Hi, All
Thanks for the welcome!
I have done as you suggested, and posted an intro in the newbie section...if you take a look, you will see I do have a fair amount of knowledge and experience to share
Regarding setting the benchmark for your build, I can appreciate that you have done some research to try to determine some reasonable targets for your build, based on what other builders are doing / have done...but I will take a moment to point out a couple of things:
1. Your customers, for the most part, WILL use an internal combustion powered 'equivalent' as the benchmark to evaluate your e-bike. This is not exactly fair or reasonable, but in most cases, it is simply the familiar frame of reference. 'Range anxiety' is a HUGE issue for most folks considering any type of EV, simply because 'refilling' (charging) any EV takes a lot longer than just filling a gas tank (AND, range is usually less). Even if the batteries can be easily swapped out, you can't just drop by the nearest gas station to acquire a fully charged battery. Any experienced EV owner will tell you in practice, this is a non-issue, but it takes most folks some time to 'adapt'. My point is, when it comes to selling your final product, the closer it performs in all regards to the 'closest internal combustion equivalent', the easier it will be to close sales with prospective customers. Educating the entire world, one customer at a time, is exhausting!
2. In the research you have done (and continue to do), be very aware there is a tremendous amount of 'hype' out there...in my own experience, almost nothing in the e-bike realm achieves real-world performance even remotely close to the published specs. If manufacturer 'X' claims their product has a top speed of 35mph, a range of 35 miles, and carries a 17 AH battery powering a 3000 watt motor, in all likelihood:
i) Top speed can be achieved by a 110lb professional jockey riding the product naked, on completely flat pavement on a windless day, with a brand new battery, overinflated tires, everything lubed and adjusted absolutely perfectly (both the jockey and the bike), in a tuck with one hand behind his back;
ii) A range of 35 miles is possible with the same conditions as above, except never exceeding 1/4 throttle, or 15mph;
iii) the 17 AH battery capacity is theoretical, and actually is reduced to closer to 13 AH in the 'real world' once a good battery management system has been set up to ensure reasonable battery life;
iv) 3000 watts is the maximum rated power the motor manufacturer has stated the motor can handle, for no more than 1 minute at a time...in reality the controller being used is a 20 amp unit that can actually only handle 10 amps continuously, so actual maximum power is more like half what has been claimed...
The above is all fictional, and not slandering only one particular individual or manufacturer, but it is unfortunately based on reality - just an observed 'state of the industry' on my part.
And guess what? NOBODY rides their e-bike this way, so EVERYBODY gets WAY less range and performance than 'promised'!
My point is the ONLY way to know for sure is to test things yourself, especially when combining all the different components involved in an e-bike build.
My advice is to 'set your specs' 25 to 50% higher than you think you will need to achieve the desired performance, in which case you have a reasonable chance of actually achieving the results you are looking for.
I completely agree your bikes have a built-in advantage with the fuel and oil tanks proving a place to install the battery and controller - this is precisely what led me to your site, and to contact you about an e-bike build - it is a natural! Besides, they look incredibly cool
As fas as mid drive vs a hub motor, well there are definitely pros and cons, that's for sure...that's a big topic. I don't want to dive into that in this post, but I will say this much: if you want reliability, durability, and simplicity (and what manufacturer offering warranty wouldn't want that?), then a hub motor is the way to go.
Then there is the question of power, most often expressed in watts...
A simple rule of thumb is 750 watts roughly equals 1 HP. There is more to it because of the relatively high torque electric motors put out at low RPMS, but this is still a useful rough guide.
So, a 3000 watt motor output divided by 750 = 4HP. Add a 200 lb rider and at least 125 lbs of e-bike, and you get a power to weight ratio of 81.25 lbs per horsepower. Throw in some drive train losses, and this is not going to be a very exhilarating ride, and depending on the motor and controller combination (and gearing), there may well be some hills it cannot climb on motor power alone.
Hey - the above is totally fine, if that is what you wanted and expected, but what a bummer if you thought it was going to perform better!
I recently bought a Stealth Bomber B52 e-bike, which is widely regarded as the 'King' of e-bikes with its 'hugely powerful' 5500 watt motor, 72V 21AH battery, and reported top speed of 50mph, and 50 mile range.
It is great machine, truly, but if you ask me the performance is 'meh' and 'adequate'. Yes, it will pull me (275 lbs) up a steep hill...slowly...but I am not at all sure 3000 watts could do the same thing.
It largely comes down to your expectations, which in part of course are based on your personal experience, preferences, and background.
Being right in the middle, some people look at a motorized bicycle through the 'bicycle' lens, and others look at through the 'motorcycle' lens. This perspective can make all the difference in terms of whether or not an individual is satisfied with a given machine.
You mentioned at the beginning of this thread that you recently rode an electric motorcycle as well as as an e-bike - it might be worth comparing the power to weight ratios of each of those machines to the one you are designing, to make sure your design is in the ballpark you want it to be.
I applaud your idea to put additional battery capacity in the 'cylinders', but be aware that combining multiple batteries of different capacities (even if all the same voltage) is unlikely to charge and discharge in a properly balanced fashion when separated by long lengths of wire ...and this is critical to the lifespan of all lithium battery chemistries. So if you put small batteries in the cylinders and a large one in the tank, your batteries will not last as long. You may be able to 'sidestep' this by treating the smaller ones as 'reserve batteries' that are disconnected until the main battery dies, then you switch from the main to the reserve...always charging and discharging them totally separately.
OK, my last two bits for now, is to really think about water-proofing the components and connectors as you complete your design and build. The e-bike industry is terrible in this regard...almost all e-bikes CANNOT be ridden in the rain - even a puddle crossing on a dry day can destroy an expensive controller, or worse. It's a lot more critical to pay attention to this on e-bikes than it is with internal combustion machines. here is one poor guy's unfortunate experience in this regard:
https://electricbikereview.com/foru...lth-electric-bikes-and-the-stealth-bomber.34/
Cheers,
Doug