The Humber Flex is a modern, versatile electric bike built for both daily commutes and unexpected adventures. Its compact frame and low-step design make it easy to handle, while delivering a comfortable and enjoyable ride every time. Equipped with a powerful 55 Nm Promovec rear hub motor, it offers smooth, natural assistance whether you're cruising through the city or hauling heavier loads. With integrated AVS luggage carriers at the front and rear, the Flex is ready for everything from quick errands to fully loaded journeys.
How is the frame size measured?
Most E-bikes are measured from the centre of the crank to the base of the seat post tube. However, some E-bike manufacturers may measure their bikes differently depending on their style.
What is the right frame size for me?
This helpful guide will help you to find which size electric bike is best suited to you. If you would like a bit more information, don't hesitate to get in touch.
HYBRID ELECTRIC BIKES
MENS
| Rider Height | Recommended Hybrid Frame Size | |||
|---|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (inches) | Frame Size (cm) | Frame Size |
| 4'10" - 5'2" | 148cm - 158cm | 13" - 15" | 33 - 39 | X-Small |
| 5'2"" - 5'6"" | 158cm - 168cm | 15"-16" | 38 - 44 | Small |
| 5'6" - 5' 10" | 168cm - 178cm | 17" - 18" | 43 - 47 | Medium |
| 5'10" - 6'1" | 178cm - 185cm | 19" - 20" | 48 - 52 | Large |
| 6'1" - 6'4" | 185cm - 193cm | 21" - 22" | 53 - 57 | X-Large |
| 6'4" - 6'6" | 193cm - 198cm | 23" - 24" | 58 - 61 | XX-Large |
WOMENS
| Rider Height | Recommended Women's Hybrid Frame Size | ||
|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (inches) | Frame Size |
| 4'10" - 5'2" | 148cm - 158cm | 13" - 14" | X-Small |
| 5'2"" - 5'6"" | 158cm - 168cm | 15" - 16" | Small |
| 5'6" - 5' 10" | 168cm - 178cm | 17" - 18" | Medium |
| 5'10" - 6'1" | 178cm - 185cm | 19"+ | Large |
ELECTRIC MOUNTAIN BIKES
MENS
| Rider Height | Recommended Mountain Frame Size | |||
|---|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (inches) | Frame Size (cm) | Frame Size |
| 4'10" - 5'2" | 148cm - 158cm | 13" - 14" | 33 - 37 | X-Small |
| 5'2"" - 5'6"" | 158cm - 168cm | 15" - 16" | 38 - 42 | Small |
| 5'6" - 5' 10" | 168cm - 178cm | 17" - 18" | 43 - 47 | Medium |
| 5'10" - 6'1" | 178cm - 185cm | 19" - 20" | 48 - 52 | Large |
| 6'1" - 6'4" | 185cm - 193cm | 21" - 22" | 53 - 57 | X-Large |
| 6'4" - 6'6" | 193cm - 198cm | 23" - 24" | 58 - 61 | XX-Large |
WOMENS
| Rider Height | Recommended Women's Mountain Frame Size | ||
|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (inches) | Frame Size |
| 4'10" - 5'2" | 148cm - 158cm | 13" - 14" | X-Small |
| 5'2" - 5'6" | 158cm - 168cm | 15" - 16" | Small |
| 5'6" - 5' 10" | 168cm - 178cm | 17" - 18" | Medium |
| 5'10" - 6'1" | 178cm - 185cm | 19"+ | Large |
COMMUTER ELECTRIC BIKES
MENS
| Rider Height | Suggested Commuter Bike Size | ||
|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (cm) | Frame Size |
| 4'10" - 5'0" | 148cm - 152cm | 47cm - 48cm | XX-Small |
| 5'0" - 5'3" | 152cm - 160cm | 49cm - 50cm | X-Small |
| 5'3" - 5'6" | 160cm - 168cm | 51cm - 53cm | Small |
| 5'6" - 5'9" | 168cm - 175cm | 54cm - 55cm | Medium |
| 5'9" - 6'0" | 175cm - 183cm | 56cm - 58cm | Large |
| 6'0" - 6'3" | 183cm - 191cm | 58cm - 60cm | X-Large |
| 6'3" - 6'6" | 191cm - 198cm | 61cm - 63cm | XX-Large |
WOMENS
| Rider Height | Suggested Women's Commuter Frame Size | ||
|---|---|---|---|
| Feet & Inches | Centimetres | Frame Size (cm) | Frame Size |
| 4'10" - 5'1" | 147cm - 155cm | 44cm - 46cm | XX-Small |
| 5'1" - 5'3" | 155cm - 160cm | 47cm - 49cm | X-Small |
| 5'3" - 5'5" | 160cm - 165cm | 50cm - 52cm | Small |
| 5'5" - 5'8" | 165cm - 172cm | 53cm - 55cm | Medium |
| 5'8" - 5'10" | 172cm - 180cm | 56cm - 57cm | Large |
Promovec 55 Nm High-Torque Rear Motor
The Flex is powered by a 250W Promovec motor that delivers a whopping 55 Nm of torque, providing the power needed to tackle hills and headwinds with ease. This motor is backed by a 3-year warranty and is specifically developed for maximum durability in harsh climates. A built-in walk-assist function is included, providing extra help when you need to pull the bike up a steep incline manually.
Tested technology based on 25 years of experience from Promovec.
A multifunctional electric bike designed to adapt to a wide range of uses. Its thoughtfully optimized frame ensures easy mounting and dismounting, while the sturdy double kickstand makes parking effortless—even when carrying heavier loads. With flexible AVS luggage carriers, you can easily attach baskets, child seats, panniers, and more, supporting up to 10 kg in the front and 27 kg at the rear.
Wide handlebars and 20” Vertigo Speedster
These handlebars and 20” Vertigo Speedster tires give you good maneuverability and a secure feeling in the saddle – ideal for both city driving and shorter trips outside the city. With integrated lights from Herrmans, hydraulic disc brakes and solid components, the Humber Flex is a robust and reliable companion in everyday life.
specifications
Battery and Range
Promovec DT7-XL
**Battery Placement : On seat tube
**Fixed Battery : Yes
**Range according to battery capacity. It is also dependent on the different riding conditions - terrain, rider weight, tyre pressure, headwind etc.
Motor
Promovec rear hub motor 250W
Torque
55 Nm
Maximum Speed
25 km/h
Display
Promovec Graphic Slim D700+
E-connect App : Display can be connected to app for a more personalized driving experience.
Walk Assist
Yes
Gears
Shimano Altus 8 speed
Cable Routing
Semi-integrated cable routing
Stem
Fixed 60 mm
Front Brake
Hydraulic disc brake Shimano MT200, 180 mm rotor
Rear Brake
Hydraulic disc brake Shimano MT200, 180 mm rotor
Saddle
DDK Comfort saddle
Tyres
VEE Tire Speedster 20 x 3.0"
Mudguards
Yes
Frame
Aluminum
Front Light
Herrmans fixed headlight
Rear Light
Herrmans fixed rear light
Equipment
Ergonomic handles, flexible Atran Velo System (AVS) front and rear offer many options for extras and accessories
Rear Rack
Atran Velo System front (AVS) and rear (AVS+)
Kickstand
Yes, double support legs
Basket
Optional
Delivery
2-5 working day delivery time on all orders.
Returns
Cancelling your order:
If you would like to cancel your order, please contact us immediately at info@ecobikecompany.com or on 0333 050 3189. Please include your order number when contacting us.
If your order has not yet left the manufacturer's warehouse, we should be able to stop it shipping, and issue you a refund immediately.
Please note – when returning a product, it must be returned in ‘as new’ condition, with all components included, in their original packaging. There will be a charge for the return.
Returns - Changed your mind
If you change your mind after buying from us and want a refund, you have up to 14 days to let us know and have the goods returned to us. You will need to return the product to us before we can provide a refund. Eco Bike Co. can help arrange the return for a charge of £50 - a courier will be sent to pick it up from you & return it to the manufacturer.
Please note – the 14 days return period is to allow you to examine the goods as you would in a shop. To obtain a full refund, the goods must be returned in an “as new” condition with all components included in their original packaging. “As new” condition is defined as unridden.
Returns - Damages & Faulty
We ask that you thoroughly inspect all items at the point of delivery. We advise you not to accept delivery of any damaged items. If you discover that an item has been damaged, please send clear photos of the damaged items to info@ecobikecompany.com so that we can open an insurance claim on your behalf.
If your bike develops a fault through normal use (as outlined in the manufacturer's manual) you could be entitled to a repair or replacement as covered with the warranty. Please send through details of the fault to info@ecobikecompany.com and we will arrange the repair or replacement with the manufacturer.
Please note – any fault caused due to misuse of the bike is not covered by this policy. Please ensure you read the manufacturer's manual in detail before using your electric bike to avoid voiding your warranty.
Warranty
With Humber Bicycles you get the following guarantees:
5-year warranty on battery*
3 year warranty on motor
10 year warranty on frame