Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Electric Bikes Here's a place to discuss ebikes, from home grown to high-tech.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 07-06-07, 07:37 AM   #1
Brian Ratliff
Senior Member
Thread Starter
 
Brian Ratliff's Avatar
 
Join Date: May 2002
Location: Near Portland, OR
Bikes: Three road bikes. Two track bikes.
Posts: 10,060
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
low power system

I don't currently have an ebike system, but I'm toying with the idea of designing a hybrid bicycle and playing around with it. Is there a system on the market with a 100W motor and weighs ~5 lbs including batteries? I figure 100W is roughly half of the power I am putting into the pedals at 20mph. The battery would be sized like a hybrid car battery, IOW, it'd provide a boost on acceleration and hills, and drag slightly on the flats and especially downhills to charge the battery, so the battery pack would be significantly smaller than the normal (from what I can see) ebike system.

The way I figure, it'd be plugable, but it could also work as a closed system that never requires charging, like a hybrid car. Is there a system like that on the market or in someone's garage?
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Brian Ratliff is offline   Reply With Quote
Old 07-06-07, 01:58 PM   #2
krushnoi
Member
 
Join Date: Jun 2007
Location: USA
Bikes: Trek MTB + 2 e bikes
Posts: 34
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
100 watts would be useless to even try, the weight penalty and drag alone would offset any power gain. 250 watt motor is probably absolute minimum to try if you don't weigh too much. with e bikes it comes down to how much is too little and how much is too much.
krushnoi is offline   Reply With Quote
Old 07-06-07, 03:50 PM   #3
Lock
Senior Member
 
Lock's Avatar
 
Join Date: Aug 2005
Bikes:
Posts: 50
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Actually, 100 watts is the maximum rating permitted to import electric vehicles into Canada as *toys*, last I heard.

tks

Lock
Alive, and Kickin' w/350w in the T-Dot
Lock is offline   Reply With Quote
Old 07-06-07, 05:13 PM   #4
Zeuser
e-Biker
 
Join Date: Aug 2006
Location: Mississauga, Ontario, Canada
Bikes: Gary Fisher, Strong GT-S eBike
Posts: 951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Check this youtube video about a really light electrical system on a bike: CLICK HERE

If you're creative enough you can probably take the next step and make it useable in real world situations.
Zeuser is offline   Reply With Quote
Old 07-07-07, 01:21 AM   #5
meb
Senior Member
 
meb's Avatar
 
Join Date: Aug 2003
Location: arlington, VA
Bikes:
Posts: 1,745
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Brian Ratliff
I don't currently have an ebike system, but I'm toying with the idea of designing a hybrid bicycle and playing around with it. Is there a system on the market with a 100W motor and weighs ~5 lbs including batteries? I figure 100W is roughly half of the power I am putting into the pedals at 20mph. The battery would be sized like a hybrid car battery, IOW, it'd provide a boost on acceleration and hills, and drag slightly on the flats and especially downhills to charge the battery, so the battery pack would be significantly smaller than the normal (from what I can see) ebike system.

The way I figure, it'd be plugable, but it could also work as a closed system that never requires charging, like a hybrid car. Is there a system like that on the market or in someone's garage?
SPARC by SRAM and the discontinued Sinclair Zeta III are probably the closest systems to what you describe.

Here is a pic of the 172 W Zeta III which was still available about a year ago at this site:
http://www.zapworld.com/ZAPWorld.aspx?id=2242 a pic is still visible although they seem to have cleared them. They pop up on ebay occaisionally. About 9 mph, 10 lbs, you also have a headlight out of the package. It uses a friction belt drive which is vastly superior to the roller friction drives.

SRAM SPARC has 2 100W motors embedded within a S5 internal gear hub, system with batteries adds about 10 lbs. also. Pricey, close to $1000 dollars. Like the Zap DX, runs the current through the motors in series for low speed and in parrallel for high speed.

You could probably get a 100 W scooter and make that conversion for a lighter system.

If you are doing 20 mph, you are probably putting out much more than 100 W though.
meb is offline   Reply With Quote
Old 07-07-07, 02:28 AM   #6
cerewa
put our Heads Together
 
cerewa's Avatar
 
Join Date: Jun 2003
Location: southeast pennsylvania
Bikes: a mountain bike with a cargo box on the back and aero bars on the front. an old well-worn dahon folding bike
Posts: 3,155
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I think in terms of the efficiencies and the physics of it all, you're overestimating what you can get out of a "charge the battery on the flats" system. The thing about cars like the Toyota Prius is that if you compare them to a motorless bicycle, the gasoline motor alone makes the car ridiculously overpowered. (in my experience a steep uphill that slows a strong cyclist to 10mph will allow a hybrid car to go about 35mph on gas power alone.)

With that kind of power, a hybrid car can accept that the gas motor has to put out triple the effort to get forward motion by way of storing and discharging energy* than just putting power directly to the wheels. With a bicycle, that kind of loss is probably a deal-breaker-- make it a plug-in hybrid bike.

*using the batteries and electric motor

One poster mentioned outrunner motors, which if you're good at do-it-yourself stuff sound like a good option for a low-power system. They're definitely available around the 100watt size and they're sold for use with model airplanes. The ~100watt ones weigh about 1.5 ounces.
cerewa is offline   Reply With Quote
Old 07-07-07, 03:20 AM   #7
meb
Senior Member
 
meb's Avatar
 
Join Date: Aug 2003
Location: arlington, VA
Bikes:
Posts: 1,745
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by meb
SPARC by SRAM and the discontinued Sinclair Zeta III are probably the closest systems to what you describe.

Here is a pic of the 172 W Zeta III which was still available about a year ago at this site:
http://www.zapworld.com/ZAPWorld.aspx?id=2242 a pic is still visible although they seem to have cleared them. They pop up on ebay occaisionally. About 9 mph, 10 lbs, you also have a headlight out of the package. It uses a friction belt drive which is vastly superior to the roller friction drives.

SRAM SPARC has 2 100W motors embedded within a S5 internal gear hub, system with batteries adds about 10 lbs. also. Pricey, close to $1000 dollars. Like the Zap DX, runs the current through the motors in series for low speed and in parrallel for high speed.

You could probably get a 100 W scooter and make that conversion for a lighter system.

If you are doing 20 mph, you are probably putting out much more than 100 W though.
With the recharging aspect you desire, the developed Bionx system might be the best way even though it is heavier.

Alternatively, an even heavier Zap DX system still has the regenerative braking (it is no longer marketted but is still present on the newer models as an undocumented feature-it was of limitted benefit so they simply stopped marketting the feature as they did before 2003). Zap might be under 15 lbs with small 2 AH NiMH in place of the SLA battery pack.
meb is offline   Reply With Quote
Old 07-09-07, 12:28 PM   #8
johnbear
Junior Member
 
Join Date: Jun 2007
Bikes:
Posts: 13
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
http://www.schwinnbike.com/products/...ail.php?id=892
johnbear is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 06:26 PM.