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Old 05-03-13, 06:26 PM   #1
perrycas
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rear or front wheel?

Logically the rear wheel would look better as taking the front wheel off all the time for putting in the car etc might be a nuisance?
DOes the rear wheel installation suggest any added difficulties/ reliability issues other than removing replacing the freewheel gear cluster?
Thanks
Perry
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Old 05-04-13, 05:54 AM   #2
h20
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if your worried about removing a wheel the front would be easier then the rear.... that's just my opinion though
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Old 05-04-13, 02:47 PM   #3
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Nope, just the issue with changing the cassette. Most people go rear, unless you have a small 250W motor, then you can do either. Why, what do you have in mind?
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Old 05-04-13, 08:02 PM   #4
perrycas
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Yes i agree it would be easier on the back.
Ah, Chas i am still pursuing the idea of a kit from here http://www.keyde.com. I rode one here in Sydney and it seemed to fit my criteria. Though i confess i am so ignorant of most things that this idea might be a bit superfluous. If not presumptuous. I think i am looking at a 36 volt motor with a rated output of 250W and a max of 500W. Whatever that means. But i might go with a smaller motor. I have been asking around and still havent gotten a reasonable definition of what the term 'revolution' means. I am sorry to labour this and i do appreciate your giving me an idea of what might best suit me (200), but still would like to know what it actually refers to.
Another Q i have relates to matching battery to motor. If its a 36V motor does it matter if its a 33v battery? MY choices here from this supplier range -6.8, 9.3, 11.2 ah
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Old 05-04-13, 08:19 PM   #5
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Buy the most you can afford, $... 500w compared to 250w in real life, can be more than 2X as good. JMO same with 36v or 48v, hard to see the difference on paper but... real life operational difference can be huge.... again JMO
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Old 05-06-13, 10:56 AM   #6
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My other post has typical range/speed/battery for various strength motors.

36V at 200rpm has a no load speed of about 18mph, and a loaded speed of 15mph (which means you can help it by peddling up to 18mph, after that the motor is no help.

48V is 30% faster on the same motor (which is why 48V motors are often "lower speed windings" than the 36v motor, to give a similar speed.

The amps is what gives you your power, torque.

Learn about battery C rating. I have seen a lot of batteries at 1C, 1C means its max sustained current = amp hour rating. So a 10Ah, 1C battery can put out 10 amps, while a 10Ah, 2c battery can put out 20 amps (etc.)

A small motor might need 15 amps, while a larger (500, 1000w) motor might need 22 or 30 amps. If you get a small 8-10 amp bottle battery that only has 1c, it will not be able to even give the 14amps that a small 250 watt motor needs. C rate is pretty important when choosing batteries. You want a battery that can put out a lot more amps than your controller will ask of it.
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Old 05-06-13, 11:00 AM   #7
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240 watt = 24V x 10 amps.

A really small 250 watt motor at 36 volts has often has a maximum power output of 36V x 14amps = 504 watt (even though it is a 250 watt motor).

To give you an idea, 250 watt is the power a somewhat in shape person can put out. So, adding a 250 watt motor is kinda like having a second person help you pedal, rather similar to riding a tandem with a strong rider, or rather like drafting something or riding down wind. You still have to pedal, but the motor is a big help.

A 500W or higher motor is going to be a lot stronger than you or any bicyclist you have ever met.
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Old 05-09-13, 07:50 AM   #8
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My understanding is that you get less power from a front hub motor because the spacing is narrower so the motor has to be narrower. You also require torque arms because the front fork is not designed for the wheel providing power. Similarly, the front fork should be steel rather than aluminum, and I have no idea about a shock.

But I've broken two rear axles with a hub motor - I don't know why. Weight distribution or just bad luck. I figure I'd have better luck with a front hub. I don't want a monster motor, just something to ease the commute. I did read somewhere on the forum that the front really really isn't meant to provide power and that it is not held on as well as the rear wheel. You really really don't want the front wheel detaching unless you're shooting a comedy video. But I haven't heard of that happening!
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Old 05-09-13, 09:39 AM   #9
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If a EV car can have motors in each of the four wheels, why is it that we do not see electric bicycles have motors in both wheels - sort of like an all wheel drive vehicle.
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Old 05-09-13, 02:46 PM   #10
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I think on a small hub motor it makes more sense to go front. You can keep the existing drive train which is likely a cassette, giving you higher gearing with an 11 tooth cog, or a higher geared internal hub. 11 Tooth freewheels from DNP are low quality. You also get better balance with the battery on the back and its somewhat easier to convert - sometimes you need to alter the dishing on the wheel - and rear hub spacing is variable typically anywhere from 120mm with an internal hub, or 130-135mm, which means you have to play with various spacer washers, or file down the motor axle shoulder to place the motor in there properly. Its just easier all around. Do sacrifice a bit of traction though for loose uphill surfaces.

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Old 05-10-13, 01:54 AM   #11
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Quote:
Originally Posted by TiBikeGuy View Post
If a EV car can have motors in each of the four wheels, why is it that we do not see electric bicycles have motors in both wheels - sort of like an all wheel drive vehicle.
I'm sure it's because of cost. And besides, when is one motor not enough? I have seen a picure or two of dual drive motors, but I think there's good reason there isn't much of it.

I'm going to be going front hub (a 48V eZee system) - although having an IGH pretty much mandates a front hub conversion, I like the weight distribution and simplicity aspects as well. Plus, I'll have all-wheel drive - just that one wheel will be manual drive.
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Old 06-30-13, 02:25 AM   #12
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Front only motor IS all wheel drive when you pedal as well ; )
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Old 07-01-13, 04:34 AM   #13
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yes the idea of internal gears on the rear is rather nice. I saw an interesting contender for a conversion the other day, a bike i had never seen or heard of called a 'centurion' rear internal, and permanent lights fitted to the bottoms of the forks - driven by a couple of magnets on each wheel. Great idea. the guy who had it said he had picked it up on throw out day somewhere in the E subs here in sydney. Needed a service. 'mazing.
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Old 07-01-13, 06:45 AM   #14
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I also read somewhere that having a direct drive hub motor on the front (as opposed to a geared hub motor) can be very dangerous if it seizes. I'm planning on building a front drive bike but will probably avoid the direct drive motor just in case of that rare event. A bit more noise perhaps but I don't want that front wheel stopping dead.
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