ebike4healthandfitness
100 kW
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- May 19, 2012
- Messages
- 1,283
Bullfrog, The chances of finding a bike with rim brake mounts for 24" rim and also able to mount 3" wide tires is probably slim to none.
Leaf / leafmotor / leafbike high efficiency 1500w motor
- Thread starter neptronix
- Start date
Bullfrog, The chances of finding a bike with rim brake mounts for 24" rim and also able to mount 3" wide tires is probably slim to none.
Try regen on the rear instead of mechanical brakes.
A standard 26" wheeled MTB with 135mm dropouts will typically accommodate at least a 2.75"x24" tire ( you must be willing to lose a top gear or two due to chain > tire interference though )
The position of a 24" in a 26"er is ideal for using very large tires.
Here's a 24 x 2.4" in a bike designed for 26 x 2.15 tires. I could go way bigger..
A standard 26" wheeled MTB with 135mm dropouts will typically accommodate at least a 2.75"x24" tire ( you must be willing to lose a top gear or two due to chain > tire interference though )
The position of a 24" in a 26"er is ideal for using very large tires.
Here's a 24 x 2.4" in a bike designed for 26 x 2.15 tires. I could go way bigger..
Try regen on the rear instead of mechanical brakes.
A standard 26" wheeled MTB with 135mm dropouts will typically accommodate at least a 2.75"x24" tire ( you must be willing to lose a top gear or two due to chain > tire interference though )
The position of a 24" in a 26"er is ideal for using very large tires.
Here's a 24 x 2.4" in a bike designed for 26 x 2.15 tires. I could go way bigger..
View attachment 352695
I agree...I ran a 20 wheel and a 4" tire on a bike that came with 27.5" wheels and I have also gone the other way and ran a 29x3.00 tire on a bike that came with 26" fat tires.
I was thinking of using a 24" wheel and V-brakes in a frame that came with 26" wheels so the wide 24" tire would easily fit but you make a good point on the alignment of the brakes...i.e. it probably won't work if I try to use a 24" wheel in a bike that has mounts for V-brakes on a 26" wheel. Chock up another advantage for disc brakes.
The other problem is if I go with a frame that came with 24" wheels, there isn't much room for a triangle shaped battery in the frame triangle since the 24" frames are smaller. Plus the shorter wheelbase of a bike that came with 24" wheels would be less stable at speed and I need all the stability I can get.
Sooo it is back to the drawing board to come up with my next idea
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I only used the front 203mm rotor on my previous leafbike build to stop from ~5mph. The rest was regen.
Having strong regen made me finally not terrified of descending down the 10-15% grades here.
Dual 203mm discs would get too hot, would fade, and make me panic stop so the brakes could cool for 5 min so i could continue descending. If i didn't do that, i'd be dead because i would eventually lose all braking power.
Once you get up to a certain speed, any mechanical brake built for a bicycle is inadequate, even on flat land. You will be going through rotors and pads left and right and probably fighting heat on the flats with a bicycle that does 50mph.
I would run zero mechanical brakes if it was feasible to do so. Regen is the superior brake for a bicycle.
Having strong regen made me finally not terrified of descending down the 10-15% grades here.
Dual 203mm discs would get too hot, would fade, and make me panic stop so the brakes could cool for 5 min so i could continue descending. If i didn't do that, i'd be dead because i would eventually lose all braking power.
Once you get up to a certain speed, any mechanical brake built for a bicycle is inadequate, even on flat land. You will be going through rotors and pads left and right and probably fighting heat on the flats with a bicycle that does 50mph.
I would run zero mechanical brakes if it was feasible to do so. Regen is the superior brake for a bicycle.
nicobie
100 MW
I agree. It's either that or don't go over 35 mph. Or maybe over 30 mph...
chuyskywalker
10 kW
It very much is -- esk8 and EUC's work exactly like this; pure regen. esk8 typically has a reduction gearing to help really capitalize on it and EUC's just have INSANELY wide (diameter) stators so they can pump out wild amounts of amps for both accel and regen.
Bike motors sit in a space where this just generally doesn't quite work. I may give it a go with my (rather on topic) dual leaf setup coming in...tomorrow, actually.
gromike
10 kW
But what do you do with waste electricity? Like when the battery is unable to absorb all the power produced during the descent.
If you are serious about regen braking on a motorcycle maybe something like a big old resistor would be in order. Telma makes a heavy vehicle induction brake. It seems that all we are missing in that equation is that big old resistor -- where you put it is up to you.
If you are serious about regen braking on a motorcycle maybe something like a big old resistor would be in order. Telma makes a heavy vehicle induction brake. It seems that all we are missing in that equation is that big old resistor -- where you put it is up to you.
If you have a 20AH battery you could pretty easily absorb a 10A charge rate which would give you 500W braking power on a typical 52v battery. That's enough power with a 203mm front to stop quickly from 40mph.
If you are rocking a high power 1500W Leaf setup, i'm imagining you have a big battery and taking 10A or more wouldn't be a big deal, since you're probably discharging north of 40A ( 60A is where the fun starts on the 4T )
If you are rocking a high power 1500W Leaf setup, i'm imagining you have a big battery and taking 10A or more wouldn't be a big deal, since you're probably discharging north of 40A ( 60A is where the fun starts on the 4T )
chuyskywalker
10 kW
You will, in almost every scenario ever, never regen more than you spend in pushing the bike forward. In the rarest of cases where you have a 5 mile, 10% downhill grade at the beginning of your trip; just charge to 80% instead and you'd be fine. (Ok, I'm exaggerating, but you get the idea, it's very easy to account for this.)
gromike
10 kW
Yeah, I guess. But with braking, you want to failsafe.
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The Toecutter
100 kW
- Joined
- Feb 8, 2015
- Messages
- 1,468
In my experience, the 90mm Sturmey Archer drum brakes in my Milan SL are adequate for panic stopping at 50 mph. They don't have as good a stopping force as Avid BB7s, but they are close. The Sturmey Archer's advantage is that they are a lot more consistent with regard to applied stopping power than the BB7s. I never have experienced them causing the velomobile to veer to the left or the right when applied, unlike the BB7s, and thus they require less frequent adjustments and are more predictable in panic stop situations. The Sturmey Archers have more mass to absorb heat than the BB7s as well, and I've never experienced as much brake fade with the Sturmey Archers as I did with the BB7s.
The BB7s in my KMX were good for about 35 mph cruising speeds before panic stop situations got scary. I've panic stopped with them from 45+ mph before multiple times, and it was butt puckering in the best of circumstances, to say the least. Using a single handle at anything over 35 mph, the bike liked to veer left or right at random even if the brakes were recently adjusted, and they were difficult to keep in proper tune. The BB7s increased stopping force vs the Sturmey Archer drums is still going to be limited by the front tires anyhow, but the BB7s could get a shorter stopping distance by a few feet from a given speed, since the Sturmey Archers don't initially "bite" as responsively as the BB7s do and take a quarter second or so to reach their full potential for deceleration, which given the tire limitations, ends up ultimately the same as the BB7s. But that few feet in increased stopping distance could still make a difference that results in an accident... but so to would the vehicle veering into another lane during a panic stop.
Overall, the Sturmey Archers are a lot easier and less stressful to panic stop with, and unlike the BB7s, I trust them at 50 mph. But my application is for a trike, and YMMV.
The BB7s have since been replaced with a custom hydraulic brake setup purchased from Endless Sphere forum member adam333. Thus far, it is even better than the Sturmey Archers in the Milan. Not only do they stop evenly every time, but their stopping power is better than either. That KMX trike will soon be all-wheel-drive and have regen in all three wheels, so the mechanical brakes will be called upon mostly in emergency situations or if I'm doing like 90+ mph and need to stop. And IMO, you really don't want to do away with mechanical brakes, just in case you're going down a steep incline with a fully charged battery and/or require more stopping power than the regen can deliver. Redundancy is important. I'll have regen in all three wheels, plus hydraulic brakes up front, plus an Avid BB7 in the rear.
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Chalo
100 TW
Discs? Sure. But rim brakes' heat handling scales with the rim, and they can be used two per wheel if redundancy or extra pad area is desired. I used to be able to reach 55 mph riding my pedal bike to work on any day, and at that time I weighed about 400 pounds. I never had a moment's uncertainty getting stopped at the bottom of that hill using only rim brakes with Kool Stop pads on heavy aluminum rims.
This Honda RC116 racing motorcycle had a top speed of 109 mph. The only problem with its rim brake was that riders didn't trust a "bicycle brake" even though it demonstrated fitness for purpose. Sort of like how many uninformed cyclists would rather have a bad disc brake than an excellent rim brake today, racers back then trusted a bad drum brake more than a good rim brake:
If motors were passable brakes, we'd see them used that way in lots of motorized applications. But except for Segways, e-unicycles and other novelty toys, everything uses friction brakes even if it can brake with the motor. Brakes designed for braking always beat brakes designed for propulsion. And they incur less weight, less motor heating, less uncontrolled rate battery charging, less expense, and less reversing torque to loosen your axle nuts.
I use extremely tight fitting dropouts as a rule, my electric brake weighs nothing, doesn't fatigue, doesn't wear, doesn't need adjustment, provides me the freedom to run whatever wheel size i wish, and also puts energy back into my battery instead of wasting the entirety of the momentum energy to heat.
I know that rim brakes are underappreciated and have a high heat capacity relative to disc brakes ( a good property for an ebike ), but every form of friction braking is inferior to regen.
I know that rim brakes are underappreciated and have a high heat capacity relative to disc brakes ( a good property for an ebike ), but every form of friction braking is inferior to regen.
ebike4healthandfitness
100 kW
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A castle nut with a cotter pin would prevent that.
Chalo
100 TW
It doesn't matter. If they're not made of infinitely stiff material, they can flex open on torque reversal and allow the nut to back off just a touch. Repeat ad infinitum, and soon it's new frame and motor time.
If you have enough surplus heat capacity to brake as well as propel, then it doesn't weigh nothing. It weighs more than a brake does.
It fatigues your axle.
In other words, can't be adjusted like a mechanical brake. You get what you get. Maybe you can limit it to make it weaker.
At an uncontrolled rate that can be harmful to your battery, or make you use a larger or more powerful battery than you'd need without it.
It's like driving a stick shift car and only braking with the clutch. Only that wouldn't make your car's wheel fall off.
Too bad we can't do quote within a quote, anyway.
I had dropouts so tight on my 6kw bike that you had to hammer the motor into the dropouts and hammer the torque arms too.
1000+ miles of 4-6kw and 1kw of regen and the axles were just as tight when i decommissioned the bike.
I had to hammer out the dropouts when decommissioning the bike and that tells me i had basically no axle wear.
I would have gone through multiple sets of pads.
Moot point with good torque arms and drops.. moot point with something like grin's all axle/GMAC motors which relieves the axle.
Since we're talking about a leafbike 1.5kw, yes we have surplus heat capacity on hand, so let's use it.
On a number of controllers you can set the amps 1 amp at a time, very adjustable.
It's not uncontrolled, it's current limited.
We're in the context of a multi kilowatt build i think it's safe to assume we have a pack capable of intaking large current.
I had dropouts so tight on my 6kw bike that you had to hammer the motor into the dropouts and hammer the torque arms too.
1000+ miles of 4-6kw and 1kw of regen and the axles were just as tight when i decommissioned the bike.
I had to hammer out the dropouts when decommissioning the bike and that tells me i had basically no axle wear.
I would have gone through multiple sets of pads.
Moot point with good torque arms and drops.. moot point with something like grin's all axle/GMAC motors which relieves the axle.
Since we're talking about a leafbike 1.5kw, yes we have surplus heat capacity on hand, so let's use it.
On a number of controllers you can set the amps 1 amp at a time, very adjustable.
It's not uncontrolled, it's current limited.
We're in the context of a multi kilowatt build i think it's safe to assume we have a pack capable of intaking large current.
nicobie
100 MW
While that's all true, I still recommend not using regen for beginners. Too complicated. (just my opinion)
Saw a picture of a new 1.5kw leaf in chuyskywalker's thread.
Looks like the windings on this motor are massively tighter but we have a little less copper than before.
These motors look either expertly, or machine wound. Nice upgrade!
The motor i ordered in 2014 ( had what we consider fairly flat windings for the time )
I would guess that these motors are a bit less powerful than the one i ran, but probably more efficient as they have a fraction of the sloppy copper on the ends.
Just a FYI.
Looks like the windings on this motor are massively tighter but we have a little less copper than before.
These motors look either expertly, or machine wound. Nice upgrade!
The motor i ordered in 2014 ( had what we consider fairly flat windings for the time )
I would guess that these motors are a bit less powerful than the one i ran, but probably more efficient as they have a fraction of the sloppy copper on the ends.
Just a FYI.
ebike4healthandfitness
100 kW
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- May 19, 2012
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yantra yatra
100 W
I’m looking at 26”. So that should help with hill climbing? Although as mentioned not so many full sus frames around with 26” wheels. One of the good things about hub motors to me seems to be ability to switch between bikes without much trouble, but on the other hand you’re restricted to the wheel size
yantra yatra
100 W
Cool, so changes/improvements continue to be made.
Good to know
IF I had it to do over again, I'd go with a Leaf 4T motor in a 24" rim and I'd run a Schwalbe Pick-Up 24x2.6" tire. This is a link to the tire: Schwalbe Pick-Up | Super Defense | Black-Reflex | 26x2.15 | Addix E | 11159144 You have to scroll down a little bit because the 24x2.6" size is not shown in the list at the top right of the page. I know they make them because I have one
. As for other 24" tires...the Maxxis Hookworm 24x2.5" is a pretty good option.With disc brakes, you can use any size wheel you want. Using a frame that came with 29" wheels is going to keep me in the disc brake camp as opposed to rim brakes because I do not know of an easy way to run rim brakes when I install a 24" or a 26" wheel in the frame that came with 29" wheels. My current bike is a Schwinn Axum 29er and I am currently running 26" wheels. I'll eventually lace my motor in a 24" rim and run it in the rear. I did switch to shorter crank arms (92mm) so I won't have pedal strikes every time I turn...with 92mm crank arms, I don't pedal much
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I’m back to planning an ebike build for my wife. I’m not sure whether she’ll like it or will stick to it, but I’m also building it with the possibility that I may ride it if she loses interest; so easy to modify for higher performance later. So far I’m set on 60v and 20” rear hub, on a 24” Specialized Hot Rock frame, with front and rear hydraulic brakes (to help with arthritis) and have been scoping out Craigslist.
My question is, is the 2000W 60v motor sold by Leaf the same as the 1500W? I noticed that the performance graph they use in the description is for the 1500w motor. I’ve been assuming that for modeling in the Grin simulator, for the (wife’s) low power mode (20A) and a high power mode (60A) adjusting kv for a 4T wind, but want to make sure that’s a safe assumption.
www.leafbike.com
I’m too lazy to lace, so I plan on ordering the 20” wide rim, and likely run one thing like Super Moto X tires.
My question is, is the 2000W 60v motor sold by Leaf the same as the 1500W? I noticed that the performance graph they use in the description is for the 1500w motor. I’ve been assuming that for modeling in the Grin simulator, for the (wife’s) low power mode (20A) and a high power mode (60A) adjusting kv for a 4T wind, but want to make sure that’s a safe assumption.
20 inch 60V 2000W rear hub motor wheel
Convert your 20 inch original bike to ebike with leaf 20 inch 60V 2000W rear hub motor wheel.
www.leafbike.com
I’m too lazy to lace, so I plan on ordering the 20” wide rim, and likely run one thing like Super Moto X tires.
ebike4healthandfitness
100 kW
- Joined
- May 19, 2012
- Messages
- 1,283
If concerned about starting a trip that begins traveling down a hill at 100% battery charge then you got a few options in situations where a rear disc brake is not possible:
1. Add a rim brake to the rear.
2. Add a larger front disc brake.
3. Add an additional front disc brake
4. #2 and #3 together
5. In cases where #1, #2, #3 and #4 are not possible then use some combination of heatsink'd semi-metallic or metallic pad, heatsink'd brake caliper, aluminum clad brake rotors with* or without** cooling fins, etc.
*Shimano ICE tech freeza
**Shimano ICE tech
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