What spot on bikes will end up being “standard” for e-bikes? I watched reviews and some reviews and some have it in the bottom bracket of the frame, while others have it in the rear hub. There are some fairly obvious advantages and disadvantaged to both placements. I am curious, are there any e-bikes with the motor in the front hub? That could make sense for ease of replacement or repair.

Also, is it likely e-bikes will get lighter over time? So many I see on the roads here are really heavy.

Mid-Drives are the way to go. They are more efficient and also keep the weight centered and low which is what you want with heavy weight. Hub drives are lower cost and an older school solution that yes people still use but more to save money or because they are entrenched into it. When you have a hub drive you are adding rotational weight which is the worst kind of weight. Plus with a proper mid-drive the bike is generally designed around that motor so it can handle the stresses of the motor.

Yes e-bikes will get lighter. Look at stuff with the Specialized SL motors or Fazua and you will find some decently light stuff. Everything is always getting better but the best time to buy is now so you can ride.

In terms of standards there will always be new standards. That is the nature of standards

I wonder if the industry could develop a standard shape for the bottom bracket for mid-drives.

There's a rant on youtube somewhere by a mechanic pointing out the changing shapes and sizes and standards of motors and batteries. It's not a mature industry yet.
But the same thing is happening with bottom brackets and hub spacing on acoustic bikes.

A front hub system makes an excellent conversion for certain applications, mostly road riding without significant hills. The weight of the bike is distributed nicely especially if you're using the bike for cargo. This system has been operational for 10 years without maintenance or failure.

Agree, and not entirely because that's what I have. :-)

Keeping much of the mass low and in the center I suspect helps handling and stability, aided further by a battery enclosed in the downtube.

I'll also speculate that flat-fixing is more complicated with a rear hub motor. I do not own one but that's my experience with a geared rear hub bike. Removing the wheel isn't too fussy but replacing it sure is.

I expect drive components and batteries will shrink with time as the technology advances, reducing the added mass and putting less stress on the bike and wheels. So they can be lighter, too. Mine is 30 pounds and I see plenty of e-bikes 2X that.

Well, just put me on record for lighter, cheaper e-bikes with longer range between charges. 🙂

Mid drive = more torque, as they can use the bike's gearing. Great for climbing, but they apply a lot more torque to the chain & sprockets, which (so far) are not beefed up for this duty, so it means more frequent maintenance.

Rear hub drive = cheaper, simpler, gives the option to motor home in case of chain breakage. Rear wheel is what has more traction under acceleration, so this makes sense from a performance standpoint than the front, however, it leads to rear-biased weight distribution, which is no good for bikes that will be airborne or carried on lighter duty car racks.

Front hub drive = simpler, since it's separate from the mechanical drivetrain of the bike, however weight shifts away from the front wheel under acceleration, so they tend to spin out easier, which will be bad on loose surfaces or uphill. Easier to retrofit.

One of my retirement hobbies is converting regular bikes to electric. I've done all three motor types and done them on heavy and light donors..If If I apply my own DIY prejudices to commercial ebike manufacture, here;s how I see it.

Front motors will go away because of higher product liability risks. They're more likely to break forks and injure the rider. They can have traction issues. Even with a robust design, the user can screw it up.

Rear motors will be around for manufacturers who have low labor costs.It takes more work to assemble a separate controller and motor.There will be needs for specialty uses like xargo bikes.

-Mid motors will get less expensive as a component as designers make them easier to build and incorporate simpler electrics. How about a basic small motor with only a torque sensor and two powr levels. .They are much simpler to install with everything integrated in a unit and offer better performance with lower power motors.
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Also, my daughter prefers a coaster brake which makes a front hub feasible; add an IGH for the cherry on top.

I have a Cervelo Rouvida with Fazua Ride60 mid drive. It only adds 10 pounds to the weight and any 700c disc brake wheel can be used, which is a big advantage. The original wheels on the SRAM Rival model are cheap, so I sold them and use a pair of my BTLOS wheels. I wouldn't want to be wheel limited with a hub drive.

I don't think there will be a mid-drive standard for a long time, if ever. I expect mid drives to get smaller. But at this time, all manufacturers could all pick something like the Shimano e6100 Steps mount and make their motor fit. But they won't, for reasons.

Excellent point; some manufacturers don't even have compatible mounting year to year on essentially their same models. Additionally, AFAIK, there are at least seven different connectors for charging the batteries.

guess what's available...
https://www.jensonusa.com/Shimano-CN...n=&pt_keyword=

the "standards" will come as the customers find what they want the most.
automatic car transmissions are now the "standard equipment, much to my dismay...
remember Bias ply tires? some people have never SEEN a bias ply car tire.
the Beta VCR had studio quality images, but was Expensive to produce and Sony held onto the licensing too tightly.. try and find a Beta player now... even VCRs are getting scarce, eh?
DVR away, world.

the e-motor will move toward a mid configuration, the threaded Bottom Bracket frame will be the "Standard" attachment point design, torque link attachment points will be added to frames, and the charge plug design will migrate towards the most popular style...
See: Tesla Charging Stations.

remember the GM cars with the gas filler under the rear license plates?
there were several steep hills near my childhood home... we'd wait for Mr. McKnight to fly up Parkhill Dr., then light the trail of gas.... Wiamea over in the Palisades neighborhood was the best place for that game... 250 yards of WAY too steep.... we'd wait until the sun went down...... patience, OOOO, OOOO, YES!!!! Here Come a Chevy!!! wait, for, it... he's clear! KAAAA-WOOOOOF!!

The City finally rebuilt Wiamea with roundabouts and an angled intersection into the road at the bottom... the guy in the home at the bottom had placed multi-ton boulders in front of his 6 time rebuilt garage..... the three old fir trees weren't enough protection in the winter... the cars always found their ways through..i bet those trees still show the battle scars...
their Standards changed.

$56 ebike chains?
Full disclosure?
Don't forget the cost of other added wear components with mid-drive = cassettes & chainrings.

Have one of these for my mtn bike.
https://www.sram.com/en/sram/models/cn-eagl-xx1-a2
$56 doesn't sound so bad.

As power limits become more common, the mid-drive will win out on all but the cheapest models, because it can take advantage of the gearing.

I see many ebikes in the "OC". Almost without exception those on road, in parks or on bike paths are hub motors and usually individuals commuting or kids going to school or riding around, while off road they're mids. I don't expect a change since they seem appropriate for their application(s) and cost(s). The situation may be different in other parts of the country, but I doubt it.

Mids OR hubs, the price is going to rise at the end of the month. We're all not going to be happy here in the US of A...