Looking for an ebike conversion and not sure where to start?
One of the many things we do here at Grin is supply conversion parts to people who are making their own electric bicycle. We've been doing this as a business for over 15 years and most of our customers are quite seasoned too, often doing their 3rd, 4th, or 5th ebike build. But for those who are new to the scene on ebike build number one there can be a lot to take in and this page is to help you navigate through those initial steps.
Is a conversion from Grin right for me?
Presumably you are here because you want an electric bicycle for one reason or another (there are lots of great reasons) and are open to the possibility of converting a regular bike rather than just buying a pre-made factory ebike. There are quite a few advantages to this approach which we have summarized in this article here. [Link to DIY vs Factory Ebikes]
That said, a DIY retrofit is not for everyone and there are now countless factory ebikes on the market spanning the gamut of price ranges and performance. If you are happy with one of those and just want to buy a turn key setup rather than fiddle making your own, then by all means that's what you should do.
If you are drawn to the DIY side for any of the reasons above then we are here to help. There are two qualities that are important to us if you're planning to be a Grin customer:
1) You are keen to take on a project more than just buying a product
2) You generally have a hands-on and a can-do attitude when it comes to making and fixing things
Not everyone is onboard with item 2 but if you have a close friend, family member, or neighbor who fits that description and wants to help you with the build and any troubleshooting, then that works too. We don't expect you to have a multimeter in your toolbox to measure voltages, but we'd expect you to gladly purchase one if a certain troubleshooting step requires it.
What parts are needed for a conversion?
An ebike conversion at the very minimum requires a battery pack, a motor, a motor controller, and a throttle or pedal sensor. For an explanation on the role of each component, please read the following page:
At Grin, you have the option of getting all of these parts together as part of a kit bundle, or ordering them separately from our parts page. You can also order some parts from us and others from a 3rd party if you know what you are doing. Unlike many places we are totally cool with that.
What skills do I need to convert a bike?
Fortunately the ebike components that we sell today are much easier to fit on a bike than they used to be. You don't need to solder electrical joints, crimp connectors, lace up a wheel or anything like that. If you have the general mechanical aptitude to fix a flat tire or replace and adjust your brakes or derailleur, then you will likely be able to install a kit without too much difficulty in an afternoon.
Here is a video demonstration we did of a bike conversion at the 2019 BC bike show which shows the process of installing a basic front hub motor kit package.
We also wrote an article for Make Magazine which shows the step by step sequence of a similar kit install with the downtube batteries.
Those examples above are the basic scenarios. If you are adding a torque sensing bottom bracket or run into the many small but solvable fitment issues frequently encountered, then it could take a couple more hours and some specialty bike tools to get the job done.
OK, I'm sold, but you've got so many options I don't know where to begin
Usually this starts by having some idea of what motor model you want. This will be dictated both by the mechanical specs of the bike you are converting and by what you are after in terms of power and performance. The following page sumarizes the details of each hub motor model currently for sale at Grin.
If you've got a fairly conventional bike with slotted dropouts then most of these front and rear hub motor kits will fit without much fuss. If you've got either a very modern bike frame with thru-axle hubs, or a more special bike (tandem, trike, cargo, belt drive, folder etc.) then you should also read our bike compatibility guide which could rule out certain options.
To first order the motor selection determines the torque and power capabilities of the kit, while the battery voltage and capacity determines the top speed and range that you'll get on a charge. So you would first determine whether you want a smaller/lighter minimal assist system or a heavier and more powerful drive, and then select a battery model that will give you the desired range and speed.
When you add a kit to your shopping cart, it will tell you the unloaded wheel speed at various voltages, and also provide a link to launch our motor simulator with the selected components. These tools are technical but they do provide all the performance answers once you understand how to use them.
Throttle? PAS? Torque Sensor?
A more complicated question for newbies is whether you want a system that has just a simple throttle regulator for modulating the motor power on the handlebar, or if you also want a PAS or Torque sensor to power the bike automatically whenever you are pedaling. Read the following link for a nice summary of these pedal assist options.
Throttle only setups are simplest so if you are new to all this and don't want to be overwhelmed with choices we'd always say to start off with just a throttle and see that's all you need. PAS or Torque sensors are optional for all our kit bundles, and can always be added as a later upgrade.
If you do want a pedal or torque sensor though, you will be selecting either a Superharness based kit package, or a Cycle Analyst based packge. The differences between these are summarized in the Kit Type info page.
I'm still totally confused, can't you just advise me what to get?
Yes! About half of our inquiries start off with people describing their bike to us and asking what we recommend. We are very happy to do this. However, in addition to the bike make and model, we also need an indication of what performance you want out of the kit. This can be summarized by 3 details:
1) Speed: How fast do you want the system to be able to keep providing assistance.
2) Power: How much torque and power you are after. This doesn't need to be in watts or newton-meters. Are you climbing steep hills towing a 200lb trailer? Or are you a fit commuter looking for a speed boost on mostly flat terrain?
3) Range: How far do you need to go on a single charge? On this front we recommend always having enough charge to do your return trip, rather than topping up at work.
So please include that information with the inquiry to save us having to ask you. We'll usually have no problems recommending one or two systems from our catalog once we have an indication of those three points and a description of your bike.
But I heard mid-drives are better, where are your mid-drive kits?
Contrary to what you may have been told repeatedly, hub motor drives are the best option for a majority of ebike users, especially for regular commuters who require a high reliability and low maintenance vehicle system. We've worked with various mid-drive systems over the years and are quite familiar with them, but have decided to focus our business 100% on hub motors. You can read our reasons for that in the following article:
So tell us what exactly you need from the system and we can let you know if we have a hub motor solution that will do the job just as well or better than the mid-drive that you've been recommended.
Can't I just drop off my bike and have you install a kit for me?
No, Grin is not a bike shop but a technology and product development company run by engineering graduates, and we are not planning to have a service installing kits. We aim to produce and supply parts and information to people who are either keen to do an installation themselves or through a close friend or acquaintance. This also ensures that the person using the bike (or someone close to them) is familiar with how all the pieces go together so they can do first order troubleshooting and be much more resourceful when trivial things go wrong.
Then can you recommend a shop to install it for me?
We would love to say that you can take a kit to any bike shop and they will gladly install it and provide support and service too, but that is not how things are. Most bike shops are setup for simply selling proprietary factory ebikes and rely on the ebike manufacturer to provide warranty support via simple component swapping. They're not typically interested in getting their hands involved the electrical or custom side of things.
We are hoping to change this culture with conversion kits that have open standards and component interchangeability so that bike shops can embrace servicing and upgrading ebikes the same way that they do with conventional bicycles. We'll see if that gains traction. In the meantime if you really can't do an install yourself, there are the odd bike shops who have staff with a personal interest in DIY ebike builds and who can take on and embrace kit installations. So call around or check our dealers locator page.
You guys are so smart, why don't you make it super simple and easy and just have like 2 or 3 kits, get rid of all the confusing technical stuff and make a product for the masses? Who cares about volts or amp-hours or all this mumbo jumbo?
Because that is not what we want to do and who we want to be. We enjoy the challenge of filling niche applications that aren't addressed by mainstream products, pushing out innovative and customizable ebike parts to early adopters, and working with people who have creativity and needs that are a little outside the box. You can get a great idea on the diversity of builds possible by having a browse at the hundreds of customer conversion projects that have been uploaded to our project gallery.
We also take interest in educating people in how these things work, and that is reflected in the parts we design and offer which try to illuminate what is under the hood rather than hide it.
However, if you do want just a simple basic hub motor option that will work on almost all bikes, just get a barebones SX1 hub motor kit and select the correct wheel diameter for your bicycle.