Yamaha Syncdrive Sport Motor Drag

[Dieseldickie]

I love my Giant Road-E bike with the 500 watt Yamaha Syncdrive Sport motor. I have almost 3000 miles on the bike and I notice a drag which seems to come from the motor at various conditions. I'm 77 years of age and ride this bike at least 120 miles each week. (Two 60+ mile rides.)

First - when I "shift" from medium power (NORMAL) to low power ECON there is a pronounced drag for about 10 seconds. If I stop pedaling the drag seems to stop faster. This is most noticeable when cresting a hill when the higher power setting is no longer needed.

Second- When I "shift" from ECON to NORMAL there is no drag at all. It only occurs when shifting to a lower power.

Third - When climbing a hill in any power mode, if the motor senses too much torque is being applied, the drag kicks in. If I can, I change sprockets for easier pedaling, but sometimes I'm too late and have to just muscle the bike up the hill. I have worked around the problem, by shifting to the easier sprocket at the bottom of the hill to prevent this very annoying drag.

Can someone help with what is causing this "drag" and is it just a function of this motor, or is it an adjustment issue.

 

[Nealh]

When climbing torque = power so possibly you are reaching max rpm & current for the motors voltage and bemf comes into play, once the rpm is backed off bemf is then not an issue. Also too high a gear selection may be stalling the motor as it ask's for more current at too low an rpm, this may induce bemf as well. Selecting the lower gear eases the stalling and keeps the motor in a better rpm range.

Dropping from medium to low again bemf may be playing a part as the you drop to low power, the motor rpm/current maybe too high in low rpm from the sudden change from medium so it takes a few seconds for bemf to equalise as the motor rpm lowers. A

Bemf is a hard subject to explain and is an invisible physical motor element based on rpm/voltage & current saturation for the motors designed max speed rating.

 

[Dieseldickie]

Thanks for your kind explanation. I'll try to understand the physics, but it is pretty clear that the motor is not designed to overcome the torque - too high and then too low that is being applied in these specific circumstances. I've learned to "work around" the drag characteristics. Now I know the "why".

 

[Fat Rat]

Hi welcome
As above info is great
Basically your cadence is too low
These motors like a higher cadence
Happy biking

 

[D C]

From the mileage you do each week I'm guessing you've had the bike around 6 months or so.
If you bought it new, have you had a dealer service on it?
I don't normally have a "service"on my bikes but I took my 2020 Giant in for it's free service after a few hundred miles and they downloaded new software to it.
The Yamaha sync drive sport is okay at lower cadence, I'm not peddling as fast as I used to and cadence of 60 is fine on mine or even a bit less.
I don't know if yours works the same as mine but the intensity of support is tuneable in each power mode using the Giant ride control e bike app, I guess a giant dealer could do this for you if you don't use a smart phone.
Dave.

 

[Dieseldickie]

Thanks for the "heads up" regarding tuneable intensity of support. I will definitely inquire with my bike shop regarding the possibility of a software update.

 

[Dieseldickie]

I took the E-bike with the Yamaha motor drag into my bike shop and they did the software update that was recommended. Problem solved!! No more drag when shifting from medium to low power. They said it was actually a battery software update. Apparently the battery was told to "shut off" for a few seconds (maybe 10) and then pick up again in low power. That is now gone! Immediate lower power, when shifting "down". Thanks so much for your kind and helpful suggestions.

 

[D C]

I took the E-bike with the Yamaha motor drag into my bike shop and they did the software update that was recommended. Problem solved!! No more drag when shifting from medium to low power. They said it was actually a battery software update. Apparently the battery was told to "shut off" for a few seconds (maybe 10) and then pick up again in low power. That is now gone! Immediate lower power, when shifting "down". Thanks so much for your kind and helpful suggestions.

There's just been another update.
I used the Giant ride control Smart Phone app to check how much battery percentage I had left after today's ride and it wouldn't open until I pressed the update button. The update took about three minutes.
If you're happy with how it works now and you don't use the smart phone app, you may be happy to leave things as they are.

Edited to add this:

"We have a small firmware upgrade for your bike making the Smart assist mode easier to access. Simply hold your UP or DOWN button to enter smart assist mode. To exit smart assist mode simply press UP or DOWN to go back to ACTIVE mode. We also fixed some small connection bugs to make the app easier to use and more reliable."

The up date is working well, the smart mode is now the default mode at switch on and the transition from smart mode to manual whilst riding goes to normal rather than to eco.

Dave.