liveforphysics wrote:Can someone give me a reason why anything could be possibly be more efficient than a direct drive hub?
If you are referring to 'looses in the drive train' then no.
If you are talking about running a motor (ice or electric or steam
)at its optimum RPM then that is what transmissions do most efficiently.
MadRhino wrote:Mid drives are time consuming, both in building and maintenance.
I hope that you are mistaken on that last bit
wayover13 wrote:I've looked around the web for a bit now, hoping to find some more or less unbiased assessment of how hub motors compare to mid-drives. So far I've not turned up much.
Can anyone else add additional pros/cons for either and help to fill out the list so we can come up with a more comprehensive comparison?
I think a person's specific needs and/or desires are a big part of the equation. The perfect solution for bunny hopping over hill and dale all day long is probably not even close to what is most suited to go pick up a bottle of milk and a loaf of bread at the local quicky-mart.
Then there is the cost and complexity of the build to consider as well. A pre-built front wheel with a small hub motor is by far the simplest and easiest to install in most cases. For a simple steel frame bike it can take as little 1/2 of a hour from start to finish. If however there are other parameters to complicate matters (suspension and/or non-steel forks, matching front and rear wheels, the need for speed, heavy payloads, or desire for way too much power
) then the alternatives bear consideration. Also an individual's mechanical and electrical abilities as well as access to the proper equipment comes in to play. My current project is rebuilding a vintage touring frame. For that task I have to acquire some specialized tools for the bottom bracket and head set ( ... when I was a kid we got by with a screw driver, spoke wrench, crescent wrench, water-pump pliers and a hammer
I just completed an evaluation for my next project between a 36 volt 250 watt front hub and Bafang 36 volt 250 watt mid drive. I concluded in this case that the advantages of the mid drive out weighted the additional cost and weight. However there were some additional parameters that influenced that conclusion. I am retired and will be disposing of my Honda Insight electric hybrid. I am cheap and it needs a new battery pack, yearly inspection, registration, insurance, oil changes, ....etc. The bike will be a backup for the 'grocery getter' utility ebike. It is to be an urban leisure bike to be ridden exclusively on paved streets. Additional Parameters:
(1) Max required speed 15 to 20 mph
(2) Max required range 5 miles
(3) very small battery for lighter weight
(4) I am anal retentive about matching wheels
(5) self built wheel set for double butted spokes for shock absorption of (something NOT offered in pre-built wheel kts
(6) both front and rear drop-outs are forged Aluminum
(7) have to acquire and install a bottom bracket and crankset anyway
(8) three speed IGH rear hub (less gear changes to deal with
(9) more time than money
Full thread here: http://endless-sphere.com/forums/viewto ... =3&t=70586
My point is that the pros and cons vary according to the application.