At first blush it would seem that motors providing the same rated torque should perform comparably under load. Out of curiosity I took a look at one brand of emotorcycle and compared its torque specs to my ebike. The emotorcycle I reviewed was a Zerocycles Model Zero-FX; the ebike - my Specialized Vado 5. The Zero FX specs I reviewed are published here; https://www.zeromotorcycles.com/model/zero-fx . Some Vado 5 specs are here; https://www.specialized.com/us/en/turbo-vado-5-0/p/171132 . Other data for this comparison was published a couple of years ago in a series of charts including these;Okay, but it sounds like you're being a bit subjective in terms of "comparable" across the brand.
What bothers me the most, is that, when it comes to engineering, it has to be logical, objective and scientific.
The torque rating should not differ by whatever marketing plan they have.
The little tiny ebike motor can apparently create as much or MORE torque than a much bigger motorcycle electric motor.
These are scientific numbers. They should not be differing between brands to brand.
The Vado 5 is equipped with the Specialized 1.3 motor.
From these sources you can see that the torque specs are close enough to reasonably compare these mid-drive motors; 106Nm for the Zero FX and 90Nm for the Vado 5. So why would 'even the casual observer' overwhelmingly choose the Zero FX over the Vado 5 for hill climbing or just about any other condition other than exercise, despite the 2:1 retail price and 2:1 weight ratio (with an assumed 150lb rider)?
It comes down to this relationship;
Power = Torque x Speed; as quoted in an earlier post here. Let me elaborate -
First I looked at gearing. With these mid-dive motors the rated motor torque is available to the wheel when the gearing has a 1:1 ratio, i.e. the same speed at the motor shaft and the wheel. The Zero FX has 90t rear and 18t front gear for a 5:1 wheel speed ratio. As such it delivers 5x its motor torque to the wheel. The 11 speed cassette on the Vado 5 is 11-42t with a 48t chainring. For climbing, riders would typically select larger cogs on the cassette yielding a gear ratio of nominally 1:1 delivering 1x the motor torque to the wheel. This is compounded by the difference in drive wheel size. The Zero FX has an 18" wheel with 2.5" tires having a circumference of ~72". The Vado 5 has 700c wheels with 1.75" tires with a circumference of ~92". Based on gearing alone the Zero FX can provide up to 530Nm of torque to its wheel while the Vado 5 is at 90Nm. This ~6:1 wheel torque ratio becomes something like 6.7:1 when considering the wheel size difference. This explains a fair part of the hill climbing difference between this bikes, without even considering motor power.
Torque is part of the comparison between these 'bikes' but to know the full story we need to compare the peak developed power for each motor, and their power/speed curves. For the Zero FX, the available specs are 20KW @ 4300rpm. I didn't find a power/speed curve. The charts for the Vado 5 give us 550W @ 90rpm. Quite a difference in power with similar motor torques. I think it's safe to say that the 36:1 spread in available power will easily overcome the 2:1 difference in weight with plenty of power to spare to climb steep hills. On the other hand, even with 11 speeds available to the rider, the Vado 5s much lower power output will cause the bike to bog down on hills the Zero FX climbs with ease. The Vado 5 power/speed curve shows that the power drops off below 90rpm with the drop becoming steeper below 60rpm meaning of course that as the rider is unable to keep his cadence high, the motor power drops causing what is in effect a cascading event and the bike bogs down. With a steep enough hill this might also happen with the Zero FX, but well after the Vado has had to stop.
Conclusion, torque ratings need to be considered with along with specs for motor power and rpm. Otherwise it's like comparing apples to oranges; hence the apparent confusion.