Commute Speed

[nublar]

Just did a 15 mile commute (one way) in ~40 min on my Urban Plus in urban Los Angeles. Used about 45% battery to average 20 mph on max assist including stoppage time. 400 feet of elevation gain.

 

[Bruce Arnold]

I have a lot to learn
I was considering an ebike with a 500 watt Yamaha, 36 volts. It comes with a 500 watt/hour battery with 13.8 AH. My commute is 22 mile round trip and its pretty hilly. I planned on primarily using the eco setting. Should I be looking at a different bike???

You'd be pushing your luck with that battery, especially if it's a hilly ride. I use a rough estimate of 20 watt-hours per mile when I'm doing back-of-the-envelope calculations like this. (The harder you push it, the more watts you burn, but if you're going to stay in Eco most of the way, then it's a decent estimate.) 20 x 22 = 440 watt-hours on a 500 (well, 496) watt-hour battery. That puts you down into the range where the drain on the battery will shorten its useful life. The same bike, same 13.8 Ah battery but with 48 volts -- no problem. That gives you 662 watt-hours and a hefty reserve on your 22 mile round trip. If they've got a bigger battery for that bike, go for it if at all possible. Otherwise, plan to take your charger with you to work, give it some juice before riding back home.

 

[Gator]

Thanks for your quick reply.
I checked the specs and the motor is 250 watt nominal with 500 watt peak. Would this make a difference on consumption? The EBR review says the battery has a 60 mile range depending on conditions. It is a Giant Quick e + I am talking about. After reading the article I thought I would get two commutes with one charge. I rented/test road a Giant Explorer last night and rode 20 miles. The battery started out at 85%. When I returned the bike it was at 67%. Now its top speed is 20MPH though? I am just trying to make sense of it all. Not trying to dispute your numbers just trying to learn =D

 

[E-Mike]

@Bruce Arnold , how do the voltage and amp-hours come into play? I thought it was just the watt-hours that dictated how long the battery will last? Not all 500 watt-hour batteries are created equal?

 

[Bruce Arnold]

Thanks for your quick reply.
I checked the specs and the motor is 250 watt nominal with 500 watt peak. Would this make a difference on consumption? The EBR review says the battery has a 60 mile range depending on conditions. It is a Giant Quick e + I am talking about. After reading the article I thought I would get two commutes with one charge. I rented/test road a Giant Explorer last night and rode 20 miles. The battery started out at 85%. When I returned the bike it was at 67%. Now its top speed is 20MPH though? I am just trying to make sense of it all. Not trying to dispute your numbers just trying to learn =D

I don't know what effect the motor would have on battery usage -- there's nothing more open to speculation than what that particular set of numbers really means.

The figures I gave you are estimates. There are so many variables. Whether the bike has cadence or torque sensing. How much of the work you do. Wind. Hills. Temperature (cold temps decrease performance.) I don't mean it as gospel, only as a rule of thumb, and I hope you take it that way. I may be over-conservative, but when you say that it's pretty hilly, you've got to figure that you're going to burn through more watts. I'd rather have some spare juice in the tank.

Few things sour the ebike experience for people more than having insufficient battery.

 

[Bruce Arnold]

@Bruce Arnold , how do the voltage and amp-hours come into play? I thought it was just the watt-hours that dictated how long the battery will last? Not all 500 watt-hour batteries are created equal?

Volts are a measure of the current's potential to do work. Amperes are a measure of the amount of current flowing. Watts are a measure of the work that has been done. 13.4 amp-hours means that you could draw a current of 13.4 amps for one hour, one amp for 13.4 hours,

Think of a garden hose. Amperage is the amount of water actually flowing through the hose. The water pressure would be voltage. Watts would be the work you could do with the water, like hosing mud off your car.

Amp-hours times volts equals watt-hours.

 

[drewberz]

Wow, thanks for all the excellent information and advice. I'm almost wishing my commute were longer and more hilly now .

Rich C., my max speed varies of course but just glancing at a few rides, I'm reaching 30mph fairly regularly on the downhills. I'm assuming the e-bike won't help me much there.

I should mention the average speeds I mentioned are moving speeds. 2-5 minutes sitting at traffic lights is typical for me. A couple times I barely missed a green light on an uphill and was convinced that I would have made the light if I had a motor.

A couple of you mentioned different bikes like Stromer, Juiced CCS, etc. Being new to the market, one of the reasons I'm thinking about the Trek Crossrip+ is I'd really like to test ride the bike before buying. Are those brands available in bike shops, or mail order only? I'll have to do some googling to learn about those bikes and to see if they're sold in Colorado. Another reason I like the Crossrip+ is the road-bike styling with drop bars. I was under the impression that aerodynamics are an issue if you're trying to keep the speed high, although based on Michael Mitchell's reply, maybe that's only if you're trying to conserve battery? I believe I can get to work in max assist on a single charge if I wanted to, and I can charge the battery at work for the ride home. But, Bruce Arnold, it sounds like doing that will lead to having to replace the battery sooner?

I'm definitely encouraged by the idea that I can still get good speed without changing into bike clothes. And, once the school year starts and the kids take the bus 5 days a week, I'll be able to ride to work every day. I see e-bike being a huge advantage then, because I won't get worn out so much. For the summer, I have misc. kid transport duties, so I get to ride to work 2, maybe 3 times a week if I'm lucky...

i would even argue that the times you are doing low 30's+, the e-bike will slow you down. the motor cuts of at 28mph (it seems to cut at 27.6) meaning i get NO assist after that point. i ride a giant road-e+ and i can feel the resistance and weight. i can usually go faster on a normal bike on short but not so steep descents and definitely faster on short and steep descents, with a given effort.

i seem to average 23mph over 24 mi. with 900 ft. elev. one way and have a biking (but not race fit now) background.

i suspect your commute would be a little faster, but you could commute more frequently because you would certainly be less fatigued. i think you are wise to test ride an e-bike on your route first.