Cadence, torque and power, oh my!

[dynamic]

I have a cadence question. But first some background.
I finally received my first priority current today (picking up second tomorrow). There is a lot I like about the bike. Brakes are amazing, comfort is good, fun to ride, cvt is *awesome*... etc. However, it feels quite a bit different than the only other e-bikes I have ridden: specialized como 3.0 and vado 4.0 (older models). Sometimes, the priority appears to have power well beyond those two. Sometimes, it.... doesn't.
One thing I could say about the vado 4.0, is I always felt like I was hitting my stride. This made the uphills almost as fun as the downhills.
On the current, sometimes it feels like something isn't quite there. It's harder even in full assist than my memory of the vado. But not *always*. ( I did my hill almost 3 times between the como and the vado, with the last one being the vado and it was the *easiest* of the day. Today I only did the same hill on the current. Once.)
I am one that likes to pedal slow and hard. This brings me to my question/theory.

Is it possible the vado motor is more forgiving of slower/harder cadences?

My understanding was higher torque should have been *more* effective at lower cadences, so the 140nm current should have dealt with that better than the 70nm vado 4.0. So far, that is not consistently my experience.

Do I just need to adjust and keep my cadence up?

I am toying with the idea of renting the vado again to do a direct comparison. If I had the ability to test ride a vado 5.0 igh, I would do it. (not available)

Thoughts?

 

[fooferdoggie]

the higher cadence will bring the motor to its optimal rpms so it can generate the most torque. my bosch the min is about 60 rpms below that and you will bottom out on torque before you hit the peak.

 

[dynamic]

the higher cadence will bring the motor to its optimal rpms so it can generate the most torque. my bosch the min is about 60 rpms below that and you will bottom out on torque before you hit the peak.

I don’t have a cadence sensor. So I don’t have a good way to observe my rpms reliably. At least, as far as I know, there is no readout for rpms.

But, if that’s the case, I would think I would feel the responsiveness of the motor increase as I reached it’s rpm sweet spot?

 

[fooferdoggie]

I don’t have a cadence sensor. So I don’t have a good way to observe my rpms reliably. At least, as far as I know, there is no readout for rpms.

But, if that’s the case, I would think I would feel the responsiveness of the motor increase as I reached it’s rpm sweet spot?

I doubt there is an exact sweet spot usually its a range. the NM torque rating seems really high for a 500 watt motor. but find a somewhat steep hill and test it with varies spinning speeds.

 

[Stefan Mikes]

Well, you have got what you paid for.

• The IGH is less efficient that the derailleur is. Good watts of your motor are used to warm the air outside.
• Specialized e-bikes can produce mechanical power well over 500 W in the peak (depending on the motor model). Your motor probably uses 500 W of electrical power, which gives the actual mechanical peak power of some 400 W. The marketing thing.
• It is highly improbable your motor could produce as much as 140 Nm of torque. Torque is the power at the crank divided by angular rotational speed. Vado 4.0 you mentioned offered max torque of 72 Nm. As the rotational speed of the crank on all e-bikes you rode was similar, Priority Current would need to deliver some 1000 W (or more) of mechanical power to get at 140 Nm. Don't you have a feeling you were cheated by Priority? The marketing thing again.

Regarding the cadence. As you know, Specialized e-bikes offer the cadence value on their displays. The latest Turbo e-bikes even colour-code their displays to encourage you to pedal above 70 rpm (the display indicator turns green if you do so). The famous Specialized motto is "Cadence is the King (or Queen)". Mid-drive motors are happy with higher cadence because they become more efficient and deliver more torque there.

 

[dynamic]

Well, you have got what you paid for.

• The IGH is less efficient that the derailleur is. Good watts of your motor are used to warm the air outside.
• Specialized e-bikes can produce mechanical power well over 500 W in the peak (depending on the motor model). Your motor probably uses 500 W of electrical power, which gives the actual mechanical peak power of some 400 W. The marketing thing.
• It is highly improbable your motor could produce as much as 140 Nm of torque. Torque is the power at the crank divided by angular rotational speed. Vado 4.0 you mentioned offered max torque of 72 Nm. As the rotational speed of the crank on all e-bikes you rode was similar, Priority Current would need to deliver some 1000 W (or more) of mechanical power to get at 140 Nm. Don't you have a feeling you were cheated by Priority? The marketing thing again.

Regarding the cadence. As you know, Specialized e-bikes offer the cadence value on their displays. The latest Turbo e-bikes even colour-code their displays to encourage you to pedal above 70 rpm (the display indicator turns green if you do so). The famous Specialized motto is "Cadence is the King (or Queen)". Mid-drive motors are happy with higher cadence because they become more efficient and deliver more torque there.

Let’s just take specs at face value for a minute. The current has a peak power of 680 watts (higher than 4/5.0 vado) and 140nm of torque. More than that, it behaves like it does sometimes.

Before I assume priority is lying about everything, I would like to explore other reasons for my experience. I was aware igh eats power. But it has more than 10% more power than the vado I tried. (The number people throw around as losing, and I would lose that on the 5.0 igh as well)

That brings us to your third bullet point. 140nm may be unobtanium on 680watts (will do math later). Assuming the specs above are otherwise true, then the current should ultimately have more assistance than vado even if not at the advertised 140nm of torque. Right?

And it does…. Sometimes. Sometimes this bike accelerates amazingly well.

I am not an electrical engineer, but, my best theory is the curve of power availability to cadence is more favorable on the vado for my natural pedaling style. Possibly by design. If that is the case, then the solution is find cadence sweet spot on current and keep it there?

 

[dynamic]

I just got home with my wife's bike. And, I think the problem is actually the reverse. This time I just went for "casual" riding, rather than hitting the hill hard. And it was a whole different experience. The bike picked up the slack dramatically. Less is more?
I just kind of casually kept a moderate cadence and the bike just swooshed me along. I will do a direct comparison to my bike to make sure they are working the same. But, I suspect I just need to get used to the optimal cadence.
Interesting. I have other problems to solve, like the seatpost trailer I bought doesn't fit on the bike when the rack is on. GRRRR. And the thudbuster takes up too much seatpost space to allow the trailer to fit as well.

 

[dynamic]

This is a case of learning to keep a bike in its sweet spot for power. I flew up the hill on my bike this morning with about 20 lbs of trailer behind me. The bigger problem is on the way down with my kid in the weehoo trailer, the sway was terrifying. I had to ride the brakes down and keep us under 10 mph to feel safe. And it was just constant back and forth swaying.

Trip worked though! Looking at solving other issues.

 

[fooferdoggie]

This is a case of learning to keep a bike in its sweet spot for power. I flew up the hill on my bike this morning with about 20 lbs of trailer behind me. The bigger problem is on the way down with my kid in the weehoo trailer, the sway was terrifying. I had to ride the brakes down and keep us under 10 mph to feel safe. And it was just constant back and forth swaying.

Trip worked though! Looking at solving other issues.

we only have the single but I ahve not felt anything going downhill. but we dont have the same amount of weight on it either. but man if I ride the tandem with it by myself and. the trailer empty it throws me all over.

 

[dynamic]

we only have the single but I ahve not felt anything going downhill. but we dont have the same amount of weight on it either. but man if I ride the tandem with it by myself and. the trailer empty it throws me all over.

You have the weehoo turbo? (The one with pedals).

I think the issue is my kid doesn’t naturally balance on a bike yet. And he is 77 lbs. there were times when it felt balanced, particularly on smooth road where I was comfortable lifting off the brakes and could let momentum take hold. Then it felt fine.

Haven’t done uphill with him in it. Attached a photo. Trying to find a rack that will fit under that arm. It makes a lot of noise going uphill empty.

 

[fooferdoggie]

our grandkid is only 35 pounds but she can ride a bike without training wheels so that may make a big difference.

 

[dynamic]

our grandkid is only 35 pounds but she can ride a bike without training wheels so that may make a big difference.

Yeah, my 8 year old is way behind on that. He is very cautious and isn't exposed to friends riding bikes, so he has no real self motivation. But, even if he could ride, I know he couldn't handle the hills here. So I am not sure what to do after he outgrows the weehoo.

 

[fooferdoggie]

Yeah, my 8 year old is way behind on that. He is very cautious and isn't exposed to friends riding bikes, so he has no real self motivation. But, even if he could ride, I know he couldn't handle the hills here. So I am not sure what to do after he outgrows the weehoo.

maybe a tagalong bike?

 

[dynamic]

maybe a tagalong bike?

They all have the same rack issues (as in, they won't work with a rack). And I think balance will be even worse since he doesn't naturally ride yet. I bought weehoo in part because the toddler will be ready for it next season and likely outgrow his rackmount seat. Even if the 8 year old is riding, he will be beyond the weight limits of everything next season. So he will be on his own bike or not at all. I might try one of those tow cables, assuming we are both ready for that.

 

[fooferdoggie]

They all have the same rack issues (as in, they won't work with a rack). And I think balance will be even worse since he doesn't naturally ride yet. I bought weehoo in part because the toddler will be ready for it next season and likely outgrow his rackmount seat. Even if the 8 year old is riding, he will be beyond the weight limits of everything next season. So he will be on his own bike or not at all. I might try one of those tow cables, assuming we are both ready for that.

the burley is the way to go it mounts on the rack and it should help with side to side issues.

Kid Trailercycles

Find the ideal kid's trailercycle at Burley and make the most of your family rides. Shop our collection of durable and stylish trailercycles.

burley.com

 

[dynamic]

the burley is the way to go it mounts on the rack and it should help with side to side issues.

Kid Trailercycles

Find the ideal kid's trailercycle at Burley and make the most of your family rides. Shop our collection of durable and stylish trailercycles.

burley.com

The rack is compatible with like 3 bikes. And none of them are disc/ebik/igh/belt drives. But, yeah, I agree. I just don't see how it can be mounted on the priority current. (that's the feedback consistent about this product, I haven't looked at trying to hook it up myself).

 

[fooferdoggie]

The rack is compatible with like 3 bikes. And none of them are disc/ebik/igh/belt drives. But, yeah, I agree. I just don't see how it can be mounted on the priority current. (that's the feedback consistent about this product, I haven't looked at trying to hook it up myself).

I thought it was a clamp that attached to a rack and its adjustable? been awhile since I looked at it.

 

[dynamic]

I thought it was a clamp that attached to a rack and its adjustable? been awhile since I looked at it.

It needs a specific rack: moose rack from burley. Which, incidentally, is possibly not compatible with the burley dash toddler seat. So I still can't swap them. They also look iffy on panniers (weird shape rack)
I don't see why the moose rack *wouldn't* work. But that's the feedback (maybe those people don't have eyelets on their bikes?)
I also think a tagalong is probably too much until he rides his own bike (most say not to put a kid on a tagalong who isn't a confident rider on their own). There are other tagalong bikes that attach to seat post. But I am back to no rack. ;P
I feel like some company needs to take on the "make it easier for parents to do all the things through a modular accessory set".

 

[Kayakguy]

They all have the same rack issues (as in, they won't work with a rack). And I think balance will be even worse since he doesn't naturally ride yet. I bought weehoo in part because the toddler will be ready for it next season and likely outgrow his rackmount seat. Even if the 8 year old is riding, he will be beyond the weight limits of everything next season. So he will be on his own bike or not at all. I might try one of those tow cables, assuming we are both ready for that.

Our grandkids started out on Striders (aka "balance bikes" generically) where they propel themselves by kicking or walking with their feet. Gets them used to balancing a bike in a non-scary way (I wish they had been around when I was learning to ride--I had a hell of a time). After they transition to real bikes, they have to learn not to stop by dragging their feet.

 

[dynamic]

Our grandkids started out on Striders (aka "balance bikes" generically) where they propel themselves by kicking or walking with their feet. Gets them used to balancing a bike in a non-scary way (I wish they had been around when I was learning to ride--I had a hell of a time). After they transition to real bikes, they have to learn not to stop by dragging their feet.

Our kids won’t use them. Both have had access to striders. So neither really want to learn to ride.