PAS on hills

Thom473

Member
In email exchanges with Radbike during assembly and initial riding and in reading the owners manual, we are instructed to climb hills in low gear (OK, that's how you climb hills in a normal pedal bike)...but we are told to keep the PAS level low so human power predominates in the ascent. That last part is counterintuitive since climbing hills is when you need the most assistance. When I asked, they said it was to keep the motor/controller from overheating. That's still counterintuitive since motors and controllers work best at high rpm. While reading http://em3ev.com/store/index.php?route=information/information&information_id=7 I saw that they also recommend low gear...but they recommend high PAS on hills and suggest that you have a greater probability of burning out your motor or controller if you use low PAS.

Since I'm new to ebikes, I'd like to know what to do for sure...what do you folks do?
 

mrgold35

Well-Known Member
I might be working my Radrover motor a little harder with around 280-290 lbs total weigh with bike accessories, Topeak rack bag+panniers loaded with "just in-case stuff", Osprey backpack stuffed work cloths/lunch, and cold+cool weather riding gear. It is mostly uphill on the 6.5 mile ride home (4900ft to 5400ft) with a few steep and a little long inclines. My rule of thumb is to keep the watts at or below the 500-550 level and pedal at the highest gear my 50 year old legs can do. I'm more of speed PAS 4-5 rider for commuting compared to leisure PAS 2-3 on the weekends. My 20-25 minute bike ride home is also my cardio workout for the day.

Not sure if it makes a difference in long term to the hub motor at 500 watts going uphill slower in the recommended PAS 2 or really pedaling hard in the highest gear possible at 500 watts at PAS 4-5 on the same hill?

We have a storm moving in today and I'm expecting a head wind all the way home of +20 mph. I usually have to drop my PAS down to 2-3 just to keep the watts below 500 depending on how stiff the headwind+gust are.
 

flymeaway

Well-Known Member
That's still counterintuitive since motors and controllers work best at high rpm

You are correct. When climbing a hill the most important factor is keeping the motor running at a high RPM. Select the gear used to keep your cadence fairly constant during the climb and use whatever PAS level you want. If......and it's a big IF! you cannot keep the cadence at a high enough level and the motor runs at a lower speed you should reduce the PAS level to avoid overheating the motor and or controller. I generally keep my hill climbing cadence above 60 even if my forward speed is slow on long steep grades. On less severe grades, even if the grade is long, I can keep the cadence above 80, and yes, one of the reasons we buy electric bikes is to take advantage of the higher power levels to assist in hill climbs.

Court J.
 
Last edited:

George S.

Well-Known Member
The information on the EM3ev site is specifically for a mid-drive motor, a BBS. There is a big difference between a hub and a mid-drive. When you are in a low gear on an MD, the motor is in a low gear. On a hub, you cannot change the gearing of the motor. You change the gear for the pedals and the chain, basically, so you can work harder.

The info from Rad would be discouraging to me, but it depends on what kinds of hills. The quality of a hub motor is the ability to shed heat under stress. Cheap hubs are less robust. They might lay out what they mean, like at what grade. I think you should tell people not to stress the motor. They could include a temperature display, that would help a lot. They could educate customers on when a motor is stressed. You can touch the housing.

The more expensive hubs do a better job of shedding heat, but there are exceptions that just seem to shut down. Telling people not to use the motor on a hill is crazy. Maybe they are using too cheap a motor? What motor do they use and what is the wholesale/retail cost per unit?

A mid-drive in a low gear solves the problem but DIY units start at $500. There are hubs that do fine with 7 or 8% grades. Some level of pedaling definitely helps.
 
I switched to an e-bike because I specifically wanted to take the sting out of hills. I'm perfectly capable of tackling them on my regular bike, but I wanted to reduce my overall commute time, as I often work 10-12 hours for several days.

My mid-drive IZIP Peak+ works really well for my 25-mile (round trip) commute. The route's climbs aren't steep, but one is somewhat lengthy.

(Link Removed - No Longer Exists)
 

Barkme Wolf

Active Member
According to Radwagon Users Manual "Do not climb hills steeper than 15% in grade."
I called them about this and they said it should read that power output should be kept under 500w on hills steeper than 15% in grade.
They said they would update the manual to show this error but have not yet (on line manual).
The person I spoke to said it was to prevent over heating, if I understood correctly.

Side note- The spoke size is also inaccurate on the website which I was told would also be corrected.
 

mrgold35

Well-Known Member
I lived in the west and southwest most of my life and I can't tell you what % the grade for a hill just by looking. It would be a nice future upgrade to see a temp reading or a blinking warning code if you are close to overheating the controller/hub motor. I can see getting different temp readings in winter at 25 degrees and pushing the motor/controller harder compared to summer months with temp +100 degrees. If you can air cool a motorcycle engine, it seems you can do the same with a controller and hub motor.
 

Kingsinger

Member
15% grade is a pretty steep hill. Seattle has a lot of hills, but most aren't steeper than 15%. The steepest street is reputed to be a little under 22%. But even the counterbalance at Queen Anne Ave, one of the more famous steep streets in Seattle, is apparently only 14%. So for most people, this is probably not going to be an issue that much. If you're going to do serious mountain biking with steep grades, you'd probably want a mid-drive anyway, no?
 

Barkme Wolf

Active Member
Hate to differ with you and maybe I am confused but my research shows:
https://www.seattle.gov/transportation/steepest.htm

I ride from Renton to Redmond and run up several long steep hills greater than 15%. I keep my PAS set at 2 regular and 3 on hills, haven't had an issue in over 2000 miles although I have been passed up by people on Radrovers and other electrics, I assume they did not read the manual.
 

Kingsinger

Member
You're probably right. I'm familiar with the google maps elevation info for bike routes, but I got those Seattle figures from here, because I found it easier to extract information about specific stretches of road: http://veloroutes.org/hillgradecalculator/ But the info here definitely could be wrong. Slope percentage is rise/run, yes?

In any case, many of those really steep grades on your link are only a block long. For example, I used to live near East Boston Street (listed as 23.8% grade). I think I might have even ridden my bike up it once. I've definitely driven up and down it many, many times. There's no doubt it's one of the steeper grades inside the city of Seattle. But it's quite short (253 ft). If we extend that route even one more block to 10th Ave E, then the overall grade of the climb drops to 16.1 % (85/528)

By contrast, the Holgate Street Overpass coming up on to Beacon Hill is listed as 13.4% (although I'm not sure what stretch of road they are using to calculate that). In any case, it seems like a much more daunting climb on a bike to start at the Office Depot on Airport Way S and climb up Holgate to the Baja Bistro on 14th Ave S, because it's mostly a steady climb for almost 3/4 of a mile, and the overall grade is a little under 7%, with the steepest part apparently 13.4%.

Along the same lines, if you're riding your bike from 1st Ave in Seattle up James Street to Broadway, that route may well include a stretch between 4th and 5th Ave that is 17.1%, but according to the numbers on veloroutes, that route has a rise of 339 ft and the run at 3696 ft (.7 miles). So that's an overall grade of 9.1% for the route.

Anyway, I'm no expert on this stuff, so I don't know what's more important, the absolute steepest part of a route, or the grade of the route as whole. But it would seem to me that the 15% figure ought to be viewed in the context of how long the hill climb is, because the longer the motor needs to deal with the steep hill, the longer it's going to be under extra load.

Undoubtedly, trying to climb a 250 ft stretch of road with a 23% grade from a dead stop is probably something one would be wise to use some care about (or avoid). On the other hand, hand, if you hit 250 feet of 23% grade with momentum, in the context of a climb that's .7 miles long with overall grade of 9%, it doesn't seem like that's necessarily going to be an issue, as long you're careful, no?

JL
 

Kingsinger

Member
Btw, how long does it take you to make that commute everyday on your Rad? I can't imagine the estimated time on google maps is correct, as it's assuming an average speed of 9.5538 mph.
 

Barkme Wolf

Active Member
You're probably right. I'm familiar with the google maps elevation info for bike routes, but I got those Seattle figures from here, because I found it easier to extract information about specific stretches of road: http://veloroutes.org/hillgradecalculator/ But the info here definitely could be wrong. Slope percentage is rise/run, yes?

In any case, many of those really steep grades on your link are only a block long. For example, I used to live near East Boston Street (listed as 23.8% grade). I think I might have even ridden my bike up it once. I've definitely driven up and down it many, many times. There's no doubt it's one of the steeper grades inside the city of Seattle. But it's quite short (253 ft). If we extend that route even one more block to 10th Ave E, then the overall grade of the climb drops to 16.1 % (85/528)

By contrast, the Holgate Street Overpass coming up on to Beacon Hill is listed as 13.4% (although I'm not sure what stretch of road they are using to calculate that). In any case, it seems like a much more daunting climb on a bike to start at the Office Depot on Airport Way S and climb up Holgate to the Baja Bistro on 14th Ave S, because it's mostly a steady climb for almost 3/4 of a mile, and the overall grade is a little under 7%, with the steepest part apparently 13.4%.

Along the same lines, if you're riding your bike from 1st Ave in Seattle up James Street to Broadway, that route may well include a stretch between 4th and 5th Ave that is 17.1%, but according to the numbers on veloroutes, that route has a rise of 339 ft and the run at 3696 ft (.7 miles). So that's an overall grade of 9.1% for the route.

Anyway, I'm no expert on this stuff, so I don't know what's more important, the absolute steepest part of a route, or the grade of the route as whole. But it would seem to me that the 15% figure ought to be viewed in the context of how long the hill climb is, because the longer the motor needs to deal with the steep hill, the longer it's going to be under extra load.

Undoubtedly, trying to climb a 250 ft stretch of road with a 23% grade from a dead stop is probably something one would be wise to use some care about (or avoid). On the other hand, hand, if you hit 250 feet of 23% grade with momentum, in the context of a climb that's .7 miles long with overall grade of 9%, it doesn't seem like that's necessarily going to be an issue, as long you're careful, no?

JL
I am only going
Btw, how long does it take you to make that commute everyday on your Rad? I can't imagine the estimated time on google maps is correct, as it's assuming an average speed of 9.5538 mph.
About an 1:30 flat out no rest stops but I take my time and enjoy the view so I do it in about 1:45. I use a few short cuts Googles isn't hip to. On the bus it takes 2-3 hours depending on if the transfers match up. Same trip in a car varies but the one time I clocked it against a driver and he beat me by about 15 minutes in normal rush hour traffic.
 

Kingsinger

Member
So average speed of a little under 12 mph. Or a little under 14 mph if you go flat out. Not bad. So when you say the car beat you by 15 minutes, is that 1 hour 15 minutes for the car? Or an hour and half? In either case, that's a crazy low average speed for the car? Google maps estimates 40 minutes as the long drive for the car. Even that's only a 30mph average for the car. And if it takes an hour by car, which I bet it often does, then that's only a 20.7 mph average speed for the car. Crazy.
 

Barkme Wolf

Active Member
So average speed of a little under 12 mph. Or a little under 14 mph if you go flat out. Not bad. So when you say the car beat you by 15 minutes, is that 1 hour 15 minutes for the car? Or an hour and half? In either case, that's a crazy low average speed for the car? Google maps estimates 40 minutes as the long drive for the car. Even that's only a 30mph average for the car. And if it takes an hour by car, which I bet it often does, then that's only a 20.7 mph average speed for the car. Crazy.
Hour and a half in car on a good day. When it is not rush hour it is a 45 min drive by car, easy. This is why I quit driving years ago. Even though the bus takes longer, I can get stuff done durring the commute. Kingsinger- are you in my NW electric bike group on FB? Not a lot of posts since wither hit but I try to keep it updated. The other members share better stuff than I do most of the time.
 

J.R.

Well-Known Member
Very valuable information you (users!) guys offer in this thread. Good read, hills and ebikes interest many of us. Interesting note; the only time I had an overheat shutdown on an ebike was powering through snow, on an 18% grade. Overheat in snow! Hills hurt.

For fun I posted this awhile back about bikes and hills.

https://electricbikereview.com/forums/threads/the-dirty-dozen-a-37-grade-hill-climb.3177/

As far as I know, no ebikes have done it...yet!
 

Barkme Wolf

Active Member
To be clear, I have never had an issue with over heating but have almost never run the motor over 500- 550 on a hill (I am poor and am overly cautious about my investment).
Over 2200 miles on it in under 6 months.
 

Barkme Wolf

Active Member
Not an electric bike user yet. One of these days, though. Trying to learn ...
Testimonial:
I had not ridden a bike since the late 80s. I smoke and am generally lazy but at a healthy weight. I was having back problems and the seats on the bus were not helping.
I got my e-bike on a Friday and by Monday my back was feeling better (did PT to fix it). After 2 months I put 1000 miles on the bike and had fun doing it. I am at over 2000 miles today.
Things they didn't tell me-

You will need clothes specific for riding.
There is maintenance up keep costs you can mitigate with DIY
Your butt will need protection.
Spokes are going to break.
Bio-Bikers will scorn you and challenge your speed.
Flats are inevitable (I got 4 in the first month....4) get good at fixing or upgrade.
(I got Mr.Tuffy liners and only had 1 flat after- I will upgrade to Schwalbe Marathons when I get the money)
https://www.schwalbetires.com/bike_tires/road_tires/marathon_plus_tour

Hope that was good info for you-
 

mrgold35

Well-Known Member
Best parts of my day is ebike commuting to and from work everyday. I only commuted with my old pedal power bike a few times in +3 years and hills, 10-20 mph windy days, and 95-105 degree summer heat suck all the joy out of it. Not an issue with my ebike commuting 3-5 times a week at 15 miles per day. Had to drive today because we had overnight rain that changed to snow with a sheet of ice everywhere this morning.

I never even thought about an ebike before until the end of last summer. The amount of choices we have today at affordable prices just didn't exist a few years ago. It feels like we are just entering an ebike renaissance and it is just going to get better.

I haven't touched my old bike since I purchased my Radrover in September.