u/richj8991

Former viral researcher here, out of the lab for 20 yrs. Reading a book about Covid 19 and Wuhan. Keep seeing the furin cleavage site controversy. Proponents of the natural covid evolution stress that the furin cleavage site is out of frame, so if they engineered covid 19, why would they sloppily make a coding sequence out of frame? But what if they did that on purpose, so they they made the entire plasmid ready to go except for one codon. Then when they did pcr, one primer had the correct codon sequence. They could use for example 80 bases in the primer, correct the sequence in the middle and the primer would still bind even if one or more bases are misaligned in the middle. Possible?

I see online comments all the time from the so-called experts that mid drives by definition are more efficient because the motor works with the bike's chain and rear gears. It's not that simple.

First of all, there is throttle vs. pedal assist. If you are using pedal assist for either bike, often the display will show watts; my mid drive used more watts on a level surface than my geared hub drive. I'd say 350W on avg vs. around 250-275W. If you do pedal assist, then there can be a specific watt range for each pas level. I never used pas on the mid drive so I can't compare that, but for the throttle, the controller kept the hub drive more efficient. Same controller as on the mid drive btw.

Why would anyone think that a mid drive would use less power on a flat surface at the same mph as a geared hub drive, all other things being equal like bike and rider weight. It's going to use the same or more power for the same mph as I have found. The chain has nothing to do with it. I think what people are trying to say is that a mid drive CLIMBS more effectively offroad, which it does. But that is independent of the actual watts used. Remember we are talking about a mid drive vs. geared hub drive, not a direct hub drive.

My geared hub drive typically got 30-35 miles per 17.5Ah charge. I switched over to a mid drive and it averaged more like 27 miles and 2700 feet of climbing per charge. Then I got a 20 Ah battery. I thought the range would improve but it didn't for some reason. That mid drive later busted a gear and I shelved it and put on the front hub drive again. Now with the 20Ah battery I'm getting 34 miles and 3400 feet of climbing. Like it should have been with the mid drive. The hub drive is more efficient!

Maybe it was just my display setup with the throttle (same brushless kt controller) but I definitely used more watts getting up to speed with the mid drive than with a geared hub drive. I would prefer a mid drive offroad but the hub works better than you may think and it has a noticeably longer range.

Not sure why. If it makes any difference the 450W mid drive was around a 22x reduction total including a dual chain 2.75:1 44t/16t freewheel sprocket, and the bafang 500W hub drive is a planetary 5x reduction. Maybe the higher reduction on the mid drive forced more watts getting up to speed?

Sorry for the rant, but IME they are complete crap compared to brushless. I will give you my experience with both and you can chime in with any comments or suggestions.

My first e-bike was a brushless geared front-hub drive, 500W nominal, 1000W peak. It worked fine, it's just that I mountain bike and an extra 10 lbs on the front is not great for descending hills. It's also difficult to take the front tire off due to the torque arms, etc. It's still sitting in my garage and after this brushed fiasco that I'll explain below, I may throw in the towel and revive this brushless hub motor. I think it has 7000-8000 miles on it. Some controller wires have been partially melted but otherwise there have been ZERO problems with a brushless motor.

A few years ago I bought a brushless mid-drive that was a dual chain system. It was far more finicky to setup but it worked (a similar 450W nominal 1000W peak system as the hub drive). Climbed hills great, blah blah blah. 3500 miles on it. Then this February I took off in a high gear from a stop, heard a snap inside the motor, and then a loud thunk thunk thunk roughly every pedal revolution. The motor still works but the noise is horrible and the gearing will fail at any moment, I can tell. So it's on the shelf now (I can't take it apart, they glued it super tight). And they are not selling it now. I have a carbon frame that is too thick for a run of the mill Bafang mid-drive so I need a dual chain setup (CNC would be fine for $1000, but replacement motors for brushed are between $50 and $115).

So I got what I 'thought' was the 450W replacement motor. The tip-off should have been from the 24/36V setup instead of 48V. Chinese GNG mid-drive, they of course never told me it was brushed. I look at the power wires, there are only two, I'm like WTF. The controller doesn't even have a display option. So after about 15 hours of playing around with the wiring and the 2nd dual chain setup, I finally get it to work. Now this is where I have to admit I'm at fault: I used a 48V battery for a 36V motor. And ran it full throttle up a modest incline. However, I was shocked at how fast the motor overheated, literally in under 30 seconds. It was so hot that black semisolid plastic insulation was leaking out of it. It was toast after 5 miles. A grand total of 5 miles. Brushed motors have a heating problem...I've run full throttle up a hill with a brushless motor and never had it fail. You can blame 48V but the controller is rated at 35A, and so even with a 36V battery if I would have used that, the controller can take over 1000W. The motor CANNOT. Because it's brushed.

So I get a replacement motor. This one lasted 25 miles. And then? I even have a fan underneath it and a temperature sensor to make sure it doesn't overheat. So last Tuesday I'm offroading very modestly, really just coasting down a short section to a flat location, and heard a weird click underneath me. I at first thought it was the drivetrain slipping a gear into one higher, sometimes that happens when you coast or start pedaling again if the chain is between two cogs on a cassette. It then falls into the next higher gear and everything is fine. Keep in mind I was NOT under any e-power at all. Suddenly the brushed motor ramps up power to max. Without me touching the throttle. Somehow one of the 3 pin throttle wires touched one of the two power wires and bypassed the throttle. Now you can blame the cheap throttle I bought (which is in the trash now) but something like this never, ever happened with a brushless setup. Brushed setups are so delicate, one thing goes wrong and the wiring or motor is fried. So I had to immediately turn off the battery. But now I have no power. When I turn on the battery, the the power shoots up again to max. After the 3rd time I turn on the battery (only for 3-8 seconds), the motor cannot work properly and is only putting out like 30W, not even enough to carry its own weight. So now I get a 2nd replacement motor, coming in the mail. I have separated the wires as much as possible in a cramped space in the frame's triangle. I also now have a fuse cutoff and will experiment with 15A and 20A fuses to see how much power I can get before either the fuse blows or the motor gets over 60-70C. If this 3rd brushed motor fails for whatever reason (if I can't get at least 1000 miles out of it), I'm going back to brushless, this is ridiculous. I got over 10,000 miles from 2 brushless motors and can't even get 30 miles from a brushed one.