Surface 604 YunBike C1 Review

Surface 604 Yunbike C1 Electric Bike Review
Surface 604 Yunbike C1
Surface 604 Yunbike C1 180 Watt Gearless Hub Motor
Surface 604 Yunbike C1 Removable Battery With Usb Charging Port
Surface 604 Yunbike C1 Velo Comfort Ergonomic Saddle Curved Bar
Surface 604 Yunbike C1 Ergonomic Grips And Bell
Surface 604 Yunbike C1 Four Colors High Step Mid Step
Surface 604 Yunbike C1 20 Inch Wheels Kenda Kwik Tires
Surface 604 Yunbike C1 Formula Linear Pull Brakes
Surface 604 Yunbike C1 Integrated Led Light On Battery
Surface 604 Yunbike C1 Rear Mounted Kickstand
Surface 604 Yunbike C1 Red Spoke Accent 12 Gauge
Surface 604 Yunbike C1 Single Speed Drivetrain Chain Cover
Surface 604 Yunbikes On Car Rack
Surface 604 Yunbike C1 2 Amp Charger And Battery Pack
Surface 604 Yunbike C1 Electric Bike Review
Surface 604 Yunbike C1
Surface 604 Yunbike C1 180 Watt Gearless Hub Motor
Surface 604 Yunbike C1 Removable Battery With Usb Charging Port
Surface 604 Yunbike C1 Velo Comfort Ergonomic Saddle Curved Bar
Surface 604 Yunbike C1 Ergonomic Grips And Bell
Surface 604 Yunbike C1 Four Colors High Step Mid Step
Surface 604 Yunbike C1 20 Inch Wheels Kenda Kwik Tires
Surface 604 Yunbike C1 Formula Linear Pull Brakes
Surface 604 Yunbike C1 Integrated Led Light On Battery
Surface 604 Yunbike C1 Rear Mounted Kickstand
Surface 604 Yunbike C1 Red Spoke Accent 12 Gauge
Surface 604 Yunbike C1 Single Speed Drivetrain Chain Cover
Surface 604 Yunbikes On Car Rack
Surface 604 Yunbike C1 2 Amp Charger And Battery Pack


  • A light weight, compact, single speed electric bike that's well suited to neighborhood riding or short commutes... optional fenders and front or rear rack expand utility
  • Smaller capacity 187.2 watt hour battery limits range but the torque-sensing pedal assist requires more active riding and the motor is also smaller, just sipping power you end up doing alright distance wise
  • Two USB charging ports, one on the battery for off-bike use as a portable power source, optional free mobile app, simple intuitive built in display panel, unique integrated LED lights for anytime riding
  • Stiffer ride due to narrow tires and lack of suspension, the trigger throttle only activates walk mode ~2 mph, limited top speed of ~15.5 mph with assist, only seems to show units in metric

Video Review



Surface 604


YunBike C1



Body Position:

Upright, Upright Relaxed

Suggested Use:

Neighborhood, Commuting, Travel

Electric Bike Class:

Pedal Assist (Class 1)
Learn more about Ebike classes


1 Year Comprehensive, 3 Year Frame


United States, Canada

Model Year:


Bicycle Details

Total Weight:

34.7 lbs (15.73 kg)

Battery Weight:

3.2 lbs (1.45 kg)

Motor Weight:

4.4 lbs (1.99 kg)

Frame Material:

6061 Aluminum Alloy

Frame Sizes:

17 in (43.18 cm)

Geometry Measurements:

19" Seat Tube Length, 20" Reach, 21" and 28.5" Stand Over Height, 60" Length

Frame Types:

High-Step, Mid-Step, Compact

Frame Colors:

Graphite, Mint, Red, White

Frame Fork Details:

Rigid Alloy, 11 mm Axle with Bolts

Frame Rear Details:

11 mm Axle with Bolts

Attachment Points:

Bottle Cage Bosses, Fender Bosses

Gearing Details:

1 Single Speed, 11T Rear Sprocket


170 mm Crank Arms, 44T Chainring


Wellgo Aluminum Alloy Platform, Cage Type


Custom CNC Alloy, 1-1/8"


Custom CNC Alloy, Hollowed


22.5" Length, Aluminum Alloy, Flat or Swept Back

Brake Details:

Formula C1 Mechanical V-Brakes, Formula C1 Levers with Motor Inhibitors


Rubber Ergonomic


Velo Ergonomic

Seat Post:

Aluminum Alloy

Seat Post Length:

350 mm

Seat Post Diameter:

31.6 mm


Alloy Double Wall, BMX Brand, 32 Hole, Brass Eyeletts


Stainless Steel 15G Front 12G Rear, Silver with Single Red Accent Spoke

Tire Brand:

Kenda Kwest, 20" x 1 1/8"

Wheel Sizes:

20 in (50.8cm)

Tire Details:

40 to 65 PSI

Tube Details:

Presta Valve


Plastic Chain Guard, Side Mounted Kickstand, USB Charging Port Beneath Display, Second USB Charging Port on Battery (Acts as Power Bank), Frame Integrated LED Lights, Flick Bell on Left Bar, Optional Clamp Rack $59, Optional Front Basket $59, Optional Plastic Fender Set $29


120 kg (260 lb) Max Load, Locking Removable Battery Pack, 1.8 lb 2 Amp Charger

Electronic Details

Motor Brand:

Yunbike C1

Motor Type:

Rear-Mounted Gearless Direct Drive Hub
Learn more about Ebike motors

Motor Nominal Output:

180 watts

Motor Peak Output:

250 watts

Battery Brand:


Battery Voltage:

36 volts

Battery Amp Hours:

5.2 ah

Battery Watt Hours:

187.2 wh

Battery Chemistry:


Charge Time:

3 hours (2 Hours for ~80%)

Estimated Min Range:

10 miles (16 km)

Estimated Max Range:

25 miles (40 km)

Display Type:

Yunbike, Fixed Backlit Monochrome LCD


Battery Level (4 Bars), Speed in km/h, Assist Level (1-3), Trip Distance, Total Distance, Hold + Button to Activate Lights and Display Backlighting

Display Accessories:

Walk Mode Trigger Throttle on Right, Power Button on Battery (Pressing Alternates Rear Light Mode: Solid, Chasing, Flashing), UMA Smartphone App (Distance Ridden, Map History, Battery Level)

Drive Mode:

Torque Sensing Pedal Assist (Strain Sensor in Motor)

Top Speed:

15.5 mph (25 kph)

Written Review

The YunBike C1 is a dainty little electric bike from Surface 604 that leans more towards human powered cycling than zippy moped or gocart feel. Weighing in at roughly 35 lbs with the battery attached, it’s one of the lightest weight electric bikes I’ve ever tested… and yet it’s also one of the most affordable. The bike keeps things very simple with just one gear (making it a single speed) but doesn’t compromise on safety or utility with integrated LED lights and a plastic chain guard. It’s also no slouch in the style department, coming in four different colors and two frame designs. You can choose from either the traditional high-step diamond frame or a unique angled top tube mid-step that might be easier to stand over for petite riders. They’re clearly going for a his and hers dynamic with the colors and frame differences but in practice, the two are basically the same size. The biggest difference I noticed is that the mid-step “hers” frame comes with a swept-back handle bar that will be easier to reach.

If you’re venturing outside of the neighborhood, keep in mind the YunBike has a more limited top speed of just 20 Kilometers per hour (15.5 mph) vs. the more traditional US top speed of 20 mph. Given the smaller 20″ wheel diameter and narrow tires, I’m not sure I’d feel comfortable going too much faster than 20 anyway. The brakes are sort of average; cable actuated linear pull design with old-school rubber pads, but they get the job done. Both brake levers send a signal to cut motor power for safety. I did notice a wheel release lever on the brakes that helps them spread wider and get around the tires which was nice. Again, lots of the details on this bike have been scrutinized and optimized. That includes the threaded bosses on the downtube meant for adding a water bottle cage. Believe it or not, many e-bikes forego this sort of thing. The bike has a QR code printed on the stem that you can scan with your smart phone to download their app (or search for UMA Bike) but it freaked me out at first being all in Chinese in the screenshots. I took the risk, downloaded it and explored the different settings. Basically, you choose your type of bike and can then connect with other riders in a social area, see a map with points of interest or read your ride stats. Sadly, despite having a newer phone and trying my best to pair via Bluetooth I was unable to actually get the app going.

In terms of drive system performance and layout, I feel that the YunBike makes a couple of good compromises. First, because it has such a small capacity battery pack, the YunBike has opted for a pedal-assist only drive mode configuration. This is a mixed blessing because remember, it’s a single speed bike. By making you work a little harder, the motor can operate more efficiently and thus provide a decent range per charge. The downside is that struggling feeling of starting out from zero. Yes, the assist does kick in and help you but it’s not as much as other ebikes. Frustratingly, there is a trigger throttle sitting RIGHT THERE begging to be pressed… but when you do, it only gets you going a couple miles per hour as it is set to be a walk mode trigger. Maybe they will change this in the future but at least it does something. And, hidden just below the display panel is one of two USB charging ports! This could be used for additional lights like string-lights for the holidays, keeping your phone topped off (especially useful if you’ve got the app running) or perhaps powering portable speakers. The second USB port is built right into the battery pack and is designed to be used separately from the bike… like a backup power bank. Very cool little additions here in my opinion.

Overall, the bike is easy to use and understand. It’s a bit rear-heavy given the motor and battery are both at the back and there’s more effort involved with pedaling but it’s still easier than a non-electric bike. They felt moderately comfortable but clearly aren’t designed for touring or off road riding. Surface 604 does sell optional front and rear racks as well as fenders for people who want to commute or have to endure inclement weather. The bike isn’t perfect but the price is inspiring and I could see myself hopping aboard for quick neighborhood errands and simple enjoyment. Not a lot can go wrong if you just top the battery off now and again and keep those tires from getting too low. Seriously, because they are so narrow, it will be easier to get pinch flats by jumping curbs or just letting them go soft so check regularly. And that’s one of the little bummers here, the tires on the mid-step model didn’t say how full to inflate them? I was guessing upwards of 50 PSI depending on your weight, similar to road bike tires and then discovered that the Kenda Kwest model tires on the high step model do say 40 to 65 PSI. Big thanks to Surface 604 for partnering with me for this review.


  • Even though this ebike just looks like a cute getaround type product it can actually become quite practical if you purchase the optional front or rear racks and fender set… it’s neat that it comes stock with a plastic chain cover to keep you clean and all of the accessories are priced well and fit perfectly vs. trying to find something yourself aftermarket for such a unique sized bike
  • I was impressed with the little kickstand, funny as that might sound, because it’s sturdy and mounted far back – out of the way of your crank and pedal so you can oil the chain or walk the bike backwards without colliding
  • The four color options are really fun and the little style enhancements like a single red spoke and the unique tire tread add a bit of charm
  • I love the mid-step frame, it is still sturdy and basically the same dimensions as the high-step but makes mounting and standing over the bike easier for shorter riders, it also has a curved back handlebar to shorten the reach :)
  • Both models have comfortable ergonomic grips and come with basic flick bells so you can signal to other pedestrians or your friends in a cheerful way
  • I absolutely love that they included two USB charging ports! The first one is easy to reach and use while riding (mounted just below the display panel near the right grip) and the other one is on the protected end of the battery pack meant to be used when you aren’t riding… like a backup power source for your portable electronics!
  • Whether you’re riding for fun around the block or using this as a compact light weight commuter the integrated LED lights improve safety and keep you seen by cars
  • This ebike is very affordable at just under $1k but doesn’t compromise on style or warranty, you get one year comprehensive coverage from Surface 604, a company that has been around for several years as of this review in 2016
  • Being a single speed, the bike isn’t going to get out of true as easily… you won’t have to worry so much about dropping the chain or dealing with a derailleur and shifters that might otherwise crowd the cockpit bar area
  • I love that the battery can be removed to reduce the weight of the bike and that you can charge it on or off the frame… sort of, the plug at the base can be a little tricky to reach and plug/unplug as a result
  • The gearless motor is very durable and quiet, it should hold up well with lots of use but does weigh a bit more than geared motors, though it’s so small that the weight isn’t so bad
  • I love that they were able to fit bottle cage bosses on both frame types! This makes it easier to bring along hydration (note that it’s a tight fit on the step-thru, consider a side-mount cage like this), a mini-pump with Presta interface or something like a folding lock for security


  • Try as I might, I was unable to figure out how to change the display panel or the smart phone app from Kilometers per hour to Miles per hours… perhaps they’re trying to help America finally convert to metric ;)
  • The app is shown with Chinese characters when you search for it in the app store or scan the QR code on the stem and it’s rated 17+ age strangely… but once downloaded it is in English and allows you to search for points of interest, get feedback about your ride and connect with other riders
  • My heart was broken when I discovered that the trigger throttle only activates a walk mode… not a throttle mode (meaning you can only go a few miles per hour with it vs. top speed), this would have been very useful for getting up to speed after stop signs and lights considering the bike only has one gear
  • Because the YunBike uses a torque sensor for pedal assist I felt like I had to push harder and work more than with other “neighborhood” electric bikes, that’s not something I always want, especially since there are multiple levels of assist and sometimes my commute is short so I’m not worried about conserving power
  • The ride isn’t super comfortable given the super skinny tires… they are efficient and light but the bike doesn’t have any sort of suspension so this is really your only shock absorber aside from the saddle, consider swapping the rigid seat post with a 31.6 mm suspension post like this Thudbuster short travel model but note that it will raise the minimum saddle height a bit
  • The battery isn’t especially large, nor is the motor especially powerful at 180 watts nominal, thankfully the top speed is lower at ~20 km/h (that’s 15.5 mph) and you have to pedal to get the bike going so range doesn’t suffer quite as much as with comparable bikes
  • Overall, this electric bike is more like a bicycle than an ebike and for someone like me who rides a LOT of ebikes for reviews, that was a bit disappointing at first… but then I came around and enjoyed the simplicity of it
  • The narrow tires could get pinch flats more easily so keep them full… unfortunately they don’t have a recommended PSI range printed on them so I’m guessing 50? And, the narrow 20″ tubes to replace them might be difficult or expensive
  • The brake lines are reversed from what I am used to in America… the right lever activates the front brake vs. the rear and this was confusing at first, I have heard about some people having an instinct for which lever to pull and ending up feeling uncomfortable when it isn’t set up their way, perhaps this could be adjusted by your local shop?


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Comments (18) YouTube Comments

Jakub Ditrich
4 years ago

Are you serious to call Surface 604 a maker of this bike..? That is really funny.. this is UMA C1 from InnoMake Technology in Hangzhou – China, backed by Xiaomi – check it out here. Also the price offered is about 5 times higher than the retail in China. So guys, calm down.

Court Rye
4 years ago

Hi Jakub! Someone else mentioned this on YouTube and I was told that this was a bike that had been designed outside of Surface 604 when I covered it. My approach is to take each model at face value… regardless of what it costs on the other side of the world, regardless of who the original designer was, the review I shot accurately reflects the hardware and user experience in the USA. For me, ~$1,000 is still a decent price for the bike and the reputation and warranty from Surface 604 is good :) I’d rather buy from them than risk having it shipped and given that they negotiated a business relationship with InnoMake or Xiaomi and are legally carrying it as a rebranded product is all good. That’s how business works… many of the computer products we buy in the US for example, are also made by third party companies that are less well recognized. Note that I did critique the app for not working quite right and having Chinese (or another language) in the search results. I think the review is fair but I welcome your thoughts and appreciate the call out.

I also want to mention that if the YunBike had been fully designed by Surface 604, I believe the throttle would have worked for more than just walk mode and that would have been an improvement to the design in my opinion. It’s great when companies work together to approach international markets and bring better designs that fit the end user, I hope that InnoMake and Xiaomi read my review and consider the ways that their next iteration could be improved for people like me :)

Jakub Ditrich
4 years ago

hey Court. Thx for reply, I am chilled, don’t worry. Just dislike when the public gets confused, this is not an OEM stuff, the young chinese manufacturer is really rolling out its own brand. I can ask them if they gave to US company a permission to brand the product. The rest of your test is OK, I have had similar findings using this version of YunBike.

The price – well the market decide whether ok or high… Jakub

Meraj Husain
3 years ago

You will fail or fed up to get any spare part of this bicycle from company or factory or service Center. I have Facing The Problem. My display unit has broke, neither dealer nor company are ready to solving this issue. Just wait n watch.

Court Rye
3 years ago

Sorry to hear about this Meraj, I wish the situation was different for you but appreciate the feedback to help others :/

3 years ago

Just got a reply from Surface 604. They have dropped the Yunbike. I kind of liked the model. First I noticed that the drop bar frame model was nowhere to be found on the website. The higher frame model is still on the site, but no longer being sold.

Court Rye
3 years ago

Hmm, I wonder if you can find a dealer and get it at a lower price now that it has been discontinued? It was an interesting bike, I would have liked it more if the throttle was more useful :)

K Samson
3 years ago

Managed to get my hands on a brand new mid-step one of these for $450 cdn due to it being discontinued. Since I saved a bit of money I decided to beef the bike up with 1.5″ rims & tires (had to rebuild back motor wheel which was surprisingly easy) mid rise handle bars & longer brakes. Unfortunately, the frame will only accommodate the slight upgrade in wheel width to 1.5″. Anything bigger will rub against the frame, but even this small upgrade makes for a dramatically improved feel & handling on the road. I’ll likely throw on a suspension seat to improve it further.

The biggest bonus with the bike is the battery pack with its usb port. Detached it from bike and brought it to a cabin retreat where it provided enough off the grid power to recharge 4 phones and 2 laptops for a week.

Court Rye
3 years ago

That’s awesome! Good for you, hope the YunBike works out well and thanks for sharing some of the upgrades you figured out :)

1 year ago

Charger price? Where I can buy charger in Richmond, BC Canada? Anywhere available on line?

1 year ago

Hi Khurram, I’m not sure about this. Perhaps you can contact Surface 604 directly and ask? I don’t think that they sell the YunBike anymore but the charger may still be available, or someone else might chime in :)

12 months ago

Where can I buy C1 model charger and tire tube in Vancouver Canada?

12 months ago

Hi Nireman, I’m going to email you and someone who used to work with Surface 604 to see if they can help you. I called them and they thought they might have an extra charger! Keep an eye out for that email today and if you don’t see it, email me or leave another comment.

10 months ago

Please let me know where to buy charger for Surface C1 in Canada.

10 months ago

Hi Nireman, unfortunately, I don’t think they sell them anymore and I don’t know where a charger could be found. This came up from another user a while back. You may be able to search and ask around in the EBR Forums here.

6 months ago

Please tell me the length of the rear wheel spoke. The unit is centimetres. I think there are two kinds of spokes.

6 months ago

Hi June! Honestly, I’m not sure about the length of the spokes on this one. Perhaps someone else will chime in to comment :)


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