The Great "Gearing vs Hub Motor" Debate

[Lowell]

So is riding recklessly on public property.

But those are separate issues.

"Riding Style" and "bike legality" are not the same thing.

And besides... we actually alienate the rest of the world that has lower limits. Can you imagine 250 watts like in Europe and elsewhere? The vast majority of the world are now and will forever be on low powered electric bikes because most laws make it that way. Gears are specifically useful for low powered systems. We should in a sense be "thankful" that there is a law in place that clearly says it's "okay" to have 750 watts. That's a pretty workable power number. It could have been 250 Watts!

Spinning dreams of futures with 5 hp bikes is pointless... it will never happen...

Tell that to all the dealers selling X5 hubs and 72v, 35/40 amp controllers. Those things come over by the container load from China, and they're going on peoples bikes. Most of those are probably in the 3-4hp range though.

 

[safe]

Tell that to all the dealers selling X5 hubs and 72v, 35/40 amp controllers. Those things come over by the container load from China, and they're going on peoples bikes. Most of those are probably in the 3-4hp range though.

That's why there is probably "trouble" brewing down the road. The laws will clearly never allow this, but the enforcement is so lax at this point that illegal machines don't trigger a response "yet".

I used to ride two-stroke motorcycles, but now they are banned. (they do allow under 50cc bikes for some reason) If I were to "predict" the future I'd expect a similiar path where people get all excited about these 3-4 hp hub motors only to see them banned later on.

From wikipedia:

"From 2007 onwards and for a minimum period of five years, FIM has regulated in MotoGP class that two-stroke bikes will no longer be allowed, and engines will be limited to 800 cc four-strokes."

Realistically a 750 Watt motor passes the "physics test" of being enough to propel a well streamlined rider to speeds of about 40 mph on the flats. This means that if you "work at it" you can get a pretty fun little ride.

The only "future" as I see it is if the "hub motor community" is proactive and ATTACKS the issue head on and does something like make it a requirement to have a drivers license in order to operate one. Otherwise you are never, never, never going to see children allowed on 3-4 hp electric bikes.... the law is simply not going to let that happen.

In this I'm being a "realist"... high powered hub motors have no future the way things are now... (the first hub motor related lawsuit will cast a "chill" over the whole concept... there will be nothing legally to stand on)

 

[Lowell]

Somehow I think the police are going to have better things to do than crack down on overwatted e-bikes, at least where I live. Street racing used to be a huge problem here in Greater Vancouver, and all the ricers keep the police plenty busy writing tickets for various illegal car modifications.

It would be extremely difficult and time consuming to equip officers to hand out tickets. In order to hold up in court the officer would have to have been trained, use an officially calibrated watt meter or dyno, and have reasonable grounds to stop you. Depending on how the local regulations are worded (input or output power) it would require the officer to tie in series with your battery wires and then ride your bike around. For output power, the bike would have to be confiscated and sent somewhere for testing.

I predict that a person will have a greater chance of being ticketed for jaywalking than an overwatted ebike.

 

[Stevil_Knevil]

5 horsepower will NEVER be legal...

NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER...... maybe?.... Nope.... NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER, NEVER....

For the "real world" of the electric bike you nead to deal with gears...

(and that's okay, because 750 Watts is still enough to have some fun )

Well then, cracking into the 50MPH club on a STREET LEGAL electric machine is going to require that you register it as such. It only hurts for a second.. grin and bear it :wink:


-S

 

[Lowell]

Laws may vary, but I don't think you can register anything here without a VIN number.

 

[Stevil_Knevil]

Yep, VIN numbers are required, as are a whole slew of legal requirements. It's not the fall that hurts.. it's when you hit the ground.


-S

 

[Geebee]

Lowell, a quick question how would the X5 pull from a standing start on a 25-30% grade (we are talking way steep hills here)? Just curious.

 

[Lowell]

Lowell, a quick question how would the X5 pull from a standing start on a 25-30% grade (we are talking way steep hills here)? Just curious.

Never tried it on that steep a grade, but this should give some idea of the low end torque:

http://endless-sphere.com/forums/viewtopic.php?t=461

With the front brake locked, full throttle will push the front wheel skidding across the pavement from a dead stop. The simulator predicts around 140Nm of torque...not sure how accurate that is though.

 

[Geebee]

Not a real good guide as I have an old geared hub motor in the front of a chopper and not seated it will do the same at lesser rpm's though.
Wife was not impressed with the marks on the pavers
It will spin off the line on small hills when seated.
Only having an on/off switch instead of a controller helps though.
"With the front brake locked, full throttle will push the front wheel skidding across the pavement from a dead stop." can't do that though.

 

[Lowell]

Not a real good guide as I have an old geared hub motor in the front of a chopper and not seated it will do the same at lesser rpm's though.
Wife was not impressed with the marks on the pavers
It will spin off the line on small hills when seated.
Only having an on/off switch instead of a controller helps though.
"With the front brake locked, full throttle will push the front wheel skidding across the pavement from a dead stop." can't do that though.

Front wheel drive and rear drive are a lot different in terms of traction though. Static weight distribution on my bike is about 65% rear, and the bike weighs about 100lbs. CG is 1-2 inches behind the bottom bracket.

This quote pretty much sums it up:

"Dave says: If the Phoenix had been available 3 years ago, I probably wouldn't have built the insane-a-cycle. Phoenix costs one-third of what I spent, and its performance is more than anyone can justify. It's the most exciting product I have ridden since the Tidalforce. I think Phoenix makes the most useable, cost-effective light electric vehicle available today."

 

[Matt Gruber]

Laws may vary, but I don't think you can register anything here without a VIN number.

every bicycle i ever owned has a serial #

 

[Lowell]

Laws may vary, but I don't think you can register anything here without a VIN number.

every bicycle i ever owned has a serial #

Serial number yes, but it's unlikely the feds would assign a VIN number to an ebike.

http://www.nydmv.state.ny.us/homemade.htm

 

[Leeps]

Well im getting in late on this converation.
My opinion on gears is that they cant hurt they can only help. They give you more torque to the wheels with less power required from the motor. It is in effect the torque output of the motor that leads to loss and motor heating at any given speed. Thus gears give you the option of greater tractive force with less total load at the motor. Thats it in a nutshell, the question of quarter mile time and total performance, whell ill leave that to the individual case. If i end up in san francisco with crazy hills to climb ill take gears.
Joe

 

[Mathurin]

Well I think it was bocoptibikeguy who'd concluded that gearless systems yeilded better eff then geared systems, though as I understand he lives somewhere flat.

 

[Lowell]

Well im getting in late on this converation.
My opinion on gears is that they cant hurt they can only help. They give you more torque to the wheels with less power required from the motor. It is in effect the torque output of the motor that leads to loss and motor heating at any given speed. Thus gears give you the option of greater tractive force with less total load at the motor. Thats it in a nutshell, the question of quarter mile time and total performance, whell ill leave that to the individual case. If i end up in san francisco with crazy hills to climb ill take gears.
Joe

Agreed on all points. If I could have gears that wouldn't slow me down through shifting, and wouldn't break, I'd be all for it. They would also have to be weather proof and low maintenance, ie internally geared hub motor.

 

[Lowell]

Well I think it was bocoptibikeguy who'd concluded that gearless systems yeilded better eff then geared systems, though as I understand he lives somewhere flat.

With the right setup, it's not hard to cruise in the 85-90% efficiency zone with an X5 hub motor. A good geared motor setup can produce the same numbers at the motor, but then you have gear/chain losses. The difference could be around 5-8% in favor of the hub motor, but it would depend on each bike setup. Since I live in a city where the highest point is only 12m above sea level, advantage hub motor.

Aero losses could also be smaller for the hub motor, although I don't have any good way to verify that. Certainly some of the 'motor hanging out in the wind' reduction setups I've seen look terrible from an aero point of view. A package like the Stokemonkey might have very comparable aero drag to a hub motor, but of course there's the mechanical losses from the extra chain and bottom bracket, and the lack of real power handling.

 

[tno]

Laws may vary, but I don't think you can register anything here without a VIN number.

every bicycle i ever owned has a serial #

Serial number yes, but it's unlikely the feds would assign a VIN number to an ebike.

http://www.nydmv.state.ny.us/homemade.htm

evglobals have vin #'s

 

[Lowell]

That bike is from a major manufacturer. My post was talking about home built ebikes. Do the EVglobal bikes come with DOT approved lighting, horn, turn signals etc?

 

[tno]

evglobals come with DOT approved headlights, taillights, brake lights, and horn. I think it can be registered. The bike feels a lot heavier than other ebikes I've tried and is kind of slow. I put an x5 into it and it really flies now.

 

[Lowell]

That's pretty cool that it comes stock with all those things. The X5 is really nice, isn't it.
I tried to look up evglobal.com but it doesn't seem to work

 

[tno]

evglobal quit producing ebikes but they still sell them in europe:
http://www.ebike.co.uk

I use to ride a 36v ~350w merida geared bike. the gearing did make the bike ride better than a regular 350w powered bike. but the motor just didn't have enough torque to power the higher gears. the motor would spin out in 1st and 2nd gear but could never reach full rpm's in 3rd and 4th gear.
The x5 feels a lot more powerful than any electric bike I've tried. It can climb all hills in san fran. On the really steep hills like the ones on webster street in the marina, it will go around 9-10mph. it can climb up oshannessy all the way to the top of twin peaks at over 30mph. I don't use the speed too much though. I stay around 20mph and use the power mainly for going up hills. that way, I only use 3Ah going 13miles. I run the x5 at 84v.

 

[fechter]

it can climb up oshannessy all the way to the top of twin peaks at over 30mph. I don't use the speed too much though. I stay around 20mph and use the power mainly for going up hills. that way, I only use 3Ah going 13miles. I run the x5 at 84v.

Holy crap! That's some serious hillclimbing. Does the motor get hot?

 

[tno]

the x5 feels warm after all my rides on flat land or hills. so I would say that it is not running at peak yet. also, my motor is the 505 so it probably has a bit more torque than some of the others mentioned here. the top speed is ~40mph.

 

[safe]

I run the x5 at 84v.

Wow

At 84 volts DC if you get electricuted your chances of dying from it are quite high.

From wikipedia:

"Various safety and insurance organizations consider anything outside of the ELV range (i.e. greater than 50 V) to be dangerous and in need of regulation. Voltages above this range are capable of producing heart fibrillation if they produce electric currents in body tissues which happen to pass through the chest area. The electrocution danger is mostly determined by the low conductivity of dry human skin. If skin is wet (especially with electrolytes, including sea water) or if there are wounds, or if the voltage is applied to electrodes which penetrate through the skin, then even voltages far below 40 V can be lethally high. On the other hand, voltages above approximately 500 V have a natural defibrillating effect, so sometimes a higher voltage can be safer than a lower voltage, though by no means safe. A DC circuit may be especially dangerous because it will cause muscles to lock around the wire. It has also been noted that accidental contact with high voltage power lines has not always been fatal because sometimes the victim is thrown clear of the power line by the intensity of the arc that is created and has survived, although with extremely severe injuries."

It's interesting that most "legal" ebikes are sold with voltages of 48 Volts or less. This is probably to gain some level of safety compliance based on the "50 Volt Limit" where the chance of death begins to occur. Beyond that and you would be constantly "looking over your shoulder" expecting a lawsuit the first time "Johnny" gets electricuted and dies from it.

This becomes another argument for lower voltage small motored "geared" bikes over these "monster" over volted hub motors. You are less likely to kill yourself if your electric bike is running only 48 Volts.

However, this high voltage concept does seem to work and despite it's legality and (now) safety concerns it's still a heck of a way to trick out your ride. :wink:

Note: It's interesting that from 0 to 50 Volts they say it's "safe" and from 50 Volts to 500 Volts it's "deadly" but that above 500 Volts it switches back into something where your heart is not prone to stoppage. I would guess severe burns would occur at that high of a voltage, but you might actually live. Amazing. I don't think this should make us advocate 500 Volt electric bikes however...

 

[tno]

definitely be afraid of high voltage. if you are ever electrocuted with high voltage and are still alive, go to the nearest hospital right away and stay there for 24hrs. muscle cells have resting membrane potentials of -90mv while neurons are at -70mv. the electrons floating around your body after an electrocution might depolarize neurons and cause seizures that you can die from. you can leave the hospital after 24hrs, because the electrons will have dissipated and you'll be fine. Also, if you get shocked across your heart while your SAnode (pacemaker) depolarizes, the shock will burn out your SAnode. Then if you are still alive, you'll need an artificial pacemaker for the rest of your life.

In my setup, I have 2 battery packs that connect in series to make 84v. The stock 36v battery pack has contact connectors that are difficult to touch with your hand. So to disconnect the power, simply pull out the 36v battery pack without having to touch any connectors. the 48v battery pack is then not as dangerous to handle by itself. The controller and wires are all inside the evglobal plastic body so you can't touch them. I think this setup is relatively safe.