First Look: Rubbee X e-bike conversion kit

I dreamed of jumping on my bike and cruising across town with as little effort as possible. Problem was, my bike is a very basic six-speed folding model, and not so easy to use in hilly Wellington. So, I decided to investigate how I could upgrade my basic bike into an e-bike.

E-bikes are growing in popularity, but they come with a large price tag. An alternative (and cheaper) option is to convert a standard pedal bike – one you might already own – to an e-bike.

Personally, I wasn’t convinced I wanted an e-bike all the time. Short trips to the shops don’t need extra power. But I did want a boost for long or hilly rides, so I did some research into removable e-bike conversion kits and came across the Rubbee X.

The Rubbee X is a removable motor that mounts on your bike’s seat post. It’s a self-contained plastic box with controls, batteries and a wheel that sits on top of the rear tyre and moves the bike by pressing on the rear tyre and providing drive. Pronounced ruby (it’s hard not to say rub-ee, seeing as the drive unit rubs on the tyre), it’s easy to install and remove, can be quickly swapped onto another bike and is inexpensive compared to other e-bike conversion kits. I thought it was a winner!

Types of e-bike conversion

If you want to convert your standard pedal bike to an e-bike, you’ve got a few options available. It depends how permanent and easy to install you want the conversion to be, which in turn depends on where the e-bike unit is mounted.

• Front hub – mounted on the hub of the front wheel, this type of e-bike motor powers the bike by turning the wheel. This type of installation is semi-permanent; it can be removed by replacing the wheel.
• Mid drive – mounted on the body of the bike, this motor powers the bike through the turning of the gears. This type of installation is permanent.
• Rear hub – mounted on the hub of the rear wheel, this type of e-bike motor powers the bike by turning the wheel. This type of installation is semi-permanent; it can be removed by replacing the wheel, but swapping out a rear wheel is more difficult than a front wheel due to the gears.

The Rubbee X is similar to a rear-hub conversion, in that it powers the back wheel. That’s where the similarity ends though, as the motor sits above the wheel and drives the tyre. It’s also far less permanent. There’s no need to remove the tyre (or any other part of the bike) to revert to a standard bike. The Rubbee X can be removed without using any tools.

The big attraction of units like the Rubbee X is their quick and easy installation.

Pedal-assist e-bikes

You'll need to decide whether you want your new e-bike motor to be pedal assist or throttle controlled.

Throttle-controlled bikes work as you would expect. When you push or twist the throttle, the motor goes. You don't need to be pedalling the bike.

Not all e-bikes have a throttle. Most use a sensor to detect when the pedals are turning, before engaging the motor. You need to be pedalling to get motor assistance, and when you stop pedalling, the motor stops too.

This type of e-bike – known as pedal assist – still gives you a boost, while conserving power usage. However, you do need to put effort into pedalling, even with motor assistance.

The Rubbee X converts your bike to pedal assist, with the cadence sensor mounted on the pedal.

Installation

For me, installation was where the Rubbee X really stood out.

The Rubbee X unit clips (without tools) onto a bracket fitted to the seat post. Any time you want to remove the unit, you unclip it from the bracket. Then you can store it or mount it on another bike. All up, adding or removing the unit takes only a few seconds.

Fitting the bracket to hold the unit was also easy. It’s held in place by four bolts fixed with a hex key and adjusting the height so that the motor unit is pressing on the tyre properly takes only a few minutes.

Getting ready to use the Rubbee X is simple too. Once it’s clipped onto the seat post, simply lower the unit until it’s resting on the tyre and you’re ready to roll.

If your bike has a rear rack or a mudguard over the back tyre, these will need to be removed so the motor can make contact with the tyre. This was the most time-consuming part of the installation for me, as my bike had both a rear rack and mudguard. No need to worry about getting splashed though, as the Rubbee X stops any mud and water flicked up from hitting you.

Power

There is no denying the Rubbee X provides plenty of power (see specs below).

The unit has three power settings that correlate to the number of batteries you have – the more batteries, the more power. The Rubbee X base model comes with one battery which can power Eco mode. Adding a second battery gets you Cruise mode, while three batteries enable Power mode. You can buy the batteries separately, so if you want to start with the basic kit (one battery), you can upgrade later.

When I first put the Rubbee X on my bike, I set it to Cruise mode: straight away it gave me a surprising kick. For biking through town, I could happily keep it on Eco, or Cruise if I fancied a bit more speed. Even on Cruise, the power is a bit much for my little folding bike but would be perfect for a bike with bigger wheels. I tried out Power mode on the hills and had no trouble cruising up, something I wouldn’t normally be able to do. I just had to try not to stop, or it was hard getting started again.

Changing the power mode on Rubbee is easy if you have long arms. A button on the motor lets you cycle through all three modes, as required, but you need to reach to the back of the motor to do this. Alternatively, if you are using the app you can also change the power mode here.

Ease of use

Riding

I found riding with the Rubbee X to be easy, so long as I was pedalling.

The Rubbee X motor engages whenever the cadence sensor on the pedal is moving, which means you need to put in some work before the motor will start. If you stop pedalling, the motor stops running and then you can feel some resistance on the tyre.

The only time I found this extra resistance an issue was when I had to start pedalling on an incline – for example, after stopping at lights on a hill. Then, I had to put in real effort to get going again, but a second later the motor kicked in and I was off.

Biking in wet weather was a bit of a concern as this motor unit relies on friction with the tyre, but I didn’t find this to be a problem. If the unit is mounted at the correct height for good contact with the tyre it shouldn’t slip in wet conditions, but if it does then readjusting the unit height is quick.

The App

The Rubbee X app is designed to be like a dashboard you use while biking, showing speed, power and remaining battery life, and allowing you to change power modes. It can even tell you the temperature and voltage of the motor.

The app connects via Bluetooth to the motor. I had some connection issues when I first set off, probably because there was a human body between the phone (mounted on my handlebars) and the motor (behind my seat). When it did connect though, the information displayed was helpful.

Admittedly, I don’t use my phone while I’m biking – I’m out there to enjoy the scenery – so the connection issue wasn’t an inconvenience for me. If you’re a stickler for data, you might find it more frustrating.

Charging

Charging the Rubbee X was a breeze. You can either charge the motor while it’s still attached to the bike or unclip and charge it in a more convenient place. The motor unit has lights to indicate charging progress, which turn off when it’s fully charged. You can also check the battery level via the app.

Changing between bikes

This also couldn’t have been easier. Simply unclip the Rubbee X from the mounting bracket and clip it onto a mounting bracket on another bike. This does require you to have multiple mounting brackets and extra ones cost $179 each. But if you don’t want to fork out for an extra bracket, moving the bracket between the bikes only takes a few minutes.

Noise and wear on tyre

This was a big concern for me when I started using the Rubbee X. The motor rubs on the tyre, so would it be loud and annoying?

However, while there was some extra noise compared to an unpowered tyre, it isn’t excessive or distracting.

My second big concern was whether the Rubbee X would cause additional wear on the tyre. During the time I used the unit, I saw no signs of extra wear. If you were using your Rubbee X all the time though, it would be reasonable to expect more wear than normal.

The Verdict

The ultimate question is: would I buy this e-bike conversion unit for my own bike? The simple answer is yes!

For my biking needs, which are across town trips (not too many hills) and weekend leisure rides, the Rubbee X was awesome. And at less than $1000 for the basic kit it’s a budget friendly option for e-bike conversion. A pedal-assist e-bike isn’t the best choice for everyone, as you still need to put in effort before the motor kicks in. But I think the Rubbee X is a great option for casual riders or those not willing to commit to a full e-bike yet.

Rubbee X specs

Compatibility:

• wheel size – 16–29 inches
• tyre width – 0.5–2.5 inches
• seat pole diameter – 22–35mm.

The Rubbee X was kindly lent to us by Rubbee Australasia for this review.