Middrive vs. rear hub for my first e-bike

flyer23

1 µW
Joined
May 6, 2017
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2
Location
Seattle, Washington, USA
I'm looking to convert my cargo bike. It's a steel hybrid (Novara Metro) with an Xtracycle Free Radical attachment.

About my riding:
The good news is that I rarely go more than about 10 miles at a time. Oftentimes less than 5 miles. Even when I drive a car. Pretty much everything I need is close.
The bad news is that we live towards the top of a pretty decent hill, and everything I want to go to is at the bottom of the hill. It's about a mile, averaging about 4-5% grade, maxing out at about 7% grade. I would love to replace more car trips with bike trips, and I'm starting to realize that the hill is often the main factor when I choose to drive rather than bike. I can ride up the hill with no problems, but it's slow and sweaty and not much fun.

The other good news is that once I get off the hill, it's almost all flat, and I have no problem pedaling quite a bit to extend my battery range (and get a little exercise)
The other bad news is that I'm often hauling quite a bit of weight. I'm about 130 lbs, the bike is about 40 lbs, and it's not uncommon for me to haul 70-80 lbs of cargo or more.

Budget: I don't want to go super-expensive, since maybe I won't use this e-bike as much as I think I will... but I also don't want to cheap out, either. Seems like I can get a pretty decent build in the $1000-$1500 range, and that's fine. Cheaper would be great as long as it doesn't totally sacrifice quality. I definitely want to convert this bike vs. buy a new e-bike, too much sentimental value to this bike :)

I've been leaning towards a middrive, mostly for hill climbing capabilities and easier tire changes (I'm usually hauling my kids, so anything that makes a tire change take longer when you have kids running around is baaaaaaaad) and the installation seems doable. I've priced out BBS02's and BBSHD's in my price range... any opinions on whether the BBS02 is enough to meet my needs or if I should go with the BBSHD?

Alternatively, a local dealer has a deal on a rear hub motor that comes out to just under $1300 installed, 2-year warranty, and he'll throw in a rear disc brake, which I think is a good idea with the extra weight and speed of an e-bike. (I currently have rim brakes front and back.) If I wanted to add a disc brake with a middrive, I'd need to buy the brake itself plus a new disc compatible wheel, which really drives up the cost.

Or I could buy a rear hub kit myself... how tough are they to install?

Any thoughts on the best solution for my needs?
 
I think you'll be a lot happier with a mid drive like BBSHD or BBS02 than you will with a hub motor. Hub motors are easier to install, and they don't punish your bike's pedal gears. But they don't excel at a big range of loads unless you use a really powerful one, which means lots of weight and a costly battery. When your power is modest, you get much better performance at high speeds and on steep climbs by using the mid drive.

Tradeoffs of the mid drive include increased bike maintenance and having to think harder to get the best the motor has to offer. In your case, I think it's worth it.
 
Pretty much any choice will do fine for the little slope that you have. Yet the low speed that you ride would make most hub motor running poor efficiency. Also, the loaded cargo bike being heavy already, I believe the BBSO2 is your best buy.

A hub could be a very good choice if your bike had smaller wheels, or if you'd ride faster. The better brake on the rear is not a noticeable upgrade, it is the front brake that is doing most of the work.
 
7% is climbing 7 ft on a 100 ft course. If you find it steep, you must be living on the salted flats. :wink:
7% is 4 degrees of slope.
 
For the money and your needs a BBS02 would be the best fit. You'll probably use the throttle more than the cadence PAS and it really simplifies installation.
 
Triketech said:
For the money and your needs a BBS02 would be the best fit. You'll probably use the throttle more than the cadence PAS and it really simplifies installation.
The PAS in a BBS02 is completely internal. You don't need to install anything. I agree with getting a BBS02 unless you don't mind the extra money for the BBSHD.
 
7 percent grade is steep enough to make a lot of non-enthusiast bicycle riders walk up instead of pedal. I personally would need over 750W at the wheel to climb a 7 percent grade at just 12mph.
 
Cargo bike? Definitely step up to BBSHD. Much more forgiving than the BBS02.

I've found BB drives to be much easier to install than rear hub motors. In fact, my 1st BBS02 easily moved around to several bikes as sort of an audition. Once you have crank arm puller, BB wrench/socket tool and chain breaking stuff it's fairly simple to install and re-install BBSXX.

Hub motors (particularly rears) will often only fit the bike they're intended and dished for. And obviously, you can't swap a 26" hub motor wheel into a 20" wheel folder frame, can you? I easily did that with my BBS02....
 
Chalo said:
7 percent grade is steep enough to make a lot of non-enthusiast bicycle riders walk up instead of pedal. I personally would need over 750W at the wheel to climb a 7 percent grade at just 12mph.
If my mental math is still good, that would make you about 350 lbs. You have to admit that the average cyclist would need less than half that power, and that is on 1:1 gear ratio.
 
My local topography is similar to yours, I live 2/3rds up a fairly steep hill, but the rest of my usual routes are reasonably flat. I use my long tail cargo bike to haul kids and groceries. The bike (radwagon) started life as a pre-built 750W DD rear hub, but I found it inadequate on hills. The problem is that the moment you slow down at all, the DD losses efficiency, thus reducing the speed even further... you get the picture. I decided to change to a BBSHD and it is night and day. I can haul kids and stuff up the hill in a much more predictable and enjoyable way. So, for cargo applications and hills I would strongly recommend the mid drive based on my experience.
The install was straightforward even though I am an inexperienced bike mechanic. You do need a couple of tools such as the thing to extract the bottom braket and the special tool to tighten the motor.
 
OptimusPrime said:
The PAS in a BBS02 is completely internal. You don't need to install anything. I agree with getting a BBS02 unless you don't mind the extra money for the BBSHD.

Yes it is, and its pretty good for a cadence PAS. But it still sucks on gearshifts. Sure you can put a shift cutout on it but they are not without their troubles, especially climbing hills. Considering his ride profile and needs I figured he would mostly end up using the throttle.
 
Triketech said:
Yes it is, and its pretty good for a cadence PAS. But it still sucks on gearshifts. Sure you can put a shift cutout on it but they are not without their troubles, especially climbing hills. Considering his ride profile and needs I figured he would mostly end up using the throttle.

Yes you definitely don't want yo get caught on a hill in the wrong gear. But if you look ahead and anticipate your needs it's not a big deal. That said, I am a throttle man myself.
 
Thank you, everyone, for the input! You've convinced me to go the middrive route :) I've already gotten all the tools and such, and I've done some basic bike maintenance in the past (I did my Free Radical conversion on my own, and I've also swapped out cranks before) so I'm pretty confident I can handle the install.

Not sure if I messed up the grade calculations. Put it this way, I'm not a wimp when it comes to hills, but this one takes some effort, especially with a loaded-down bike.
 
A light bike with a light rider "might" get away with hubmotor. A fully-loaded cargobike? Get a mid drive. I find myself agreeing with Chalo's assessment (above) on this one. If you use a smallish chainring, and keep the motor spinning by always being in the right gear on that particular hill...the BB02 should work well for a 7% grade. personally, I think if you pay a little extra and get a BBSHD, you will be glad you did. I have more than one ebike, and have ridden quite a few different models at the Interbike meets. My BBSHD is the one I ride the most.

I may experiment with more volts or more amps, but...the stock 1500W is pretty satisfying. Plus...you can use only 750W, if you want to.
 
spinningmagnets said:
A light bike with a light rider "might" get away with hubmotor. A fully-loaded cargobike? Get a mid drive. I find myself agreeing with Chalo's assessment (above) on this one. If you use a smallish chainring, and keep the motor spinning by always being in the right gear on that particular hill...the BB02 should work well for a 7% grade. personally, I think if you pay a little extra and get a BBSHD, you will be glad you did. I have more than one ebike, and have ridden quite a few different models at the Interbike meets. My BBSHD is the one I ride the most.

I may experiment with more volts or more amps, but...the stock 1500W is pretty satisfying. Plus...you can use only 750W, if you want to.

ding ding ding...best post of this thread! :D
 
Go for a 48V 1000W hub motor. It will have plenty of power. Cost less than half a mid drive setup. Last many times longer. Won't wear out your bike gearing, and will work even if your chain bike gears break. It will also give you regen/electronic braking for stopping power. A 7% grade is nothing for a standard wind DD hub motor hauling up to 275 lbs. That's what I used to weigh. Any 48V 1000W 470 rpm or less motor. The only drawback is the tire is a little harder to change. But not much.
 
A hub build is possible and likely to be more reliable, but would require speeding. Climbing 7% is not steep for a hub, but it has to run in its efficient speed zone. I climb 10% avg for 2.5 miles almost everyday, and I do it with a badly overpowered hub motor without any cooling, at 50 Mph. At the top, my motor is barely warm.

The typical ride with a cargo bike is slow, when you have kids as cargo especially. A hub build, even with a slow winding, would need to be in a smaller wheel. That is why I recommended a BB drive, that would let the user climbing slow.
 
All above have posted great info. After almost a year riding a DD hub motor at 2300w, I'd absolutely recommend a mid-drive for your intended uses. All around a little more versatile than a hub motor. Don't get me wrong, I love cranking the throttle and feeling the rush of acceleration with no shifting or pedaling, but for a more utility oriented bike with precious cargo, mid-drive's the ticket.
 
If you do lots of miles, you should consider direct drive.

I had few bbs02 and they all started to have problem at some stages... because parts do wear down.

If you don't want to open the motor for fixing, don't want to change frequently the chain, the brakes pad, change the cassette... then go DD.

You'll thank me later, especially if you do lots of miles.

Mid drive is nice when you don't cycle much, but as soon as you do 500+ miles / month, dd is a no brainer
 
Hub motors can provide all the torque you need for climbing, but you need to choose a low speed one. Most DD motors are too fast for a cargo bike, but a 12T MAC or 201 rpm Bafang BPM would have no trouble hauling heavy loads up hills. There's no answer to which is the best. they both have advantages and disadvantages. Hub motors are normally cheaper. Crank motors are easier to fit, provided that you have a standard bottom bracket (check first). Hub-motors give a more relaxing ride due to less gear-changing and crashing gears. Crank motors have a better speed range. For me, I'd choose a hub-motor for road use and a Crank one for off-road, but I don't have a cargo bike.
 
O'course the one option that no one has mentioned to you is the Stoke Monkey. Direct drive or geared hub motor driving through your gear train via a tandem crank set and totally under your throttle control. For someone dealing with the combination of issues you've cited this would seem to be ideal!
 
Clearly, there are good things about any of the options. I just want to mention that I see a fair number of "cargo" bikes around, with 750W direct drive hub motors. We have hills here, 4-5% is more common but there's some 7%. I can't guarantee that everyone with one of those bicycles actually uses it to carry heavy loads. The model I usually see has an advertised weight of 73 lbs, and payload capacity 350 lbs. That payload isn't going up a 7% hill, but your 300lb total weight should be doable under 750W.
 
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