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Looking at converting a MTB to E-bike...need suggestions.

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Looking at converting a MTB to E-bike...need suggestions.

Old 08-08-12, 11:56 PM
  #1  
BrooceLee
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Looking at converting a MTB to E-bike...need suggestions.

Hello,

This is my first post on these forums, but I have spent the better part of the last 5 days perusing the forums here and would like some input on recommendations for my situation.

I bought a 2010 Diamondback Response XE from Dick's Sporting Goods in December of 2010 and love it. It's got front and rear disk brakes, 21 speed, trigger shifters, front lockable suspension (which I leave locked most of the time) and hardtail rear, and I put Kenda Kross Plus tires on it so it's nice and smooth on the road but if I take it off road, I still have some traction.

I usually only ride about 20 miles and almost always on road or bike path. My favorite route takes me 18 miles round trip, with three large hills that usually takes me down into a relatively low gear. I average about 12 miles/hour over the course of the trip.

I would like to convert my bike to an e-bike and have been looking at direct drive hub motors mainly for the torque and top speed advantage. I would like the ability to cruise at 20-25 miles/hour and the ability to climb without pedaling. I ride for the joy of riding, not necessarily for the aerobic benefit. I want something quiet as I'm usually riding with a group so that's why I've been looking at hub motors. I would like to put on a rear rack and a set of waterproof panniers to cover the motor and hide my battery and other gear.

When not using the electric power, does a direct drive motor really have a resistance that you can feel? And if you put a freewheel on it, does the resistance transfer to the pedals? I would like to be able to ride without having extra drag from the motor.

I should say, I weigh about 165 lbs, but I have 4 kids under age 6 and have a trailer bike that attaches to my seat post (the one wheel kind with a seat, pedals and handlebars for an older kid to sit on and ride.) and sometimes, if I'm feeling in shape enough, I attach a bike trailer to the trailer bike and haul two more kids in that. My wife rides and hauls the fourth kid in his own trailer usually with our other gear for picnics or whatever. When I have the whole train connected, it adds probably 170 lbs. With my bike weighing close to 50 lbs as it is, that's a grand total of 385 lbs that I pedal on my own. Even minor hills are hard to conquer with that much weight. This is another reason for wanting the e-bike conversion and needing to keep my gear in the side panniers rather than on top of the rear rack as the trailer bike has to attach to the seat post.

Money is not so much a problem, it will just require more time if the price is too high for what I can afford right now.

From what I've been reading, I'm thinking a 48 volt rear hub motor and 48 volt 15ah lifepo4 battery should do the trick. My question to all you experts out there is, what do YOU suggest for motor size and type and battery size and type? And where should I go to get good quality parts? I don't mind paying more for quality parts but I've experienced my share of bad product for a cheap price. I don't want to go that route. I don't have any experience with any of the vendors and so I'm coming to you for advice and any advice is much appreciated.

Thank you in advance for your responses.

~Matt
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Old 08-09-12, 08:46 AM
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Hello, Matt. Welcome to Bikeforums.net.

You may want to try using two Bikebins (https://www.bikebins.com/), one on either side of a bicycle rack with holes cut out on the vertical side closest to the pedals to allow the battery wires to go through. The Ping 48v 15Ah battery will fit vertically. You can have one battery on each side in each pannier. I would also drill a few small holes on the bottom of the Bikebins to allow any liquid to escape should it ever get in. Use a 1 inch grommet to neatly dress the holes on each side for the wires. The controller you can attach to the bicycle rack's two extension arms which hold the rack to the bike horizontally. This will allow you to use the seat post to attach your trailers.

All the components are listed and links placed on the Papamotor 48v 1000w thread: https://www.bikeforums.net/showthread...onversion-kits

You could use two hub motors, one on each wheel for added torque, if your front fork can handle a hub motor but you'd decrease your range.

Please keep us posted on your progress.
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Old 08-09-12, 09:58 AM
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Yes, a direct drive hub motor will have a bit a resistance when you are pedaling without any power. It's like your tire is a bit flat.

I didn't like that idea so I went with a geared hub motor (an eZee kit from ebikes.ca). Geared motors are smaller, lighter, and less noticeable. But they are a little noisier and don't do regenerative braking.

Since I enjoy pedaling my eZee geared hub works great for me. I can pedal under my own power the majority of the time and only use the motor when I hit an annoying hill. Then instead of huffing and puffing up a hill in my lowest gear at 5 MPH I can zip up it at 15 - 20 MPH. On the flats my 48V 20A system will do mid 20's, but as I said I usually pedal that myself rather slower.

You'll always have to trade off top speed against hill climbing power and range. This is a real problem on low powered 250 - 500 watt systems. A 48 volt system with a basic 20 Amp controller (like mine) will give you about 1000 watts of power. That's enough power to easily exceed 20 MPH and get you up decent hills. But it's not so much you have to worry much about overheating your motor.
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Old 08-09-12, 02:54 PM
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Do the math and add in your time, buying an E bike may come out less than your conversion project.
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Old 08-10-12, 01:46 AM
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fietsbob, I appreciate your concern about budget but I enjoy building things and this will be more of a hobby than an investment. I would prefer to build it so I know more about how it works.

LandKurt, Couldn't I just install a pedal assist sensor that would always apply a little bit of voltage to the motor while I am pedaling? The only time it would be an issue is if the battery ran completely dead for some reason. This would not happen of course as I will be conscious of the amount of capacity left in my pack.

EBikeFL, Thank you for your suggestions. I read through your entire forum about the papamotors project. I was a very good detailed review and overview. I'm still interested in exploring some other manufacturers, particularly those here in the states. I own a small business and highly value buying local and keeping jobs in the states.

If anyone else has had good experiences with any other brands or if you think a different solution other than a DD rear hub motor and LiFePo4 battery pack would be better for my situation, please let me know. Thank you for your responses so far. This is exactly what I need to get my project rolling.

By the way, my bike currently has little metal inserts around the axle hub in the rear fork. Is this acceptable for reinforcement? Or do I still need to get the upgraded part to make it stronger?
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Old 08-10-12, 05:11 AM
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I would reccomend a geared hub over a direct drive, especially if you want to pedal. I have both, so I know what each is like. Do you want a simple conversion about $500. I recommend clean republic hill topper. They say 5minute conversion, it is almost true, you usually need to file down axle a bit or file the drop out a little, everything else goes together. It took me 30 minutes, because I had to enlarge the dropouts. It come with 24v sla battery to get you started, I increase another 12v sla battery to get 36v, makes a difference, no pedaling 24v give 17mph tops, while 36v gets you into the lower 20's. When you can afford it get Lifepo4 batteries(safe) or lipo(not as safe). with Lithium you get longer distance, batteries are better and lighter. I think you can now order Lithium batteries instead of sla. anyway, here is a link...........

https://www.electric-bike-kit.com/hill-topper.aspx

watch video, for 5 minute install

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Old 08-10-12, 05:18 AM
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Matt;

this is my Yescomusa direct drive bike 48v 800watt, I can use either Lipo 50v 0r 75v arranged 18s2p(75v) or 12s3p(50v). I have my mount in the triangle.....





Jerry
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Old 08-10-12, 06:03 AM
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I would say you want torque more than power and speed. And if you are dragging your kids along I would want far better quality components than what you are looking at on a big box store bike.

I would recommend a mid-drive bike for the torque. I also agree with feistbob about buying an already built bike for the price and because the quality of components are going to be much better than what are on your Dick's Sporting Goods bike. Google: Klakhoff The bikes are going to be in the $1500-2000+ range. The components are as high of quality as one can find. The motor is made by Panasonic. I added an Xtracycle to my Panasonic rig and have regularly carried 200+ pound loads with it in the Appalachian foothills. It has lasted me tens of thousands of miles.

Steer clear of front hub motor kits. To be pulling that kind of weight with one you will be putting way too much torque on the front fork. Also when pulling your kids 10-12 miles an hour is as absolutely as fast as you need to be going. 8-10 is probably more like it.

The batteries on a Klakhoff are also mounted low on the frame which means the center of gravity is lower. The more weight you add to the bike the twitcher the handling is going to be. Keeping the weight low will keep the handling more reasonable.

Last edited by Allen; 08-10-12 at 06:08 AM.
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