Use of gears and pedal assist

[Gurnard]

Hello.

I am wondering how you guys use your gears? I have a centrally mounted motor with shimano 8 speed derailleur. I am trying to figure out how to get the most out of the pedal assist with gears. Sometimes it seems just leaving it in 5th is the best performance for cycling along and starting off, not much benefit to changing down gear.

I can't help feeling I am missing the point somewhere. So wondering do you change down for hills, or when you come to traffic lights to pull way easier? Or are gears generally just used to go faster?

I have set pedal assist to 5 step? Is this common or do you guys find it overkill and just stick with 3?

 

[Emo Rider]

Hello.

I am wondering how you guys use your gears? I have a centrally mounted motor with shimano 8 speed derailleur. I am trying to figure out how to get the most out of the pedal assist with gears. Sometimes it seems just leaving it in 5th is the best performance for cycling along and starting off, not much benefit to changing down gear.

I can't help feeling I am missing the point somewhere. So wondering do you change down for hills, or when you come to traffic lights to pull way easier? Or are gears generally just used to go faster?

I have set pedal assist to 5 step? Is this common or do you guys find it overkill and just stick with 3?

I have a Panasonic crank drive and an eight speed cassette. I do use my gears all of the time. I feel using the gears and upshifting as l pick up speed helps improve my range and increases my rate of acceleration. If your bike is a hub drive, downshifting when going up a hill will certainly assit your motor.

 

[anotherkiwi]

Same on a hub drive. If you are in the right gear at the right cadence the motor does it's bit. It took me a few km to figure it out but became clear as soon as I had more correct gearing on the bike.

Am I running the correct ratios is the second question to ask after am I in the correct gear.

 

[(NoLongerRegistered#15675)]

By coincidence there has been a long thread about this subject recently.
The motor in my yam mid drive is most efficient at around 2k revs. This (we believe) equates to a cadence of around 65, so in this case whatever gear gives a cadence of 65-75 should in theory give best range. (and not necesarily most help ??? which would arrive at max torque figure for motor (approaching zero)
You may well be using torque characteristics of your motor (ie pulling off in higher gear) but possibly at detriment to best range.
Again quoting figures I found.Yam max torque is at approaching zero rpm (cant be at zero,unit depowers) motor is only 62% efficient. By 2000 rpm motor is 97% efficent, (ie watts used against watts power out)
I,d guessed going for high cadence thereafter would help efficiency but in theory this is not the case as motor efficiency falls off above 3500 rpom, (back to sub 80% by 3800)
So use gears, keep cadence around 70 and get bike above 15,5 mph to depower it totally...then you are on your own... and motor is infinitely efficient..

Having said all that (and this was the contentious bit) It may well be most efficient to use motor at a less efficient part of its rev range (ie slower) but pulling higher gear ???? We never got a good conclusion on this.
And the other thing to think of.. you and bike require so much energy to accelerate upto speed and overcome drag. Wether this comes from bike in wrong gear or correct one may well have no bearing ?
(My Mondeo pretty much gets identical mpg in 4th,5th and 6th at 60 mph , I know slightly different but you see where I,m coming from)

 

[Gurnard]

Thanks for the responses, fantastic as ever.

The main thing I had was changing down gear too low meant my chain line was out (I have a damaged bafang where the bottom bracket is bent in, mentioned in another thread). So if I am in low gear the gear change slips a few times, then chokes and then chain fell off.

I fitted a Kore chain tensioner that I had sitting around from another project and this has fixed it for now it seems so I can go into low gears without the chain coming off.

Now I tried like Emo Rider suggested to ride like I would with a normal bike: low gear when uphill, wind or starting, and it does seem better than trying to push on in high gear. Although I do find 1st and 2nd pretty useless and I never seem to get over 6th, on an 8 speed cassette. So maybe a closer grouping on the cassette might be more use.

 

[Jay Russell]

I use mine close to using a conventional bike. It's like the power assist settings are chain rings.

I tend to cruise about in tour unless there is a hill to be had then I use sport or turbo. I tend to stay in the higher half of the cassette, the lower half will come into play when I'm off road I think.

Jay

 

[Deleted member 4366]

I guarantee that you won't see any difference in efficiency by tuning your pedal speed to a particular cadence. There's too many factors involved.

The only thing you have to worry about is not letting the motor struggle at too low RPM. Pulling away in top gear is fine as long as you don't do it on maximum power, otherwise you get too much stress on the components in the drive train. I used to do that on one of my mid-motor ebikes that had, let's say, adequate power, until one time, the solid steel drive sprocket, literally went bang and broke in two.