I’m trying to convert both my wife and I’s bikes into ebikes so we can ride them more often and drive our cars less. I’ve never done somethings like this. For the very little I’ve done so far, there are three types of kits: front hub motor, rear hub motor and mid drive motor. Which of these is best for inner city commuting? Which one is cheap and easy to install?
To my knowledge:
- Cheap/easy: usually front hub kit
- Best: depends on frame, mid if possible (gears, p/w ratio)
I’m a hobbyist though, and it sounds like you’re aiming for economy. My impression is that the economy of conversion has become increasingly debatable; i.e., it may be less expensive in the long run to sell old bikes and buy prebuilt as opposed to modifying what you have.
How mechanically inclined are you?
I did a mid drive conversion because of the lower centre of gravity and to not have to move the motor’s weight as the tire spins. However, rear wheel seems easier and was fairly cheaper the last time I looked (approx 4 years ago). I believe the rear hub comes preinstalled in the wheel, so you’ll need to switch over the tire but that is easy.
It was a fairly easy process, hardest part was removing the bottom bracket with only 1 person (tool would slip, ended up using ratchet straps). Took a couple hours of work but I had everything I needed to do the job.
You’ll need:
- battery (likely most expensive part)
- battery mounting hardware (depends on where you put the battery)
- motor
- zap straps to tidy up the cables
- Allen keys
- bottom bracket extraction tool (if you go mid drive)
From what I saw, front drive motors were the least desirable as it alters the bike’s handling and feel.
In my neck of the woods the motor was ~$400 and battery ~$800 but I went for a large battery.
I actually kinda like front drive but it has to be torque sensor on the bb, and very dialed in. It gets this pseudo-dual drive feel. It was less of an assist and more of a mirroring what my legs put in to the rear, except for when the gears changed 2 or more positions. If there was a reliable way to track gears and match the motor output I would have kept that bike. Realistically though I would also recommend mid, especially for hilly routes.
What kind of bottom bracket did you have? I’m still not familiar with all of them but so far the ones I worked with haven’t been that troublesome sounding.
Here is a breakdown of everything I did on my bike.
this is similar to the bottom bracket tool I used. I’m not sure what variety of bottom bracket I had, but this tool fit. Just needed a second person or a ratchet strap to hold the tool on without slipping.
Well, it’s rather simple these days, just slap an ‘e’ on it and you’re good to go!
Bikee?
It does depend how hilly your area is, mid drive will be a lot better at tackling hills when compared to a hub drive motor so I think you should factor this into your decision.
When I built mine (10 years ago) mid drive was considerably more expensive as well although I’m not sure on the prices now, I presume it is still similar as hub motors are generally just cheaper tech. Mid drive will also come with additional costs in the form of wear and tear, it puts considerable amounts force through your drive chain which will wear out chains, cassettes etc a lot fast so you will be needing to replace them as general maintainance when they start to wear out, you also need to bear in mind you may snap chains due to the additional torque going through them.
Hub motors are going to be cheaper to maintain as well as install. Essentially you are just adding the wheel with the motor on, running the cabling to your controller, battery etc and away you go.
You should add some form of torque bracing with those little arm things, you can get a battery that attaches to your bottle cage mounts but it is a pretty simple install.
I personally think you should go rear hub and it keeps the weight over the back of the bike, it drives the correct wheel so you weight keeps it from just spinning out but also I have heard of motors twisting forks from the added torque where as I’ve never heard of one twisting a frame in the back.
The easiest will 100% be a front hub motor but then all that weight is over the front of the bike and it just seems wrong to me personally to drive a front wheel but you need to weigh up the factors and decide what is best for you :)
If you can fit one, i heard mid drive is the best, especially one comes with torque sensor. Pros: it seems easiest to fit and maintain, and from others that ride with it they said it’s the best way to drive the bicycle. Con: it’s the most expensive option.
The next choice is rear hub, but you will need a pedal assist sensor or torque sensor added to your bottom bracket to get the function. Pros: it drive from the rear, pushing all the weight in front of it in a much stable way. Also cheaper than mid drive. Cons: it will makes servicing the rear wheel much more complicated with all those wire running around.
The last choice is front hub, it’s for when your bike’s rear hub spacing can’t fit a motor hub and you can’t reasonably cold set it. Not an issue for more recent bike, but if you have old bicycle with single gear, this is always the case, like my old bmx. Also for when you have internal gear hub. Pros: it’s easier compared to rear hub to convert your bike, and maintenance is less complicated. Cons: it will skid a lot when the motor kicks in. Like, a lot. Especially when you throttle to help start the motion. It basically trying to pull the weight of the bike, which usually at the rear, and it will have some hard time gripping the ground while pulling the load, especially when you goes full throttle. In my experience, it’s not possible to ride in full speed the motor is capable of because of the fluctuating traction. It’s also made for a bad sand bike as the front will very likely dig into the sand and make you fall down(experienced this myself). Still, it’s very capable to ride up to 23kmph and pull me uphill, which is good.
For the motor power, it based on how hilly your ride is and how heavy the whole bike + cargo + rider is. In general 250w nominal 400w peak is enough to handle anything, anything above that will give you a bit of boost if you’re on a heavy side. Mine is front hub 36v 250w nominal 450~500w peak, and it can drag a roughly 95kg total load(55kg me + 35kg bike + 6kg grocery) to go up to 23kmph, albeit i need to pedal harder when going uphill. Though for the voltage, 36v is the minimum you should have, 48v is much more common and can deliver the power better.
As for the battery capacity, since you mentioned intercity, i’d suggest something more than 10ah so you can commute 2 way without charging. 15ah is ideal, taking those range anxiety away. My 15ah lead acid battery(i know i know) can go for 44km round trip with 60% or so capacity to spare, with climb around 220m.
Easiest to install would probably be one that attaches to the back and runs the wheel by friction.
I’ve tested one of these that a friend had. I feel like if I bought and installed that I would resent it, the money I spent on it, and myself for not just spending a bit more and getting a stronger motor. If its someone living in flatsville, flatoslavia where the biggest hill is only recognizable by ants… no who am I kidding, I’d just ride a non electric fixie or 3 speed igh.
