Need advice putting together bike that's good on hills...

[DahonElectric]

As I recalled from the Ping ebay website, their batteries are rated 1C sustained and 2C peak or is it? Battery voltage is not a true indicator of battery prowness. C rating is, and my NiCad 5C rating works damn good on the hills, being only a 36V. You can have a 48V 10Ah with a 0.25C rating and it is not going to deliver the load requirements compared to say a 36V 10Ah with a 2C rating or even a 24V 10Ah with a 4C rating from ebikes.ca. Operating voltage is what gives the initial burst, but for sustained output, you need a high C rating and that comes at a price.

DE.

From Ping's website: http://www.pingbattery.com/servlet/StoreFront
its 2C on the V2, and claims the V1 is 2C as well, though most people who have posted there experiances with the V1 say its best as a 1C battery. He's now issued the V2.5 which is also 2C.

Volts give you speed. higher voltage pressure gives higher RPMs from the motor, but it's relitive. 24V on one motor might be as fast as 48 volts for another. Commonly we say increasing the amps gives more torque, but thats a convention, and not entirly true. Its an increase of wattage that increases the torque. increasing the ampreage without increasing the voltage gives you more torque at the same speed, theoreticly.

Higher voltage gives you speed on a lower operating motor voltage, this is called over-volting. If the motor needs 48volts to operate at its proper efficient speed, then it needs a 48 v battery pack. There is no speed gain. There is a speed loss if you operate it at 36volts. Voltage is voltage. As far as the ebike electronics is concerned, it is only looking at the battery to operate properly with the proper operating voltage. Remember that you are not only over-volting the motor, but the controller too! Voltage is voltage and a battery can have a voltage reading across its open terminals, but if it has no ability to deliver current, it does nothing to the device but the battery voltage will sag dramatically. If the battery can deliver sustained current, not only it will not sag dramatically but be able to continue to service the load of the motor. Remember that the battery is providing the operating voltage for the motor. If the battery voltage sags dramatically down due to load, it will no longer provide the proper operating voltage of the motor and thus, the motor slows down. That was what I meant in the earlier message that if the eZee motor can function fine with a 36V battery pack, having a pack with a higher C rating will ensure that the battery will be able to service the load during an uphill climb. However, if the 48v pack has the same C rating as the 36v then all is even better! If the 48v has less C rating and you are loading the battery beyond the means of delivery, you simply will kill the battery sooner than later. It's good to see that Ping has improved their batteries quite a bit, but I am still a bit skeptical about their claims. Earlier Pings did not fair too well on high loads as this original poster will be planning on using the ebike for.

DE.

 

[DahonElectric]

But still I'm a bit confused here. Why are you riding a nice light weight bike and needing a monster motor? It's either you don't have the cardiovascular capacity to ride the bike by itself on flat ground or the hills in your area against are like 22% grade, which I highly doubt unless of course you live in cities like San Francisco?

gah...sorry about the confusion. i was obviously too tired when i posted my most recent message. :wink: what i forgot to mention is that in doing this research on ebikes, i've expanded my thinking on how i can use the bike because the electric assist opens up a bunch of options. for example, i'm realizing that i could use our burley trailer for getting groceries, i could go take our son on his trailer bike on trips that are too hard to reach without the assist, etc. so things like that are what were making me consider the possibility of needing/having extra power.

in terms of the hills, i'm told most of the hills around here average about 8% grade, with some around 12-15%, and a couple of the more remote hills being around 20% grade. i'd also be interested in riding in downtown seattle (near us), which has hills around 15% grade i'm told, though they're typically a block long, then level off at an intersection, then continue again for a block, etc.

but i'm realizing that maybe i'm trying to do too much in one package. it's probably not realistic (or maybe i should say wise) for me to try to build a system that's light for tooling around and that's burly enough (pun intended) for pulling a bit o cargo up hills. so now i'm thinking that maybe i should just use my jamis to build a simpler system for just helping me; and maybe with that experience under my belt, if i decide i need a system with more power, i'll buy a steel bike to build a more powerful setup. am open to comments/suggestions on that, though.

i'd still love it if someone could provide me some numerical and relative power ratings for the rear motors i'm looking at (assuming the battery is the same in each case).

Depending upon which Burley trailer you have (axle mount or chain stay), you may not be able to attach it to your rear hub system. If you plan to tow, then yes you NEED a 48v pack with high C rating and large Ah. You will also need to get another bike, something more beefier than the Jamis. You probably notice I have 2 ebikes and this was the reason. The Bionx is a good system, but it's simply not up to the task in terms of towing heavy duty stuff. And my trailer uses a rear axle as the mount, so the rear hub is out! The BMC V2 or the eZee make good towing motors. The 9C makes a good towing motor as well, but it is not geared. It's very affordable. I've seen a few eZee and 9C bikes here with Xtracycles or trailers hauling kids and groceries going up the hill (8% grade), so it can be done. The terrain in Vancouver is similar to Seattle (both rains a lot too!).

In my opinion, there is nothing wrong in getting into a simpler system. I got into it with a Bionx as it doesn't get any simpler than this. All closed and no tinkering and I learned a lot about this system and what I would need for my next. You would probably end up with 2 ebikes.

ebikes.ca has a simulator of motors they sell with the controller and battery packs. You can use that to simulate what you need.

DE.

and finally, thanks to all of you who helped explain how the voltage, amperage, c-ratings, and wattage relate to available power and torque...that really helps.

 

[hillbilly]

This is strictly in the "for what it is worth" category as I have barely 50 miles of actual ebike experience. However, I am riding a bike with a lot of similarities to the one you are considering. Mine is a Trek 7300 hybrid with a BMC v1, 30 amp controller and Ping 36v 15 ah 2.5. (I'm north of you, surrounded by hills.)

My limited experience indicates that my set-up is pretty good for paved 10% hills if I pedal hard in my lowest gear. On hills that are perhaps 5-7% I can pedal up in a mid-gear at 9-12 mph, getting a nice workout but not gasping. (I can't comment on towing a trailer until I can convince my dogs that the Burley will actually be fun but my guess is that the 8-10% hills would defeat us.)

On a flat road without pedaling: an honest 18-20 mph. While being chased by a dog and pedaling for my life, +25 mph.

When I first got into this I wanted a bike that would do everything I describe above and also take me up to higher elevations on the local logging roads -- with light camping gear. I now understand why this will require another bike -- which is why I'm considering a Yuba Mundo cargo bike and still pondering how to power it.

But that's another story, and one I'd rather you didn't share with my wife....

 

[Russell]

Cloudcover,

You are aware that your Jamis has a 130mm rear spacing and rear motor wheels are 135mm, or even a tad wider?

My criteria was pretty much the same as yours so instead of trying to address every question you posed you might just want to read my comments about my bikes.

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=8579

http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=10458


My recommendation would be to buy an eZee kit (with or without their battery) or a BMC V1, either will give you 20 mph at 36V, light weight, no cogging and good torque.

This is a pretty slick battery set-up

http://www.evcomponents.com/ProductDetails.asp?ProductCode=H3610R

or you could wait a while until AmpedBikes.com gets their geared motor kits in full swing and their downtube battery box in production as it should represent one of the best values around for a geared kit.


-R

 

[dogman dan]

Russell is the one with the similar needs to yours, so your bike ought to resemble his. Start with your original idea I think, and see if you like having a motor. If you want expanded capabilities, then you might end up wanting a bike more like Zoot, with a longtail frame and a big ol clyte 530x motor on it that can haul bricks and mortar up hills all day.

Beating the horse to death, Cheaper steel frame. Or at least some steel forks on the bike. With a steel frame, ya can bend out the rear if it needs it. You should be able to get one cheap on the used market.

You won't notice the weight much, with a motor. The great thing about assist is you can use it sparingly if you want to and just make the bike feel light, or mash the throttle and fly.

I wouldn't run a controller above 15 amps on a 10 ah ping. A 10 ah ping is fine for bafangs with lower amp controllers, but a BMC v2 for example would be better off with a headway pack from EV components or fatpacks. A 15 or 20 ah ping would supply more amps if you need it as the others say.

 

[cloudcover]

Beating the horse to death, Cheaper steel frame. Or at least some steel forks on the bike. With a steel frame, ya can bend out the rear if it needs it. You should be able to get one cheap on the used market.

hmmm...okay, i'm warming to the option of getting a steel frame (a bit). would something like this be good: http://www.schwinnbike.com/chl/eng/Products/Road/Details/1357-S9WORTD-World-Tour-DLX

or is there another bike that's favored by folks on this forum? (i was also thinking about something like the xtracycle radish, but i'm not sure i'm ready to go the cargo bike route right now...i'm guessing the trailer on my bike will be enough for starting out).

 

[GCinDC]

i'd recommend some suspension and disc brakes! unfortunately full suspension limits any room up front to store batts, but many here have found a way.

i haven't heard of any preferred bikes here, but i've seen mostly mountain, comfort and cruiser bikes...

i thought for a while about putting new handlebars on mine that lowered me into more of a racing profile, but i've changed my mind. i like be higher up, particularly in traffic, as i can see more, and it's easier for my neck to look backwards from an upright posture. less aerodynamic but i also don't need the leverage to pedal...

 

[Drunkskunk]

or is there another bike that's favored by folks on this forum?

That Schwinn has a 1" head set. that limits your fork choices if you decide to upgrade later.

There is no single bike, or style of bike that is favored by people here because the spectrum of use is so broad.

I personaly have a Kona Stinky DownHill style bike, and another bike thats more of the hybrid/comfort style converted to electric. Both have diffrent uses, diffrent styles of riding.

If you're looking for a good generic Bike, the old school, mid 90s Steel framed mountian bike with 26" wheels, a high center bar that leaves a large triangle area, and a 1 1/8th" headset (with or without front suspension) is just about ideal. Roadbike geometry with beefed up componants and plenty of room for batteries.
The only place to get one of those anymore is Craigslist, but its worth the effort. IMHO, the older style with the larger triangle (and most were steel, most now aren't) is just a better generic platform.

 

[wildnrg]

To climb hills I'd have to say a chain driving system rather than a hub motor for the simple fact that a chain driving system is able to use the bike's gears (especially the low gears) to get up those hills. Can you image climbing a hill on a higher gear, your legs would be really over worked compared to using a low gear.

Sure electric motors don't really need gears, but putting them under a high load = higher battery drain. My 24V 500w can go up a hill doing 25-35km/h in 4th gear, but I have the option of using 1st or 2nd at a slow speed but using less battery to get up the same hill. You don't really get that choice on a hub motor system.

I'm sure that a 1000W hub motor would beat me up a hill, but because my bike is a dually I have a 9kg max I can put on my rear rack, which basically means a 48V 1000W system is out of the question as batteries would weigh too much. I'm sure a 500W hub motor would not beat me up a hill tho.

 

[GCinDC]

cloudcover,

you make any decisions yet? i'm just curious to hear where you're at now...

 

[cloudcover]

cloudcover,
you make any decisions yet? i'm just curious to hear where you're at now...

hi gc -

thanks for asking. well, i'm not fully there yet but i'm getting closer. i think i'm going to split up my functionality into two bikes: (a) a surly big dummy with the xtracycle attachments for going to the grocery store, taking kids to school, etc; and (b) something like my jamis for just tooling around. for the surly big dummy, i'm leaning towards a bmc-v2t motor with a 48v 10aH battery. and for the "tooling around" bike, i'm leaning towards something like the new ampedbikes.com geared motor...though i'll need to wait a bit for them to get the rear hub version. i'm happy to be talked out of either, though. :wink:

i'm getting a bit confused on the battery technology aspect, so i'll search a bit more on this forum to see if i can clarify matters...and if not, i'll likely ask for more help. :|

thanks again.