Torque vs Cadence Flat SW Florida

[leehop71]

I have 2 cadence bikes. The 26” Denago I use to make store trips.

It’s hard to use PAS 4 and 5 because of ghost (no resistance) pedaling.

I’m wondering if torque would be better in that scenario?

I’m ‘assuming’ with torque, I can put it in gear 7, PAS 5, and still get pedal resistance and good speed?

 

[Jeremy McCreary]

With simple cadence-sensing, your only 2 assist power options are effectively 0% and 100% of the motor's max output. In most cases, changing assist level only changes the max assisted forward speed.

With pure torque-sensing, you can ask for 0%, 100%, or any motor power in between. That means many more ways to dial in the right combo of exertion and true cadence (crank RPM) for conditions. And more utility from your highest PAS levels.

However, would need a lot more info to even begin to confirm your assumption — including rear wheel diameter, available gear ratios, and your idea of a comfortable true cadence and exertion level.

Bottom line: Only one way to know for sure if a torque-sensing ebike will meet your needs: Test one for yourself.

 

[leehop71]

With simple cadence-sensing, your only 2 assist power options are effectively 0% and 100% of the motor's max output. In most cases, changing assist level only changes the max assisted forward speed.

With pure torque-sensing, you can ask for 0%, 100%, or any motor power in between. That means many more ways to dial in the right combo of exertion and true cadence (crank RPM) for conditions. And more utility from your highest PAS levels.

However, would need a lot more info to even begin to confirm your assumption — including rear wheel diameter, available gear ratios, and your idea of a comfortable true cadence and exertion level.

Bottom line: Only one way to know for sure if a torque-sensing ebike will meet your needs: Test one for yourself.

Gotcha! Thanks.

 

[Gionnirocket]

To avoid ghost pedaling with a cadence-sensing bike you need a programmable one like those with a Bafang BBS Series mid drive motor. They allow you to set the max cadence for each PAS so as you approach that pedal speed it will taper off assistance.
In general a torque sensor bike gives you a more natural feel allowing you to input though out.
But yeah... Test riding one is worth a 1000 words.

 

[sc00ter]

If you get ghost pedaling in the higher gears you can put a larger front sprocket in the front. I hate doing the running hamster when going fast but since I rarely ride at high speeds I've been living with it on my cadence sensor ebike.

I've yet to ride a proper torque sensor ebike. I had one (Cero One) and hated the Shimano Steps system. I called it Shimano Shuffle because it was sluggish off the line, making crossing dangerous streets really fun, and I could never hit 20mph. I got spoiled by cadence "bacause" I've never experienced a proper torque sensor system. Anyways, go take a few torque sensor ebikes out for a spin. There's a reason the Vado makes all the best-of listings and I don't think its Specialized paying influencers for votes.

 

[fooferdoggie]

If you get ghost pedaling in the higher gears you can put a larger front sprocket in the front. I hate doing the running hamster when going fast but since I rarely ride at high speeds I've been living with it on my cadence sensor ebike.

I've yet to ride a proper torque sensor ebike. I had one (Cero One) and hated the Shimano Steps system. I called it Shimano Shuffle because it was sluggish off the line, making crossing dangerous streets really fun, and I could never hit 20mph. I got spoiled by cadence "bacause" I've never experienced a proper torque sensor system. Anyways, go take a few torque sensor ebikes out for a spin. There's a reason the Vado makes all the best-of listings and I don't think its Specialized paying influencers for votes.

the problem with a larger chainring is then you cant put out as much torque because you down have the leverage. always tradeoffs. but to go 28 you only need a I think a 44t chainring and 11t on back.

 

[harryS]

Go to a bike shop and arrange for a test ride of a torque assist system. See if it does what you want, It's possible to get exercise on most any any bike. Just set the assist low and go faster than what it will support.

Some cadence systems are fairly responsive within a given speed range, but others are very crude. I tried to get my wife to ride a torque sensor bike, but she couldn't press the pedals hard enough when we were riding in 20 mph gusts.

 

[leehop71]

Go to a bike shop and arrange for a test ride of a torque assist system. See if it does what you want, It's possible to get exercise on most any any bike. Just set the assist low and go faster than what it will support.

Some cadence systems are fairly responsive within a given speed range, but others are very crude. I tried to get my wife to ride a torque sensor bike, but she couldn't press the pedals hard enough when we were riding in 20 mph gusts.

That may be the key, winds! Hills are no issue but wind is here.

Because there are no hills there is no benefit of PAS 4 and 5, however I can ride against ANY wind strength with PAS 2 or 3 and cut right through it!

I can still ride in PAS 3 gear 7 and maintain a 22.3mph.

 

[m@Robertson]

A KT controller on a cadence-based hub motor setup will eliminate the 100% on/off issue. However you have to DIY the thing.

That may be the key, winds! Hills are no issue but wind is here.

Because there are no hills there is no benefit of PAS 4 and 5, however I can ride against ANY wind strength with PAS 2 or 3 and cut right through it!

I do the same thing on flat ground with my hub motor commuter. In Fresno CA there is a steady strong wind every day in the Valley in the afternoons.

Basically what I did was gear the bike - both front and rear - so I had a big 50T chainring up front and a wider range cluster in the back (11-30 I think... I never use the bigger cogs. Its the 11T that matters). At that point, in the mornings with no wind I can ride with PAS on full blast, still not ghost pedal and run right around 28-30 mph while getting a good workout. Then when the winds hit on the way home at end of day, I downshift one or two cogs to maintain my cadence. Speed goes down but effort level stays the same. If I need to I can dial PAS back too and work harder. That happens on occasion because the city is laid out in a grid so if I go to a sidestreet its a 90 degree turn and suddenly I may have a tailwind instead of a headwind.

 

[Rome]

Torque is easily often confusing.
I have Bulls emtb Brose motor no way ghost pedaling this thing. You the rider have to put pedal power. Motor will multiply pedal weight applied up to 400%
That is what I caĺl torque. Cadence basically is leg power you put into spinning the crank.
Some bike controllers , you the end user can make your motor run with very little pedal pressure and it will hit top speed with correct adjustments .
Ghost pedal comes this way. Your bike will hit top gear speed as long you are spinning the crank 60 rpm.
Very little effort. That's ghost pedaling or monkey pedaling.
On one of my bike I have throttle it allows me to monkey pedal. There's pedal resistant even at 25mph beyond that it's basically a freaking electric dirt bike. All throttle.

 

[leehop71]

My throttle on both bikes top out at 20mph. When I’m on a store run on two fairly busy streets at 30mph and 35mph.

The 30mph street has no bike path and the 35mph street DOES have a bike path and is a much longer stretch!

I like to use PAS 3 and gear 7 at 22.3mph on each road.

 

[Jeremy McCreary]

A KT controller on a cadence-based hub motor setup will eliminate the 100% on/off issue. However you have to DIY the thing.

Could you elaborate on the KT-based cadence-sensing scheme? What exactly does assist level control in this system?

 

[Gionnirocket]

A KT controller on a cadence-based hub motor setup will eliminate the 100% on/off issue. However you have to DIY the thing.

I do the same thing on flat ground with my hub motor commuter. In Fresno CA there is a steady strong wind every day in the Valley in the afternoons.

Basically what I did was gear the bike - both front and rear - so I had a big 50T chainring up front and a wider range cluster in the back (11-30 I think... I never use the bigger cogs. Its the 11T that matters). At that point, in the mornings with no wind I can ride with PAS on full blast, still not ghost pedal and run right around 28-30 mph while getting a good workout. Then when the winds hit on the way home at end of day, I downshift one or two cogs to maintain my cadence. Speed goes down but effort level stays the same. If I need to I can dial PAS back too and work harder. That happens on occasion because the city is laid out in a grid so if I go to a sidestreet its a 90 degree turn and suddenly I may have a tailwind instead of a headwind.

I guess if that's the only thing that works... but bogging down the motor with inefficient gears and/or having to maintain a high speed seems like an poor way to run a railroad.
Doesn't the KT controller allow for cadence level settings like the Bafang BBS*?

 

[m@Robertson]

I guess if that's the only thing that works... but bogging down the motor with inefficient gears and/or having to maintain a high speed seems like an poor way to run a railroad.

I wanted it that way. The bike had a job which was to get me somewhere in a convenient amount of time (i.e. speed is a benefit), and give me a workout, in a town that is laid out on cheap land with low traffic density, so everything is spread out, so its routine for lots of stores and whatnot to be miles away. Commuting for miles on flat ground on dead straight streets, I found the ideal setup was to set PAS to full blast, and then gear the bike so I could push past that top assisted speed via sets of rep intervals where I would push past the max speed to about 32 mph via muscle power, or relax and pedal and let the bike propel me at about 28. Wash, rinse and repeat over the course of the ride. The bike lanes were roads that oftentimes had speed limits of 50 mph, so an ebike going 32 attracted no attention whatsoever.

Usually.

This was my 2wd twin-hub commuter and this was another 50 mph road. I'm keeping up with traffic in part of the vid because the cars had slowed down for the cycling club on the single-lane segment (that road has been made into 6 lanes since this vid was made).

Doesn't the KT controller allow for cadence level settings like the Bafang BBS*?

Nope. Nothing like it unfortunately. You do have a setting that increases or decreases the power that is in between the 5 levels. Its C14 IIRC. So if you originally had default PAS that has 15% increases between levels (I just made that number up) instead you get a 20% increase between levels. The 'increase' version could deliver just a bit more acceleration power than you could get on throttle, in fact. Instead what KT controllers have is 'imitation torque control' which is entirely automated in its behavior.

Could you elaborate on the KT-based cadence-sensing scheme? What exactly does assist level control in this system?

As noted above, it is entirely automated. There is no documentation, either. Here's what happens: From a standing start, you engage the pedals and as soon as the sensor senses movement (you can adjust this with different magnet rings that range from 6, 8 or 12 magnets. I usually use 8 and get engagement after a pedal move of from say midnight to 2 o'clock). Once movement is sensed, the system will engage for a short time at very low power. Then as your speed goes to say 2 or 3 mph the power ramps up to peak after a few seconds. As your speed increases, the power tails off pretty quickly until eventually you are cruising on flat ground at 28 and your hub is only putting out as little as 20 or 30 watts. You can adjust this initial increase via a 'slow start' setting that has 3 levels, and essentially flattens and lengthens the power delivery curve. This keeps you from having very strong acceleration right off the bat but still rolls on the power fully. It just takes an extra 3 or 4 seconds or so to get there.

So thats starting from zero on flat ground and going up to cruise. Lets say you approach a hill. You maintain your cadence, but the bike is now climbing a hill and its slowing down, and so are your legs. The bike senses this change in speed and cadence and you can watch it slowly ramp the power back up until its pouring it on again to get you up the hill as best it can. As you crest the hill, your speed increments back up, maybe your cadence picks up some as well and you can watch the controller ramp the power right back down again as you get back to cruising speed.

Going downhill, as your speed gets up past a certain point the motor ramps power down to almost nothing and feeds just a minimum. Just enough to make the hub motor free-spinning like a normal hub.

 

[Jeremy McCreary]

As noted above, it is entirely automated. There is no documentation, either. Here's what happens: From a standing start, you engage the pedals and as soon as the sensor senses movement (you can adjust this with different magnet rings that range from 6, 8 or 12 magnets. I usually use 8 and get engagement after a pedal move of from say midnight to 2 o'clock). Once movement is sensed, the system will engage for a short time at very low power. Then as your speed goes to say 2 or 3 mph the power ramps up to peak after a few seconds. As your speed increases, the power tails off pretty quickly until eventually you are cruising on flat ground at 28 and your hub is only putting out as little as 20 or 30 watts. You can adjust this initial increase via a 'slow start' setting that has 3 levels, and essentially flattens and lengthens the power delivery curve. This keeps you from having very strong acceleration right off the bat but still rolls on the power fully. It just takes an extra 3 or 4 seconds or so to get there.

So thats starting from zero on flat ground and going up to cruise. Lets say you approach a hill. You maintain your cadence, but the bike is now climbing a hill and its slowing down, and so are your legs. The bike senses this change in speed and cadence and you can watch it slowly ramp the power back up until its pouring it on again to get you up the hill as best it can. As you crest the hill, your speed increments back up, maybe your cadence picks up some as well and you can watch the controller ramp the power right back down again as you get back to cruising speed.

Going downhill, as your speed gets up past a certain point the motor ramps power down to almost nothing and feeds just a minimum. Just enough to make the hub motor free-spinning like a normal hub.

Thanks for the explanation. Interesting approach. Sounds like true cadence (crank RPM) is being taken into account, not just the presence or absence of crank rotation.

Does this KT system offer on-the-fly assist levels (apart from the "slow start" adjustment)? If so, what exactly do they control?

 

[PCeBiker]

Does this KT system offer on-the-fly assist levels (apart from the "slow start" adjustment)? If so, what exactly do they control?

Yup, KT has 5 assist levels much like PAS mode settings.
Each PAS mode has a maximum power and maximum speed setting.

 

[PCeBiker]

Sounds like true cadence (crank RPM) is being taken into account, not just the presence or absence of crank rotation.

I'm pretty sure that it doesn't measure cadence.
It just applies power differently if you are moving or not.
The power can be turned down to apply gradually when you start from a stop.

I chose C5=3 to turn my power down to half. (to use less power and increase my range.)
C5=0, 1, or 2 allow for slow start power levels.


I might try C5=0 to see what happens. I don't have to use full power, at least not all the time.

I think I tried it once, but it didn't work because I don't have my cadence sensor hooked up?
I can't remember?

 

[Rome]

Sheesh man codeine in my system is weakening.
Can you guys hash this out without all this KT meter chart?
It is beyond my high school level of education.
Primary reason why I chose Canbus. No need to mess around with cadence and tourqe settings.
I was able to navigate DPC display to change maximum speed to 47mph.
It doesn't lag at 35mph.
I use the 11 speed to vary smoothness of pedaling performance and presence of tourqe is readily available.

 

[leehop71]

Sheesh man codeine in my system is weakening.
Can you guys hash this out without all this KT meter chart?
It is beyond my high school level of education.
Primary reason why I chose Canbus. No need to mess around with cadence and tourqe settings.
I was able to navigate DPC display to change maximum speed to 47mph.
It doesn't lag at 35mph.
I use the 11 speed to vary smoothness of pedaling performance and presence of tourqe is readily available.

A lot of this mechanical DYI stuff is like rocket science for me, mainly because I know just enough about mechanics to be dangerous!

Guitars and baseball I can hang tough!

IMHO, just having more gears (speeds) would be the fix to this cadence ghost pedaling issue!

Obviously there is a reason why most of the affordable e-bikes come with only 7 speeds and my guess would probably come down to the thing that makes the secular world go round as it’s all about the money!

 

[PCeBiker]

IMHO, just having more gears (speeds) would be the fix to this cadence ghost pedaling issue!

Yeah, that would do it.

You can't go smaller in the back because your smallest is probably already an 11 tooth gear, so you'd have to install a bigger sprocket (chain ring) on the front.

It's not that difficult. You just have to get the right part, and maybe a longer chain, but there is no programming or circuitry involved.
Easy fix.

If you install a larger chain ring, then your first gear will feel more like your current second or third gear (depending on the size of your new chain ring), so you won't be able to add as much pedal power from a stop or at slow speed, but your new 5th gear will feel like your current 6th or 7th gear, and you'll have 1 or 2 more gears to use for higher speed.

I know @Jeremy McCreary knows how to use gear calculators, and used it to choose new "sprockets" for his ebike.
Maybe he can help with some rough calculations to figure out what chain ring you may need, and which ones will fit your ebike?