Ready for Gears

[brainfarth]

I'm ready to ditch my direct drive hub for a geared hub, but I'm not sure what I'll need to pull me up 10% grades(or greater). My current setup is sold by Papa Motors http://goo.gl/bDZw7Q
As it stands now, I can get a 30 mph run at one hill and have to peddle like crazy about 3/4 of the way up, while I'm holding the throttle down. I think this is kinda hard on my system, so before it melts down, I'd like to buy a new hub. Which brand and ratio would you recommend?
Edit so you dont have to chase down the site: 48v (1000W(Standard 20A)-1500W (Peaks 30A)

 

[DAND214]

You want a good geared motor, then look here http://em3ev.com/store/index.php?route=product/category&path=36
Complete kits or motor with wheel too.


Dan

 

[wesnewell]

Try as I might I just can't understand why people have problems going up hills with a DD hub motor. I'm 270 lbs and can fly up 20% grades at 30mph without pedaling with my 1000W motor. Ok, I'm running 88.8V 24s lipo with a 40A controller, but I didn't have a problem when running 14s and a 30A controller either. I just don't like the idea of a geared motor. No regen braking. Noisy compared to DD. Gears that break and wear out. And can't take as much power and speed.

 

[alfantastic]

You want a good geared motor, then look here http://em3ev.com/store/index.php?route=product/category&path=36
Complete kits or motor with wheel too.


Dan

+1

 

[dogman dan]

10% shouldn't be that hard on 48v. Sure, you slow down, but if you can still maintain 15 mph you can do that for miles.

If you slow to less, it's still ok if the hill is not miles long. If your motor is not too hot to touch after that hill, stop worrying. If it's not miles long, chances are your hill is not damaging your motor. Below 250F inside them is fine.

EM3 may still be the place to get a motor better on hills. The 10t dd motor is essentially the same thing you have, but a slower winding. Run at 48v, it will be quite slow, only 19 mph or so. But it will grind up 10% with no problems for quite some time.

EM3 also sells a 9t motor, that might be a good compromise. not quite so slow, but still better at hills that a 7t. The slower motors do not have more power, they just heat less going slow up steep hills. You'll climb the hill slower, but with less wasted energy into heat.

10t dd motors with 30 amps of 72v is a really good setup. Fast enough, yet able to climb 15% for miles. Still just underpowered enough to avoid frequent meltdowns. 72v 20 amps works good in really hot climates.

 

[Chalo]

I'm 270 lbs and can fly up 20% grades at 30mph without pedaling

Where? Paved 20% grades are rare even in Seattle, almost nonexistent in Austin-- and the Dallas region is flatter than either one.

 

[dogman dan]

I'm sure there are some grades that steep. But I bet they aren't 3 miles long or longer.

The volts and amps he's running will make a motor zip up hills. If you get up them in less than 15 min, it's likely not to melt the motor.

 

[Drunkskunk]

I'm 270 lbs and can fly up 20% grades at 30mph without pedaling with my 1000W motor.

I'd love to know where this 20% grade hill is. I need a chalange, and Wyle is close enough for me to make the trip just to try it.

 

[Russell]

There's NO WAY you're going up a (true) 10% grade on 48V at 30 MPH with a hub motor. Weight makes a difference but for example a 260 pound combined rider + bike need about 2500W (output power) to do it.

The simulator at ebikes.ca http://www.ebikes.ca/simulator/ is a great way to try various motor/battery/controller combinations.

-R

 

[wesnewell]

There are lots of short ones around here coming up from the river bed between Lavon and Ray Hubbard. Hwy 205 from hwy 78 into Rockwall has some longer steep grades. Check mapmyride. Or google maps. Alpine Dr. You'll know why it's named that. Bennett rd coming up from the river bottom beside Wylie east HS. Lots of other places with short steep old asphalt roads.

 

[wesnewell]

There's NO WAY you're going up a (true) 10% grade on 48V at 30 MPH with a hub motor. Weight makes a difference but for example a 260 pound combined rider + bike need about 2500W to do it.

The simulator at ebikes.ca http://www.ebikes.ca/simulator/ is a great way to try various motor/battery/controller combinations.

-R

14s lipo is 58V. With 40A controller that's 2320W of power. I'm running 24s 100V, so 4000W. I may have been running 18s when I did the test. A 10% slope is only 5.7 degrees. I took the figures from mapmyride.

 

[dnmun]

since i am the only one who has driven to his house i can guarantee the grades on the hill up to his place is as steep as it gets on a public roadway. one wrong turn sent me down a gully and it was 1st gear to get back up it. i wonder if wouldn't be better off driving through the gears like with a mid drive motor. or ecospeed type drive.

 

[iperov]

I rode geared hubs for ~1000km and back to DD FTW.
Winter -23C ate gears, I cannot replace them every 3 month.
And DD have less noise.

 

[brainfarth]

So... I based the grade on Google terrain and it was off by quite a bit. On my way down the hill today, I used my cell phone and a level app to measure a few spots. The easier way up to my place is 7 degrees and the ugly fast hill is 12 degrees. This puts them at 12.3% and 21.3% grades.

 

[wesnewell]

Do a 50% shunt mod on the controller to increase torque.
http://endless-sphere.com/forums/viewtopic.php?f=2&t=31643
Hopefully your bms has more than 30A output.

 

[Russell]

There's NO WAY you're going up a (true) 10% grade on 48V at 30 MPH with a hub motor. Weight makes a difference but for example a 260 pound combined rider + bike need about 2500W to do it.

The simulator at ebikes.ca http://www.ebikes.ca/simulator/ is a great way to try various motor/battery/controller combinations.

-R

14s lipo is 58V. With 40A controller that's 2320W of power. I'm running 24s 100V, so 4000W. I may have been running 18s when I did the test. A 10% slope is only 5.7 degrees. I took the figures from mapmyride.

You are using INPUT power, and MAX input power at that with no accounting for losses, efficiency or the power curve of a particular motor. Again there are quite a few factors which affect hill-climbing however I have found the simulator at ebikes.ca works well for me provided you start with good data, the actual slope for example. Nevertheless using 58V, 0.05, 15AH battery with a 4110 FET 40A controller, 26" wheel, 260 lbs, race bike (tuck) with an NC 2806 the simulator estimates a no-pedal speed of 23 MPH up a 10% slope.

From my own experience using small low-power geared motors and spinning as fast as possible I can climb an 8% grade at 14 MPH at 750W input and 17 MPH with 1000W input. The steepest hill of any length nearby (well it used to be nearby) has a steady 13% grade. It was all I could do to get up it at 7 MPH with 750W and my small geared motor. With a larger Bafang BPM I managed 10 MPH w/1000W peak input and 14 MPH w/1350W peak input, again with a lot of pedaling. BTW, the simulator estimated 11.3MPH for that last combo or 14 MPH with 144W net from me. FWIW

-R

 

[Drunkskunk]

That alpine road shows to be a 5% grade when MapMyRide maps it west to east, but maped east to west, it does show a small stretch of it at 20%, and mostly at 1% for the rest of it. Google maps street view shows it's pretty consistantly steep, so I may head out that way to give it a try.
Hwy 205 I used to ride back in my Lycra riding days. I think there was a BBQ stand on that corner way back then, but I hear there's a restraunt out there now. Its a solid 1% grade up those hills, which was hell on a long ride. We used to hit that riding from Rockwal up to Farmersville.

 

[dogman dan]

12.3% for more than 300 feet will choke out a typical hubmotor with only 1000 ish watts. But I'm sure it could be charged with lots of momentum and 3000w or so. 20% is much harder, but well within the envelope for a 10t dd hubmotor drawing 2000w. A 72v 40 amps controller, suitable battery for 40 amps, and a 10t dd motor will definitely do it.

At 48v 40 amps, a 10t motor will still get up it, but you would have to pedal harder I bet, and have a slow top speed.

But now we are talking 20% not 10%. So just a motor upgrade is not so likely to do it for that. 10% is pretty easy, 20% better be really short, even for the slower motors.

I don't think just a motor upgrade is going to make you really happy, It's time to build yourself your featherweight motorcycle that resembles a bike. Get into the 3000w club. (input max potential watts) But it doesn't have to be a cromotor, if you will only strain it that hard for a few short hills.

 

[Russell]

Here's my 13% hill

Hit 49.6 and 50.1 MPH on two different bikes just rolling down the thing!




-R

 

[John in CR]

If you're lacking just a bit up your main hill, just add a small geared hubbie to the front, and then you'll be able to tackle anything.

 

[John in CR]

There's NO WAY you're going up a (true) 10% grade on 48V at 30 MPH with a hub motor.

LOL! This morning I maintained 75mph up a grade that peaks at 8%, and I'm not afraid to point my bike up any paved road starting from a dead stop. With one of my smaller DD hubbies, I've stopped at the very steepest point of a 25% average grade and gone right up it no problem. Sure most ebike DD hubmotors are too steeply geared and geared hubs can be the answer at lower power, but otherwise every DD hubbie I've owned except maybe the horribly out of balance 9C garbage I picked up could embarrass any geared hub available climbing with the loads mine push. Well, everything except carrying your bike upstairs, but I've never owned any vehicle I needed to carry up stairs.

Weight makes a difference but for example a 260 pound combined rider + bike need about 2500W (output power) to do it.

For hills weight is almost everything other than wind resistance, and I don't know of any ebike motor type that makes a real difference in terms of wind resistance, unless you count the guys using a prop and an RC motor which isn't much more than an ineffective toy approach.

 

[Russell]

[
LOL! This morning I maintained 75mph up a grade that peaks at 8%,

But you didn't do it on 48V!

How much power did it take?

-R

 

[John in CR]

[
LOL! This morning I maintained 75mph up a grade that peaks at 8%,

But you didn't do it on 48V!

With the motor wound for lower voltage and controllers to match the result would have been identical.

How much power did it take?
-R

No idea. I don't dare take my eyes off the road to look at the CA at that speed. The 12km route that I did in 10min 19sec use 1012 watt-hours. Traffic on the other roads and the bumpier sharper curved route back (the route cyclists take over the same hill really slowed me down for the 69.7kph avg. Peak power input for the trip was 245.7A at around 100V with sag, but that would have occurred shortly after the on-ramp as I passed through 80kph or so. BEMF would have kept current somewhat lower than peak for the 2.5km blast to the top. Traffic was light so it was a great 10min ride.

 

[wesnewell]

IIRC, map my ride has this 2000' stretch at 20%, but there's about 300' in the middle that's flat.

 

[dogman dan]

More than a third of a mile of that grade will do the trick to test a motor. That would choke hell out of most stock ebikes, even 48v ones. Definitely short enough to volt up and charge the hell out of it though. How does the 30 amps controller on 48v handle it? I mean the stock 1000w yes kit. Does it get up it, or stall to less than 10 mph?

My local test hill is lame by comparison, mostly 6%, but three miles long with no pedaling gives a motor a good workout, especially if it's over 100F weather. Good for comparing motor temps at the top. Cool at the top tells you it's working better than other motors or voltages.

A bit farther from the house, I have a 13% grade for about a mile and a half long that convinced me about slow winding motors being great for hills. After seeing that test, I volted up to 3000w and had a slow motor off road bike that balks only on 20 degrees. You've seen the vids.