Cyclone 650w-1680W up to 60v @2100W without overheating

[richj8990]

When you put more voltage on this engine you need to consider:
- The weakness that came from a cheap motor kit
- The problem that came when you put a lot of power on a bike not build for that (overheating and transmission problems)


Weakness came from cheap motor kit
Cyclone 1680w engine came with mounting brackets in ergal, very light but not strong enough!

I know what you mean, on a different chain drive kit I'm really needing to shore up the non-drive side. I think it will finally work but yes the motor/sprocket will flex about 10mm over to the drive side and not only can the chain pop off, the sprocket can hit the pedal, or should I say the pedal hits the sprocket.

If you put enough power on the engine, the brackets flex under the engine torque causing the engine chain spill out from the cog on crankset (terrible situation).
To make things worse, the only way to fix engine at the opposite side of the cog (see the picture below) is with steel clamp holding the left bracket …..no way that it works with the desired power!

 
Overheating problem
After many tries, I figured that you have overheating problem if you run the engine using the incorrect gear (maybe you haven’t the correct one!).

The only way to avoid overheating, that is a very common problem for this engine (even without power upgrade), is to use the engine at elevated speeds. Thanks to Endless Sphere I learned that more fast engine spin less heat is made (it something related to the current impulse), it works!

Make some calculation:
Engine specification from Cyclone website are “Electric Motor kit 1680 Watt 48Vup to 60Nm, speed 4500rpm” and they realized this graph (handworking?)

If my readings are correct, to have maximum torque the engine must run at 1000 rpm and to have the maximum efficiency (EFF) is @ 3000 rpm.

The gear reduction is about 1:30. Then, if the engine spin at 3000rpm, the pedaling cadence is about 100rpm (3000rpm /9.33 primary gear reduction/3.15 secondary reduction). For humans is quite hard keep 100 pedaling rate per minute. At upper speed it became

Bottom Line: if you want to run your engine at the optimal speed forget to follow the engine by pedaling!

How I can manage that?
It is quite simple, going on flat I love pedaling. I use engine at not-best performance (cadence at the crank set about 60 rpm)
On mountain, I would like to use it near to maximum speed 4500+ rpm (good torque and good EFF), simply pedaling is impossible.

Configure the correct gear to avoid overheating
The easy way: put throttle to the maximum, if the engine speed increase slowly you must change gear to the light one.

To avoid overheating you need to change your riding stile, the throttle must be always near to the maximum (full gas) and you can regulate the bike speed you want by using the bike gears.


The overheating problem came on long slopes, after a while engine stop spinning and became very hot.
It is because engine strive al low rpm unable to reach optimum speed. The only way to avoid overheating is to reduce gear to reduce engine strive and reach the correct engine spin.

Unfortunately neither with 32t front and 36t rear gear I can reach optimum engine spin, so can we do?

40t 42t sprocket/cassette/chainring adaptor/expander MTB 7/8/9 speed. I put on the adaptor the 44t 104mm cog (my deore long cage derailleur liked it)
To avoid cog slip I also fixed my sprocket cassette with the sprocket adaptor with two bolts to distribute torque generated by the engine on the entire hub freewheel.
The result is: no more overheating and incredible climbing hill ability. My fatbike wheel loose traction on rocks before enging stop spinning.

I think that's true for a lot of these motors in general; mine seems also to be around 30:1 total reduction, but that calculates to 50 rpm pedal cadence, not 100 if it's at the normal efficiency of 1500 rpm. Are you sure the best efficiency is 3000 rpm and not 1500 rpm. The other issue is that if you are in a lower gear, even uphill the cranks will spin out and you can't go any faster. That's really annoying. On an e-bike, going 3-4 mph uphill even on singletrack seems ridiculous; I can go 2.5-3.0 rpm purely on human power up a 7-12% grade with a 25-30 lb normal bike anyway, so what's the point of having electric power? You want "and" need to go faster on an e-bike than that uphill, so a really low gear is not going to cut it for the entire purpose of having the bike to begin with, efficiency be damned. If you can't go more than 5 mph uphill, what is the point of having an e-bike offroad?

Right now I'm using 46T drive chainwheel, 36T cassette chainring, and 11-52T rear cassette. Those three pieces of metal are large enough that somewhere in-between there is a decent efficency for the motor uphill. I like either 28 or 34T in back; that gives fairly close to 1:1 for the cassette chain, and then 46/16T (sprocket) gives close to 3:1 reduction. You can't make it work with 32 front / 36 rear? For me, going to 46 or 52T in back again seems ridiculous and my chainline won't allow it anyway. I'm using the rear wheel for other non-bikes so that's why I'm still keeping an 11-52T cassette on it; but it's simply not needed for the mid-drive.

 

[richj8990]

Ooookey.
If you want to know the speed, you need to identify the cadence, that is the number of rotation of the crankset (rpm = round per minute).

Cadence = <Engine Speed under load> x <Total reduction Ratio>
Cadence = <70% of Engine Speed declared> x <Gearbox Reduction x Engine Freewheel/engine cog>

For example in my case:
“Electric Motor kit 1680 Watt 48V up to 60Nm, speed 4500rpm”

The values:
- Engine Speed declared= 4500rpm
- Engine Speed under load = 3150rpm
- Gearbox = 1/10 (from Cyclone datasheet, for Cyclone 3k I thing 1/6)
- Engine Freewheel = 13t (Standard Cyclone is 14t)
- Engine Cog = 48t (Standard Cyclone is 44t)

Cadence = 3150rpm x (1/10) x (13/48) = 85 rpm

For 1800-3000W
"Cyclone 1800-3000W 36-72V 100Nm 100Km/h 600-1000rpm"

The values:
Here is the messy point....MY GUESS is that 1000rpm is not the Engine Speed but the Engine Freewheel Speed
IF it is true
Cadence (@72Volt) = 1000rpm x 70% x (14/44) = 198 rpm WTF!!!!!
Cadence (@48Volt) = 700rpm x 70% x (14/44) = 155 rpm

Note:
Normal people have pedaling cadence from 60 to 90 rpm

Once you had the Candence evaulate speed is quite easy, we can use this calculator Bicycle Bike Gear Ratio Speed and Cadence Calculator.

In my case (fat bike has 30inc wheel)

At full speed yesterday I reach 54km/h it is because the engine overvolted speen faster then 4500rpm.

Note about the torque:
there is NO WAY that my engine put 60N/m @4500, my gess is that engine put 6N/m, considering the reduction 10:1 in the gearbox, at the Engine Freewheel We have 60N/m (like a Ford Fiesta).

For Cyclone 3k 100N/m is at the Engine FreeWheel.

I'm guessing my internal reduction is 10:1 too. You are using a 44T chainwheel and the sprocket is 13-14T. That's at least 3:1.

Under load 3150 rpm..., 30:1 reduction is yes a bit over 100 rpm, but that's assuming a 1:1 pedal chainring to cassette, as in 36T front 36T rear. Correct me if I'm wrong but the Bafang BSSxx models only have around a 22:1 reduction; they come with a 44-52T chainring and most people use 8-speed, so the max gear is usually 34 or 40T. That's far worse of a scenario than this one with 30:1 reduction. And their drivetrains work. Something is wrong in the calculations...I think it's the engine efficiency that is not 3100 rpm. It really should be 1500 rpm, no?

 

[richj8990]

One other thing: I think you are assuming full throttle with the cadence calculations. Half-throttle may not be proportional, eg. 50% throttle may not really be 2250 RPM when the max rpm of the motor is 4500, but for the sake of argument let's say it is.

50% throttle = 2250 rpm = may not be exactly half of 1680 watts, but will provide a ballpark of 840 watts, which is a LOT for climbing with a mid-drive

10:1 internal reduction = 250 rpm

44T chainwheel / 14T sprocket = 3.14 reduction = 79 rpm

cadence normally 50-90 rpm, so if you had a 32T in the front, then you can use between 28T - 40T in the rear


This makes sense because on a flat surface, if you are doing 32/11 you just negated the drive chain reduction and are back to 250 rpm IF the throttle was 100%. But it's not. Throttle on a flat surface is maybe 15-30% which means rpm is 15-30% of 250 = 40-60 rpm cadence for a slow, cruising pedal speed. This makes more sense...you have to estimate the watt output first with how much throttle you are using for what gradient.