EMTB Motor Torque stats

[Rob Rides EMTB]

Hi all,

I've been trying to collate all this data and have managed to grab a few bits from different places. I had some help from a helpful chap called Jason King. He knows a thing or two about electrical motors and helped create a spreadsheet.

Comparing TQ120, Levo SL, Brose Mag S, Fazua with Black Pepper Update, Bosch Gen 4, Shimano E8000.

Anyway, plots the main motors against each other.

 

[ses310]

Interesting stuff, the Bosch Gen 4 seems have have the most linear curve with the least drop off in torque as the cadence rises

 

[kntr]

Interesting stuff, the Bosch Gen 4 seems have have the most linear curve with the least drop off in torque as the cadence rises

Ive heard that due to the less drop the bike actually feels like it has more power than the Levo.

 

[Rob Rides EMTB]

Interesting stuff, the Bosch Gen 4 seems have have the most linear curve with the least drop off in torque as the cadence rises

Sure does look like it. BUT I forgot to add, that Bosch CX Gen 4 mechanical watts are not available anywhere. So I took the previous gen CX mechanical watts of 600 (that I read somewhere but cannot validate it as nothing official exists from Bosch as far as I could see) assuming that the newer is putting out no less than the older version!

 

[ses310]

Sure does look like it. BUT I forgot to add, that Bosch CX Gen 4 mechanical watts are not available anywhere. So I took the previous gen CX mechanical watts, assuming that the newer is putting out no less than the older version!

As you say I think it's a safe assumption the new motor will be out a similar watt figure if not slightly higher.
I'm looking forward to a few test rides once lockdown eases and see which I fancy.

 

[OldGoatMTB]

Interesting, I do enjoy this kind of information but find its a bit easy to make too much of the stats. I do almost all my riding in Eco mode, which I have turned a little bit higher than normal, with occasional use of Trail mode for extremely difficult climbs.

Let me add that I find this graph a little surprising as I thought Shimano said the motors were most efficient when cadence was between something like 60 and 120 RPMs, with maybe 70 to 100 being the sweet spot.

 

[Rob Rides EMTB]

Interesting, I do enjoy this kind of information but find its a bit easy to make too much of the stats. I do almost all my riding in Eco mode, which I have turned a little bit higher than normal, with occasional use of Trail mode for extremely difficult climbs.

Let me add that I find this graph a little surprising as I thought Shimano said the motors were most efficient when cadence was between something like 60 and 120 RPMs, with maybe 70 to 100 being the sweet spot.

This graph doesn’t represent efficiency. So could still be correct in that the motor is most efficient in between those cadences ?

 

[Sami Tuominen]

Sure does look like it. BUT I forgot to add, that Bosch CX Gen 4 mechanical watts are not available anywhere. So I took the previous gen CX mechanical watts of 600 (that I read somewhere but cannot validate it as nothing official exists from Bosch as far as I could see) assuming that the newer is putting out no less than the older version!

Maybe it should then read gen 3?

 

[OldGoatMTB]

This graph doesn’t represent efficiency. So could still be correct in that the motor is most efficient in between those cadences ?

I think the following quote is what I was struggling to remember:

“The Shimano STEPS E8000 offers three assistance modes (Eco, Trail and Boost) and is the strongest motor in our group test. The optimalcadence for it to produce its maximum output is around 70–90 rpm. Conversely, under 50 and above 105 rpm, the E8000 provides barely any support.”

Shimano STEPS E8000 review | GRAN FONDO Cycling Magazine

 

[steve_sordy]

Useful chart Rob.

If you use the correct units, torque x revs = power.

In other words if the power is limited, the torque drops away as the revs rise.

The torque will be limited because if constant power was delivered and the revs were to drop, the torque would increase beyond the drive train's ability to withstand it, and it would break.

That is another way of saying that the torque curves are all programmed, they do not happen by accident.

What I don't know is what happens when the programming is spoofed by the various fixes to allow faster speed by making the bike think it is going at a lower speed than it really is.

 

[Sami Tuominen]

Personally, I would see that it would make the most sense to describe power in a chart. Everyone who drives a shimano motor knows that less than 40 revolutions per minute is not much power available, even if, according to that chart, it would be in the best range then.