Best E-Power choice for real MTB riding?

[briogio]

Hi,
I've done a search on this site of the BMC V3 and it doesn't seem to hold up well to rough and tumble of mtb riding, it was what I wanted to use for power, and suprise, suprise I want LOTS! I will be using a Kona Stinky, cheap and cheerful, and space in the triangle. I liked the look of the "Ego" kit too, but I'ld like to have the knowledge of all you mad scientists out mapping out our E-Power futures with your DT, (Destructive Testing).
Fanx all!

 

[MadRhino]

I ride the mountain, with a very powerfull setup (Clyte 5304, at 100v 90A, 150A phase current). I'm not yet satisfied with the mountain riding ability, but it's a beast on the road with any hill. The problem in the mountain, is the poor efficiency at lower speed, overheating when the trails get technical and you have to slow down.

I came to the conclusion that a real mountain E-bike would have to be built as a chain drive, more like a E-motocross. One interesting motor is the Agni B95 R, that would deliver 35hp. This would make for an expansive bike though, but efficient at any speed and capable to climb any trail. It could be built on a good downhill bike for lightweight, or on a 125 motocross frame for endurance.

 

[briogio]

Interesting that you would suggest the Agni, I was advised to use 2 of them on my Ducati E conversion, plus I was going to make an E mtb to get my feet wet first. I've read the "How to build your own electric motorcycle" so I'm slightly less stupid about E power Anyway I'll take your suggestion and get an Agni, it sounds like the best motor out there and certainly has LOTS of POWER!
One question though do I hook it up to the rear wheel or into the crank like the "Ego" kit?
Thanks for the advice!
I'll post my build, really appreciate this site :wink:

 

[MadRhino]

I will probably fit a sprocket adapter to the disc hub, and drive the left side with a torque converter, leaving the right side intact for pedal ability. Driving the motor chain separately, implementing regen assisted rear brake, is an interesting feature for mountain riding. A torque converter is also interesting, if it can be found light enough.

The Agni weights about the same as my Clyte hubmotor, and the same Lipo battery size would do better with it. I think that a very efficient setup with a good range can be made around 85 pound, and 35hp on 85 pound is a very powerfull ride, that would leave most motorcycle behind.

 

[briogio]

Yup that's what I figured too, around 85lbs with a 20Ah battery pack. I might rethink my Stinky bike idea, I don't know if it'll be strong enough, but maybe I could brace it up with my motor, and at least, partial batt., mount. The Agni's right on though, give me a chance to get to know one, and have one, when I move on to the Monster.
Gotta ask though, what is that bike with the babe in your profile picture?
I've got to figure out how to do that picture thing.

 

[Hillhater]

http://www.youtube.com/watch?v=lkLHqGrCE_Y&feature=player_embedded
http://www.youtube.com/watch?v=YPHThtr5GME&NR=1

 

[MadRhino]

Gotta ask though, what is that bike with the babe in your profile picture?

It's a Stinky, leopard special Stinky. :wink:
It is solid enough to build on it, you might want to upgrade some components, even extending the swingarm maybe, but you'll like it when powered.

I've got to figure out how to do that picture thing.

Edit profile

 

[MadRhino]

http://www.youtube.com/watch?v=lkLHqGrCE_Y&feature=player_embedded
http://www.youtube.com/watch?v=YPHThtr5GME&NR=1

I like it, but it has no pedal.

 

[LegendLength]

An RC motor would be best for mountains for two reasons: gearing and no unsprung weight.

I'm not sure why you'd need 35 HP though, I reckon 8 - 12 HP would be enough to have a good ride. You wouldn't be flying up hills but you'd still get up them with good efficiency.

The weight of that whole setup would be absolutely no problem for a stinky frame IMO. They are known as a strong and heavy frame.

My goal is to build something very similar. I already have the stinky and downhill forks. Large rims are on the way and I will deck them out with 2.5 inch tyres (3.0 in the future).

I'm currently running a 9c hub motor but that is still great on all but the steepest hills (i.e. back wheel sliding out due to steepness). Eventually I'll try to put an RC motor on it but i know it's going to be a very difficult task.

 

[neptronix]

I second the 9C motor, or crystalyte..

For eBikes, 2-5 horsepower is a lot actually. On my MAC i have been able to climb some 7% grades at over 20mph, and i'm about 220lbs.

A DD hub motor on 50 amps and high voltage is a very strong climber. RC setups are great, but expensive, and noisy ( high pitched ). If you are looking to ride in a place where motorized vehicles aren't allowed, an RC motor will be a dead giveaway. Those things sound like blenders in heat.. .. a DD on the other hand is almost completely silent.

 

[dogman dan]

It's a compromise to to ride dirt with hubmotors. A lot depends simply on the terrain, grades of climbs, size of the boulders and logs, etc.

I've tried a few kinds of gearmotors and a few dd motors. All work ok on the milder terrain, relatively smooth trails or roads, relatively flat hills up to 10% or steeper stuff short enough to charge up on momentum. Rear hub for sure unless the terrain is really mild.

But enter the wild areas and you fry the motor every time, or just have a tough time riding the rough trail with all that weight. These trails are often of a type riding a motorcycle on them would be a bitch. Some mtb trails are for mtb's only. Just too hard to ride em on anything heavy. Another case that gets tough is pole line or pipeline roads. These roads take a straight path through the terrain and have crazy steep inclines. Real rock crawler or buldozer roads that again can even kick your ass on a nice dirt bike.

For me the compromise that worked best is a low speed winding dd hubmotor. I found the 5304 in 24" rim still a bit too fast for the speeds that the local trails ride at, which is sub 20 mph mostly. The 9 continent 2810 worked great for me at 48v 22 amps. I could easily ride up sandy washes and only the very steepest parts of the local trails required any pedaling. But it left me wanting just a bit more, and when I gave a lot more, I melted down my motor immediately. I went straight to 72v 40 amps, and while riding those pipeline roads, I climbed too many steep hills too slow and fried it. I just gotta learn to stay on the shallower grades. Those pipelines are just too steep. Some of the hills are a challenge to walk up, let alone ride em.

The one nice thing about the 9c on 48v 22 amps was that while above 750 watts, the speed was only 20. So the locals on the blm trails were ok with me riding it on the trails that ban motorcycles.

 

[briogio]

Wow! That's great information, thanks a lot.
The noise factor is important where I want to ride, good to know the Stinky is strong because it's the easiest to come by. I realise the Agni at 35 hp is probably overkill!, but I will be using a pair of them on my Ducati Monster conversion, do they make noise?
Thanks again :wink:

 

[MadRhino]

Yes, a chain drive will make noise, especially with a 35hp brushed motor. That is why I built with a hub, I wanted to be silent on the streets. But I realized that a hub will always be limited for mountain riding, because its efficiency is near its top speed. If you make it fast, it will overheat when going slow.

Now, I realize that a single bike can't be good for the street and the mountain, unless you can be satisfied with a slow setup. I'm planning a mountain specific build, the one I made is only good when the trails are nice enough to speed.

 

[kfong]

I've been really happy with my BMC ebike setup, it's been working out fine with very little issues. I built it specifically for trail riding around the metro parks in my area. It had to be stealthy enough not to get attention. I’ve even rode it past a park ranger without him even taking a second glance. I was pedaling of course, but I usually pedal anyways since this extends my range and fun factor. The max speed is 21mph on the flats but it was the climbing ability due to the internal gears which makes it quite torqkey that I was after. I can get up most of the big hills in my area with a little assist. I usually ride continuously for a couple of hours with very little stops, even in 90 deg days. The speeds in the single tracks are not that fast due to all the twist and turns. Wide opens areas aren’t much interesting for me to ride. I have my other ebike for flat terrain. It’s also fairly quite as well, my wheels put out almost more noise. With 24Ahr, my max trail riding range to date has been 32miles. With all 27 gears available, I'm able to assist or still ride it if power runs out. This is really important to me if you find yourself deep in the woods, especially if it's infested with mosquitoes.

Here is a pic, I need to take a more recent one, once spring riding starts with the new rear bracket. Since the topeak kept breaking without it.

 

[briogio]

Nice clean setup kfong, that's how I'll do it too. Your BMC is internally geared right? I guess it's held up well, but do you bang it around? jumps, logs, rocks? I'm an old downhiller that weighs 190lbs so I'll be pretty rough on it. I figured that a non-geared hub might be better for that, but I know they're heavier which'll tax the rear suspension more.
Anybody have any recommendations for a hub motor that'll take the bashing? Also I thought about the overheating thing, I was thinking of modifying the sides with intake and exhaust vents, like on the old front drum brakes of vintage racing motorcycles, but the sides probably turn, still could swiss cheese it for cooling?

 

[dogman dan]

Venting the hub definitely helps. But in my area, you'd just fill er up with sand. I'd love to ride the bmc motor too, but my local trails are really just too rough. If I'm bending up this many rims, I know I'll be beating up the clutch inside a gearmotor a lot. The gearmotors really do work great though, the nicest climber I ever rode was the heinzmann gearmotor. Amazing torque, but using it at low speeds like that really heated it up FAST.

But a geamotor like the bmc must be a great choice for you kfong, in your locality. My local trails are just too steep or too rough in too many places. For hucking jumps and such though, I keep hearing others say go direct drive for that kind of pounding. Mine have taken the pounding well, provided I stop when they get hot in time. I really liked my 6x10 9 contintent motor at 48v, (15s lipo) which was putting out 1000 watts. But then I doubled the controller amps, and put 20s lipo with 72v in, and smoke came out fast. Halfway between should be doable though.

So a good thing to try would be 18s lipo, and 30 amp controller. With 2000 watts, you should get a lot more riding time that I did with 3500 watts, but still have a lot better performance than 1000 watts. You must have a thermometer inside the motor for overvolting, or have a battery so small you know you will stop in time. This setup should give you nearly 20 mph up moderate hills, and pedaling needed only above 10% grades.

One thing to note though, is I don't have that great of mtb's. A full on DH bike should be able to handle the 25 pound weight of a clyte motor a lot better than a $350 mongoose junker I ride. For me, I liked the 15 pound motor better. But I haven't ridden one on a bike with real quality suspension.

 

[MadRhino]

If you go for a hub, I'd say that a Clyte is best. Although I'm not satisfied of my bike as a mountain trail ride, it does climb, jump, accelerate incredibly... and survived alot of heat and abuse. Since I feed it with 100v 90A, it does show its limits though, and I don't believe that air cooling would be sufficient, because it is at low speed that it overheats. I'm still building with a hub this springtime, with a slower Clyte (5306) that I will feed more volts and less Amps. It should be better for the specific mountain abuse but still, I know already that I will be satisfied only with the chain drive that I plan to build next winter.

I know that I would have killed any other motor out there, with the abuse that the Clyte suffered in the mountain. I stripped an axle at nearly 15000w because of hardened torque arms, and I know that it will take it next time, with my new thicker softer dropouts. The new X74 series is very interesting and if I ever give a further try with a bub build, I would do the kind of mod that Lowrider made on it, but I'd use the extra room in the big custom axle to run a liquid cooling line.

 

[kfong]

Hi Dogman, I’m trying to finish my 6x10, I picked up last year because of your review of it. It’s going on a tidal force with 16S A123. I’ve been working on getting them in the triangle part of the bike. There isn’t much room for a 6P setup, so it will need to be a custom fit. The mounting system had me stumped, but I think I have it worked out now. It will be interesting to see how this compares to the BMC. Too bad the Tidal Force isn’t a FS bike. I will be putting disk brakes though. The bigger clyte motors were not an option for me. They are just too heavy for me to want to pedal in the trails, especially when you have a break down. Having a lot of weight in the back isn’t all that great either.

Since trail riding consists mostly of low grunt RPM’s, any hub motor built for speed and power is going to heat up. The BMC V2T and the 6x10 are slower motors designed for running at lower speeds. They won’t heat up nearly as much, I will know more about the 6x10 this summer, but as far as the BMC V2T goes. I rarely need to worry about it overheating even in 90deg weather. I am running it only at 40volts and current limit to 35amps. This isn’t a motocross setup, you need to pedal on the steep stuff, but it’s a good compromise between power and distance.

One thing to note, geared motors have a freewheel. direct drives don't. You get the advantage of ebrakes with a hub motor but the cogging drag when it's not powered. With a freewheel, no cogging takes place when you are left stranded without power and cussing, pedaling your way back because you pushed your distance too far.

The gears being less durable than the direct drives are a problem, so far I have had no issues. As long as you keep the wattage in a reasonable range, the BMC seems to be reliable. I'm running the stronger green gears. I did have a clutch problem, but that has been resolved with the newer V3 clutch. I crash regularly with my bike, some of the trails here I’m lucky to make it through without at least 1 crash. I jump logs when I see them, we don’t have big drops here so that probably has kept the BMC safe. I do release the throttle before I land. I ride it no differently than I would ride a trail bike. I weight 155lbs so that helps as well. There isn’t much of a choice currently for a good mountain bike setup if you want to keep it light and still ride without power. One approach that seems to have a lot of promise is going with a dual motor setup with smaller gear or hub motors. Something I need to try one day. Also the newer pancake style motors show some promise.

For those serious about mountain biking, keeping the setup as light as possible is important. Having an RC setup would be nice, but I would get kicked out of the parks due to the noise and obvious attention they bring.

 

[briogio]

What breaks or burns when you mtb with a geared motor? If it's the gears I could replace them with metal ones.
Do hub motors turn the sides? because if not I could fabricate an inlet scoop and put a K&N in it to filter the crap, and then a simple cutaway for an exit.
Is it possible to run a temp gauge wirelessly, or not, to your front "instrument" gauge?, then you could make shure you don't exceed a certain temperature. The difference in weight between a geared and a non-geared motor is just too great for me not to use a geared one.

 

[neptronix]

What breaks or burns when you mtb with a geared motor? If it's the gears I could replace them with metal ones.
.....

The difference in weight between a geared and a non-geared motor is just too great for me not to use a geared one.

The planetary gears are what break. They are made out of nylon as far as i know. Stronger ones are coming out but their offroad handling ability is really unknown.

I feel the same way you do about the geared motors. However you should examine the new crystalytes. They are 8lbs lighter and supposedly freewheel better.

Weight doesn't detract from the power too much when you can push horsepower in the double digits, lol..

 

[briogio]

Thanks Neptronics for that, if the Crystalytes are only a couple of pounds heavier I could live with that. I'm amazed and a bit baffled as to why they would put nylon gears in such a hot and stressed environment, if somebody doesn't make metal replacement gears, they should!

 

[neptronix]

metal gears exist, but i have read on here that they are quite loud. Also the solar gear ( i hope i'm using the term right, it is the outmost gear that all the planets mesh against ) cannot really be replaced.. so you got metal on nylon.. hmm.. bad scene!

I believe the new crystalytes are around 14lb.
MAC/BMC motors are 9-10lb.

Is reliability and more power capability worth adding 4lbs to your bike? I'd say yes.. and then go build a light geared motor commuter for the side project

 

[briogio]

You're right, 4 pounds is worth it and I really don't want a noisy engine that other people can hear. I'll keep it simple, I've only ever heard good things about the Crystalytes and I know they just came out with a new series. Thanks for helping me make up my mind, love this forum!

 

[dogman dan]

I'd love to give clyte another try, with a slow wind of thier new motor. So many motors, so little time, even less money. Right now I just repaired my melted dwon 9c 2810 slow winding, and am going to give it another go till something better can be afforded.

Too nice to motor up even moderate hills at 15 mph while others are huffing and puffing up em at 8 mph.

 

[kfong]

Dogman, how did the repair go? Did you end up rewinding it. Did you change anything, were you able to find better mangnet wire? I would of like to have seen the rebuild, pics ect. Useful if I end up burning mine out. Adding even more wire would have allowed you to up the voltage if there were room or was it pretty much filled already.

I'd love to give clyte another try, with a slow wind of thier new motor. So many motors, so little time, even less money. Right now I just repaired my melted dwon 9c 2810 slow winding, and am going to give it another go till something better can be afforded.

Too nice to motor up even moderate hills at 15 mph while others are huffing and puffing up em at 8 mph.