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Old 09-18-09, 07:17 PM   #1
Colin1234
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Ah?

IM a total newbie but ive bene trying to come up with a strategy to moterize an old schwin i have. it will be solely electric drive fixed gear with a 48 volt 1000 watt motor. i would like to be able to reach speeds of 35 miles an hour (please tell me if this is unrealistic). im thinking for bateries i will either go with the ping 48volt 10ah 15ah or 20ah can anyone here give any sort of estimate of what those three batteries range would be.
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Old 09-18-09, 07:23 PM   #2
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Ps. anyone recomend a good controller?
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Old 09-18-09, 08:23 PM   #3
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Colin,

I think you may find more e-bike builders who can help you out in this forum. http://endless-sphere.com/forums/viewforum.php?f=3

I don't know where you're located. If you're in the EU, the legal power of e-bike motors and speed is significantly limited. It's not quite so limited within North America, but going over 20 MPH may raise issues. If you're in the states, you need to determine whether your state of residence will require you to license and insure the bike as a moped. Good luck.
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Old 09-19-09, 05:55 AM   #4
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I think it is unrealistic in terms of safety and wear and tear on the bike. If you want something that fast, you need to move up to scooter.
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Old 09-19-09, 09:22 AM   #5
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35 is realistic, but unsafe sounding for your bike. I don't think I'd like to go over 30 unassisted on my current bike (I do pedal up to mid-40's going down smooth familiar hills). 22 unassisted is entirely fine with me.
With a very solid frame you could get yourself up to 45-50+ if that's what you want. Here's some info for you to look into, but I DO NOT recommend it. Get as big a controller as you can. 72 v, and like 35+amp (or bigger, if you want...). Get two Ping 36v 20ah and hook them up to give 72v. Get a 1000w BMC rear hub motor. Wear all sorts of padding and hard helmet. Be sure to leave all your bike parts to charity in your will.
Do some more research over at endless-sphere. I know some of them really like to push some theoretical limits just for the sake of seeing what controllers etc can handle.
Oh, and make sure your brakes can handle it, too.

ps- don't do it on a road, because when you crash and burn it gives the rest of us a bad image.
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Old 11-18-09, 12:28 AM   #6
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Quote:
Originally Posted by Colin1234 View Post
IM a total newbie but ive bene trying to come up with a strategy to moterize an old schwin i have. it will be solely electric drive fixed gear with a 48 volt 1000 watt motor. i would like to be able to reach speeds of 35 miles an hour (please tell me if this is unrealistic). im thinking for bateries i will either go with the ping 48volt 10ah 15ah or 20ah can anyone here give any sort of estimate of what those three batteries range would be.
It can be done using the right hub motor, controller and battery combination. However what it appears that you haven't figured into play is aerodynamic drag. Your bike would take over 1000w to do that speed with no wind. 489W will let me do 30mph in my trike (velomobile). I could have done better efficiency wise had I'd removed the flag, mirrors and headlights but my speed would not have improved as I was at the limit for that hub motor, battery voltage and controller combination. I was running a Crystalyte 406 at 48V with a 20Ah controller Since you asked, I do think your being unrealistic.

The two photos were taken at the 2008 e-Power Challenge in Portland, Oregon. My race was for 24 miles and I averaged 30mph and less than 15Wh per mile for a total usage of 360W. I had four 12V 18Ah SLA batteries. I removed the rear wheel hub motor for the 2009 e-Power Challenge and mounted a slower hub motor (C'lyte 408) as a bottom bracket drive. The 48V SLA pack was replaced with a 36V Headway LiFe and still I was able to do 30mph thanks to the efficiency of running a motor through the gears. Next year I'm not planing to race the velomobile as it can't carry the speed through the corner of the race track. I'm currently building a tilting trike for the e-Power Challenge.

http://www.ohpv.org/HPC/ePowerEvents.html

Bill

Take a look at these two sites and play around with the numbers.

http://www.ebikes.ca/simulator/
http://web.archive.org/web/200808221...ish/espeed.htm



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Old 11-18-09, 11:04 AM   #7
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The key to remember is that the bottom bracket it not designed to take a torquing force, it is designed rather to withstand a pulling force from the chain. Therefore, you have to be very careful when builing high powered electric bicycles, as you can easily break the bottom bracket, and if this hapens in heavy traffic the consequences would be dire.

I agree where if you want to go 35, look into modifying a moped or scooter which are already designed to safely travel at those speed under motorized power.
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Old 11-18-09, 11:07 AM   #8
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Also, here's another great site the figures in total weight, rolling resistance, incline, and wind resistance to calculate how fast you can go for a given energy input: http://www.noping.net/english/
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Old 11-18-09, 12:36 PM   #9
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Also, here's another great site the figures in total weight, rolling resistance, incline, and wind resistance to calculate how fast you can go for a given energy input: http://www.noping.net/english/
Same calculator as I listed above. Since kreuzotter.de went off line the only way I've known to access it is through the internet archives. Thanks for the link
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Old 11-18-09, 02:23 PM   #10
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I have a 2.5 Version ping 48volt 15ah for a 600 watt motor, 50 amp controller- it averages 5ah = 15miles ( I feel comfortable doin 30 miles on a charge). Speed ~15 mph average, 28mph top speed. Los Angeles, CA area.
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