A pedal chain wheel first of all is geard UP to for at least 3 to 1 being that for each pedal rotation the wheel will go around three times or so.To add a 10 to 1 reduction from the motor to the chainwheel by the time the motor reduction gets to the wheel it will reduced to a 7 to 1 reduction by uselessly having the gearing going back up 3 to 1 before it gets to the wheel using week inefficient twisted bicycle chain for motor powering.
Even a single motor reduction of 10 to 1 streight to the wheel hub with STREIGHT efficient chain and sprockets will be much more efficient with LESS parts even though you may otherwise use a chainring motor set up to think you are getting any more efficiency from driving the motor through the multi speed derailer or hub gears.
Also the smaller power motor you have MORE losses by needing a larger reduction ratio to achieve the required torque needed and have the motor operating close to its best RPM band.
Most any kind of high speed GEAR reducers eat up 10 to 15% of your total out put power, besides making a lot of noise..
A motor rated at the max power you wish to use contionusly that has good torque to be run at lower RPMS with a good efficiency will have a much broader EFFICIENT Motor and Wheel speed range with the least motor and reduction losses.
If you want to pedal hard most of the time for a longer range than 10 miles or you don't mind more batteries on flat land riding to increase the range a little it don't matter if your efficiency sucks.
A easy install hub motor is somewhat hevier to achive close to the same range and overall efficiency as geard motor/chain ring set ups sucking up about the same power.
HalfLifeT1
09-17-07, 01:54 AM
Those are two different applications, i think your comparison is a bit out (apples and oranges). Direct driving the wheel through fixed gearing is one application. Driving the chain ring is another application. Driving the chain ring allows the user to take advantage of the different sproket sets on the bike. A direct drive set up would only allow for a fixed ratio.
Picking a radom "fixed" gear ratio for the chainring out put is out of context to that specific application. Because there would be other ratios to select through the derailleur/chain ring compination.
Just my $.02.
geebee
09-17-07, 03:37 AM
What about a geared hub motor? would not its efficiency at least equal your single speed chain drive.
The7
09-17-07, 07:52 AM
What about a geared hub motor? would not its efficiency at least equal your single speed chain drive.
IMO:
a) The order of efficiency: gearless hub motor > geared hub motor > single-speed chain drive
b) The order of weight: gearless hub motor > geared hub motor > single-speed chain drive
If the weight of the motor is an very important factor, single-speed chain drive could have the highest overall efficiency.
If the weight of the motor is negligible (when compared with the rest of the ebike and rider), gearless hub motor could have the higher overall efficiency.
Otherwise, the geared hub motor could have the highest overall efficency.
The7
09-17-07, 07:52 AM
What about a geared hub motor? would not its efficiency at least equal your single speed chain drive.
IMO:
a) The order of efficiency: gearless hub motor > geared hub motor > single-speed chain drive
b) The order of weight: gearless hub motor > geared hub motor > single-speed chain drive
If the weight of the motor is an very important factor, single-speed chain drive could have the highest overall efficiency.
If the weight of the motor is negligible (when compared with the rest of the ebike and rider), gearless hub motor could have the higher overall efficiency.
Otherwise, the geared hub motor could have the highest overall efficency.
EbikeHawaii
09-17-07, 03:26 PM
What about a geared hub motor? would not its efficiency at least equal your single speed chain drive. I was comparing a Direct mid drive to a chainring drive with a gearmotor such as this opposed to a direct mid motor/ hub drive with NO motor gear reducer."Gear Box achieves 80 to 90% efficiency." this is the efficiency of ONLY the gearbox.
http://tinyurl.com/2twp42
The issue with this
type of gearbox is the efficiency of these motor and gearboxes is around 35-45 %.
http://www.phantomgolf.com.au/power.asp
You can do some internet searching to find the facts on how efficient the best gearboxes are when driven by 3000 to 4000 rpm motors to get a 300 to 400 rpm wheel speed.With low cost High quality chain and composite sprockets your drive efficiencies are much higher and quieter through out a wider band of rpm when using a motor that has a higher torque to begin with that is not available in any hub motor in a 5 lb package for 750 watts of power.
Many may THINK that a multispeed hub may make up the all the multi reduction losses of a high rpm motor system of low power but they are only dreaming.If the bike won't perform well with a single ratio a few more hub gears will not make much difference in the motors efficiencys as much as it will adjust for the pedalers comfort or cadence.
It is possiable to incorperate a lighter 7 lb hub motor in a wheel with tons of torque at 750 watts or more that will handel any condition efficiently with a large efficiency range but at about twice the price of what is available now. Only 1 moving part ! and can be mid mounted for a nice 1 to 1 hub drive with a slow moving chain. The optrion of having a heavy unsuspended hub motor wheel or a high performing mid mount on a full suspension bike would possiable with a single motor that would cover extra rider or battery weights to be efficient through out a much wider band. The down fall is that there is not a market to make such a efficient motor for bicycles yet!
They do make much more efficient motors and drives for E-autos and industrial E-vehicles where the savings on KWs add up fast.
geebee
09-17-07, 08:25 PM
"Many may THINK that a multispeed hub may make up the all the multi reduction losses of a high rpm motor system of low power but they are only dreaming.If the bike won't perform well with a single ratio a few more hub gears will not make much difference in the motors efficiencys as much as it will adjust for the pedalers comfort or cadence."
You are so incorrect and yet you are to blind to see it or test the idea out.
2 days ago I rode a 250w power assisted bike up a contiuous grade well over 20% with barley any input from me, the drive would have stalled if not for the fact it was geared down via the B/B and rear derailluer to allow low power consumption at extreme torque levels, in my book a fully stalled motor is a lot less efficient than a motor happily spinning at high rpms up a steep hill whilst staying cool and using very little power.
EbikeHawaii
09-18-07, 03:00 AM
[QUOTE=geebee;5286827 in my book a fully stalled motor is a lot less efficient than a motor happily spinning at high rpms up a steep hill whilst staying cool and using very little power.[/QUOTE] True. A 750 watt system not needing gears would be even better and at a decent speed.
Doug5150
09-18-07, 04:42 AM
Those are two different applications, i think your comparison is a bit out (apples and oranges). Direct driving the wheel through fixed gearing is one application. Driving the chain ring is another application. Driving the chain ring allows the user to take advantage of the different sproket sets on the bike. A direct drive set up would only allow for a fixed ratio. .....
Driving the chainring is a nice idea, but for two not-so-little problems:
--the first is that the chainring needs some kind of freewheel for the pedals, if you don't want to have to pedal all the time and possibly for safety reasons as well. There's no easy way for a homebuilder to do that.
--The second is that the chainring doesn't turn real fast normally, 60-100 RPM's, which is pretty slow and no small compact engine is going to make a lot of torque at such low RPM's. You'd need a relatively big heavy engine for the idea to work well.
-------
The smallest motors around are the home-built friction drives that people make. Lots of people have seen that they can get decent torque out of a small electric motor IF it is spun very fast (-how long it will hold up doing that is another question entirely...).
The biggest motors around are the hub motors, they have to be big because they need lots of torque, but run at relatively low RPM's.
Now the OP says that the chainring spins at around 1/3 the RPM's of the wheel?.... so that means to spin the chainring directly, you'd want a motor about three times as big as a hub motor. And what's a hub motor weigh?
~
EbikeHawaii
09-18-07, 12:09 PM
Driving the chainring is a nice idea, but for two not-so-little problems:
--the first is that the chainring needs some kind of freewheel for the pedals, if you don't want to have to pedal all the time and possibly for safety reasons as well. There's no easy way for a homebuilder to do that.
--The second is that the chainring doesn't turn real fast normally, 60-100 RPM's, which is pretty slow and no small compact engine is going to make a lot of torque at such low RPM's. You'd need a relatively big heavy engine for the idea to work well.
-------
The smallest motors around are the home-built friction drives that people make. Lots of people have seen that they can get decent torque out of a small electric motor IF it is spun very fast (-how long it will hold up doing that is another question entirely...).
The biggest motors around are the hub motors, they have to be big because they need lots of torque, but run at relatively low RPM's.
Now the OP says that the chainring spins at around 1/3 the RPM's of the wheel?.... so that means to spin the chainring directly, you'd want a motor about three times as big as a hub motor. And what's a hub motor weigh?
~ A 5 lb mid-mount 750 to 1500 watt motor with a 8 to 1 chain ratio run directly to a freewheel on a multi speed gread hub defies your description of a direct drive mid mount.The pedal chain is a paralellel chain to its own freewheel on the multi speed hub working in common with the motor in any gear selected.There are small well built motors out there with the torque and efficiency to do this at a fairly low RPM in a light weight small package.Staton Inc uses this system with a NuVinci hub and I have used this type of system for about 8 years without any failures.
This is the best way to drive a Auto with a suspended hub motor IMO.If bicycles had gear motors with this type of motor and gear reducer chain would still be needed to keep the weight off the wheel in a suspension application.
http://www.motionsystemdesign.com/Issue/Article/25016/Automobiles_that_ride_on_pancake_motors.aspx
http://www.ntn.co.jp/english/news/news_files/new_products/news20051115_1.html
Or if someone did want to drive a multispeed hub with a disc hub motor and didn't mind the 7 lbs of unsuspended weight this type of motor could be slid into a Shimano type of freehub in place of a freewheel. Since there would be 0 cogging a freewheel would not be needed.This hub motor could be removed fron the wheel in a couple minutes.
http://ocw.mit.edu/NR/rdonlyres/Aeronautics-and-Astronautics/16-810January--IAP--2007/6DFA8743-3720-421F-903D-D782FDCE45B1/0/projepeddie.pdf
Doug5150
09-18-07, 04:57 PM
A 5 lb mid-mount 750 to 1500 watt motor with a 8 to 1 chain ratio run directly to a freewheel on a multi speed gread hub defies your description of a direct drive mid mount...
Yea but it adds complexity, and sensible folk would want to reduce that. How's about we get rid of one of them chains!
Use the motor as it works best--to DIRECTLY drive the wheel (if you don't want multi-gear motor power) or DIRECTLY drive the chainring (if you do want multi-gear motor power).
Probably the biggest advantage that the hub motor electric kits have is that they just replace the front wheel--they don't need a bunch of extra mechanical junk to work.
~
EbikeHawaii
09-19-07, 05:44 PM
Yea but it adds complexity, and sensible folk would want to reduce that. How's about we get rid of one of them chains!
Use the motor as it works best--to DIRECTLY drive the wheel (if you don't want multi-gear motor power) or DIRECTLY drive the chainring (if you do want multi-gear motor power).
Probably the biggest advantage that the hub motor electric kits have is that they just replace the front wheel--they don't need a bunch of extra mechanical junk to work.
~ This is why I use a 5 lb motor with one moving part plus 1 chain for up to 1600 watts of efficient power in a lightweight package without the need of gears.. or a 20 lb unefficient hub motor.Less complex than a Currie USPD and does not break spokes like heavy, ratteling, lopsided hub motors do.There is also not a need to lace a wheel to install a single ratio hub motor that may not work right for your use.
Lowell_
09-20-07, 01:49 AM
"How to win friends and alienate everybody" by Randy Draper.
Where's that nutswinger Krushnoi anyways?
EbikeHawaii
09-20-07, 04:46 AM
"How to win friends and alienate everybody" by Randy Draper.
Where's that nutswinger Krushnoi anyways? How to keep off topic and get personal by low well.
Lowell_
09-20-07, 10:31 AM
This is why I use a 5 lb motor with one moving part plus 1 chain for up to 1600 watts of efficient power in a lightweight package without the need of gears.. or a 20 lb unefficient hub motor.Less complex than a Currie USPD and does not break spokes like heavy, ratteling, lopsided hub motors do.There is also not a need to lace a wheel to install a single ratio hub motor that may not work right for your use.
Hub motors seem to work well enough for you to back down from your $10,000 hillclimb challenge, or have you forgotten about that already?
EbikeHawaii
09-20-07, 01:16 PM
Hub motors seem to work well enough for you to back down from your $10,000 hillclimb challenge, or have you forgotten about that already?
I had already won the challange several times. YOU will not ever make 10 miles up this Volcano on your heavy hub motor moped.. If you think you can then DO ITor shut up!
Lowell_
09-20-07, 01:36 PM
I had already won the challange several times. YOU will not ever make 10 miles up this Volcano on your heavy hub motor moped.. If you think you can then DO ITor shut up!
How much money are you willing to bet? Probably as much as your threads are worth, ZERO.
EbikeHawaii
09-20-07, 02:46 PM
How much money are you willing to bet? Probably as much as your threads are worth, ZERO. Why do you need to bet.If you think you can just DO It but please don't start any forest fires.
Lowell_
09-20-07, 04:08 PM
Why do you need to bet.If you think you can just DO It but please don't start any forest fires.
Have you forgotten that you're the one that issued the $10,000 challenge in the first place? I'm not about to spend $$$ to ship my bike over to Hawaii without a potential payout. When you grow a sack and are ready to race, let me know.
EbikeHawaii
09-20-07, 11:10 PM
Have you forgotten that you're the one that issued the $10,000 challenge in the first place? I'm not about to spend $$$ to ship my bike over to Hawaii without a potential payout. When you grow a sack and are ready to race, let me know.
You go ahead and get arrested in the National Park driving your flame thrower by Yourself!
krushnoi
09-20-07, 11:36 PM
"How to win friends and alienate everybody" by Randy Draper.
Where's that nutswinger Krushnoi anyways?
LOLwell you're still in one piece after all this time? I thought the monstrosity Widowmaker e-bike of yours would've bitten you by now, or maybe the clueless Canadian patrolmen would have finally got smart and confiscated it and fined you for stupidity.
Lowell_
09-21-07, 04:02 AM
Glad to see you're back krushnoi, for a while I thought you ran scared after your stupid fest in the 'plate/register/insure' ebike thread. I see you're still putting down Canadians... got an axe to grind with us?
Just in case you forgot, here's the original text.
-------------------------------------------------------------------------------------------------
Originally Posted by krushnoi For a canadian troll you talk tough. Another internet tough guy. I'm so impressed. Go ride your Darwin-award winning cycle, trollboy.
What does Canadian or American have to do with anything?
The fact is that you posted a stupid comment without knowing what you're talking about, and I called you out on it. It's ok though, next time all you have to do is click the link before you spout off.
http://www.e-ride.ca/Electric_Scooters/index.html
Just in case you missed it the first two times.
Glad to see you're back krushnoi, for a while I thought you ran scared after your stupid fest in the 'plate/register/insure' ebike thread. I see you're still putting down Canadians... got an axe to grind with us?
Just in case you forgot, here's the original text.
-------------------------------------------------------------------------------------------------
Originally Posted by krushnoi For a canadian troll you talk tough. Another internet tough guy. I'm so impressed. Go ride your Darwin-award winning cycle, trollboy.
What does Canadian or American have to do with anything?
The fact is that you posted a stupid comment without knowing what you're talking about, and I called you out on it. It's ok though, next time all you have to do is click the link before you spout off.
http://www.e-ride.ca/Electric_Scooters/index.html
Just in case you missed it the first two times.
-------------------------------------------------------------------------------------------------
Lo Well go start your own thread to trash if you can't talk about the thread subject.
Lowell_
09-21-07, 10:10 PM
Lo Well go start your own thread to trash if you can't talk about the thread subject.
How much power do you lose through the SRAM dual drive in 1st and 3rd gears?
EbikeHawaii
09-22-07, 06:01 PM
How much power do you lose through the SRAM dual drive in 1st and 3rd gears?I can truthfully say that I do not notice any efficiency loss in first and third gear as opposed to second gear (locked out 1 to 1 100% efficiency minus chain losses.) but I know there has to be a couple % in losses depending on load and rpm even though the sram hub gears turn slow up to about 400 RPM most of the time.
If you consider reduction of chain losses by using high 219 or 8 mm quality timming chain with high performance Kevlar or composite sprockets you have whiped out all hub losses compared to using any other chain and sprockets.Besides quieting down the sprockets and chain 90%. Running with a high torque low rpm motor better than 90% efficient through all rpm ranges also helps in friction and noise reduction..