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electric

  • Author: Dan (---.ks.ks.cox.net)
  • Verified User: dan614
  • Date Posted: 10-15-08 17:01

I recently bolted a 48v 1000 watt motor to my Red Line bike but it still doesn’t have enough power to go up hills, can any body out there help me out with this?
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Re: electric

  • Author: mopedjay (---.proxy.aol.com)
  • jasont
  • Date Posted: 10-15-08 18:39

1000 watts should get you up any hill with no problem

what do you have for gearing
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Re: electric

  • Author: Dan (---.ks.ks.cox.net)
  • Verified User: dan614
  • Date Posted: 10-16-08 12:46

14 tooth sprocket on the motor going to a 30 tooth on the back wheel (20 inches)
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Re: electric

  • Author: black twingle (---.gac.com)
  • jconstantinos
  • Date Posted: 10-16-08 13:13

That gearing is way too low. Here is why:

A “26 inch” bicycle wheel is actually 559mm diameter wheel. This is about 22 inches; if you’re using standard tires, the total diameter will be about 25 inches.

Each time that wheel spins once, you travel a distance equal to its circumference – that’s 78.5 inches, 6.5 feet, or one 807th of a mile. Each time your wheel spins 807 times, you’ve gone a mile.

You want to go up hills at what, 15 miles per hour? To go fifteen miles in one hour your wheel would spin 12,100 times; during each minute of that hour your wheel would spin approximately 200 times.

So, that’s your goal with this math – 200rpm. A good motor for electric bicycle applications spins between 2 and 3 thousand times per minute – a bad one spins even faster.

Let’s assume you have the awesomest of all awesome ebike motors, and it operates at 2000 rpm (which is very optomistic). You would need 1:10 gearing to get your 15 mph, and you’ve currently got a little bit better than 1:2. With this ideal motor, you’re geared to go 75 miles per hour.

So, gear WAY down. They do not make bicycle sprockets in the size that you will need – consider using a washing machine belt, or running the motor through two gear reductions using a jackshaft.

If you are still having problems, you will then need to look at your batteries (the real motor that is pushing your ebike), and your motor controller.

The way you are running your electric motor right now is very likely damaging it.
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Re: electric

  • Author: Taylor (---.columbus.res.rr.com)
  • Verified User: sinister78
  • Date Posted: 10-16-08 13:55

way to drop some knowledge twingle. dope.
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Re: electric

  • Author: black twingle (---.gac.com)
  • jconstantinos
  • Date Posted: 10-17-08 11:26

Ah crap, I scared him off.

Dan, come back, I didn’t mean to jump on you.

My last ebike project eventually failed because the struts I cantilevered out over the rear wheel of the project bike couldn’t support the gear-reduction jackshaft without twisting under load. That’s what I get for half-assing it – for my next project I’m using much heavier tubing, and I’m better at welding now.

I was working with a Schwinn “Impact” mountain bike (one of the most inappropriately named vehicles ever, but free). You jumped straight to hopping up your Redline – brave man.

How did you attach the sprocket to your electric motor? Welded, or bolted? Where did you place the motor to avoid kicking while pedaling? Do you have pictures of the drive system? The whole bike?

It was ebikes that got me into mopeds – I was building one, and my girlfriend half-mocked me for “building a moped.” “Hmm..” I thought, “what is this ‘moped’ you speak of, and why is it so awesome?”
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Re: electric

Was doing research on this gear reduction thing that you speak of…I don’t know if you can see in this picture how I got the sprocket on the motor but what I did was to take the original sprocket that came with the motor off. Weld that to a large flat washer and then weld a 14t sprocket to the washer. I added a few filler welds for extra strength. Because I used the original sprocket all I had to do was bolt the whole assembly to the motor. Since we’re talking welding, angle grinders work good for cleaning up the welds and to expose any gaps in the bead.

As far as motor placement, it is sitting right in front of the back tire, I’m 5’8” and have plenty of clearance while peddling.
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Re: electric

  • Author: Dan (---.ks.ks.cox.net)
  • Verified User: dan614
  • Date Posted: 10-17-08 13:55

Check out electricycle.com, I think I might try something similar.
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Re: electric

  • Author: black twingle (---.gac.com)
  • jconstantinos
  • Date Posted: 10-17-08 15:01

Oh my freaking god it’s not just a Redline, it’s a RAIN CITY!

Belt pedal drive? Also, you have, what, some kind of super-wide hub that let you fit an extra sprocket on the left in addition to a disc brake? Do you have an above, or behind picture?

This is an awesome project. You won’t have any pedal clearance issues because the pedals are like three feet away from the wheel – you couldn’t have picked a better bike to start mounting motors and batteries to.

So, a couple of things:

+ I’m totally copying your motor sprocket design. I used the stock motor sprocket to drive a fine-toothed gear from an electric scooter – I don’t have a pin driver for whatever tiny chain those things use, and it was a complete PITA to work with.

+ Eric Peltzer – the guy in the link you sent – is amazing. At this point his bike is basically a fifty-pound electric dirtbike – he had to go through a number of revisions until he got it right, though. I recall that he complained how his first two-chain, four sprocket gear-reducer was so loud that he might as well have used an internal combustion engine.

+ This post is too long.

+ Here is a page from a motorized bicycle kit site that has some pictures of the giant sprockets that these kits use. I got a spare one of these off of ebay, and the seller actually pre-drilled it to bolt up to six-hole bicycle disc brake mounts.

Even the giant 60+ tooth sprockets they use won’t gear you quite low enough, but it gets you that much closer.
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Re: electric

The largest brake rotor that will fit is a 203mm. I sandwhiched the sprocket with the offset (1/4”) to the inside. The stock brake caliper is riding about 3/4 of an inch above the sprocket, so I can’t go much bigger than 30 tooth without cutting the mounting bracket for the brake off. I DON’T WANT TO DO, I started to but changed my mind when I came up with this solution.
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Re: electric

a view from the back
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