What determines and assists hill climbing capacity?

[PP100]

Having struggled today in a hilly part of London/Essex borders on my pushbike I could have so much done with my fictional Rambletta (am on the wait list)
but it prompted a question - How does the assist setting relate to hill climbing?
If I in theory set the assist to the highest setting - does that help with hill climbing or does that only increase speed, do other build factors such as motor type/wattage more relate to hill climbing capacity?

 

[vfr400]

While we wait for an answer from Woosh about how their controller works, whichever system the controller uses, you'll get maximum power up the hill when you set it to maximum - if that answers your question. There are no serious hills on the Essex/London border, so I'm pretty sure that any electric bike will sort you out unless you've had a few too many pies; however, if you've done those hills without a motor, they'll be a breeze with one.

 

[peter.c]

Old church hill on the way to Langdon hills country park is about the steepest round here and thats not a problem buzz past the Sunday lycra lot

 

[PP100]

While we wait for an answer from Woosh about how their controller works, whichever system the controller uses, you'll get maximum power up the hill when you set it to maximum - if that answers your question. There are no serious hills on the Essex/London border, so I'm pretty sure that any electric bike will sort you out unless you've had a few too many pies; however, if you've done those hills without a motor, they'll be a breeze with one.

Well on a topographic map of London, a stand out area is around the Woodford /Buckhurst Hill borders - where I was roaming.
I know compared to most they aren't big hills at all , but I didn't have the stamina to tackle all of them one after the other, on the route I took . I have to stop and walk the bike up some so I look forward to the help when my E Bike eventually arrives.

 

[Wicky]

Before buying my pedelec I test rode a variety of bikes at the Redbridge Cycling Centre in Essex which has road cycle circuit and mountain bike course.

Confirmed my choice of a rear hub drive for getting up hills. Unfortunately KTM discontinued the type (Pansonic eRace) but I still enjoy changing up inro to top gear while keeping up top assisted speed up the steepest hill.

KTM eRace P 29 - Review

In all honesty, really we are fans of E-MTBs with centre-motors. With their low and central centre of gravity, they can be ridden on demanding trails as easily as their motor-free siblings. However, rear hub drives do have certain advantages. They work directly via the rear wheel, so have great...

ebike-mtb.com

 

[Edward Elizabeth]

Motor torque.

Gearing.

The strength in your legs.

The meatiest motors at legal power outputs are in the 50-60NM range. 60NM is sufficient to haul my 19 stone (I'm 6'5" mesomorph, not a Lard-O) up the steepest inclines, albeit I'm an experienced cyclist with good legs and lungs who is able to give a good bit of effort myself.

I'm going to be controversial now - at legal power outputs, used on the road, motor placement is about the least important consideration. Start upping the power, or start flinging it about off road, then it takes on more importance, but on tarmac with the relatively weedy legal power output it matters litte.

 

[Benjahmin]

I'm not so sure about 'weedy' motors.
A 15A controller at a nominal 36v will be developing 540W (battery allowing) on top setting. Chris Frome and the like, develop in the region of 300-350watts when mountain climbing. Even allowing for inefficiencies the motor develops far more, so long as you can keep it in the rev range where it puts the power to motion rather than heat. So, for a hub motor, this would be >50% of it's full rpm/speed. Practically speaking keeping a hub at 8mph+, when climbing, works well for me.

 

[vfr400]

Motor torque.

Gearing.

The strength in your legs.

The meatiest motors at legal power outputs are in the 50-60NM range. 60NM is sufficient to haul my 19 stone (I'm 6'5" mesomorph, not a Lard-O) up the steepest inclines, albeit I'm an experienced cyclist with good legs and lungs who is able to give a good bit of effort myself.

I'm going to be controversial now - at legal power outputs, used on the road, motor placement is about the least important consideration. Start upping the power, or start flinging it about off road, then it takes on more importance, but on tarmac with the relatively weedy legal power output it matters litte.

Your opinion is coming from a frame of reference at the extreme end of rider experience. At 19 stone, you have to pedal 40% harder than an 80kg rider on the same bike when on any upward incline. 80 kg riders rately find ebike motors' power (actually torque) to be inadequate.

 

[Edward Elizabeth]

Absolutely. You need to remember as well, that some of my extra weight is additional muscle mass (I'm not a fattie, just a normal bloke scaled up by 25%) , so some of that extra mass is earning its keep in terms of power.

Nevertheless, a 60NM motor gets me up hills with relative ease that I could not even ride up beforehand. At my weight - or more correctly, mass - I do not find legal power assistance levels inadequate. As you say, a featherweight 80kg weakling should have no problem if I dont.

But fundamentally, I answered the question correctly before then relaying my own experiences. At legal pedelec level the considerations that affect hill climbing ability are...

Torque.

Gearing.

The grunt that the rider themselves is able to deploy with their legs.

That was my answer to the OPs question.

 

[boyabouttown]

Not sure what the quoted torque is of the rambletta motor is but the wife goes up the same hills as i do, without any trouble, no heart pumping, no wheazing, legs not burning. My ebikemotion rear hub, 40 n/m has me doing all the above. I am lighter than her and have stronger legs, although she is probably cardio fitter than me. My bike is nearly half the weight of hers but she still cycles up hills like mary poppins.

 

[MontyPAS]

But fundamentally, I answered the question correctly before then relaying my own experiences. At legal pedelec level the considerations that affect hill climbing ability are...

Torque.

Gearing.

The grunt that the rider themselves is able to deploy with their legs.

That was my answer to the OPs question.

Plus a good battery with plenty of AMPS!
Hills eat amps!

 

[WheezyRider]

Plus a good battery with plenty of AMPS!
Hills eat amps!

Amps eat controllers. Better to increase voltage.

 

[MontyPAS]

Amps eat controllers. Better to increase voltage.

Overvoltage pops controllers also!
Max voltage is normally governed by cheap 60v Electrolytic capacitors in the manufacture of the controller units.
You have to come to a compromise with headroom of the caps working voltage.
My 52v battery reads about 56v when fully charged, so those caps are already getting close to maximum

 

[WheezyRider]

Overvoltage pops controllers also!
Max voltage is normally governed by cheap 60v Electrolytic capacitors in the manufacture of the controller units.
You have to come to a compromise with headroom of the caps working voltage.
My 52v battery reads about 56v when fully charged, so those caps are already getting close to maximum

Standard capacitor voltage ratings are 35V, 50V, 63V, 100V. So in most controllers from 36V upwards, 63V caps tend to be used. I've had no problems with 14S battery packs at up to 58.8V max. I have upgraded to 100V caps on some controllers, but then the limit is set by the MOSFETs, which are typically rated between 65 and 70V for the 36V controllers I've seen. These can be upgraded too with a bit more effort.

 

[flecc]

Plus a good battery with plenty of AMPS!

Amps eat controllers. Better to increase voltage.

Overvoltage pops controllers also!

Best take the car instead. At least you'll get there!
.

 

[WheezyRider]

Best take the car instead. At least you'll get there!
.

No guarantees... more likely to kill or be killed in a car than on a bike. Plus cycling has many benefits compared to taking the car.

 

[vfr400]

You don't need high power, high volts or high current to climb steep hills. You need torque, which you can get with relatively low power.

I converted a Bromtom with a tiny Q85 motor and a 14 amp controller at 36v. It could drag an all-up weight of 110kg up my 14% test hill without pedalling. That bike would be happy doing an Alpine tour, even with its 3-speed Sturmey Archer gears, though you might want to carry a spare battery or two.

here's the owner, forum member Andyfthesouth, enjoying it in the Brecon Beacons:

 

[flecc]

No guarantees... more likely to kill or be killed in a car than on a bike. Plus cycling has many benefits compared to taking the car.

Not true, we are safer in a car.

Even if I take the highest claimed figure for people regularly cycling, 8% of the population, which is demonstrably not true, there's some 24% more cyclists killed. This comment on the government statistics illustrates:

"The vulnerability of people walking and cycling, who have a fatality rate more than 20 times that of someone in a car, highlights the urgent need for action to address the dangers of motor traffic, as the Government seeks to encourage more people to choose to walk or cycle."

DATA:

Well over 45 millions are carried routinely in our some 30 million cars and they suffer some 46% of the annual road deaths of circa 17,500. i.e. some 8050 deaths. Even with the low count of 45 million car occupants that's one death per 55,900.

3% of the population claim to cycle regularly and they suffer an average of about 110 deaths annually. That's one death per 18,100.

9% of the whole population, nearly 1 in 10, would have to cycle as regularly as people use their cars with no increase in deaths for the cyclist death rate to as low as that of car occupants, and we are not remotely near that rate of cycling nationally in normal times. We may have been a bit closer to that due to the Covid-19 crisis, but no doubt much of that will disappear as people get back to work and the winter weather arrives.
.

 

[PP100]

Thanks for your replies , I see I have opened another can of technical worms!
Basically , in practical terms, my question is : The difference between an assist setting of say 2 compared to 5 - On 5 the speed is obviously increased on flat ground but does this significantly increase the climbing power?

 

[Nealh]

Thanks for your replies , I see I have opened another can of technical worms!
Basically , my question is : The difference between an assist setting of say 2 compared to 5 - On 5 the speed is obviously increased on flat ground but does this significantly increase the climbing power?

It depends on the controller system some use speed control while others use current control. Systems with speed control one will invariably not notice any difference in power as max current is supplied in any assist level, though max assist speed in each level will be different.
Where as current control delivers more current with each increase in assist level which is noticeable more so on inclines, the max assist speed in each assist level is the same.