Speccing out very fast e-bike - will this setup work?

Some of the battery mavens here can probably speak in more detail but if memory serves each Dewalt pack is only 2.3 amp hours. So doing the math that would net you 4.6 total amp hours at 72v. My guess is that at speed and drawing the full 35 amp capacity of the controller you could come up short in the range department. Especially if there are any hills and you do not pedal but use the motor only for hard accelerating, 35amps from a 4.6amp hour pack will only be about 8 minutes at full power draw, I think. Jump in here battery experts. Should you keep the amp draw down the range should be quite adequate as you have 331 watt hours to work with. That could get you around 20 miles at 15mph, no wind, on the flat, if you pedal to get up to speed and help a little along the way.

The bikes themselves look up to the job with dual suspension and disc brakes. You will want both over 20mph with all that weight (nothing personal but the motor is quite heavy too) much over 30mph and the geometry of a MTB can cause them to get a bit twitchy in the handling arena.

A word of caution, should you get an X5 with the 10mm axle resist the urge to file or grind the drop out. It appears that both frames are aluminum and they can suffer immediate and catastrophic failure when modified. File down the flats on the axle instead. I repeat do not grind on the frame dropouts. This is a hugely powerful motor and will stress the frame considerably. Also keep a very close eye on your spokes as the X5 is notorious for snapping these like dry spaghetti.

Good luck and please document and post your progress here at V as we all like to see such projects develop.

I kinda wonder about using one large hub motor on the rear wheel, and the stress put on spokes already loaded.

I think it would better to use a front hub motor, that way, only the motor stresses the spokes on the front wheel, and the
rider pedaling stress's the rear wheel.

I was thinking why not use, two less powerful hub motors, then only use both when needed, (large hill or need for speed)
would be more efficient to use one smaller motor at other times, at full capacity then one larger motor at half speed.

Also I think the range for the battery pack depends on your route, your key factor, is hills.

Then rolling resistance then wind resistance, takes over at speed.

So high pressure tires, would help. How about a airfoil to decrease wind resistance at speed.

Perhaps a longer route with less hills is faster?

Lifting 220 pounds up a hill is quite a load so if you had hill data you could calculate these things.

Don't know if you insist on building this one yourself. I've long been one to stick with what I know, so no bike building for me. You guys are all pros in my book.

But I do know that the components can add up in price quickly and with that in mind, do you have a price that you're willing to spend?

The only reason I say that is I spent $700 on my Charger ebike and I average about 23 MPH and peak at about 30 MPH before things get scary--and it's good for a 20 mile commute. Of course I disabled the speed limiter to get that, but out of the box, I thought it was a great deal for the performance it returned to me.

But if you're the type who wants to build it yourself (hey, I'm the same way with computers) then I say go for it. Sorry I can't adequately answer any of your questions here, but thought I'd chime in.

kringle777
Red XM-2000
Moss Green "Charger" ebike
Sacramento, CA

The rear spacing is 135mm with or without disc brake. The motor will fit but you will probably end up with a maximum of 6 speed, most likely 3 speed cassette. Should you decide to front mount then the suspension fork will have to go and a rigid chromoly fork be used. The aluminum suspension fork won't cut it. They have been known to break at the axle mount with all but the smallest , say 250watt hub motor.

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This post has been added to our Building E-Bikes Collaborative Hand Books.
There also may be some information in our EV Batteries Collaborative Hand Books that you may want to read.
If you have any problems locating the information you need let us know, and keep us updated on your progress.
A Blog would be very nice, so we could follow your progress, and don't forget the pictures, we love them.

Stleride
Your Moderator Team Captain

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The controller of 72v 35a should not be a problem for the motor to handle, Crystalite sells one. As for the batteries you'll just have to try them and see if you can keep off the throttle. I've only seen a couple of these and the packs were 20a and 35a. Personally I'd want a minimum of 10a for a X5. That would be 15 minutes at full power draw. You should probably figure out your batteries first as this will be the biggest expense.

If you need to cut a few corners Craigslist usually has a ton of good lightly used rides for about 50 cents on the dollar. You would be surprised how many people only use a new bike a couple of times then store it.

I'm with you in that I find building and learning is more than half the fun. Good luck.

I think you could get 8 miles but would use everything you got but with some pedeling you would be fine. I have a smaller set up running a crystalyte 409 motor at 66v and my no pedel range max is around 8 miles on 4 dewalts. Your controller will be consuming more current but the dewalts don't seem to really care at all. I am going to start using my bike for an 9 mile commute to work everyday now and just bring my chargers. If you want check it out heres the link: http://visforvoltage.org/vehicle/magudaman/1282

I strongly advise you stay away from the 500 series motors. They suck a huge amount of current even at lower speeds. I use a 408 at 72 volts, 35 amp controller, four Dewalts and get tremedous range. You should always pedal, you just don't have to pedal all that hard. I can hit 30 MPH up a fairly steep grade. Range drops off fast with speed but certainly, six Dewalts will get you a well past eight miles. I often take fifteen or twenty mile trips with my four.

I wouldn't discount the 500 series motors. Russ makes a great argument for the 408 (which I recently got for my bike.) But the 500s do have greater capability. If there's a need for more performance they might be a good choice. Lots of folks seem pleased with them.

My main complaints with the 500s are their weight (the 400s are already quite heavy), the cost and the size. According to various reports and performance curves they can be just as efficient as the 400s. They can also provide more power if/when you need it.

Check out some performance curves here:

http://www.ebikes.ca/simulator/

I've not tried a 500 series motor yet, but am impressed with their capabilities.

Richard

Don't be afraid of doing an ebike conversion people. Unless you are trying to use an outlandish selection of mix-matched free garbage parts, there is nothing at all to it. You buy a kit where it comes with everything that is needed, then you simply wired everything to the controller (hard to get wrong with a good kit if even possible to get wrong), make sure everything is tight, and you're good to go. The hardest part of the whole experience is deciding where you are going to locate the controller and battery. For the vast majority of you who are using cookie cutter mountain bikes, this is a no brainer and many kits come with battery racks and/or bags. I don't have a normal bike at all, and it was ridiculously easy for me, I could only imagine how quickly I could have put it together on a mountain bike. Don't be afraid of putting together a kit. If you are not technically inclined you buy a kit and a battery pack designed to work with that kit, and you pretty much don't need to have any knowledge about anything. If you can connect connectors that only possibly connect one way, you can put together an ebike kit. Just do it...research what kit is right for you, and do it.

And if you must ride with a Phoenix motor and 35-40A and 36-48V, get a GOOD helmet and don't kill yourself please so the law ends up coming down hard on all of us people who are keeping our ebikes to the mandates of law and the laws of common sense and safety.
An ebike that does 40-50MPH is NOT an ebike...it is a motor vehicle and it isn't a speeding ticket, it's driving an unlicensed, unregistered, uninsured motor vehicle and is the reason why they never wanted ebikes to be legal in most places to begin with. Please be careful and don't ruin it for others....We're still on a pilot test and I don't want them to make it illegal again at the end of the pilot because they had all these people riding around on electric motorcycles without licensed, or registration, or insurance, or safety considerations....motorcycles and LSM and scooters don't use bicycle tires and spokes! But other than that....rock on!

Giant Stiletto Bike
500W Golden Motors 20" front wheel kit
190lb rider
Flat ground speed: 36kph
Top speed: 44.8kph

I agree that it is not very sensible to exceed 30 mph on a bike in regular traffic. I am 190 pounds and have been very pleased with my Crystalyte 409 motor, 20A controller, CycleAnalyst and 72 volt 2s3p DeWalt battery pack. I always pedal, but never very vigorously unless climbing very steep hills. There is a lot of climb capability there if you need it, but with a moderate power draw of 11-15 watts/mile on flat ground you should be able to get 18-20 miles with this set-up.

As an aside, I am down to running a 4 pack, 72 volt setup after I smoked one of my DeWalt packs while experimenting with different battery configurations and accidentally mis-wiring a pack. I strongly recommend a fool-proof wiring harness less you get carried away in the excitement of the moment.

As advertised, the pack puffed a bit of acrid smoke and stayed pretty warm for about 15 minutes, but was never too hot to handle.