front suspension forks w/front wheel motor

[Alphorget]

Help!
I plan on putting together a off road bike using dual X-lyte 5 series motors. The bike will be used to traverse steep mountain terrain. I have many questions regarding this endeavor. One big question is using front suspension with the big crystalyte motors. I have been reading that the x-lyte 5 motors are to powerful to use with front shocks. I can see how the torque produced by these big motors would cause problems with conventional front shocks. I was thinking of using a modified springer front end off a motorcycle or making a scaled down one off plans I found on the web http://www.custom-choppers-guide.com/springer-fork-plans.html. I'm thing the springer front end would handle the torque issue. I'm wondering if there are any existing front ends (conventional of otherwise) out there that anyone knows of that might work. Any ideas or input?
Thanks,
Arnold

 

[pwbset]

That's going to be one heavy bike (like 50lbs in motor weight alone )... not to mention you'd need a heavy ass battery system to power 2x X5s. A single rear 5305 with enough juice will get you up anything. I've got some 20% grades in my commute and am going to upgrade to a 5305 when I get the money for sure. I'd never go front because it would just spin in the gravel/single track/fields anyway.

.02

 

[dogman dan]

Sounds fun. Not many MTB forks can even fit the big hub between them so it's a custom job for sure. I've wondered about a small motorcycles forks combined with a couple very good torque arms that somehow use the motorcycles axle hole as a mount so the tourque arm itself becomes a hefty dropout. At that point, you may have a frame around that you bought to get the forks, and you see where I'm heading. Whew! too much for me now but to fantasize. I think if you can solve the problem of how to carry two batteries that can independently power two big hubs, and have dual controllers and throttles, a really bitchen dirt bike could be had. Just riding a trail with peadle power in the rear and motor in front has shown me the potential. With independent controll, I think you could learn to feather which wheel when and really do some cool trials riding. If you just want to go fast, then put an etek on a small dirtbike. I like the idea, but I'm leaning more to dual gearmotors, but I'm told, I'll need quite a set of forks for one of those up front too. Maybe a singe battery -controller -throttle but with a hub selector switch would work just as good. Not so much all wheel drive as selective wheel drive.

 

[RLT]

My build was/is similar, except that I used dual Wilderness Electric brushed motors.

It worked OK (until the brush holders melted down yesterday) but I didn't really like the weight on the front end.... Although I probably have more batteries than you will use, and had to mount half of them in front of the head tube/handlebars.

The WE motors, (even before the brush holder problem) were just a little short of power to climb more than a couple of hundred yards of 15% grade without significant pedaling effort, but other than that, the basic setup worked pretty well. No problems with the (steel) front fork suspension being strong enough, although I did beef them up pretty well with some pretty hefty home made torque arms. Using a 53xx there might be stretching things, even with a great torque arm setup.

That setup just fell short of doing what I need it to. Maybe if I was a hundred pounds lighter... Anyway, I pretty much proved that the concept works, but I think I only added to the question if it is really worth doing.

Why not try starting out with a 5304 (or 5305 if you will settle for less than 25MPH in exchange for greater torque) in back, and if that doesn't do it for you, then add something to the front?

That is probably going to be MY next step, although I think I'm asking for more than it can deliver: climbing long 15-20% grades at (close to) 20mph, 30 miles minimum range, 30mph (or a little better) sustained cruising speed on the flats, on no more than 48V.

I don't think I'll achieve that with any single hubmotor, so one of my crazy ideas is going with a 5305 on back for the hill climbing torque, and a 405 (+ or - 1) on front for speed.
That way you don't have to worry as much about the torque ripping off the front forks.

Although I do have a new unscientific theory: If you are using front AND rear drive, the torque forces will (usually, but not necessarily always) be significantly less on the front forks than with just a front hubmotor alone. So it MIGHT be possible to put a torque monster up front, and still survive, as long as there is as much or more torque pushing from the back at the same time.

 

[Alphorget]

That's going to be one heavy bike (like 50lbs in motor weight alone )... not to mention you'd need a heavy ass battery system to power 2x X5s. A single rear 5305 with enough juice will get you up anything. I've got some 20% grades in my commute and am going to upgrade to a 5305 when I get the money for sure. I'd never go front because it would just spin in the gravel/single track/fields anyway.

.02

Granted it will be heavier than a mountain bike but it will be much lighter than a gas powered dirt bike. With two wheel drive and big knobby tires it should be able to climb much steeper grades than a dirt bike and at much slower speeds. I plan on using a 72volt 40ah lipo battery pack. I may even go beyond a 5305 motor. Kenny at Crystalyte can custom build the 5series motors up to a 5316 (wow). One big problem is calculating how many windings I would need on the motor to balance the motor windings/vols/amps/controller so that I get the most efficient set up considering the average speed (5 to 15mph), the average % grade and the weight of the bike/rider. That's an awful lot of information to sift through.

 

[pwbset]

Kenny at Crystalyte can custom build the 5series motors up to a 5316 (wow).

Holy crap seriously?! What's the process to get that done? Do you have any contact information or should I just send a general email to Clyte? I like the thought of like a 5311 for the 20% grade parts!

 

[Link]

Kenny at Crystalyte can custom build the 5series motors up to a 5316 (wow).

What the crap!? And I thought I was crazy for thinking about making a 5307.

 

[Alphorget]

Kenny at Crystalyte can custom build the 5series motors up to a 5316 (wow).

Holy crap seriously?! What's the process to get that done? Do you have any contact information or should I just send a general email to Clyte? I like the thought of like a 5311 for the 20% grade parts!

You can e-mail Kenny at Clyte but hear is the info I got from him. He said he will custom make motors up to a 5316 but there is a minimum order of ten motors. I will order the minimum order and keep four or five of them and probably sell the extras. I'm a wrench turner and fabricator but not well versed in electronics so I would really appreciate any information on how to calculate the correct number of windings the motor will need for optimum efficiency at slow speeds on very steep terrain.
Thanks,
Arnold

 

[Drunkskunk]

Wow! impressinve piece of information.

Calculating the windings is pretty straight forward. use the calculator from Ebikes.ca for a base. Them, everytime you double the windings, you cut the speed in half. If you then double the voltage, you get the original speed back, but at double the torque.

The best example of this is using the 40X seies motors, and looking at a 404, and a 408 for comparison.

A 5310 would be insain!


As for a front fork, nothing made would survive that kind of torque, but an all steel springer could probably be built to do it.

 

[johnrobholmes]

A rough estimate of speed for motors is that doubling the stack height cuts motor speed in half if wind count and gauge is held constant. So to keep the same speed you will need to half the wind count.

 

[Link]

I'm a wrench turner and fabricator but not well versed in electronics so I would really appreciate any information on how to calculate the correct number of windings the motor will need for optimum efficiency at slow speeds on very steep terrain.

Well, in general, the higher the turns, the more torque and less speed, but a 5316 is going to need a stupid amount of voltage to get any decent speed. Like 200V easy.

Plus, the more turns, the thinner the wire, and the thinner the wire, the more resistive losses you get. :?

 

[pwbset]

He said he will custom make motors up to a 5316 but there is a minimum order of ten motors.

After some guesswork using the ebike simulator Link is clearly dead on about a 5316... a much more realistic winding would be like a 5309. I currently run 84v and around 40a peak and near as I can tell a 5309 would top out around 17-22mph and pull like a frickin horse... 100+N-m or more.

 

[dogman dan]

Ahh yes, but how long before it melted itself? I know the answer for a BD36 if it is over 100F, 400 miles. For slow speed hill climbing, I think gearmotors. For getting a big heavy tow going, and then proceeding at speed, the fancy wound motors would be good. Any power not turning into motion is turning into heat.

 

[pwbset]

Ahh yes, but how long before it melted itself?

I doubt a 5 Series would have any trouble with over heating unless you're running sustained Doctorbass-type power levels up mountains in the Sahara. At my measly 2,000ish watts it would be totally fine I have no doubt at all. They have much better heat dissipation than a 4 series or BD36. My lowly 4011 is handling 2,000 watts just fine for 10-15 minutes at a time in 65-85 degree heats... so far. :wink:

EDIT: Yeah... at the power levels I'm talking about a 5 series probably wouldn't even get hot... now this is how you push a 5 series :lol: :

http://endless-sphere.com/forums/viewtopic.php?f=4&t=4983&st=0&sk=t&sd=a

 

[ateene]

Here is another option for building custom springer forks http://bikerodnkustom3.homestead.com/brainfork.html

 

[dogman dan]

The problem is the steep hills, since any power not turning into motion turns into heat. I know exactly what it took to melt the magnets right off a WE motor. Since I live in nearly the Sahara desert, I may have to deal with heat issues more than you. I just thought I would point out that slow moving hubs get angry fast.

 

[Alphorget]

The problem is the steep hills, since any power not turning into motion turns into heat. slow moving hubs get angry fast.

as I can tell a 5309 would top out around 17-22mph and pull like a frickin horse... 100+N-m or more

Calculating the windings is pretty straight forward. use the calculator from Ebikes.ca for a base. Them, everytime you double the windings, you cut the speed in half. If you then double the voltage, you get the original speed back, but at double the torque.

The best example of this is using the 40X series motors, and looking at a 404, and a 408 for comparison

Great info!
Here is my conundrum.
I want to have the capability to climb steep terrain at a slow speed like 5mph with the highest motor efficiency possible in order not to excessively over heat the motors while still retaining the ability to travel over level ground at about 20-25mph. Finding this balance has me stuck. Running dual motors will help reduce to load on the motors and help to keep the heat down but I am concerned about excessive heat at low speeds. In looking at the simulator atebikes.ca it appears that a 5308 to a 5310 would achieve what I'm looking for but I'm not sure. The simulator does not provide enough information to determine if the efficiency would be enough with these higher windings to prevent overheating at slow speed with a load on the motor. I'm sure that there is a way to calculate which motor would work best but it is beyond my ability. Seeing as I need to buy ten of these custom wound motors at a time in order to get Kenny to build them I want to dial in the best configuration possible. I know I could use geared motors but I really like the beefy 5 series motors. I
I want to build a mondo back woods EV Billy Goat.
Tell me I'm not crazy!

 

[pwbset]

I want to have the capability to climb steep terrain at a slow speed like 5mph with the highest motor efficiency possible in order not to excessively over heat the motors while still retaining the ability to travel over level ground at about 20-25mph.

Take this all with a grain of salt as I may be totally wrong, but you could just create a voltage switch (series/parallel switch) for your battery pack. So on level ground you can go balls to the wall full power mad volts and speed, but climbing a super steep hill you can step back your voltage, which should reduce the speed where efficiency is greatest thereby producing less waste heat.

I know on my current rear 4011 when I climb the mountain full throttle at 84v the motor gets crispy hot... when I climb the same mountain at 56v I can run full throttle all the way until LVC and the motor barely gets hot. I've since learned to just back off the throttle at 84v as this does the same thing essentially, but allows for more torque if needed in bursts. It's all discipline and practice. I'm noticing that throttle control alone can make the difference of an entire amp-hour for me over my 8mi one way commute... it's just extremely hard to be that disciplined about it.

 

[Alphorget]

you could just create a voltage switch (series/parallel switch) for your battery pack. So on level ground you can go balls to the wall full power mad volts and speed, but climbing a super steep hill you can step back your voltage, which should reduce the speed where efficiency is greatest thereby producing less waste heat

.
Thanks for the input. That is very interesting.
The results from fiddling around with the simulator does seem to support your idea. The efficiency gets better and the watts go down. The only draw back is the lower thrust. As long as the the thrust doesn't get to low to pull the payload up a steep incline it seems like this approach should work. Using two motors would help to compensate for the lower thrust. Would using a Milwaukee 3s3p pack enable the user to switch from 28v 7.8ah to 56v 5.2ah to 84v 2.6? It seems like this configuration would work but I can't help but wonder if it works why I don't see other people using it seeing as overheating under load seems tom be a very common problem.

 

[Alphorget]

you could just create a voltage switch (series/parallel switch) for your battery pack. So on level ground you can go balls to the wall full power mad volts and speed, but climbing a super steep hill you can step back your voltage, which should reduce the speed where efficiency is greatest thereby producing less waste heat

Milwaukee 6pck - 3s2p @ 84v5.2ah

You rate your pack at 5.2ah which would be 2.6 per battery. The web info I got on the Milwaukee batteries show them at 3.0ah. Help me out here, is it 2.6 or 3.0?
Thanks

 

[pwbset]

You rate your pack at 5.2ah which would be 2.6 per battery. The web info I got on the Milwaukee batteries show them at 3.0ah. Help me out here, is it 2.6 or 3.0?

Yeah... I'm seeing around 2.6ah of useable amp hours. Milwaukee says 3ah and indeed you could get that if you bypassed the onboard battery BMS and took the cells down to 2.5v each like the Milwaukee test discharge graphs show. In reality the onboard BMS cuts the pack power when each cell is well above 3v... like 3.2v-3.4v. This is clearly to improve cycle life and justify their warranty etc. etc. but results in lower actual capacity. "Marketing".

I climb 1,600ft during my morning commute so I'm hitting that 2p pretty uber-hard most of the way. I average around 35-50wh/mi. I just Friday had my local Milwaukee service center friend plugin his little Milwaukee battery pack reader and I've done 75 cycles on my batteries and their overall capacity is already down to 85% of factory fresh, which surprised me quite a bit... clearly having only 2p is taxing these batteries. They come hot off the charger at 4.15v per cell. Anyway... I have no confidence that I'll be able to get the rated 1,000+ cycles out of these batteries the way I've wired mine. Hoping that warranty is actually useable. :wink:

As for why not wiring a series-parallel setup it's just simplicity in my case. I want 84v available all the time, but with throttle disciplineyou can achieve what you were talking about all the same. It's oddly counter intuitive to back off the throttle on the steepest parts of my commute (20% grade), but the slower I go the more the motor helps me out. It's weird feeling, but it totally works. With barely open throttle and minimal pedaling I can maintain 8-10mph on that 20% grade. If I pedal balls to the wall and full throttle on the same part in the same gear I can maybe get 14-15mph, but the motor heats up quick.

 

[pwbset]

Would using a Milwaukee 3s3p pack enable the user to switch from 28v 7.8ah to 56v 5.2ah to 84v 2.6?

EDIT: I'm really not sure about the wiring you'd have to do for series/parallel switching or how feasible it would be. This stuff below is simply some pack configuration examples.

9 batts doesn't work so well for this and that's another issue. If you used 8 batts you could do a 2s4p @ 56v10.4ah or (if you had a burly high voltage controller) 4s2p @ 112v5.2ah and that would be an easy switch. If you wanted to do a 3s3p with the switching you mentioned you'd have to disable a batt pack when you switched... so you could do a 3s3p and then switch to a 2s4p -1 pack. A single series this wouldn't be effected by... like you could have all 9 packs in parallel with 1s. Make sense?

One easy thing I've done with my setup is that if I want 56v for shorter range or just to run to town and back I simply remove 2 batts and go 2s2p. Some photos of my battery board are here:

http://endless-sphere.com/forums/viewtopic.php?f=6&t=4716&st=0&sk=t&sd=a&start=30#p72912

 

[johnrobholmes]

I think there is really two methods for having a bike with a "climbing gear" that are most viable. One is to have multple speeds. One hill climbing gear and one speed gear. The other is dual motors. Have a small slow geared outrunner with freewhel on the rear for hill climbing. Have a front hub motor for speed on the flats.

The dual motor sounds like an interesting idea. The trick would be the dual throttle and and proper gearing of the hill climber.

 

[Alphorget]

I think there is really two methods for having a bike with a "climbing gear" that are most viable. One is to have multple speeds. One hill climbing gear and one speed gear. The other is dual motors. Have a small slow geared outrunner with freewhel on the rear for hill climbing. Have a front hub motor for speed on the flats.

The dual motor sounds like an interesting idea. The trick would be the dual throttle and and proper gearing of the hill climber.

Wow, I'm getting allot of great information here.
A geared motor for hill climbing that would freewheel when not in use is a really interesting idea. It would really help in conserving energy too. Does anyone know what the beefiest geared motor on the market is?

 

[Drunkskunk]

The Metal geared version of the Puma. It will tear up any hill. The only problem is, a geared hub would tear off an aluminum fork. You would need a rigid fork, or a motorcycle fork for that kind of power, and probably one of those DH 1.5 inch headsets too.