Hillclimbing Dash

Craig

New Member
Wanted to thank everyone in the forum for the solid information here and the detailed video review, which convinced me to buy my Dash this past Saturday. Me: mid-50s, 220 lbs and out of shape, my last bike purchase was a 90's MTB. Probably a perfect ebike candidate, as I have a short 5.5 mile RT commute but there is a 3/4 mile long, 9% grade hill to climb along the way.

Wondering if I the Dash could get me up that hill was my biggest concern before buying, and I'm pleased to say that the Dash powered up it 3X on its first charge -- I went 18 miles with 2 bars still showing before deciding to recharge tonight for the first time. The hill is taxing, though, even pedaling like crazy going up that hill at PAS4 I lost a bar each climb. The rest of the ride on the flats at PAS1 the meter didn't even move, so my range may be a worst case example. Didn't want to temp fate and try for a fourth run until I have a better handle on what hillclimb range is really left with 2 bars.

The frame fit information here was also reassuring -- although I bought the bike at Ebikes of New England and was able to try it out in person, if you can't the Medium fit my 5'10" 32" inseam perfectly.
 

Craig

New Member
Hi, haven't actually tried any throttle only climbs (have always been in PAS). Should be possible to figure it out based on 40NM torque and rider weight, but I've pretty much forgotten all the physics I knew years ago. Maybe I'll just hop on and see when it stops raining.
 

Court

Administrator
Staff member
Sounds like it's working great for you Craig! Thanks for the testimonial about the hills and battery life. Good call taking it in for a charge vs. deep cycling. I've heard that the first several rides are best to discharge around 50% then recharge.
 

Craig

New Member
Rusty, I asked one of my engineer friends about hill climb throttle only for the Dash and here's what he told me:

How steep a hill you can climb throttle only is dependent on the weight of the rider and motor torque. If we assume the bike’s weight with rider is 110Kg (about a 200 pound rider) then F= Gravity that must be overcome (N) = Mass * G (N) where G=9.8 M/s^2 so, F=110*9.8 = 1079.1N.

Now factor in the hill and f = F sin (theta) (0 degrees is flat, 90 is vertical). Torque is f * l where l is the radius of the wheel, which for a 700c wheel is about 0.334M. So, Torque = .334 * 1079.1 * sin (theta).

Don’t have specs on the Dash’s motor, but let's guesstimate the hub motor is rated 18NM continuous/40NM peak. If we solve the above for Torque = 18 NM then theta is 2.9 degrees. Convert 2.9 degrees into percent grade (rise/run (sin (theta)), and you get roughly 1 meter in 21 so round down and figure a 4% grade throttle only for a 200 pound rider. If we look at the peak torque of 40NM, theta increases to 6.4 degrees (or about a 10% grade) but peak numbers are generally REALLY optimistic and you’d need to know the power curve of the motor as that 40NM peak torque may be at zero speed.

Anyway, if you solve the above for your own weight + weight of the bike, you can get a rough idea of how much hill the Dash+you could climb throttle only.​

Hope that helps.
 
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Brambor

Well-Known Member
no it doesn't hahaha but I'm impressed. I'm in technology but my math skills are long gone. I'm envious of your skill Craig :)
 

Craig

New Member
Well, thanks but you're really envious of my friend Mike's engineering skills - he just sort of rattled that off and I wrote it down. My excuse is that engineering classes were 35 years ago and those brain cells now handle more important things like "where are my keys".
 

Court

Administrator
Staff member
Well, thanks but you're really envious of my friend Mike's engineering skills - he just sort of rattled that off and I wrote it down. My excuse is that engineering classes were 35 years ago and those brain cells now handle more important things like "where are my keys".
I think I found them Craig!

keys-for-craig.jpg
 

wwjd

Member
I have a 15 degree driveway that is about 120 feet long. I have to get a good running head start running the bike in 9th gear, and on the last 15 feet or so I won’t make it without turning the throttle control for some more power from the battery. I am a 235 lb. guy by the way. Not many people seem to realize that you can still use the throttle control in pedal assist mode. The instructions make it sound like you can only use it from a dead stop at a light signal or stop sign to get some assistance in going, but you can use it at any time in any pedal assist mode for a little more boost. All the other grades around my house which max out at about 10 degrees I can climb without getting a running start. But it also taxes the energy levels of the battery as well. Just make sure you don’t have any steep hills to climb at the end of your commute. The battery just might not have enough power anymore to get you up those grades. It is always good to tackle grades and headwinds at the beginning of your commute and not at the end of your commute. Otherwise, you just might find yourself out of gas (at least as far as the battery is concerned).
 

DanielMAlvarado

New Member
Love the Dash on flat and flat-ish roads, but it's not strong enough to get me up my local hill.

(it rises 90 feet in 0.5 miles--my geometry skills are failing me :) )
 

wwjd

Member
Yes, I find that anything over 10 degrees and the bike pretty much comes to a halt. I have a 15 degree grade on my driveway that is about 120 feet long, and I have to get a good running start going as fast as I can in 9th gear in pedal assist and in open throttle. For the last 15 feet or so I am just barely making it up my driveway. But I do tend to make it without having to downshift.

By the way, I found a formula online that calculates your weight and the degrees you are climbing, based also upon your speed, to let you know how many watts you would need to get you up such an incline as mine on my driveway. At 234 lbs., going about 12 mph, and at a 15 degree incline, I would need a motor at around 865 watts to keep me going without pedaling. So it really behooves the electric bike manufacturers to take advantage of this by installing at a minimum 750 to 1000w motors. They are available. California law, where I live, allows a maximum of 1000w on a bicycle. This size of motor, along with the 48v batteries that are now coming available, makes climbing a lot of these hills more feasible and almost a cinch to handle. And the higher the amp hours (ah) increases the mileage you can get out of these bikes (about 2 miles for each amp hour). These electric bike manufacturers need to build these bikes with the more heavier person in mind, and for which even the frames of these bikes are capable of handling of such a guy as myself, according the specs. The E3 Dash specs out at 230lbs., so motors should be put on these that can handle that weight and not that of a person weighing only 165 to 175 lbs. or so.

I don't remember where I saw the article on calculating weight, speed and degrees. But here are some of the formulas that I worked out based upon the initial one given to me that I found online. Granted, you will have to spend some time trying to figure all of this out. But if you are serious about getting something for the hills in your area, then it behooves you to understand the mathematical formula and purchase something that you think will work for you. I don't go up 15 degree slopes (or let alone 10 degree slopes) that often, so getting a bike with such a motor for those kinds of slopes wasn't that important to me. But I would need a bigger watt motor with my weight to climb up these inclines without having to pedal (the main avenue from my house down to the local town is 8 degrees, and the E3 Dash makes it, but barely). For those interested, here are the formulas below:

Formula online: Watts = (total) weight (kg) x 9.81 x speed (M/sec) x gradient (%/100). For example, 100kg (220lbs.) at 20kmh (12.5mph) at 4% (3% hill + 1% w+r) = 100 x 9.81 x 20000 x 0.04/3600 = 218 Watts. As another example, 100kg (220 lbs.) at 28kmh (17.5mph) at 5.5% (3.5% hill + 2% w+r) = 100 x 9.81 x 28000 x 0.055/3600 = 417 Watts. That is approximately what you can expect from 250w (200w) and 500w (400w) motors. (Note: 111kg = 244.5 lbs. and 20kmh = 12mph)

So, 111kg (245lbs., what I use to weigh) x 9.81 x 20000 (20kmh/12.5mph) x 15% grade (0.15/3600 = .0000416) = 905.97 watts of power I would need in an electric scooter (or ebike) to get up my 15 degree driveway. At 15mph (24000) this would be: 1,087 watts of power needed; 1,020 watts at 14mph (22530); 947 watts at 13mph (20920).
 
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Pace

Member
The E3 Dash specs out at 230lbs., so motors should be put on these that can handle that weight and not that of a person weighing only 165 to 175 lbs. or so.

The 231 lbs spec'd in the dash manual is all-up weight -- rider, accessories, and the bike itself.

I think in the case of the step hill you mention hitting in 9th gear and just barely making it, it may help to shift down like you would do unassisted. I say this because it seems like that would allow you to contribute power more effectively even though the gearing isn't helping the motor itself. Might be interesting to try several runs in different gears.

For major hill work, the mid drives like the peak would probably be better since the motor can leverage the bikes gearing.
 
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wwjd

Member
Thanks for the heads up, Pace! I would shift down if I had to, but I tend to just make it without doing so, so I just leave it in 9th gear.

And, wow, if that's the case that 231 lbs. is total weight including bike and accessories (as I also now read it in the manual on p. 8), then most of us shouldn't even be riding these bikes. We have been sold a bill of goods by the dealers that is not up to par with the weight of a lot of us. Like Daniel said above, "...only girls can ride the Dash" and young boys at that! These bikes alone weigh in at 49 lbs, so that means a person can weigh about 172 lbs., with the gear no more than 10 lbs., for a total weight of no more than 182 lbs. The last time I weighed 182 lbs was when I was 17 years old. My ideal weight for my height is about 195, so even that won't work according to these specs. I also got this bike in the hopes of helping me to shed some weight. At my age it is very hard to get back to about 195, but I'm trying with proper diet and exercise. This bike is doing a pretty good job of pushing me forward considering my weight and all. And for that, I am pleased. Once I shed some of this weight I know I will be able to travel even further than I am now, and even ascend some grades a little easier. But even now on the flats I am getting roughly 35 miles on a charge in PAS 1. So I can't complain about that.

As far as the Peak is concerned, I was looking for something with a bigger motor than just 350 watts, and I am not too familiar with mid-drives. For my size I need a bigger wattage motor to get me up some steep grades around here. Plus, I didn't want a mountain bike. I was told the Dash is a hybrid between a mountain bike and a cruiser. Ideally, I was looking for a cruiser like the Path+, and the Dash seem to fit both worlds with also the added speed. I also raised the handlebars and brought them more forward to me, and had a cruiser type seat installed. With the plethora of bikes that are out there it gets a little overwhelming in trying to decide what best fits a person. My concerns from the data that I had gathered were getting the biggest motor possible with the strongest battery possible and the need for a bike to go at least 30 miles (for my weight) without pooping out on me. As I said above, for my weight I really need about a 865 watt motor to make it up a driveway such as mine that is 15 degrees, and I do have an electric 1000 watt scooter with a 48v/12ah lithium-ion battery that serves this purpose very well in order to get my mail without having to pedal (it's the old arthritis in the knee thing that prohibits me from walking). Bicycling doesn't seem to put the same forces on my knees that walking up and down my driveway seems to do to me.

Anyway, I guesstimated that the Dash would suit me well for what I need, and so far it seems to be doing just that---except for the BB sensor now not working to assist me in pedaling. I am now in the process of getting that resolved. One of the reasons I got this bike was because of the pedal assist. There are plenty of them out there that work in only throttle mode. Initially, I was also wanting a gear-driven motor in the hub rather than a gearless one that is in the Dash. That might have been better for torque. But this gearless motor on the Dash isn't all that bad...except for the "cogging" effect that tends to slow the bike down while freewheeling. But with all that said, it would have been nice to have been able to try a Peak to see how that might have worked for me. That's the problem, you cannot just go to your local bike shop and try one these out. You have to try and study all of this online and determine what is the best fit for you, along with your budget. So, price was another important issue for me. I wanted to keep this thing around $2000, or less. And I ended up paying a little bit more than I really wanted to for this Dash. The new 2015 models are around $2900 and getting way out of the ball park as far as affordability is concerned. Prices need to start coming down, not go up!
 

Pace

Member
I think izip makes that weight spec on the conservative side, it sounds like the bike has been working for you and that's what's important. I tried a lot of bikes at several dealers, and while I didn't think the dash was the absolute best bike, I think it was the best value, especially if you need the extra speed/power. It doesn't sound like anything out there for 2k or less would have been better for you.

I agree with you on the 2015 pricing though, I was surprised to see the bike go from $2500 to 2900. That's still better than most of the other 28mph production bikes, but would have made me look harder at some of the better spec'd options from other brands.

Apart from a few small issues though, the dash is a good match for what I was looking for: a fast commuter that can also handle some lousy roads without a fuss.
 

wwjd

Member
Another thing that I forgot to mention that I was looking for was a battery located at the down tube under the seat or where it sits now on the Dash. I did not want one that was top heavy over the rear wheel. When trying to find a bike like that, one really begins to narrow down their options. There is a relatively new bike out there called the "e-Joe" which is a very good contender, and under $2k. It too has pedal assist and throttle mode, but no cruise control (which is kind of nice at times when you don't feel like pedaling). I rented one of these bikes at the beach for a day and it propelled me forward very well, even in some strong head winds, and it took me about 32 miles on pretty level ground for the most part, with me using all levels of pedal assist (but I pretty much stayed in 2 though, and then at 1 as I began to see the battery getting low). It has a 36v battery with 16 ah (that's right, 16 amp hours; which translates into more mileage). It also has a geared hub motor for torque. A guy on a $13k carbon bike couldn't even keep up with me; and when he finally did catch up with me after I had come to a stop, he realized I had a battery. About the only problem with the e-Joe is that you are limited to 20 mph (as most of these bikes are with pedal assist) and the frame has a step-thru design which makes it look more like a girls bike. But, hey, being able to step through that frame was actually kind of nice. Also, the color options in blue and watermelon were not up to par for me. It use to come in white and tan, but they discontinued that option. And, it comes with a rear rack, fenders and a headlight built into it...along with an LCD display. Not too shabby! But one thing I can say for sure, Currie seems to be there for you when all the others are either non-existent, trying to catch up, or don't even care. My local dealer that sells these Currie bikes has been outstanding, and when they call Currie they seem to be all ears in trying to help their dealers and their customers. You will even notice that on this forum.