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

[cloudcover]

hi folks -

i'm about to embark on a bike conversion project and have been browsing through numerous posts on this forum, which have been very helpful. but before i get too far into it, i was hoping to get some guidance to steer me in the right direction for further research. here's my situation:

• starting point: jamis coda comp flat-handle road bike -- steel frame with a carbon fiber fork -- about 25 pounds (details here: http://www.jamisbikes.com/usa/thebikes/street/coda/09_codacomp_spec.html) with a 160 lb rider.
• primary objective: make it easier to deal with the numerous hills where i live, some of which are very steep
• secondary objective: keep the overall weight as low as possible, so i can still contribute as much energy as i want by pedaling
• tertiary objective: have things look as elegant/stealthy as possible (ideal would be something like the cytronex bikes: http://www.cytronex.com)
• NON-objective: i don't care about going fast -- 20mph maximum is more than enough for me -- i'm not in a hurry.
• NON-objective: i don't have a particular budget and so don't need to find the least expensive solution -- but at the same time i don't want to pay more than is necessary. in short, i'm interested in getting value for the money.
• NON-objective: i'm not planning to use the electric power as the sole source of power most of the time -- i don't mind pedaling (i have a motorcycle for when i really don't want to pedal)

and here are my questions:

1. motor: given that i have a carbon fork (and some other positive factors), i was thinking that i'd probably use a rear hub system. but there seem to be numerous systems out there and i'm having a hard time telling what would be the best option, given my objectives. the main systems i've seen based on the research here are ezee, nine continent, bmc v2-t, and crystalyte (not really into bionx, given that it's a proprietary system). it looks like the ezee or bmc ones might be best suited for hills, but that's just my impression. any suggestions?

2. battery: my typical route for running errands is about 12-15 hilly miles roundtrip. my guess is that a 36V 10aH LiFePO4 battery would suffice. but does a 48V battery (instead of the 36V) give me better torque for hill climbing? also, i'd like to have extra capacity -- in case i needed to go on a longer trip now and then. in any event i wouldn't want more than the total weight/range of something like a 48V 15aH battery.

ideally, it would be nice to have something that can be configured for lighter vs longer range. for example, the giant twist freedom dx bike has two battery packs, and you can use just one if you know you won't need the longer range, or use both if you will. i've read about some of the custom setups using bosch/makita/etc batteries, but that seems pretty complicated. if i can use only one battery, then i think maybe 48V 10aH might be a good compromise between range and weight.

so i'd love any suggestions on the battery issue. i've been looking at the pingbattery.com site, which seems to have several options and really good prices. but i'm not opposed to a battery module that's designed specifically for use in bikes.

3. battery mounting: from what i've read, it sounds like with a rear hub motor, it would be nice to have the battery mounted somewhat forward on the bike (in terms of weight distribution)...like on the downtube. but i haven't seen any good options/suggestions for how to do this, as a practical matter. i'd love links to any suggestions for that.

and if there's no good option for mounting mid-bike, the idea of using paniers seems the most elegant/stealth option. are there any descriptions of how best to do that, including specific parts/sources/etc? especially if i'm using something like a pingbattery.com unit.

one thing i want to make sure about is that the battery is securely mounted, so it doesn't rattle around when i ride across bumps, etc.

4. anything else?: is there anything else significant that i should be thinking about that i haven't mentioned above?

thanks in advance for any guidance!

 

[dogman dan]

See posts of Russel's bike for something similar to what you want.

48v rear bafang motor would do ya nice. Holmes Hobby is the place to get em, laced into the rim of your choice. You won't want a cheap kit rim on a nice roadbike. 10 ah lifepo4 will do it. A pack from Ping would be ideal, about 10 pounds weight. It should be easy to put in a triangle bag, or custom box of some kind there. But a battery that light won't carry so bad on a rear rack either. It's the 20 pound ones, that wreck the balance of a bike when carried high on the rear. Get tourqe arms for the motor, I bet your bike has pretty light aluminum dropouts on the rear. The really ideal solution would be to fashion a custom deraliur hanger that incorporates the torque arm into it.

But if it were me,,,, I'd never wreck the fine road bike with any motor. Get a fairly light 700c bike and put a motor on it. Even a front hub, since the bike will have a steel fork. Once motoring, the extra ten pounds will be nothing. Say you start out at 23 pounds on your current bike, maybe it's less, but then you add 20 pounds of motor and battery. 43 pounds. Starting with a fairly light steel bike, 30 pounds, you are only 7 pounds heavier, and still have the light bike when you want to just pedal. A 50 pound ebike will feel like a 10 pound bike going up the hills.

 

[cloudcover]

But if it were me,,,, I'd never wreck the fine road bike with any motor. Get a fairly light 700c bike and put a motor on it. Even a front hub, since the bike will have a steel fork. Once motoring, the extra ten pounds will be nothing. Say you start out at 23 pounds on your current bike, maybe it's less, but then you add 20 pounds of motor and battery. 43 pounds. Starting with a fairly light steel bike, 30 pounds, you are only 7 pounds heavier, and still have the light bike when you want to just pedal. A 50 pound ebike will feel like a 10 pound bike going up the hills.

yep, that makes sense. but the "problem" is that i already have another very nice lightweight road bike for when i just want to pedal. i'd bought the jamis for easy tooling around and hitching on a trailer bike with the kids. so if i don't use the jamis bike for the conversion, then i'm looking at buying another bike -- which isn't a huge deal, but then i'll end up probably not using the jamis bike and it'll just sit there. i suppose i could try to sell the jamis bike, but it seems you take a pretty big haircut on bike sales and so by the time i was said and done, i'd probably not save anything significant.

A pack from Ping would be ideal, about 10 pounds weight.

do the ping batteries include a bms and a good charger? in other words, if i order the battery from ping, are there any other related parts that i'd need to buy from him or from elsewhere?

It should be easy to put in a triangle bag, or custom box of some kind there.

in terms of using a triangle pack for the battery, are there folks who have used that who might be able to give me some guidance on how to affix it as securely as possible -- so it doesn't rattle around too much when riding?

thanks!

 

[johnrobholmes]

The bafang is good for assist, so if you are cool with pedaling along it is great.


For real hill climbing the PUMA (bmc v1) has done me very well. Lots of power and good for 48v. You won't need to pedal at all if you don't want to, but it is heavier than the bafang.

 

[cloudcover]

The bafang is good for assist, so if you are cool with pedaling along it is great.
For real hill climbing the PUMA (bmc v1) has done me very well. Lots of power and good for 48v. You won't need to pedal at all if you don't want to, but it is heavier than the bafang.

how do those options compare to the ezee motor -- in terms of advantages/disadvantages. just asking because the ezee seems well-regarded.

 

[dogman dan]

Yup, JRH, but I got the idea he just wanted assist, so I suggest the lightest motor out there. A real hill machine would call for a big gearmotor in a 26 inch wheel or a 5405 in a 20 inch wheel and most likely a MTB or BMX frame.

The pingbattery comes with bms and charger. His prices are high, but so is his reliability and customer service.

I put some nicads in a triangle mount using some poplar 1x6 lumber and some 1/8 sheet aluminum. The 1x6 was cut to just the right width, and then the battery was sandwiched between the aluminum sheets using screws into the wood. This made a box, with wood around the edges, and aluminum sides. The wood parts could then be strapped to the frame with sheet metal strips and screws. But again, I doubt carrying 10 pounds on a rear rack will be a problem.

As for the bike, well, if it's not your best bike, that's different for sure. But I still am a very big supporter of the idea of using steel frames, or at least steel dropouts for hub motors. In 5000 miles, I still have not used a torque arm. Steel for me. You could put a stout steel front fork on the jamis and then run a frontie. That balances nice with the battery in back. Others have good results with aluminum frames as long as they use a torque arm or even two. The jamis will make a nice ebike. But do leave your nicest bike cherry for just pedaling.

The ezee kit would be a good choice too, but it may be a tad heavier than a bafang. I belive ebikes ca puts it into a decent rim, or will spoke the rim of your choice. And of course, they have stellar CS.

 

[GCinDC]

I gotta recommend the BionX PL 350.

I've got a Jamis too, and after 6 months hanging in the garage, I've been using it again cause I fried my main battery management system!

I gagged at the price of the BionX when I was looking, and I spent NINE MONTHS researching these, originally for my wife who wanted to commute with a child but couldn't manage the hills.... I finally pulled the trigger on a 48V 500W Golden Motor kit (20lbs) for $300 and then ended up spending another $600 on a Ping battery (20lbs?) which ended up being insufficient for the task... I set it up on her old trek and it weighed a TON. She tried and took off pedaling... I told her to hit the accelerator but she WANTED to pedal it on the flats...

Too bad, I thought, I'll have to keep it for myself...

I turned around and bought her the BionX PL 250. She LOVES it, and it works like clockwork, unlike a lot of the stuff I've been dealing with and trying to fix... It's got a lot of very well thought out and manufactured features, like Regenerative braking, which everyone on this site would love to have but can't because it burns up our electronics! (someone please prove me wrong and send the thread...)

I saw more BionX users on the V is for voltage forum, not as many here...

Personally, I like going FAST, and don't really care about weight anymore. I like pedaling, but now only use two gears, one for VERY steep hills and the other the rest of the time. I like the mad max nature of mine.

So that's the big question for you. Do you want to tinker and solder and GO FAST?

With the money I've spent so far, the BionX would DEFINITELY have been the cheaper choice. (I bought last October.)

Just some things to think about. I'm waiting now for a $700 delivery from Hobby King for 6 Li-Po battery packs including $250 worth of chargers! :lol:

 

[cloudcover]

I gotta recommend the BionX PL 350

thanks for the input and for sharing your experience! a few questions:

1. you mentioned that the golden motor and ping battery combo weren't "up to the task" for your wife's needs. in what sense is that? not enough power/torque for the hills? not enough range? etc?

2. what has been your experience with how well the bionx does on hills? i was under the impression that some of the geared motors (like the ezee, bmc, etc) were better performers on hills.

3. in terms of the regenerative capability of the bionx, what's been your experience in terms of % recharge? i'm curious because i was also looking at the new trek ride+ bikes (as a ready-made solution) and they indicated recharge up to 10%, which doesn't seem very significant.

thanks!

 

[el_walto]

I've had an x5304 at 48v 35A and an ezee at 48v 20a. I prefer the ezee for climbing the steep hills in this town, it's lighter, and the freewheel makes it a really smooth ride.

 

[dogman dan]

If he's refering to the 48v 12 ah ping, I'd agree that it's too small, but not that it weighed 20 pounds, 15 more likely. But it should have worked ok, and not had cut outs. Mabye a runt cell making it really an 8 ah pack? Or the 500 watt bike actually came with a 1000 watt controller? Hard to say without the details.

Edit, even my fuzzy math says 48v x 30 amps aint 500 watts. So the ping needed to be about 20 ah to handle that motor in my opinion. Max continuous on a 12 ah ping is 24 amps right?

In any case, for an guy that doesn't motor continuously, some version of gearmotor is what you want. The bionx is good for those that like to pedal too, and go speeds under 20 mph, etc. Not sure how good such a low wattage is on really steep hills though, like 10%. But I have never seen or rode a bionx, so ignore what I have to say about them.

 

[GCinDC]

...the golden motor and ping battery combo weren't "up to the task" for your wife's needs. in what sense is that? not enough power/torque for the hills? not enough range? etc?

not at all what i said. indeed they were far too much power & speed for her! that may not have mattered so much if they didn't weigh A TON. It's a different world w/ ebikes. I used to throw my Jamis on my car's rooftop rack, but I wouldn't even consider putting my Diamondback comfort bike up there w/o removing my ping battery now. W/o the battery, my wife can barely take it off her car's REAR rack. (which she had to do yesterday after rescuing it when i got a flat...)

2. what has been your experience with how well the bionx does on hills? i was under the impression that some of the geared motors (like the ezee, bmc, etc) were better performers on hills.

honestly pitiful. but it's a PL 250, as in 250Watt, considering i'm used to an 1800Watt system (dogman's right!) I never knew what the wattage meant... I just knew what I wanted to feel! For my wife however, it's ideal! She doesn't want to ever go faster than 20mph. And trucking up hills at 14mph is perfect for her... So for anyone bigger, or wanting more speed, torque, the 350 or better yet 500 would be good...

3. in terms of the regenerative capability of the bionx, what's been your experience in terms of % recharge? i'm curious because i was also looking at the new trek ride+ bikes (as a ready-made solution) and they indicated recharge up to 10%, which doesn't seem very significant.

In general it's the same, except on the BionX you can set the mode to 4 levels of regen! ride it like an exercise bike to charge it! She actually does that down some hills when she doesn't bring her charger, to make sure she's got enough juice to get back up the hill on the return... but i'm about to send her battery back because it never had the range it should have. in any case, regen *feels* good. it's nice to save the brakes. and it's great to know i'm recharging the batt, even if not much... nice to have in a pinch. i don't know of ANY regen system more efficient.

my questions for you are:
- where do you live? because chances are there's a dealer near you with bikes you can try, and there's nothing better than trying!
- how fast have you ever gone on your bike?
- are you willing to solder?
- do you have disc brakes?
- do you commute on your bike?

as for frame mounts, i spent months thinking about and building my own, twice, and now am about to change it again!

but if you get a small battery, these always looked good to me: http://us.itselectric.ca/category_s/53.htm

 

[DahonElectric]

A light weight bike should marry with a light weight electric system. Again, if you plan to ride the bike and have assist, then both the eZee and the Bionx are quite light. And you want a light electric system, because anything heavier will change the ride characteristic of your bike. Ideally though and in my opinion (I've ridden and rented a few e-bikes incld X4 and X5 motors), the kit must weight either equal or less than the bike's weight which are the appeal of both the eZee/light geared hub and the Bionx kit. If you plan to own a motor bike with very little pedaling, then by all means by the most powerful and heaviest motor you can afford. The Bionx system works by measuring the pedal forces, which means it amplifies your pedal strokes to get your bike to go faster. So the performance of the bike relies heavily on your hill climbing ability. If you are a capable rider already (good hill climber) but needs a break climbing the same hills everyday going to work, the Bionx system is a great system because you can adjust the assist level as you please. It keeps your aerobic system working consistently and much more so than say an equivalent geared hub system with a hall effect throttle and a Watts-Up or a Cycle Analyst. If you are a not so great hill climber however, then an eZee kit would be a better choice. Why? Because you can manually adjust the assist level via your hall-effect throttle switch. With the Bionx system, the throttle is an ON or OFF switch with the assist level regulated by the computer and the programming algorithm is based heavily on battery conservation (I've tested this already with same hill Bionx vs Cycle Analyst programmed with all limit functions (Cruise Control) enabled). eZee being a geared hub is a capable hill climber and are one of ebikes.ca best selling motors in Vancouver, BC. And Vancouver is very hilly. I am personally impressed with the quality of the eZee kit. The wheel for instance is built up to North American's standards with a nice rim and good wheel built and the overall feel of it screams quality. It almost equals the quality of the Bionx system. Another advantage of the eZee kit is that it freewheels regardless if you have the battery or not. You can not do that with a Bionx system -- you must supply some power to it or you will ride your bike with a flat if you take the battery out. Same with any brushless motors that are out there. So if you have a 25lbs bike with a 8lbs eZee motor attached, then you have a 33lbs Jamis, which is still isn't bad since my Devinci St-Tropez weighs just as much (33lbs) and I was able to keep up with some of the lighter carbon bike guys before the conversion.

If I had known the poor quality of the 9C wheel (still sucks today no matter how much truing I did), I would have gone with the eZee kit. Should have taken Justin's advise, but it would mean I have to commit more money to the project which I wasn't willing to at the time. Besides, the 9C hub is strong towing a trailer up a relatively steep hill with little pedaling which is why I still like it as a little motor bike.


DE.

 

[DahonElectric]

And I almost forgot that you must stick with a rear hub system due to the fact that you've got a carbon fork.

DE.

 

[Drunkskunk]

You're going to want a geared hub motor.
The biggest reasons are:

• Higherst hill climbing torque

• Lighest weight

• Freewheel to reduce drag when not in use

Having a freewheel will mean you can't have regen, but as you noted, they don't add a huge amount even in perfect conditions. 5% is excilent. 10% is ... Possable under some conditions, maybe, once in a while. IMHO its a neet gimmic, but you could also just get a battery that was a little bit bigger and be assured that the power was there, rather than hoping you had to hit the brakes enough.

What Dogman recomends is an excilent choice. An alternitive would be the BMC V1 (puma) 400watt or the V2 600watt motors. The V1 is smaller but lighter.
And for the battery, the LiFePO4 Ping batteries are an excilent choice for a long life battery, but if cost isn't an issue, LiPo or LiMn batteries are almost half the weight and size, meaning you could carry 36V, 10Ah, 5 pound battery in a standard frame bag.
The down side is LiPo and LiMn die of old age in couple years, but if size and weight are important, nothing is smaller.

I'm running RC airplane Lipo batteries. they weigh 1.3 pounds each, and 4 together make a 37 volt, 10Ah pack. they cost $60 a piece. I have 8, and can run my bike on as few as 2 if I want to save weight.


As Dahonelectric points out, with your carbon fork, you will have to run a rear motor.

 

[dogman dan]

Excellent point about the batteries. The lightest setups out there are often a bafang, and a really small lipo battery. Some just want help with 2 miles of a 15 mile ride, and for them, a really light battery is a big deal. The RC stuff can put out the amps without being big. Bosh fatpacks come to mind too, but I have no experienc with em. What do they weigh apiece? a couple pounds?

 

[docnjoj]

Around 2.6 lbs for each Fatpack in virgin state. Chop the weight about 8 oz by removing endcaps and other junk like boards. Very good batts so far (1.5 months)
otherDoc

 

[cloudcover]

A light weight bike should marry with a light weight electric system. .... Ideally though and in my opinion (I've ridden and rented a few e-bikes incld X4 and X5 motors), the kit must weight either equal or less than the bike's weight which are the appeal of both the eZee/light geared hub and the Bionx kit. .... So if you have a 25lbs bike with a 8lbs eZee motor attached, then you have a 33lbs Jamis, which is still isn't bad since my Devinci St-Tropez weighs just as much (33lbs) and I was able to keep up with some of the lighter carbon bike guys before the conversion.DE.

great points. based on your comments, others' comments, and some further research, i think i'll probably go the route of a brushless geared motor. and the leading candidates for that appear to be the bmc, ezee, and bafang. i have to say i'm tempted by the bmc v2-t because of its power/capabilities. the specs at cycle9 indicate that the bmc v2-t motor weighs the same as the bmc v1 at 8.5lbs, which is only a smidge more than the ezee motor at 8.4lbs, but about 1.8-2lbs more than the bafang at 6.6lbs. so even with the bmc v2-t, it seems like the bike + motor weight would be around 34lbs.

so the questions i now have are:
1. i'm having a hard time gauging how these motors compare to each other in terms of their capability for helping on hills. i'd love to get opinions on where they'd fall on a 0-100 scale. for example, if the bmc v2 would constitute an electric assist capability of 100 on that 0-100 scale, what would the bafang rate? and for that matter, where would the bmc v1 and ezee fall on that scale? it's just a way for me to get a quantitative sense of capabilities, so i can assess weight and cost trade-offs.
2. assuming range isn't a factor, is a 48V/10AH ping battery reasonable in terms of getting the max out of the motor's capability? or could i get the same benefit using a 36V/10AH ping battery? i'm not worried about the cost so much as whether i'm getting any benefit from the 2 lbs or so of added weight of the 48V versus the 36V.

thanks again, folks...this has been very helpful so far.

 

[GCinDC]

i came to the exact conclusion in my research a year ago, that the BMC represented the best value for me at the time. But then I added up the numbers and thought, heck I should buy a bionx kit for the same dough. sure, it won't be as powerful, but it'll come with neat features, like a battery INSIDE A LOCKABLE CASE that conveniently mounts to the bike rather than something i have to put on a rear rack (which i couldn't do - child seat)...

well, then just before buying the bmc, i saw a 48V 500W Golden motor kit for $220 on eBay and bought it...

point 1: bmc seems very good (but i have no experience w/ them)
point 2: is it better than a bionX? (i don't know, but I'M sure the experience will be different, and the BMC will be more powerful.. but you're now heading down a heavier eBike path than electric assist.... [enjoy the journey]
point 3: i forgot point 3

to continue my journey, for the sake of an example, before my GM kit arrived, i quickly emailed ping for a battery. I was thinking a 48V 8Ah for a short commute. he wanted to know the specs of the kit. i told him 48V 500W, cause that's what it says... i should have known the controller's amperage, but he said the 12ah was the smallest he'd recommend. long story short, i gotta get to work, but i got a new controller that draws 30 instead of '10?' Amps (500W=48V/10.41).... and am killing the ping by drawing too much current out of it... ;-( so now i'm heading down an expensive lipo path...

point 4: listen to dogman and get a battery bigger than you need, especially if you'll be climbing long hills..

i'm not the one to do the math for you, but these are my thoughts...

 

[DahonElectric]

The purpose of the BMC V2 is to go up any hill really well on a cargo bike -- Xtracycles equipped or towing a trailer or even hauling a heavier than usual rider. This is a motor bike motor of motors for hills!
I am not sure where you live, but do you need to climb a 22% grade every day to justify this motor because I'm not sure if you are sure how steep those hills are in your area.

Secondly, ebikes.ca is located in Vancouver, British Columbia which is one hilly city. The staff themselves either run a 9C or an eZee, so both are capable climbers. The question I think you want to ask is as if I can climb hills at 20 to 30mph just like a motor bike does. Perhaps the V2 with a 48V pack. But just like Dogman said earlier, you will NEED another bike for safety and security reasons. Your bike isn't designed for this for the long haul. Bike of this quality usually have compromises on the top tube with materials that are thinner than usual to save weight. This compromise will make bike handling even sketchier especially if you have a lot of weight and power behind you. The oscillation from the rear (the fish-tailing effect) can resonate throughout the whole frame which makes riding rather unsafe. You'll feel it. One of the reasons I choose the Dahon and the Devinci for my ebike conversions are the fact that they are stiffer than a comparable steel frame, especially on the top tube section. Both the Devinci and the Dahon have stiff top tubes -- Dahon is stiffer (smaller folding frames are usually that) thus the ride is better even with all that weight and power at the back. The Devinci is less so, but still manageable because this bike was designed specifically to haul loads. I looked at your Jamis bike specs, but am not sure how a powerful motor will effect the ride quality of your bike. If a bike comes with a carbon fork, the frame is usually tailored for performance and speed and puts little emphasis on hauling loads.

The difference between 48V and 36V is basically operating voltage and range since the voltage drop off of the 48V takes a bit longer than 36V. 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?

DE.

 

[Drunkskunk]

the 36 and 48V, 10AH Ping batteries are only capable of a sustained 2C.
In english, that means it can only provide amps at 2 times it's capacity, or 20 amps for sustained periods, like climbing hills. A sustained peak of 720 watts and 960 watts, respectivly.

A motor that is rated at 400 watts is a little missleading. The rating isn't the peak power, but only it's sustained normal draw at full speed on flat ground. to accelerate, or climb a hill, a motor will draw much more than this. in most cases, atleast twice. To run propperly, a 400 watt motor needs a battery capable of providing 800 watts minimum sustained.

So in this case, the 48V 10Ah ping could just the 400watt V1 BMC, but wouldn't be able to handle the V2 600 watt. the 36V 10Ah would be too small

As for hill climbing power, the V2, 600 watt is the most powerfull, but all 4 should be good choices.

 

[GCinDC]

excellent points.

fyi, once i got my GM kit, i turned around and bought a bike to suit it... :lol:

 

[DahonElectric]

the 36 and 48V, 10AH Ping batteries are only capable of a sustained 2C.
In english, that means it can only provide amps at 2 times it's capacity, or 20 amps for sustained periods, like climbing hills. A sustained peak of 720 watts and 960 watts, respectivly.

A motor that is rated at 400 watts is a little missleading. The rating isn't the peak power, but only it's sustained normal draw at full speed on flat ground. to accelerate, or climb a hill, a motor will draw much more than this. in most cases, atleast twice. To run propperly, a 400 watt motor needs a battery capable of providing 800 watts minimum sustained.

So in this case, the 48V 10Ah ping could just the 400watt V1 BMC, but wouldn't be able to handle the V2 600 watt. the 36V 10Ah would be too small

As for hill climbing power, the V2, 600 watt is the most powerfull, but all 4 should be good choices.

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.

 

[Drunkskunk]

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.

 

[cloudcover]

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).

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.

 

[GCinDC]

funny how the game changes, huh? :lol:

since you're near seattle, why don't you find a shop to try some out? is thisclose to you? or this place: http://www.mcelectricvehicles.com/bikes.html

it's so hard to imagine what they're like... would help so much to TRY some..