I am researching the heck out of a bike I can use as an overland trail bike. We have a Winnebago Revel on the way and need to match it up with a bike that can get us around some cool trails.
I've noticed some bikes have the option of a 350 w Mid Drive and a 500 w Hub Drive. Can someone help me compare these? I know there are some positives and negatives to both.....
BTW - such a great forum ! This site rules!
Not all hub drives are equal and not all mid drives are equal.
First thing you need to do is decide on a budget.
If it's no more than $2000, that answers your question right away - rule out mid drives. Very few will be found with mid drives on them below this price, and if they are I would run far away, bc its very hard to build an ebike with a quality mid drive below that price (for now anyway).
Generally You wont' find a quality mid drive on a quality ebike for under $2500, nor many models or brands, and you are best starting at around $3000 budget if you want a mid drive thats going to provide the reliability (i.e. not stripped or failed after one season) you likely want to see in any ebike purchase. (irrespective of drive type).
In general, the mid drive (vs Hub) will give you the following:
1) Usually better torque for a given wattage of motor you choose.
2) Usually a better range for a given battery capacity
3) Hill climbing ability will vary greatly between mid drives - for example, Evelo couples their mid drive with a Nu Vinci hub, which allows you to override a 'transmission' to simulate 'gear 1' of a cassette or freewheel on a regular bike. The NuVinci replaces a traditional geared derailleur. For any mid drive comparison, You want to look at the torque specs to compare. If you are seeing 60,70 80 NM (newton-meters) thats pretty darn good. (often hub drives are generally around 30,40, or 50 nm,) Rear hubs can also see that level of torque (up to 80 nm) depending how they are designed, and geared internally. One example is the 350 Watt Hub drive on Surface Boar. Its rated at 80 NM, and it 'feels' like the power of a typical 750 watt motor, but the trade off with that is it's top end speed is limited to 20 mph. So if you are off roading, its an excellent bike for hilly terrain, again in a rear hub drive.
4) Mid drives can provide a lot more wear and tear on chains and cassettes, and with that higher torque, can stretch the chains/weaken links, and wear out the cassettes or free wheels faster than hub drive given the same wattage, and other ratios between crank gear, and rear cassette. (Note I use cassette and free wheel interchangeably in this dialogue. For simplicity Im referring to the traditional 6 to 10 sprockets you see on a rear hub regular bike or in this case too an ebike)
5) If the mid drive does have a torque sensor, and its properly tuned, the ebike will feel a bit more like a regular bike in terms of the fact that as you press harder, the greater the response is from the drive, and the resulting output to the wheel is similar. Keeping in mind, that motor is applying A LOT more leverage and torque than you as the rider would traditionally do without assistance. I've read up to 5 times, but haven't checked out the physics calcs myself.
6) Over time, mid drives will have more maintenance, and are more complex, and require much more sophisticated software to operate proficiently, than do rear hubs.
They are rarely able to be 'serviced' by the typical ebike shop tech, and usually require full replacement or being sent back to the manufacturer for repair. This varies by brand. Bosch, Brose, Yamaha are known to make some quality mid drives, but they are pricey. Less costly mid drives are available from BaFang and E-Rad.
7) may be a little easier to deal with a tire change on mid drive than hub drive.
Rear Hub Drives will give you the following:
1) For about roughly $700 to $1000 less (retail), you will get a hub drive equivalent in rated wattage/torque on a given ebike, than if its equipped mid drive. Thats NOT the extra cost of the mid drive motor per se, but usually the price gap on the entire bike, where ebikes with mid drives have tended to be more feature rich overall and generally (not always) come with higher end components in general on the entire ebike, and OEM's also usually demand higher margins when selling them. Its as though their thinking is 'hey anyone who can afford to plunk down $3500 for an ebike, probably will have no issue plunking down $4500 or $5000." Im not saying that is right way of thinking, but its the retailing and marketing side of 'how high can we go on our sale price' before the consumer cries uncle ? Right now, thats not known here in the US, because we are still in the very infancy and early adopter stage. Heck regular bikes and many many models of them are priced $3000 to $5000, but those are for serious cyclists generally. Ebikes are likely getting more people who haven't biked for a long while, than they are getting 'serious' cyclists who are in awesome physical shape and their purpose for biking is very different from most would be consumers.
2) Torque and power is directly transferred via the spokes and tire to the road, so generally they do feel more 'responsive' when power is applied (up to a point), as you are eliminating motor lag, chain transfer, cassette transfer and the internal typical geared design on the mid drive.
3) Most hub motors on ebikes are internally geared, which makes them more compact, and allows for the OEM to design the level of torque vs wattage and volts into a motor. Thus not all hub drives are 'equal.' There are direct drive motors, but to put it bluntly, they are much heavier for a given wattage rating, and while possessing the ability to provide more raw torque, they will also suck down your battery faster, and be much larger in diameter in your hub. If it's 'stealth' that you want (i.e. not look so much like an ebike) then you don't want direct drives. They are also usually more expensive. Good applications for direct drives are for slower bikes, such as trikes that are heavy, or cargo bikes, and occasionally you'll see them on ebikes that are very high wattage (i.e. over 1000 watts) used for off road only, since above 750 watts they are not 'street legal' and require a license like you would need with a gas powered motor above 50 cc.
4) Hub drives are often available and set up with throttle and pedal assist, but sometimes depending upon the design purpose of the overall bike, the manufacturer will not provide a throttle.
5) There is some mis conceptions out there that hub drives 'break spokes.' Generally that is just not true when the spokes and hubs are all designed properly, and tensioned properly. Yes there can be defects but spokes break on regular bikes too, if they are not properly designed and tensioned, and the rim is not true. I wouldn't let that weigh in your decision.
You'll hear of brands like Bafang (formerly used 8FUN name too), Dupai, Shengyi, and others. Bafang is coming out with new levels of performance and tiered levels of better quality, so again, not all Bafangs are equal or the same. Personally, I would not worry about it, as the hub motors are so common, and so easy to obtain and replace, that its just not a big factor in the decision process. If you were spending less than $1200 on the entire ebike, THEN I might start to worry about the motor brand and quality.
The above is about all you need to know between hub drives and mid drives, and anything else you read is just slicing hairs on only one aspect of the overall ride and performance of an ebike.
One last thing, related to voltage of either mid drive or hub drive. If you are thinking you regularly want to go above 20 mph, you'll probably want to go with at least a 48 volt motor/battery combination, and usually at least 500 watts. That higher voltage will allow for both more battery capacity in a given physical space, and allow the motor to achieve the speed and torque you would likely desire, if you are expecting to go above 20 mph and/or expect a lot of hills on a given ride.
In summary: determine your price point (max budget you can allocate) first, then choose a few ebike brands and styles that fits your riding style and purpose best, and then lastly maybe think about what type of drive. (that will often automatically 'fall out' by your budget). Then seek to get the most bang for your buck. If you don't follow the above order in your 'decision tree' I guarantee you will drive yourself crazy, become thoroughly confused, and drive the dealers crazy too, or worse be talked into something you don't really need, or spend way too much for a given set of specs. If you do have the budget and are willing to spend $3500, by all means knock yourself out, and look at bikes with both mid drives and rear hubs. If you are off roading a lot, you may find the mid drive suits you better in terms of feel, and you can rule out looking at hub drives. (save you lots of research and ride time). But again be prepared to pay more for that mid drive, both first cost, and long term cost. Mid drives have come on pretty fast in the past 3 to 4 years. Only as recently as 4 or 5 years ago, it was very hard to find a really good quality mid drive, at a price point that wouldn't make you wince. In fact, I'd say the improvements in mid drives have been equal or very close to the dramatic improvements in battery capacity, life, and compactness in the past 3 to 4 years. (all Lithium based of course) Hub drives have been out for many more years (decades) and in general have a MUCH more proven track record. E-Bike OEM's are being courted VERY heavily by the mid drive OEMS because those OEM's really need to get the volumes way way up. China's market dominates the world for ebike motors, and they are all mostly hub drives, so hubs will always be cheaper and have much higher volumes world wide. Much larger manufacturing capacity exists for hub drives than for mid drives. Mid drives also require very specialized frame designs as well adding to cost on the bike. Maybe here in the US mid drives will become more popular than hub drives, but that could be a long while, and even then we are only talking a couple hundred thousand ebikes per year sold, maybe 300,000 in 2018, versus china which is in the millions annually. I only mention that, because just because more and more ebike OEM's are now offering mid drives here in the US or in Europe, it does not mean they are a 'better choice' or better technology. There is however a lot more room on mid drives for technology enhancement, and technology sophistication, which does mean 'more bucks' in terms of sales for the ebike industry.
have fun, but don't spend too much time reading the research - its best to just go ride them and see how you feel on the bike.
