Ability to climb

[perrycas]

I want to buy a pedal assist kit. I took a bike for a trial run here in Sydney on the route i would use it for most commonly. The Kit was a 250W 24v Keydes FW kit. It did fine until i put it at the hill that i was most concerned about. Small ring 2nd gear. The motor made crunching noises and went belly up. Pawls broken maybe?
I have since been back and measured the hill with an ipad ap. its about 11%. It's not a long hill, 40 meters or so, the rest of the hills i did are in the 7-8% range which the test bike did without problem.
I looked at the EMS kits, which seem to enjoy popularity on this forum, but so far no one there has answered my questions. Perhaps they are too basic. There is too much info there that i dont really understand, and it seems to me that their bikes are primarily for going fast. Or is that a false assumption on my part?
So i am looking at another Keydes - 36v max 500w output. 190rev Rear wheel kit. It has no throttle and is purely 'Pedal Assist' I like the idea of this model as it's in the same price range as the others I looked at, and its v light - Motor is 2k, battery about the same.
Someone kindly referred me to a thread here which I have read with interest on E. sphere on this design and realise that it is not a big powerful monster. I wouldnt have thought for my purposes that i needed one, I dont want to go fast, I just want help on a few hills.
Others have commented on the controller (internal) in these kits as being more or less fixed. The figures on their catalogue, which i think relate to the controller are: rated input 8.7A and max current 8-12A.
I am wondering if anyone might comment on its ability to do this sort of climb.
Ta
Perry

 

[dogman dan]

I would recommend the Mac motors on EM3 ev. The one you want is the slower rpm winding. The slower motors will be able to climb 11% without overheating like the faster windings do when they slow down climbing hills. The 10T should be enough, but get the 12T if you plan on even steeper hills.

Takes a bit of power to climb 11%, but not crazy high power. 1000-1500w will do it fine. You just have to have a motor that doesn't mind the slower speeds you get when climbing steep hills.

The other approach to hills is obvious. Big motor with 5000w or more, and you just go up it fast, and don't run into the fast motor going slow problem.

Smaller wheel size is also good for hills. I am assuming you have 26" wheels and don't want to change them.

As for the other motor, I think you just got a bad one. It shouldn't have gone crunch climbing a short hill. So it may be that you will be fine to just get another similar motor. One without the defect. If you have a choice, get the slower rpm one.

 

[MadRhino]

12 Amps is very low power when you want to climb.
11% is not very steep though, on my bikes you hardly notice any difference of speed and acceleration and they could climb it at 45 MPH continuous. A good climber requires a big motor and big Amps to feed it.

If you want to keep light weight and slow, a 12T mac is a good recommendation and you'd want more than 12 Amps
If you want a true performance climber, you need to think heavier DD motor and 10+ Kw

 

[dogman dan]

Yep. If you want to maintain a rapid speed up 11% you need more power.

But with 1000w or so actually showing on a wattmeter, a 10t or 12t mac should grind slowly up 11% no problem. The choke point on most "normal" hubmotor setups is about 12 or 13 %. Most typical hubmotors climb 10% reasonably well if they are fed 48v.

 

[melodious]

I'd like to point out the confusing issue with grade & slope of a hill. 10% when seen on a piece of paper or computer screen really doesn't look too intimidating.

http://en.wikipedia.org/wiki/Grade_(slope)

Even at 20%, it still doesn't look all too bad. Now look at 50%. Those look like the hills to brag about! I could swear that my small hill home seems like 35-40%. But completely safe on my rinky geared hubbed motor as long as I contribute with some moderate pedal input. Of course, I wouldn't want to tackle the same hill on a mile+ stretch. My legs would burn out, and eventually the motor too along with them.

I think a motor purchase should be made on the terrain of your area you intend to use it in. Then, whether you intend to physically assist on those climbs should be placed into the equation as well. The steeper (and longer) the hill, eventually the motor will be pulling your bike and doing much of the work.

 

[perrycas]

Thanks. Actually i made a mistake and put in 11% when it was 11deg. I didnt realise that i needed to convert this from raw. Should have said 17%. Yes i am inclined to think the motor was a bad example, there were various signs that it had had a hard life. Thanks for your assistance.

 

[dogman dan]

Ahh, well, 17% is a different animal for sure. But a good climbing motor with reasonable power should be able to get up it anyway, since it's too short to melt down the motor.

I'd still say the Mac 12t is a decent choice short of building a motorcycle out of a bicycle. Run it on 48v, at least 20 amps. Pedal hard up that hill to help it if it starts to bog too much. Likely it will grind up slow, but no problem.

Even better, would be a direct drive motor you can give motorcycle power, but a very slow one so you still go slow enough for a "bicycle" feel. I use a 9 continent 2810 winding motor. Given 72v, it climbs 17% with ease, yet top speed is merely 25 mph. The advantage of the DD motor is it can take more power without melting. Better if you are headed towards motorcycle or moped power levels.

Again, gear down with a 20" wheel for the very best performance on hills, or go chain drive through the bikes normal chain where you can shift to the lowest gear for the hills.

 

[d8veh]

I'm pretty sure that the keyde motors have rollers rather than gears like the Tongxins, so they probably slipped under torque and did some damage. Any normal geared motor will be reliable, but the bigger the motor you get, the more torque for climbing you get. In Australia, you have to comply with EN15194, which means the motor has to have 250w written on it. I don't know how seriously people take this, so it might be a good ide to check on your local forums. If you're stuck with a 250w motor, the 250w bafangs are pretty good. You can get a complete kit and battery from BMSBattery.com and Greenbikekit.com. Once you get your kit, take off the end-plate from the controller and add solder to 30% of the shunt. This will increase the torque of the motor, whilst still keeping it legal. You need a 201 rpm motor for 15mph.
http://www.bmsbattery.com/ebike-kits/423-bafang-250watts-front-driving-qswxk-motor-e-bike-kit.html
http://www.bmsbattery.com/36v/326-24v-lithium-ion-little-frog-abs-shell-ebike-battery-pack.html
These for your brakes if you don't already have some.
http://www.bmsbattery.com/459-hwbs-hidden-wire-brake-sensor.html
And some of these
http://www.bmsbattery.com/450-a-pair-of-ebike-torque-arm.html

 

[perrycas]

thanks for the input all.
yes d8veh they do seem to be related to the tongxins, there is another thread here http://endless-sphere.com/forums/viewtopic.php?f=2&t=45300
Australian rules dont bother me much i don't think i will be stopped and checked, cops here seem to do less and less on the road. If i am not going fast there's no reason to stop me.
The ride i want help on is a real roller coaster i will either be going up or down. I can cycle it with my 28" but its hard on my knees. I tend to avoid it and take the car as by the time i get home it hurts and i dont want to do it the next day. And the next....
The BMS links were interesting and they have good prices but v expensive freight - about 3x EMS. I have written them to see if they can do better. So the mac motor is the most attractive. I do feel that this is kind of overkill and wish i could definitively rule out the Keydes 36v, its so much lighter. I think i am going to ask another question about inherent problems with roller motors.

 

[Tom L]

Would a 12T be capable of climbing these two routes? Note the 130m of 30% grade in the middle shorter one (circled). Great views from my place but not really conducive to cycling. :?

 

[dogman dan]

Well, It's hard to say for sure unless I go buy one, and then go kill it. I can say that 30% is extreme grade for any hubmotor.

Can it do it? I'm sure it could, if given enough watts. Will that much watts melt the motor? Yes, for sure if that much excess power is fed to the motor long enough.

I have climbed 30% with my dirt bike, and I have melted a motor about once a year. That's putting about 2500w actually seen on the CA into a 12 turn 9 continent. Doing climbs like that, the motor gets very hot. Ideally I won't climb a hill that steep much longer than a few hundred feet. It will grind up 15% all I want though, since that doesn't take but about 1000w. 15% is about where I'd start pedaling to help.


One option you do have, is to use pedal only on the very steepest bit. Not very appealing, but it would keep you from punishing the motor on that bit. Then the 12t should be able to tolerate the lesser grades ok. Pedal enough to keep your speed up, on any grade.

Another option proven to slay the hills is two hubmotors. That way you can feed 1500w, but only feed 750w to each motor.

 

[Tom L]

Thanks Dogman. I am planning on peddling as much as I can but doubt I could keep it up with any great effect for the whole climb.

The two hub bike is an interesting idea. Sounds like it could be an alternative to a mid mount. I'm reading (struggling) through the thread on converting a hub to mid mount at the moment.

 

[o00scorpion00o]

Other pedelecs would be the Bosch motor, serious hill climber that will not burn, I cycled up 16% maybe 18% with some effort.

You can import them on E-bay. They can't make enough of them as e-bike sales in Europe have surpassed car sales

The Bosch is usually found on expensive bikes, but if you burn a motor that's a lot of money wasted, especially if the rest of the kit is fried or you can't use it again. I was very very impressed making me think it will be my next bike as I don't need more than bike speeds.

have a play around with the motor simulator on ebikes.ca

You would be surprised how quickly you can fry a geared hub, but as the rest of the lads said, getting up fast with small wheels is a good option as small wheels create less work for the motor, but you will need big power and that means more expensive batteries, and weight.

 

[Bike Xing]

Check out this thread on what hills people are riding and with what equipment:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=51114
For the 20% + stuff, mid-drives definitely seem like the way to go. Climb anything with no risk of overheating. Lighter weight but typically less power.

 

[dogman dan]

Mid drive is the way to go for sure. 30% is just extreme. But 15% is doable by the right hubmotor, or mid drive.

 

[Tom L]

It looks like the tool (bikely.com) I was using to estimate the grade could be a little inaccurate. This is the result I get from ridewithgps.com which seems more realistic (lower half of graphs are % grade). From these results I could probably get away with a 10T for my daily commute. Not so sure about the shorter trip to the shops though. As I'm not really after top speed I might just go with the 12T to be safe. Do you think this is reasonable for a 200lb (and falling!) rider using 12S2P (10Ah)?

 

[Bike Xing]

Yeah, I think the steepest paved road I've ever encountered was 17%, in San Francisco. So most everything a reasonable human encounters on roads is less than 15%. You've got to go off road or up the side of a refrigerator to get grades over this.

 

[Geebee]

If you are willing to drop speed for close to unlimited climbing ability look at an Aseako on ebay or direct.
I have a Tonaro (same system different name) the type on hill you describe would be climbed with almost no effort at low speed and no heat build up.
If speed is important and legality not, there is now a 48V version available.

 

[Tom L]

Thanks, just had a look. For the price of $2500 AUS I think I can build better.

 

[Geebee]

Yeah, I think the steepest paved road I've ever encountered was 17%, in San Francisco. So most everything a reasonable human encounters on roads is less than 15%. You've got to go off road or up the side of a refrigerator to get grades over this.

Not really, I go up an average of 25% grade every night (hits 28 in a couple of spots) in a car this is a suburban sealed road but there are numerous hills near by well above your 15% max.

 

[dogman dan]

Roads, that is a road to a house, can be crazy steep. But a state highway route tends to be lesser grades. 15% the steepest highway I've seen in my state. Most max out at 10%, but there can be miles of it continuous in the rocky mountains.

I'd still vote for the 12t mac over the 10. That's some climbing all right. Paul also sells a slower version of the dd motor. That one given 2000w, should climb that route, at a faster speed. 48v 40 amps. Cheap to replace if it does melt.

Run a thermometer inside it of course.