The Great "Gearing vs Hub Motor" Debate

[xyster]

Well hell's bells man, are you planning to ride around in a tuck all the time? No wonder you're worried about speeding tickets and attracting police attention.

 

[safe]

Well hell's bells man, are you planning to ride around in a tuck all the time? No wonder you're worried about speeding tickets and attracting police attention.

No, it's just like a street motorcycle road racer bike. Most of the time you see those guys sitting up and putting along at slow speed. In a residential area where there might be kids playing in the streets you need to be very careful and take it easy. But when you get on your own favorite road you can "go for it" and get some radical leaning and tuck in the straight aways.

I've gotten REALLY LUCKY because there has been a lot of home building going on around here and yet when the bubble burst this one housing development simply decided not to build the houses, but they built the roads. So I have my own private "race track" that I can do testing on.

When I get the fairing on it I'm REALLY going to get attention, so having a "legal limit" motor will help a lot...

 

[TylerDurden]

Don't foget yer helmet...

 

[knightmb]

LOL TylerDurden, the hubmotor is the almost the wheel itself. :lol: :lol: :lol:

 

[Lowell]

"How many people own motorcycles now or have owned them in the past?

If you want "real" speed maybe you might want to get a motorcycle? (is this place filled with a bunch of motorcycle wanna be's? ...dare I say "dorks"?)"

There's a red and white Yamaha parked in my garage... but this is real speed:

http://shepracing.com/

0-148mph in 5.1 seconds. And this is what happens when 2 wheel racer types in leather suits try and mess with real speed on the street:

http://www.streetcarforums.com/videos/www.streetcarforums.com%20TT%20VIPER%20vs%20gxsr1000.wmv

Does calling people here 'dorks' make you feel better about your low powered gear motors? Are you trying to compensate for something by putting others down?
I'm sure if there are any motorcycle wanna be's here, they would be over at http://www.gsxr.com/ or some similar forum, and not an EV forum.

 

[Lowell]

Don't foget yer helmet...

Damn, that thing would be a wheelie machine! (if it had some batteries)

How about lipo packs inside the frame?

"LOL TylerDurden, the hubmotor is the almost the wheel itself. "

The new HED Disc wheel, now with integrated hub motor!
http://www.hedcycling.com/wheels/standarddisc.php

 

[Geebee]

Safe, you are in for a real shock when you fit a shell, a tuck is no replacement for true streamlining, your speed will skyrocket and current will plummet at the current higher speeds.

 

[Lowell]

Safe, you are in for a real shock when you fit a shell, a tuck is no replacement for true streamlining, your speed will skyrocket and current will plummet at the current higher speeds.

An electric powered streamliner would have an impressive top speed for sure. Wonder how it would compare to this:

http://www.canosoarus.com/08LSRbicycle/LSR%20Bike01.htm

Some serious gearing on that bike...

 

[safe]

Safe, you are in for a real shock when you fit a shell, a tuck is no replacement for true streamlining, your speed will skyrocket and current will plummet at the current higher speeds.

I just want the limited fairing type streamlining. I know that a full shell is in "another league", but this is supposed to be a "sport" machine and not a machine that is impractical. I want to be able to "hop on it" and not "climb into it". (or be "assembled" as part of it like a lot of people seem to do)

 

[safe]

Does calling people here 'dorks' make you feel better about your low powered gear motors?

I know what real speed is and even the high wattage hub motors aren't that impressive. My point is that one should be HUMBLE with their small motors and enjoy the pleasures of getting the most out of them. (that's the fun part... squeezing efficiency out of little motors)

Raw speed is for young people with healthy organs to donate... :wink:

 

[safe]

The 500 Watt Class

Just so we don't ignore the smaller wattage machines here's the effect of taking a little 500 Watt motor and giving it an 8-speed gearbox in the rear hub.

500 Watt Unite Motor
36 Volts
30 Amp controller
729 Peak Power Watts

Everything else is the same as in previous tests...

First chart is "maximum speed" and the second is some pretty low gears that would pass a "30 mph limit" criteria. (and could climb ANY hill)

Top speed is 37 mph!

 

[xyster]

Great, then you should buy this $329, 450 watt Mongoose and fit a new crankset tied to the motor so you can go 37mph on it:

http://tinyurl.com/y8vfp4

With these no-wind, fantasy-case stats you've conjured, why people buy these stupid hubmotors, or want more than 1 horsepower, is beyond me.

 

[Geebee]

I just want the limited fairing type streamlining. I know that a full shell is in "another league", but this is supposed to be a "sport" machine and not a machine that is impractical. I want to be able to "hop on it" and not "climb into it". (or be "assembled" as part of it like a lot of people seem to do)
[/quote]

Thats where the trike streamliners or velomobiles come into it, more practical in a lot of ways than a bike and you just hop in and go.
Re the bike in the picture, the real human speed record ie. pedaled upto speed on the flat with out a tow/draughting car is over 80 mph, in a streamliner. The upright bike record under the same conditions is a lot, lot lower.

 

[Lowell]

Does calling people here 'dorks' make you feel better about your low powered gear motors?

I know what real speed is and even the high wattage hub motors aren't that impressive. My point is that one should be HUMBLE with their small motors and enjoy the pleasures of getting the most out of them. (that's the fun part... squeezing efficiency out of little motors)

Raw speed is for young people with healthy organs to donate... :wink:

High wattage hub motors are impressive in the realm of electric bicycles, which is what this forum is about.

Multi speed gears are needed for low watt motors to make them do any useful work in the real world. Where I live, the entire city is flat so 'steep grades' here involve an overpass. The majority of my planned e-bike riding will be on long flat roads, so the X5 hub is an ideal solution. Low cost and complexity with 80+ efficiency at cruise and near 90% at top speed.

 

[safe]

With these no-wind, fantasy-case stats you've conjured, why people buy these stupid hubmotors, or want more than 1 horsepower, is beyond me.

Actually, my "real world" bike was calculated to go 46 mph and I've done that, but some question of how perfectly flat the area was would call into question it's validity. Since my current "real world" bike doesn't have a fairing yet I can't expect the full number on it. But that online calculator is pretty accurate. These results are very real !!!

Think of it this way...

I'm trying to design a Honda Civic (the sporty version) with the little engine and gears.

You have designed... "A tractor" that can't go as fast as the power suggests you might, but it's solid as a rock.

Two different design ideas... both show up EXACTLY in the numbers as being correct as designed.

(or as the other guy said: "The Hub Motor is like using a bigger hammer")

 

[safe]

...the real human speed record ie. pedaled upto speed on the flat with out a tow/draughting car is over 80 mph, in a streamliner. The upright bike record under the same conditions is a lot, lot lower.

But since mine doesn't have pedals I can "tuck" in such a tight little ball that my frontal area is rather small, roughly half of what a normal bike would have. So right off the bat my frontal area makes things very, very good. Then if I add a fairing to the front and rear it will be better.

I've got to confess... 20 years ago I already discovered the power of streamlined bikes on the downhill bicycle racing that I used to do. (we used to drive to the top of a 3500 ft peak and race down 10 miles to the bottom) There was one BMX magazine (online) that was doing a story of the "most amazing thing from the past" and my fiberglass road racer bike was featured as their best example. (they had done an article 20 years ago) I spent a year trying to market the bike as a product (I had built fifty of them) but I sold next to none of them. The only sales I got was from people who rode with me and knew about the bike first hand. I worked at a bike shop at the time.

I once did 60 mph on a short downhill (clocked) and I was simply tucked behind the fairing on a bicycle.

So my background LITERALLY goes back 20 years. (you can get the aerodynamics down pretty good with regular fairings and the low narrow handlebar position)

My current bike did 46 mph and I know that on a pure flat surface it can do at least 42 mph.


It was in this issue:

june 1980
Eddy King, the master of style on the cover.
SE QUAD-ANGLE test,
Downhill ROAD RACER
RACING : LONE STAR NATIONALS
Trick riding,
Eddy King pictorial,
How to build a trick ramp

Note: I think the name of the magazine is "FatBMX" now and if you can find the article I'd be thankful. They had it online about six months ago.


http://www.23mag.com/mags/ba/ba80.htm

 

[safe]

Oh my goodness.... my old sport is still alive!

http://www.gravitybike.com

http://www.gravity-sports.com

I seriously didn't even know!

 

[safe]

http://www.researchgravitysport.com/photos/donner_pass_gravity_bike_picture.htm

http://www.a2prosports.com/fermin.html

 

[Lowell]

With these no-wind, fantasy-case stats you've conjured, why people buy these stupid hubmotors, or want more than 1 horsepower, is beyond me.

Actually, my "real world" bike was calculated to go 46 mph and I've done that, but some question of how perfectly flat the area was would call into question it's validity. Since my current "real world" bike doesn't have a fairing yet I can't expect the full number on it. But that online calculator is pretty accurate. These results are very real !!!

Think of it this way...

I'm trying to design a Honda Civic (the sporty version) with the little engine and gears.

You have designed... "A tractor" that can't go as fast as the power suggests you might, but it's solid as a rock.

Two different design ideas... both show up EXACTLY in the numbers as being correct as designed.

(or as the other guy said: "The Hub Motor is like using a bigger hammer")

http://endless-sphere.com/forums/viewtopic.php?t=147

37mph sounds about right for 18-1900w on a real world bike with suspension, lights(!), fender, mirrors and a comfortable riding position. I would hardly call that a tractor, unless you have an e-bike that goes 100+mph.

Not having pedals definitely makes a big difference in aero drag. Our local regulations only state that an e-bike requires pedals that are capable of moving the bike. I wonder how they would feel about someone replacing the crank arms with tiny arms ending in foot pegs and a small single speed chain ring or belt drive that's just enough to make some noticeable motion.

 

[D-Man]

cancel

 

[Mathurin]

Stands to reason, if you're using the same motor (say a 500w hub motor)
in both direct drive and geared applications, the direct drive version will
get better eff then the version with a transmission in at least some conditions.

Eg: 19/20th of the time when I'm using the motor I'm going at top
speed, around the 20mph legal limit. Getting that speed through a
transmission would be lossy compared to getting it in direct drive.


In my case, terrain is flat with long false flats and short steep hills, in an
mostly urban setting. I do pretty much always pedal anytime I'm using the
motor, (my ride is an actual electric bike, not a motorcycle) especially up
steep hills since 25km/h (20amps) feels like standing still after having pushed
along around 35 for 20 minutes. Yet for what it's worth I don't miss gears.
In fact I run my bike as a singlespeed.

 

[safe]

Not having pedals definitely makes a big difference in aero drag. Our local regulations only state that an e-bike requires pedals that are capable of moving the bike. I wonder how they would feel about someone replacing the crank arms with tiny arms ending in foot pegs and a small single speed chain ring or belt drive that's just enough to make some noticeable motion.

The laws here aren't specific about pedals, they are more concerned about power limits. (and even there they are willing to allow 2 hp) The biggest reason that pedals cause a problem is that it means you can't place the battery pack where a "gas tank" would go. You are forced to put it on the back (usually) and that distorts the balance badly enough that you really can't go fast without handling issues.

My bike actually feels smoother the faster I go because it's balance is near perfect. (the weight needs to be a little lower in the back however)

So pedals are a big factor...

 

[safe]

Stands to reason, if you're using the same motor (say a 500w hub motor)
in both direct drive and geared applications, the direct drive version will
get better eff then the version with a transmission in at least some conditions.

Eg: 19/20th of the time when I'm using the motor I'm going at top
speed, around the 20mph legal limit. Getting that speed through a
transmission would be lossy compared to getting it in direct drive.

20 mph speed limit is very low... though I know that's the definition of the national law. Many states allow 30 mph and I'm guessing that with gears you can get away with more if you don't get caught "in the act" itself. My worry is simply sitting on the side of the road and being confronted by the police because my bike is "different" looking. To be able to assure them that I'm running a "legal" motor is usually all it takes to make the guy relax.

Not all people thirst for (high speed) perfomance... if you are happy with 20 mph then a hub motor should fit the bill perfectly...

 

[safe]

Wind Resistance

I'm going to propose an axiom and let's see if everyone agrees:

"A bike with high wind resistance is best suited running a hub motor"

Since the advantages of gearing is that it widens the speeds on which you can go (and offers a wider range of climbing torque) it makes the most sense to be talking about gears in the case of a highly streamlined and small wattage motor bike. With this small motor and gears you can either climb a very steep hill or go really fast with very limited energy required.

The reverse is also true. A bike that has high wind resistance (your classic mountain bike with a "sit up" position) will hit a virtual "wall" of wind resistance at about 30 mph and by 40 mph you need to exceed the legal limits for power to go any faster. For this reason the "tractor" (hopefully that's not being taken as too offensive a term... see below) approach is best accomplished by a hub motor.

This seems to clarify what criteria defines the advantages and disadavantages of each.

It takes 2000 Watts to make a mountain bike go 40 mph.

It takes 625 Watts to make a streamlined bike go 40 mph.

The human powered streamlined world record is 80 mph.

So more power is pointless for the mountain bike because it's primary speed limitation is it's aerodynamics and not it's power.

Note: The idea of a "tractor" is that it is extremely powerful and yet relatively slow moving considering it's potential. This seems to be an accurate description of a mountain bike with a 5304 but I can see how someone might find that "term" offensive. We need "terms" to describe "types" of vehicles. The "road racer" is the "term" I tend to use for the very small, very aerodynamic type of design and it seems to match the reality pretty well. Ideas? Is "tractor" offensive? Maybe we should use more of a "truck", like the "macho truck" idea? They are also proportionally slow, but strong and with big motors. (quick off the line, but don't try to race a Porsche with it)

 

[Lowell]

Not having pedals definitely makes a big difference in aero drag. Our local regulations only state that an e-bike requires pedals that are capable of moving the bike. I wonder how they would feel about someone replacing the crank arms with tiny arms ending in foot pegs and a small single speed chain ring or belt drive that's just enough to make some noticeable motion.

The laws here aren't specific about pedals, they are more concerned about power limits. (and even there they are willing to allow 2 hp) The biggest reason that pedals cause a problem is that it means you can't place the battery pack where a "gas tank" would go. You are forced to put it on the back (usually) and that distorts the balance badly enough that you really can't go fast without handling issues.

My bike actually feels smoother the faster I go because it's balance is near perfect. (the weight needs to be a little lower in the back however)

So pedals are a big factor...

Unless you're running big lead boxes, I don't see why the batteries can't fit in the center of the bike.

http://www.austinev.org/evalbum/465

A claimed 42mph at 36v, 900w. With the exception of the plastic cover, a very nice and clean package with the hub motor.