at the midpoint of the top tube.
  2. Reach Reach is the horizontal distance from the center of the cranks to the center of the head tube, measured at head tube level.
  3. Stack Stack is the vertical distance from the center of the cranks to the center of the head tube, measured to the top of the head tube.
  4. Effective Top Tube Effective top tube is the distance from the center of the head tube to the center of the seat tube/seat post, measured parallel to the ground.
  5. Seat Tube Center to Top Seat Tube length is the measurement of the seat tube, from the center of the cranks to the top of the seat tube.
  6. Head Tube Length Head Tube Length is measured from the bottom to the top of the head tube.
  7. Head Tube Angle Head Tube Angle is the acute angle between the head tube and the ground (measured towards the rear of the bike)
  8. Seat Tube Angle Seat Tube Angle is the acute angle between the seat tube and the ground (measured towards the rear of the bike).
  9. Bottom Bracket Height Bottom Bracket Height is a measurement taken vertically from the ground up to the center of the cranks.
  10. Wheelbase Wheelbase is the measurement from the center of the front axle to the center of the rear axle.
  11. Chainstay Length Chainstay Length is the measurement from the center of the cranks to the center of the rear axle.
  12. Fork Offset Fork Offset, or rake, is the distance from the front axle to a line drawn parallel to the center of the head tube or steering axis.

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