Pedal Assist and Gear strategies

RecBiker

New Member
I purchased an E-Joe Epik SE in late August. I didn’t get to ride much when I first got it because of the poor air quality levels due to the fires in Northern California. It has a rear hub motor using a cadence sensor, with seven conventional gears, five pedal assist levels, and a throttle.

When I come to a hill, it’s been a hit or miss on my pedal assist level selection and gear selection. Sometimes I select a higher pedal assist level too soon or I’ll get in a lower gear too late. And sometime, my pedal assist level and gear selection is perfect. I know it depends on the steepness on the hill, but in general, what pedal assist level and gear selection strategies do you use for different types of hills? Do you use the multi pedal assist levels like a traditional mountain bicycle with three front chainrings?

Another question I have is how does the cadence affect the power output on a rear hub motor? I think the output of a mid-drive motor with a torque sensor operates by how much force it senses at the pedals (e.g., the higher the torque, the higher the motor output). Does the output of a rear hub motor vary with pedal cadence speed? I.E., do you get more power output if you pedal faster or does the cadence sensor just act like an on/off switch?
 

rich c

Well-Known Member
The cadence sensor is like a switch. It only senses motion of the bottom bracket and turns on the power. There are adjustments and settings in the controller that ramp up the power to a set rate, so it's not instant power to the assist level you have chosen. Foofer is right, you'll soon know when the assist level is right for the hill. I'd suggest for now you set it high at the start of the hill, then start dropping gears. Too much power, just bump it down on the hill.
 
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RecBiker

New Member
The cadence sensor is like a switch. It only senses motion of the bottom bracket and turns on the power. There are adjustments and settings in the controller that ramp up the power to a set rate, so it's not instant power to the assist level you have chosen. Foofer is right, you'll soon know when the assist level is right for the hill. I'd suggest for now you set it high at the start of the hill, then start dropping gears. Too much power, just bump it down on the hill.
Thanks, I’ll try that on my next hill climb. I don’t go up many steep hills, but on one that I did, I started at a lower pedal assist level and when I tried going to a higher pedal assist level, it seemed like it didn’t do anything to help. My expectation was it was going to be like shifting to a smaller chainring on a traditional bike.
 

theemartymac

Active Member
Thanks, I’ll try that on my next hill climb. I don’t go up many steep hills, but on one that I did, I started at a lower pedal assist level and when I tried going to a higher pedal assist level, it seemed like it didn’t do anything to help. My expectation was it was going to be like shifting to a smaller chainring on a traditional bike.
One thing to keep in mind with hubs as well, if they want to spin fast. The power output drops off dramatically at lower rpms, and once in those slower speeds, you aren't producing enough torque to accelerate anymore. Additionally, use caution with pinning the throttle or using max assist on a long slower climb (>2mins), as any energy in excess of what the motor can use (based on it's rpm) will just become heat, and that's how you fry hubs. I find that for some of the longer steeper hills I commute on, the best strategy for my bike is to ramp up the speed as high as I can safely do (near max assist and a higher gear) before I start the climb, and then shift down gradually and steadily as needed to keep a good quick cadence that allows me to apply steady leg power. If I fall below 15km/h, I need to start reducing the assist setting or I could quickly overheat.

I have one spot on my route to work that is 2 separate 11% grades split over 0.5km or so and about 80m total elevation gain. I'm 300lb, so I'll overheat my hub and the motor will fault if I run it too slow. If I use the above strategy, and pedal hard enough to keep over 10-15kph I make it with no issues. If I fall below 10km/h before I crest the first pitch, I need to stop for 3-5 minutes of cooling time, or I know I won't finish the second pitch without a fault. My bike becomes a lead brick due to motor drag when the hub faults out, so I can't even rely on granny gear to finish the climb manually. So a different chainring might help your ability to pedal, but it won't necessarily help the hub become any more efficient.

But my long-term solution was to pick up a mid-drive for my commutes and hillier rides. Using the gears to help me keep the motor near it's sweet spot rpm means this new bike eats the steepest hills for breakfast and asks: "is that all you got?'. ;-) The hub drive is still my city ride and errand bike, as the simplicity of the hub and off-the-line performance in stop and go traffic just can't be beat.
 

RecBiker

New Member
One thing to keep in mind with hubs as well, if they want to spin fast. The power output drops off dramatically at lower rpms, and once in those slower speeds, you aren't producing enough torque to accelerate anymore. Additionally, use caution with pinning the throttle or using max assist on a long slower climb (>2mins), as any energy in excess of what the motor can use (based on it's rpm) will just become heat, and that's how you fry hubs. I find that for some of the longer steeper hills I commute on, the best strategy for my bike is to ramp up the speed as high as I can safely do (near max assist and a higher gear) before I start the climb, and then shift down gradually and steadily as needed to keep a good quick cadence that allows me to apply steady leg power. If I fall below 15km/h, I need to start reducing the assist setting or I could quickly overheat.

I have one spot on my route to work that is 2 separate 11% grades split over 0.5km or so and about 80m total elevation gain. I'm 300lb, so I'll overheat my hub and the motor will fault if I run it too slow. If I use the above strategy, and pedal hard enough to keep over 10-15kph I make it with no issues. If I fall below 10km/h before I crest the first pitch, I need to stop for 3-5 minutes of cooling time, or I know I won't finish the second pitch without a fault. My bike becomes a lead brick due to motor drag when the hub faults out, so I can't even rely on granny gear to finish the climb manually. So a different chainring might help your ability to pedal, but it won't necessarily help the hub become any more efficient.

But my long-term solution was to pick up a mid-drive for my commutes and hillier rides. Using the gears to help me keep the motor near it's sweet spot rpm means this new bike eats the steepest hills for breakfast and asks: "is that all you got?'. ;-) The hub drive is still my city ride and errand bike, as the simplicity of the hub and off-the-line performance in stop and go traffic just can't be beat.
Thank you for your insights! I did not know about the overheating issue. This type of information was the reason I joined this group. I assume other than feeling the hub for excessive heat, are there any indications I should be aware of while I’m actually riding? If the hub motor overheats, will it destroy the motor or will it revive itself after cooling down?
 

theemartymac

Active Member
Thank you for your insights! I did not know about the overheating issue. This type of information was the reason I joined this group. I assume other than feeling the hub for excessive heat, are there any indications I should be aware of while I’m actually riding? If the hub motor overheats, will it destroy the motor or will it revive itself after cooling down?
Feeling for heat can be a red herring. Most hubs don't use the housing to actively cool the windings as there is an air space between the windings and the case. (Google or search here for 'Statorade' and 'Hub Sinks' for a rabbit hole of science on how different hubs and cooling options work/don't work) And the specific hub, drive type, and construction (direct/geared/etc.) plays a role, but for a normal sized human on a typical bike, you have to work hard to overheat one to the point of permanent damage, and normally it will cool off and resume performance.

First sign is usually power drop off, then perhaps 'cogging' where the power pulses, then heavy feeling pedals before it fails and faults out. It's important to note that they often cool slowly, and once hot, they soften and can fail over time due to repeated cycling and eventual hardening and cracking of the wiring. For a supersized guy like me, with heavy cargo, or seriously hard hills, it can be done much, much easier, especially if done repeatedly.

Watch this guy for a fun redneck science video that shows the effects of heat and cooling (although on crazy aussie customized bikes).

 

RecBiker

New Member
Feeling for heat can be a red herring. Most hubs don't use the housing to actively cool the windings as there is an air space between the windings and the case. (Google or search here for 'Statorade' and 'Hub Sinks' for a rabbit hole of science on how different hubs and cooling options work/don't work) And the specific hub, drive type, and construction (direct/geared/etc.) plays a role, but for a normal sized human on a typical bike, you have to work hard to overheat one to the point of permanent damage, and normally it will cool off and resume performance.

First sign is usually power drop off, then perhaps 'cogging' where the power pulses, then heavy feeling pedals before it fails and faults out. It's important to note that they often cool slowly, and once hot, they soften and can fail over time due to repeated cycling and eventual hardening and cracking of the wiring. For a supersized guy like me, with heavy cargo, or seriously hard hills, it can be done much, much easier, especially if done repeatedly.

Watch this guy for a fun redneck science video that shows the effects of heat and cooling (although on crazy aussie customized bikes).

Sorry for the late response, it was 2:45 a.m. here so I went to sleep. Thank you for the additional information. I’m a retired airplane mechanic (37 years), so I like these technical details. i bought this bicycle to get me outdoors during this pandemic. It’s reassuring to know I have a motor to get me home if I get too tired to pedal.
 

AHicks

Well-Known Member
There's a lot going on at first, so don't feel bad when you screw up at the base of a hill - or worse, half way up. We all completely suck as riders the first hundred miles or so (at least!). Like you say, getting your speed, the gear and PAS level right for the conditions you are in at any given moment takes some experience. Then those occasions where everything went right start happening more often and you start figuring out why! Seriously, with your mechanical background you'll find you're a MUCH better rider after you've been riding a while. Pretty strong mechanical background here as well, and one of my favorite "things" on every ride is to see/judge myself on just how effeciently the bike can be ridden.... Just how far can you get on a charge?

In the scenario where you hit a hill or big rise in too tall a gear, it really makes a difference if that too tall a gear is 6th or 7th, or if you are in 2nd. You can drop a couple gears, at least, if in a tall gear, then get on the throttle if necessary - but that's not an option if you are in second. That's time to get on the throttle right away, while down shifting to try and avoid letting the bike get too slow. The hell with the PAS level you're in. On a hill, you need to take care of business!

Give yourself some time, keep yourself challenged, and HAVE FUN! -Al
 

RecBiker

New Member
There's a lot going on at first, so don't feel bad when you screw up at the base of a hill - or worse, half way up. We all completely suck as riders the first hundred miles or so (at least!). Like you say, getting your speed, the gear and PAS level right for the conditions you are in at any given moment takes some experience. Then those occasions where everything went right start happening more often and you start figuring out why! Seriously, with your mechanical background you'll find you're a MUCH better rider after you've been riding a while. Pretty strong mechanical background here as well, and one of my favorite "things" on every ride is to see/judge myself on just how effeciently the bike can be ridden.... Just how far can you get on a charge?

In the scenario where you hit a hill or big rise in too tall a gear, it really makes a difference if that too tall a gear is 6th or 7th, or if you are in 2nd. You can drop a couple gears, at least, if in a tall gear, then get on the throttle if necessary - but that's not an option if you are in second. That's time to get on the throttle right away, while down shifting to try and avoid letting the bike get too slow. The hell with the PAS level you're in. On a hill, you need to take care of business!

Give yourself some time, keep yourself challenged, and HAVE FUN! -Al
Thanks for your encouragement. As a gear head, it’s sometimes frustrating when something doesn’t work the way you think it should or you can’t duplicate what worked before. I went on a ride today and everything worked great. I felt like a kid getting a new bicycle for my birthday. The freedom a bicycle can give you.
 

AHicks

Well-Known Member
Thanks for your encouragement. As a gear head, it’s sometimes frustrating when something doesn’t work the way you think it should or you can’t duplicate what worked before. I went on a ride today and everything worked great. I felt like a kid getting a new bicycle for my birthday. The freedom a bicycle can give you.
Trust me, I get it! The ONLY way to kill frustration is with patience......
 

TAZMANIMAN

Active Member
I have Muscular Dystrophy but I find that I can stay in whatever gear I'm in and highest power level I can buzz right up most hills, if I need more power I find that if I hit the throttle also while I'm peddling it gives a little extra boost.
 

RecBiker

New Member
I have Muscular Dystrophy but I find that I can stay in whatever gear I'm in and highest power level I can buzz right up most hills, if I need more power I find that if I hit the throttle also while I'm peddling it gives a little extra boost.
I went on my 13th ride yesterday and I actually did this for the first time. Before yesterday’s ride, I never used the pedal assist and throttle at the same time because I thought the motor could only receive input from one source (the pedal assist or the throttle) at a time. Maybe in the circuit’s interface logic it does use only one input source at a time and if it does, it is seamless.
 

Gordon71

Active Member
For me it depends on the hill. I have certain routes that I ride so know what's best depending on how steep the hill is. On some of the steeper hills I approach it in the highest gear and highest PAS level so I'm going at least 20MPH when I start up the hill and then drop the gears as needed while climbing. That seems to work the best.
 

TAZMANIMAN

Active Member
I went on my 13th ride yesterday and I actually did this for the first time. Before yesterday’s ride, I never used the pedal assist and throttle at the same time because I thought the motor could only receive input from one source (the pedal assist or the throttle) at a time. Maybe in the circuit’s interface logic it does use only one input source at a time and if it does, it is seamless.
With how weak my legs are I can feel differences in the assist and it definitely gives a little extra oomph when I do both vs just one
 

Lightning P38

Active Member
I purchased an E-Joe Epik SE in late August. I didn’t get to ride much when I first got it because of the poor air quality levels due to the fires in Northern California. It has a rear hub motor using a cadence sensor, with seven conventional gears, five pedal assist levels, and a throttle.

When I come to a hill, it’s been a hit or miss on my pedal assist level selection and gear selection. Sometimes I select a higher pedal assist level too soon or I’ll get in a lower gear too late. And sometime, my pedal assist level and gear selection is perfect. I know it depends on the steepness on the hill, but in general, what pedal assist level and gear selection strategies do you use for different types of hills? Do you use the multi pedal assist levels like a traditional mountain bicycle with three front chainrings?

Another question I have is how does the cadence affect the power output on a rear hub motor? I think the output of a mid-drive motor with a torque sensor operates by how much force it senses at the pedals (e.g., the higher the torque, the higher the motor output). Does the output of a rear hub motor vary with pedal cadence speed? I.E., do you get more power output if you pedal faster or does the cadence sensor just act like an on/off switch?

I find if I am going up a tough hill, I shift to my lowest gear at the bottom of the hill and put my e-assist at 2.
If you can’t keep up pedalling with the motor, then shift up to 2nd gear. I judge level 2 assist to be a 40% power level to the motor. And a level 3 to be a 60% power level for the motor. I don’t use level 4 or 5 going up hills, as it runs the battery down faster....and I don’t need to go 15 mph up hills that other riders are going up at 7-8 mph.

If part way up the hill I want to go faster, I bump the switch up to the level 3 assist, at which point the emotor will propel you faster than you can pedal, so you can shift up to 3rd gear. But I usually stay at level 2 going up hills, as I am able to pedal fast enough to go 7-8 mph uphill.
 

RecBiker

New Member
I find if I am going up a tough hill, I shift to my lowest gear at the bottom of the hill and put my e-assist at 2.
If you can’t keep up pedalling with the motor, then shift up to 2nd gear. I judge level 2 assist to be a 40% power level to the motor. And a level 3 to be a 60% power level for the motor. I don’t use level 4 or 5 going up hills, as it runs the battery down faster....and I don’t need to go 15 mph up hills that other riders are going up at 7-8 mph.

If part way up the hill I want to go faster, I bump the switch up to the level 3 assist, at which point the emotor will propel you faster than you can pedal, so you can shift up to 3rd gear. But I usually stay at level 2 going up hills, as I am able to pedal fast enough to go 7-8 mph uphill.
Thanks...I’ll try your technique the next time I hit a hill.
 

theemartymac

Active Member
I went on my 13th ride yesterday and I actually did this for the first time. Before yesterday’s ride, I never used the pedal assist and throttle at the same time because I thought the motor could only receive input from one source (the pedal assist or the throttle) at a time. Maybe in the circuit’s interface logic it does use only one input source at a time and if it does, it is seamless.
There were a bunch of older bikes that didn't allow both inputs, but it seems to be the norm now to allow the throttle to manually override the cadence or torque sensor when pressed. Works great on mine.
 

BigNerd

Well-Known Member
I use the same technique as @Lightning P38 , using the PAS as a gear and based on my cadence and speed, move the PAS and gears up/down.

You will get a better feel for it as you ride your rear hub more.
 

Lightning P38

Active Member
I went on my 13th ride yesterday and I actually did this for the first time. Before yesterday’s ride, I never used the pedal assist and throttle at the same time because I thought the motor could only receive input from one source (the pedal assist or the throttle) at a time. Maybe in the circuit’s interface logic it does use only one input source at a time and if it does, it is seamless.
Also, I learned from the bike at what speed the bike would go at each assist level with me pedaling.
For example, at assist 2 the e-assist maxes out at 10 mph on a level paved trail. At level 3 assist, it maxes out at 15 mph. At level 4, 20 mph. At level 5, 28 mph.

So if my buddy is riding at 10 mph on a non e bike, I know I will be able to keep his pace at level 2 assist.
As a 20 year cyclist, I always start out with the shifter in low gear like regular bikes, and shift up to the desired speed. My shifter does not display what gear I am in, I just know by feel about how many gears to shift up...and in this case about 3rd or 4 th gear.

If a buddy is riding at 12 mph, I will run out of assist on level 2 at 10 mph, but at level 3 I will be going too fast, so I have to decide whether I want to work without much assist at level 2 assist, or pedal and coast with level 3 assist. So with level 3 I pedal one or two revolutions, then coast a bit, then repeat.

The other day I was on a gravel rail trail, which reduced my speed about 2 mph, with some mature riders. So I used level 2, and it was a good match as they were going 8 mph on the 2% upgrade segment of the ride.

If I am solo on a paved trail, I will use level 3 and cruise at 15 mph. On some segments I will bump up to level 4 and cruise at 20 mph as I seem to be motivated to pedal harder and get another mph or two at the higher speed.

The only time I use level 5 is in traffic in downtown Scranton, as it boosts you off the line as quick as the cars, and I can cruise with them up to 28 - 30 mph.