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Old 12-14-09, 12:36 PM   #1
aseb
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hill climbing

Hi. I have a powabyke, and a few nearby hills that I need to give pedal assistance to get up. Help is needed for the hill climbing due to deteriorating medical condition.
I gather these use 36V 200 Watt brushed motors (UK). Currently it has a 6Ah LiPo battery but I have a 20Ah LifePO4 to fit (36V),
I've seen 500W and 750W kits that would theoretically be two or three times as powerful, as well as 300W and 700W hubs now. I have read that these ratings are not peak ones, so I guess that there may not be twice and three times the power really available for hill climbing.
Anyhow, how improved is hill climbing for the extra power? (I'm not really bothered about top speed). I haven't found anything that gives indication of hill climbing for the different powers- eg hill gradients or relative performance. I realise that many other things will affect performance- weight, motor make/characteristics- but is there an indication of how hill climbing is improved with the extra power.
I want to stick with hub powered motor for ease of upgrading. I can't recall the gradients at the moment but can note them next time I'm out if needed.

Finally, would you expect range to decrease for the higher powered motors?

thanks for your thoughts and advice
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Old 12-14-09, 01:36 PM   #2
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Originally Posted by aseb View Post
Hi. I have a powabyke, and a few nearby hills that I need to give pedal assistance to get up. Help is needed for the hill climbing due to deteriorating medical condition.
I gather these use 36V 200 Watt brushed motors (UK). Currently it has a 6Ah LiPo battery but I have a 20Ah LifePO4 to fit (36V),
I've seen 500W and 750W kits that would theoretically be two or three times as powerful, as well as 300W and 700W hubs now. I have read that these ratings are not peak ones, so I guess that there may not be twice and three times the power really available for hill climbing.
Anyhow, how improved is hill climbing for the extra power? (I'm not really bothered about top speed). I haven't found anything that gives indication of hill climbing for the different powers- eg hill gradients or relative performance. I realise that many other things will affect performance- weight, motor make/characteristics- but is there an indication of how hill climbing is improved with the extra power.
I want to stick with hub powered motor for ease of upgrading. I can't recall the gradients at the moment but can note them next time I'm out if needed.

Finally, would you expect range to decrease for the higher powered motors?

thanks for your thoughts and advice
If you really want torque, you need to look at non-hub motors. There are a some high-torque hub motors, but I don't think you'd be allowed to import one to the EU, given the legal restrictions the EU has placed on the size of hub motors allowed on bicycles.

I retired to the far northern US Rockies (I'm west of Glacier National Park). I found I wasn't riding my bike much due to knee pain when pedaling steep hills. I added the Currie conversion kit which is a 450W, 24V non-hub motor kit. I love it and ride my bike more than I drive. I pedal a lot but love power assist on the hills. I would suggest that you check out the Endless-Sphere e-bike forums. You may get some ideas for motors that will comply with EU regulations that will give you adequate torque for the hills. http://endless-sphere.com/forums/ Good luck.
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Old 12-14-09, 03:30 PM   #3
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Originally Posted by nwmtnbkr View Post
If you really want torque, you need to look at non-hub motors. There are a some high-torque hub motors, but I don't think you'd be allowed to import one to the EU, given the legal restrictions the EU has placed on the size of hub motors allowed on bicycles.

I retired to the far northern US Rockies (I'm west of Glacier National Park). I found I wasn't riding my bike much due to knee pain when pedaling steep hills. I added the Currie conversion kit which is a 450W, 24V non-hub motor kit. I love it and ride my bike more than I drive. I pedal a lot but love power assist on the hills. I would suggest that you check out the Endless-Sphere e-bike forums. You may get some ideas for motors that will comply with EU regulations that will give you adequate torque for the hills. http://endless-sphere.com/forums/ Good luck.

Many thanks for your help. I can see the advantages of the Currie type but would prefer to stay with hub motors- even if it means going over the 200W limit- for hills only. The cycle analyst allows limits to be set so I would look into this.
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Old 12-16-09, 09:22 PM   #4
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Hey aseb - I just recently installed a 500 watt rearhub motor with a 20 amp controller powered by a 36 volt 10ah lifepo4. I have been putting it to the test in these ozark mountains and am amazed at it's power. If you have a 36v 20ah battery already, just get a brushless hub motor,controller and whatever wirng & bracket set-up you'll need and swap it out. I'm not familiar w/powabykes, however "where there's a will there's a way"- goodluck
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Old 12-22-09, 06:52 PM   #5
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I've found out that although the powabyke is rated 200W it is continuous rating, its peak output is actually 700W. Also as it is a brushed motor it gives better torque at lower revs than a brushless one. And the hub has internal gears which keeps the maximum speed to around the legal maximum of 15mph but also helping with the hill climbing. It may be that it is the best choice after all.
Do you know what the peak power is of your 500W motor (and make)?
Does anyone have figures for peak and continuous power for any of the 500W and 750W motors?
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Old 12-22-09, 11:26 PM   #6
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As another poster said you might find more immediate info at endless sphere, specifically on this thread perhaps? http://www.endless-sphere.com/forums...php?f=3&t=4892
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Old 12-29-09, 05:05 PM   #7
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Thanks, I had looked at the thread from nwmtnbkr but I think it will take a couple of reads to assimilate everything. First thoughts are it is hard to compare as there seem to be no standards for the nominal ratings, rarely peak outputs seem to be given, and no torque curve graphs. It seems like get the biggest W claimed, and hope the peak output and torque curve is better is the only option.

Last edited by aseb; 12-29-09 at 05:08 PM.
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Old 12-29-09, 05:54 PM   #8
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Thanks, I had looked at the thread from nwmtnbkr but I think it will take a couple of reads to assimilate everything. First thoughts are it is hard to compare as there seem to be no standards for the nominal ratings, rarely peak outputs seem to be given, and no torque curve graphs. It seems like get the biggest W claimed, and hope the peak output and torque curve is better is the only option.
Since e-bike enthusiasts in North America don't currently have the restrictions on power that are imposed up those of you living in the EU, you might get some better answers from a those in the UK-based pedelecs e-bike forums. http://www.pedelecs.co.uk/forum/ I don't know if customs officials in the various EU member countries pay close attention to personal orders of e-bike kits from abroad or if their main focus is businesses ordering e-bikes and e-bike kits. Many members in the pedelecs forum have down their own bike conversions and can probably answer most of your questions with the added benefit of also knowing the EU restrictions imposed upon e-bikes.
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Old 01-04-10, 09:51 AM   #9
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Since e-bike enthusiasts in North America don't currently have the restrictions on power that are imposed up those of you living in the EU, you might get some better answers from a those in the UK-based pedelecs e-bike forums. http://www.pedelecs.co.uk/forum/ I don't know if customs officials in the various EU member countries pay close attention to personal orders of e-bike kits from abroad or if their main focus is businesses ordering e-bikes and e-bike kits. Many members in the pedelecs forum have down their own bike conversions and can probably answer most of your questions with the added benefit of also knowing the EU restrictions imposed upon e-bikes.
It is a very good and knowledgable forum, I have already asked there. I got some great help, including peak power of my 200W (nominal/continuous rating) motor. At 700W it is quite high, the problem being I cannot get peak figures for the 500W and 750W kits- perhaps the number they are giving is already the peak ouput. Also, the brushed motor on my bike is a geared one which helps when hill climbing, and it is geared to give only the UK maximum speed meaning that it also helps with the torque when hill climbing.
It seems impossible to compare them without buying and riding- it would an expensive lesson if there was no real benefit (but I still feel it would improve things- it just seems almost impossible to find out with any degree of certainty).
(Out of interest I know of people who have imported kits and travel past our legal limit of 15mph. Although it is not allowed there is no real checking of these things, it is unlikely that much would happen unless you brought yourself into sharp focus- a major accident or similar).

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