Okay so I want to break the 30 MPH barrier...

[IIIHorseman]

I have decided that I won't be happy with going just 24 mph max on my ebike build. Apparently, the latest Ezee kits say they run at 500 Watts on 48V 10Ah packs, but I don't think there is much I can do to get it going over 25 mph with that voltage. Should I look at another kit?

I'm still not quite sure the best motor to pair the battery pack I was looking at with (lately looking at the 48V flat pack offered by EZ-- 48V 10Ah LiMn battery Rated 25 Amps and 35Amp Max BMS). Also I don't see any posts identifying the BMC to Mac motors vs Crystallized; which are apparently acclaimed as the higher performing kit options.

[rui_fujino]

How fast(top speed) do you want to achieve? If 30mph is the target than I believe upgrading controller or the motor is enough. Just play around with ebike.ca simulator and you will see what you can get.
Could you give us more info on what bike you got? Maybe a picture will help

[IIIHorseman]

Sure this is the Bike. It's a Windsor 3.0 Dover Bike with 24 speed gears, disc brakes and Suntour Fork.

That is an interesting point. The Ezee kit comes with a 20 amp Controller and the battery has an amp output of 35 amps. Although I tweaked the simulator other controllers and really only got 1.5 mph difference. Does this mean the Ezee would be limited?

[amberwolf]

I'm using "48V" (14s 20Ah medium-c-rate LiPo-like pack, 58.3V fully charged) and a 40A 12FET, and a plain 9C 2807 in a 26" wheel, on the heavy 150lbs+ CrazyBike2, and i can eventualy get to 35MPH (EDIT: make that 32MPH; I misremembered the data) if I have a long enough off-road stretch (since max on-road allowed is 20MPH around here). (it will reach 40MPH unloaded off-ground wheel speed).

A higher-amp controller would let me reach those speeds faster on my bike (300lbs+ including rider), but on a lighter bike or a lighter rider or both, the 40A controller would likely be sufficient to accelerate to the faster speeds relatively quickly.


The biggest limiting factor is the battery itself: with a low-c-rate 60V (70V+) NiMH pack, it sagged so much that it only reached 31.5MPH max. I forget what the 48V (59V) LiFePO4 pack would let me get up to, but I don't think it was much beyond that, if even that fast, also because of heavy sagging.

You could use an RC LiPo pack, 10-20Ah, to emulate what I am using now.

As for how long these speeds can be sustained, well, I don't have a long enough run available to be able to test that.

[dogman]

Most dd kit motors will do about 35 mph on 72v 20 amps. 1500w, which rarely fries a dd motor.

Cellmans fast winding Mac motor is known to do 30 mph on 48v. Other fast windings will hit 30 mph on 48v 20 amps. Aotema front hubs, 9 c 2806.

You'll have sluggish take offs and poor hill climbing on steeper hills with the fast windings though, unless you heave some more wattage at em.

[rui_fujino]

the cheapest upgrade is to upgrade your rear wheel to 700cc. if you can then that should get your topspeed up. or maybe upgrade battery to 66v. this will easily get you 30mh

[Kingfish]

You can get to 30 mph on 36V LiPo with enough amps. The controller is the gating factor. Reprogram or mod the existing controller to take you there, or purchase a more-powerful one that can handle it. Generally, the second easiest route is to increase the voltage; Dogman has it right on the mark.

Changing the wheel size does not help because you will still be faced with pulling sufficient current to make the wheel spin and that brings us back to Square-One with the controller. Higher battery voltage is possibly with many controllers; generally most take 36-48V without mods, although I think Lyen sells some that are 36-74V or up to 100V out of the box… check with his inventory to see what's possible. Seems like every year we make progress in options.

30 mph is no longer a big feat, although holding it for a length of time is challenging because of aerodynamics; The 30-33 mph range is about as fast as one can go on a bicycle without having some sort of faring treatment for slicing through the wind. Once you get there, you’ll understand.

All the best, KF

[neptronix]

You're gonna need a high power battery for 30mph or over. cell_man's a123 packs, RC Lipo, or something with a lower C rating but a huge amount of watt-hours will do the trick.

[Kingfish]

You know, I did forget about one other thing: The winding of the motor will limit how fast you can go, regardless of amps. Generally, lower count-winds translates into faster spinning wheels at the expense of torque and efficiency.

What is the brand and model of your motor?
~KF

[FastDemise]

The 30-33 mph range is about as fast as one can go on a bicycle without having some sort of faring treatment for slicing through the wind. Once you get there, you’ll understand.

All the best, KF

I totally agree. Doing 30MPH as much as possible on my trips to school. Make sure you have good eye wear as the wind makes your eyes water something fierce.

[dogman]

Very true. If you are riding longer distances, just throwing more wattage at a higher voltage also throws the efficiency baby out with the bathwather.

But for sure, with a different motor you can still just make 30 mph with 48v 20 amps and faster windings. Aotema front hub from High tek bikes, 9c 2806, etc.

24mph from the Ezee aint bad btw, about what you'd expect. You'll be quite suprised how much more wh/mi it takes to cruise at 30 compared to 24.

[Kirk]

My trike cruises at 32 mph using a 48V 1000W hubmotor and a 48V 32 Ah 30C Lipo battery. Its pretty aero though, my seat is only 37.5 degrees from horizontal and there is a Windrapp XT fairing on the front. So the drag coefficient is pretty low. You could probably do it with 66V on your DF.

[dogman]

Definitely lowering drag helps. At some point, assuming you could lower drag to zero, you could approach your motors no load speed for the voltage you are running. That's your absolute maximum speed for that motors winding, at that voltage.

All we need is vacume tube bike lanes, and we'd be zipping along with no wind at all. But since holding your breath till you get there is awkward, we have to throw more and more power at it to go faster than 25mph. Personally, I find that a bike built for traveling further than 10 miles just gets cumbersome when asked to go faster than 25 mph. Pretty soon, it's not a bike, it's a big heavy battery with wheels.

Fun bikes can be made to haul ass for short distances with light small batteries though. Great for you if you have a short commute and the cops ignore you.