Input needed... 30mph cruise and 40-45mph top speed ebike

Well, I sold the motorcycle and now I only have my 500W 1.2kWh ebike, which is great and fun but a bit too slow at 22-23 mph top speed, 17 mph cruise, 50 mile+ range. I want to go a bit faster so 40-45 mph top speed, 30 mph cruise, and still 50 miles+ range (at 25-30 mph). I am on a tight budget and maybe some of these requirements can be flexible.

Also, I like to stick with the scooter pack batteries 36V 4.4aH 20A max cont, 35A peak. I mean I don't trust these batteries to do 35A peak so lets just say 20A is peak and I will try to stay around 15A or lower. I have 36V 32aH at the moment.

Here is what I am thinking in terms of a budget build options. Also, I cannot afford the 3000W+ rear hub wheels.

A. Fat tire bike - 3000W SBP Cyclone mid drive kit, iBiky 26" fat tire bike, 72V 24-26aH battery (scooter packs in series). This will cost me about $700. I like this build because there is a free wheel on the mid drive which will allow me to bike without cogging (magnet resistance). However, the issue here is since the batteries are not great I am limited to 20A max which is ~1500W with maybe 2000W burst. Will the bike still be able to get up to 40mph with this limit and a light rider with a windshield. I know 1000W gets you to 30mph but its not linear to 40mph.

B. Scrap fat bike - 1500W rear hub kit, 36V 50-52aH, 1500W step up converter (36V into 52V), new Schalbe Marathon tires, and existing 26" mountain bike. This will cost me about $450. It wont take me to 40mph maybe in a tuck but I should be able to maintain a 30mph cruise. Also, there will be cogging from the magnets and since the step up max is 1500W and the motor probably peaks 2000W I wont get that peak power for 40mph?

C. Super budget - 1000W rear hub kit, 36V 50-52aH, 1500W step up converter, new Schalbe Marathon tires, and existing mountain bike. This will cost me $400. Max speed will be 30 mph but I should be able to use full conversion on the 1500W step up converter.

Yeah, I dunno. The biggest concern with best option fat tire bike and cyclone mid drive is the battery wont be strong enough to utilize full power of the engine, which probably peaks at 4000W. So, it might just be a waste. I really like the look of fat tire bikes. It has such a wow factor.

Here is my current bike, the proposed fat bike look (modeled after Ducati Panigale italian flag decals), and a video of some fun on fat tire ebikes.

https://www.youtube.com/watch?v=OMwk2ttirGA

Is your bike even stable at 25ish mph? What your asking is going to take one heck of a battery so I'd pour all my money into that... Fat bike isn't the way to go IMHO...

Here are some real figures from my bike with a Mac 6t motor running on 52 volts. And even street 2.0 inch tires with much lower rolling resistance than a fat tire or a plus tire. probably half that of a fat tire.

Keep in mind that I have all the right parts for speed , low torque/high speed 6t motor, 52 volt pack charged to 58-59 volts. On level ground , with little wind.

First 1,000 watts would hardly ever get you to 30 mph. for me / my bike which is much more efficient than yours, it takes more like 1400-1500 watts to get that speed, at 30 amps.

If you want to stay with those batteries then you will have to run two of them together like you talk about above ... at 72 volts, but even then at only 20 amps max faster speed is going to be hard. You are going to have to study aerodynamics .
You will want the lightest weight DD hub you can find, or that Cyclone running on 72 volts.

Then looking at your bike in the picture ( a hard tail ) you are not going to like going over 22-23 mph , that hard tail will put a stop to faster speeds fast once your back and neck is in pain.

So look for a long wheelbase full suspension.

For doing this on a budget look at what John in CR ( Costa Rica ) has done.
and the E.S. Member in Santa Barbara , California. I forgot his name at this time , Voltron, or Volton ?

When you are looking at F.S. bikes you will notice there is not much room for batteries , so some / one pack off the front of the handlebars and one elsewhere. Perhaps a strong seatpost beam rack with metal strapping around the pack to keep it on the rack.

You are better off if you can buy a E-Bike Specific frame like one from Vector , or Em3ev.com , or the others listed on the For Sale New section of Endless-Sphere.

bakaneko said:

Well, I sold the motorcycle and now I only have my 500W 1.2kWh ebike, which is great and fun but a bit too slow at 22-23 mph top speed, 17 mph cruise, 50 mile+ range. I want to go a bit faster so 40-45 mph top speed, 30 mph cruise, and still 50 miles+ range (at 25-30 mph).

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You won't get the same range at a higher speed, from the same pack.

You need both a battery pack that can handle higher currents, and that has more capacity, if you don't want to stress the battery (so it will last).

At a guess, you would want to double the size of the pack, essentially paralleling two of the existing packs. (seriesing two also gives double capacity, but does not change the current capability).

, iBiky 26" fat tire bike,

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How well does this bike handle and operate at the speeds you're after? How good are it's brakes? How good are it's tires (or different tires that fit on it's rims), meaning, what happens to them at speed especially during hard braking?

Will the bike still be able to get up to 40mph with this limit and a light rider with a windshield. I know 1000W gets you to 30mph but its not linear to 40mph.

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You can look up the various power-at-speed calculators to determine how much power you need. There's threads around the forum with links, somewhere, or you can just look them up with google.

For hubmotors you can also look up the grin tech simulator and check out at least the ones that are already tested and in it.

If you go the converter route, the typical $30-40 30 amp 1500 watt boost converter will only supply about 20 amps or about 1000 watts with a nominal 36 volt source. And as the battery discharges, your total watts will drop since the input is capped at 20 amps for the voltage range of a 36 volt scooter battery (which I also use). So toward the end of battery life the max output is closer to 800-850 watts. This is what I get with my current converter set to 54 volt output. My previous converter actually did a little better drawing up to 25 amps instead of just 20 or so. That bike would do 30 mph on flat ground. But it didn't get to that speed quickly.

If you want to get 1500 watts from a boost converter, you'll have to try something different, perhaps something like the ebay listing below that claims it will take up to 50 amps on the input. If that converter works well, the Grin calculator says that it would get me to a little more than 30 mph (no pedal assist) with a the 9C 2706 equivalent motor that I currently use.

https://www.ebay.com/itm/1500W-50A-DC-Boost-Converter-Step-up-Power-Supply-Module-IN-10-5-60V-OUT-15-70V/252553726589?hash=item3acd600a7d:g:xYgAAOSwCGVX5UUj:rk:5f:0

Just a few suggestions:

1) Ditch the boost converter. Boost converters are heavy and inefficient. Either rewind/replace the motor for higher speeds at 36V. Currents will be enormous and it will be difficult to find a controller. In fact, 72V is a much better bet.

2) At those speeds you'll want full suspension - ideally with a mid drive. Hub drives at that weight can be problematic since they are unsprung weight. But you'll still be better off with rear suspension.

3) Fat tires really work as intended (i.e. as shock absorption) at lower pressures, and at lower pressures rolling resistance goes up. Probably better off with a 2" tire than a true "fat" tire.

4) To get to 45mph you are going to need about 3kW. That's 41 amps at 72 volts. That's a lot of power, and you have to plan for that (controller, battery protection, wire gauges, motor cooling) up front.

overloading, over-speeding and massively overpowering bicycle components will not end well

desired speeds (c30 t45) possible with rc lipo or other high c rate but range will be around 1/8 stated range goal

flat level ground no wind cruising 20 mph (500w) requires a fairly massive battery pack to travel 50 miles

exponential factor wind as major obstacle to overcome beyond 20 mph

1000w to push 30 mph wind out of the way

20 mph into a 10 mph headwind will need 1000w

add in a hill or two....

i don’t know anyone getting around these facts

desired speeds & range requires motorcycle platform and components to safely carry needed battery pack

Dude...why do you want to push your luck so much and go 40-45mph on a bike? That's like stupid fast..IMHO. You're looking at more of a full suspension dh or endo frame sort of bike to get you those speeds with some sort of stability. Then after that you're talking $3-5k...so here's what I'd do...

1) stick with your hardtail bike.
2) is that a 1000w hub motor? If not you may want to upgrade to a 1000-1500w kit for cheap.
3) don't go that big with your battery. Mounting a battery under the angle tube sounds like a bad idea....tire could come up and hit the battery over bumps, battery could fall off?, if it rains your screwed right?
4) for some reference, I commute to work on a modded 1000w kit. I get about 2200w off a fully charged 13s8p battery on mine. I typically cruise around 25-29mph. I top out around 34mph on a full charge. At about 29mph I consume around 600-700w continuous. The hardtail isn't much of an issue since I'm on paved city roads and they're not that bad. I've got a suspension fork and seatpost suspension. It gets the job done.

wturber said:

And as the battery discharges, your total watts will drop since the input is capped at 20 amps for the voltage range of a 36 volt scooter battery (which I also use). So toward the end of battery life the max output is closer to 800-850 watts. This is what I get with my current converter set to 54 volt output.

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Bad memory and math on the input amps. It will input about 26 amps. It is the output that is capped at about 20 amps and hence 1000 watts at 54 volts. I noticed this while riding home last night. Oops!

Sounds to me like the easiest option here is to double or triple the amount of 36v packs, series them to 72v, buy a cheap 48v-72v 1500w (somewhere around 600rpm) hub motor already laced, get a 72v 2-3000w controller, and you'll get that max of 45 and be able to cruise at 30ish.

I did this very same upgrade to an A2B Metro and easily hit the numbers you're looking for. However, I did add some Statorade to that eBay motor to keep temps down since I did 30-45 min commutes.

Thanks for all the replies guys. It really helps. Yes, I know this 40-45 is dangerous but that is just like peak power for when I'm on a safe, nice large shoulder straightaway and want a thrill. I will keep it at about 30 mph most of the time. I wanted 40-45 because if that is peak then the system should be able to handle 30 well. Yeah, I am flexible on some of the requirements but I want this to be my final bike. Been building various bikes and own motorcycles for a while and I think this will meet my commuting needs (within 10-15 miles, no highway).

Yeah as mentioned, I will likely double my current capacity from 1.2kWh to 2.2-2.4kWh for this build. I have one thing going for me. I am a very light rider.

I do have a question about the scooter packs. Each battery pack 36V 4.4aH and I have 8 of these on my small mountain bike atm. If the fat tire bike frame is bigger, I might be able to squeeze in another 72V 4.4aH on the top tube pack and maybe one in the mid pack so in total maybe I can get a 72V 32aH pack made up of the scooter batteries. Because the scooter packs will be in series (72V 4.4 aH) and then put into a parallel array does this greatly increased my max constant current draw capability? The original pack specifications are

Max. discharging current: 30amp
Max Continuous Discharging Amperage: 20 Amps
Rated Discharging Amperage: 15 Amps

So, in the parallel configuration I should have much better discharge ratings than the original 36V pack specifications? I think this is the case but I don't know what is the exact change. Here is what I am thinking of in terms of the battery bank design (see pic).

The 1000W-1500W rear hub is still on my mind. I do like the idea of doing 72V controller into the bigger hub. The only thing I don't like about rear hub is the cogging. I think it robs not only normal biking but also when you are coasting at speed versus a freewheel mid drive which would disengage when coasting after getting up to speed.

billvon said:

1) Ditch the boost converter. Boost converters are heavy and inefficient. Either rewind/replace the motor for higher speeds at 36V. Currents will be enormous and it will be difficult to find a controller. In fact, 72V is a much better bet.

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The 5% energy loss is hard to even notice on a commuter bike that has plenty of spare capacity. If capacity is dear, then it might matter. But even when I run my system for a fast commute (typical cruise = 25 mph) on the uphill home route, I only consume 25 wh/mile. My morning route into work is a net downhill (though it has a couple moderately steep uphill sections) and I got 20.68 wh/mile this morning (320 wh, 15.67 mile commute, 20.21 ave. speed) riding at that same 25 mph rate. I can easily drop into the teens if I shift my typical cruise to 20 mph. And this is while running about 35 watts of LED lights plus camera and phone charging. Of course, I also put in pedal effort. But the main point is that my wh/mi numbers are typical to low compared to others I've seen. The 5% loss is hard to even notice in the grand mix of all the variables.

The weight of the 30 amp converter (delivers 1000 watts) is of minimal consequence when you consider the weight of the batteries and DD motor you are likely to use. Space for mounting might be a bigger issue. The larger and heavier 50 amp unit could be more of an issue for both weight and especially for space. And in either case, you'll probably want to do something to weather proof it.

IMO, the biggest negative for the boost converter is that it is one more component that can fail. I've been thinking about replacing my controller with a 36/48v controller so I can bypass the converter in the case of failure. I've had one failure of the converter which was probably caused by my not fully seating a power connector.

All of these factors considered, the booster works out well for me in that it allows me to run 36 volt packs at 54 volts with relatively low fuss. But the closer you think you need to get to 72 volts, the more it makes sense to just run the packs in series. 72v is probably the way to go if you really intend to go 40+ mph. I'm not a fan of going that fast unless you spend the money to really make the frame, brakes and other components appropriate for that speed. The booster only potentially makes sense if you want something slower and more in the 30 mph range.

Let's start where the rubber meets the road, tire pressure is key to an efficient setup: http://www.dorkypantsr.us/bike-tire-pressure-calculator.html
Allow me to translate why 'fat tires' are not practical for such a build. It's been tried by another member, and I can't find the post, but 'fat tires' are meant for low, human, power at 15mph tops. Mount the 500W system on one, should work fine. These tires have high rolling friction, due to low tire pressure. I would expect the soft side walls to cause handling trouble at high speed. You have a great jump on resources, don't overlook physical limitations. Under such extreme conditions, as you describe, 'fat tires' will shred to threads in a matter of miles.

Start your build list on tire selection, FPS are worth the extra charge.

Your lower weight is going to be a great advantage, but there are still limits. I use a 32c rated for 9bar, and I still have to run 10bar due to personal weight (pedal, no electric). But the low friction makes down hill faster than I want sometimes.
Still want 29ers for handling and the heavier weight, or the torque of Luke's 'death bike' from a 24" (just get a 100psi BMX tire). Determine max weight, find proper tires.
Dump the, power robbing, voltage booster.

The power circuit described in the drawing, would be noted as 2S8P, and would be much larger if the '36v cells' were broken to the component cells. This will make a good power pack, but knowing statistics and the reliability of high component systems, you would be better off making two packs with a selector switch, IMO. Read a book on the subject of large battery packs to get a much better comprehension, as cells can be damaged by simple things, like not being matched.
Even a 2S4P, arrangement of '36v cells', yields a calculated 60amp. Pulling more than 15amps may damage components, if that's what it's rated for.

PS Full suspension at such expected speeds.

bakaneko said:

I do have a question about the scooter packs. Each battery pack 36V 4.4aH and I have 8 of these on my small mountain bike atm. If the fat tire bike frame is bigger, I might be able to squeeze in another 72V 4.4aH on the top tube pack and maybe one in the mid pack so in total maybe I can get a 72V 32aH pack made up of the scooter batteries. Because the scooter packs will be in series (72V 4.4 aH) and then put into a parallel array does this greatly increased my max constant current draw capability? The original pack specifications are

Max. discharging current: 30amp
Max Continuous Discharging Amperage: 20 Amps
Rated Discharging Amperage: 15 Amps

So, in the parallel configuration I should have much better discharge ratings than the original 36V pack specifications?
The only thing I don't like about rear hub is the cogging. I think it robs not only normal biking but also when you are coasting at speed versus a freewheel mid drive which would disengage when coasting after getting up to speed.

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Needed high quality tires. I run maxxis gypsy e-bike rated tires they even say moped on the side. I'll go 40 44 miles an hour. But if I Tire happen to have a leak or pop it would be a mess.

mat h physics said:

Allow me to translate why 'fat tires' are not practical for such a build.

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Yeah, I am aware of that. I might just go with a 27.5" bike and wide (2.4") tires. I want the wow-effect of fatter tires. Also, I low-sided on my 26" ebike once and hurt my wrist trying to do a motorcycle lean. I was thinking a fat tire bike will allow me to do fun stuff like that without low siding. I think this guy is overvolting a 3K Cyclone on a fat tire bike.

https://www.youtube.com/watch?v=OMwk2ttirGA&t=1s

Hmm, I am a bit confused by your explanation. But, are you saying that even though the 36V packs are in parallel that doesn't affect the rated discharge of the 36V pack (15A, 20A burst). If so, yeah that is just a limit of those batteries. I don't have the funds to do something else.

But, even with the limited amps, I think I am still going to go with the 3000W Cyclone and now on a 27.5" bike instead. Thanks for the input.

mat h physics said:

The power circuit described in the drawing, would be noted as 2S8P, and would be much larger if the '36v cells' were broken to the component cells. This will make a good power pack, but knowing statistics and the reliability of high component systems, you would be better off making two packs with a selector switch, IMO.

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If you mean switching between two separate packs, when the first runs out switching to the second, it would be much harder on the separate packs, than simply wiring htem in parallel, because each one will see twice the current demand that the paralleled pair would, relative to it's capability.

Using one larger pack is easier on the cells, and simplifies the wiring of the system, and does not require a high-current-capability selector switch (which may be bulky and expensive, depending on whether it needs to switch under load or if it only has to switch while powered off).

Even a 2S4P, arrangement of '36v cells', yields a calculated 60amp. Pulling more than 15amps may damage components, if that's what it's rated for.

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The above sounds like you mean that a battery that can supply more current than the system would draw would damage things, but this is the opposite of what actually happens. A system does not draw more current than it needs, regardless of what the battery can supply.

Having a battery that can supply more current than you need is much better than having a system that can draw more current than the battery can supply.

bakaneko said:

I want the wow-effect of fatter tires.

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Maybe you should look into using large diameter moped or motorcycle wheels and tires, then, since those are "fat" and able to easily survive the speeds you're after, while many of the bike tires are not.

Also, I low-sided on my 26" ebike once and hurt my wrist trying to do a motorcycle lean. I was thinking a fat tire bike will allow me to do fun stuff like that without low siding.

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It's not really the size of the tires (though larger size of contact patch helps, bigger tires don't necessarily give you that), it's the grip of the tires on the pavement, and the pavement conditions (anything loose and down you go regardless), speed you're at vs the angle you lean vs the tightness of the turn, weight distribution, as well as rider skill from practice on the particular bike and tires.

Regardless of what you're riding, you're probably going to go down a lot during practice, before you master leaning very far over. Even then, if conditions are wrong you can still go down.

But, are you saying that even though the 36V packs are in parallel that doesn't affect the rated discharge of the 36V pack (15A, 20A burst).

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The more parallel cells (or packs) you have, the more multiples of current you can draw from the entire set.

The individual packs don't increase their output capabilities, but each one paralleled adds its capability to the total.

Great topic. I was thinking of building a ebike with these speed requirements. Now I can see it can be difficult and expensive to achieve...

Enviado do meu SM-J530F através do Tapatalk

be realistic 2 kWh to even think about cruising 50 miles @ 30 mph

36v55ah, 48V42ah, 52v40ah, 72v28ah

take your pick but there’s no way around massively heavy/large battery pack bouncing around

fat tires = all-terrain cheap suspension for 20-25 mph cruise platforms

best try it before you knock it

not many genuine handling issues but not for road racing either

in the grand scheme of wh/ah per mile hit to efficiency is minimal

higher wind speed is much much greater influence for power requirements

be realistic

People do not understand what a ebike is or does. Till they they it. They think they know. Till it happens. And then the smile. If they knew before they wouldn't have that smile. So you are only quessing. I have a magic carpet.7,000 watts 44mph.
In Corona Del Mar that has 20 different ebikes some that go 35 miles an hour go try them out it's free. Plus it'll put a smile on your face

The butter zone IMO, is about 35 mph top speed.

Faster on bikes in traffic, potholes, the usual crappy streets is not a great idea. Sure, I've done it, and it was fun doing 40 mph on just the front wheel on the ground. Amazing that one was not a trip to the hospital.

But a long wheelbase bike can do amazingly well at 35 mph, if you manage to avoid the bigger potholes, with no suspension! The long cargo bike can carry the kind of battery weight you are talking about better as well.

Build for 60v, with a larger rear hub motor. This will be awkward with your 36v packs. But 72v will be closer to 40 mph out the gate, and 35 mph cruise most of the ride.


For the 50 miles, you will need 2000 wh at 30 mph. or more. But a bit slower, and you have 80 mile range with 2000wh. So the solution is easy, just ride sub 20 mph long enough to know you have the rest of the range at 30 mph, and finish off the ride at 30 mph.


The budget, its just gonna be double, or triple what you think. Start out easy, bump what you have to 48v with additional 12v battery, and a cheap controller. You can push 2000w of 48v through the motor you have, without much risk of melting it. That gets you to or near 30 mph, which you will like. Later on, invest in the bike that can handle 40 mph. Along with the bigger motor you can push to there too. FWIW, you can join the 40 mph club with your current motor, but a long enough 40 mph cruise WILL melt it. If you go 40 with your current motor, keep the battery down to 1000wh. 72v 10 ah. Then it will run out just about the time you are fixing to melt your motor.

Re laying er down, well, you are wearing your motorcycle armor if you go 40 mph right? It does happen lightning fast on bike tires vs mc tires. This is why the guys really riding fast have a tendency to build with moped wheels and tires. Oops, there went the budget. In reality, you really do need to corner 25 mph or less on e bikes, unless you just went out there and swept that corner yourself. The streets are just too full of gravel patches. There are good 26" x 2 " tires out there, but in the cheap stuff, a semi knob beach cruiser tire is cheap, and less prone to laydowns on a bit of street dust. That's what I run on my 35 mph cruiser. View attachment 1

To really carry a lot of battery, time to learn to weld a custom frame. This is the bike that burned my garage down, but it was sweet while I had it. It could easily carry 4000 wh. This bike I built to go slow, 20 mph top speed, and maximize range at over 100 miles.

Again re the budget, that is why I bought my 400cc scooter. Its sooooooooo much cheaper to run than a fast e bike.