etard
100 kW
Awesome Video! Any chance of letting me know where those trails are? Some serious single track there! Looks like your bike is taking a good beating without too much problem. Congrats, but are you sharing with your partners? :lol:
Electric Motocross Bicycle build (Tons of big pictures)
- Thread starter dpearce
- Start date
MikeFairbanks
100 kW
The beginning of that video gave me the serious creeps. Death on the left for sure. Geesh, that took balls.
vodka
100 W
- Joined
- Oct 22, 2009
- Messages
- 121
with this bike u definitely raised the bar for off-road e-bikes, thanks for sharing your amazing build. Just one thing, I'm not sure if you consider it as bicycle or motor bike. if it's a bicycle, it has definitely the disadvantage
of having no seat post so you're not able adjust for optimal riders position. As you can see on your Photo, this is probably not a very efficient position for pedalling.
of having no seat post so you're not able adjust for optimal riders position. As you can see on your Photo, this is probably not a very efficient position for pedalling.
dpearce
1 W
ypedal:
Bonus points + + + for not editing out the crashes !
You have done one excellent job of building that machine, light, fast and durable ( so far :lol: ! ) , I love it !
Geared hub, off road , if that motor holds up for a season without killing gears the way you are riding it , i want a rig just like that one next !
Thank you!
I plan on putting a front hub motor (and another 10Ah) on it to ease the strain on the rear motor. I did not create the hub motor, so i am not very interested in finding the limits of it ($ the hard way $), I just want to preserve it enough to test what I did build, the chassis. Two motors will ease the strain in the transient and from a dead stop conditions and low speed hill climbs, without adding too much unsprung weight to either wheel. The crystalites weigh more than the motor and batteries together, (1 BMC + 72v 10Ah, < 20lbs), so even though they may be more robust the weight penalty was too great to keep it within the target weight at the outset of the design. I will use independent throttles and configure it so each motor to be able to draw off an independent 10Ah pack for hills and acceleration, then allow the rear to draw off the whole 20Ah pack for long distance, steady state riding. So the front will only be used when needed.
I think this single motor setup has been holding up well, although I know it is running well above its limits. However it only sees the high power levels for short bursts, and I try to ride it sensibly (ie: not flogging the throttle when climbing hills with rocks, esp. at lower speeds, no WOT starts w/o pedaling). You get a feel for when to let off the throttle, the motor kind of lets you know when it doesn't like it. I try not to pull more than 3000W for more than 10 seconds, and I don't let it get too warm.
etard:
Awesome Video! Any chance of letting me know where those trails are? Some serious single track there! Looks like your bike is taking a good beating without too much problem. Congrats, but are you sharing with your partners? :lol:
Yes, that was one of my group partners with me at Del Cerro park in Palos Verdes. I got to take it home because I conceived it, paid for it, and put in the extra work to make it happen. That being said, It could not have been done without them though, not in >4 months at least.
vodka:
with this bike u definitely raised the bar for off-road e-bikes, thanks for sharing your amazing build. Just one thing, I'm not sure if you consider it as bicycle or motor bike. if it's a bicycle, it has definitely the disadvantage
of having no seat post so you're not able adjust for optimal riders position. As you can see on your Photo, this is probably not a very efficient position for pedalling
thank you! I posted that photo specifically to demonstrate the comfortable riding position.
As I mentioned in response to JohninCR's question about the pedaling position:
"The crank position works great. It was designed to have a more relaxed seating position, like a motorcycle where i can sit almost straight up, as opposed to the hunched over mountain bike position. I am 6'2" and the way it pedals for me when sitting feels more like a beach cruiser, if I need to pedal hard I just stand up. It has 5 speeds, but I usually just leave it in high, which is 34/14 I think. While this position compromises pedaling efficiency, the motor is there to back you up, so I don't feel like I have sacrificed anything at the expense of comfort. The seat also feels safer, without that danger zone in front of your seat..when you are off-roading, it is not if but when you fall, and that area in front of the seat on bicycles looks like like an accident waiting to happen, a bicycle vasectomy kind of accident..so I like how the MX style seat provides padding in that area."
Since it was a clean sheet design, the uncomfortable MTB seating position was one of the first issues to deal with.
It is not purely a bike, it is not purely a motorcycle, it is a hybrid of both, somewhere in between. That was the intent, so (in my opinion) there was no reason to compromise comfort for this drawback of pedal only bikes. As JohninCR mentioned somewhere else on the forum, I too have most of my fun at lower speeds when riding a dirtbike, especially after breaking my leg 2x in the last 3 years (not from riding dirtbikes btw). Since then I have lost some of my interest for high speeds (and crashing at them) unless I am in a cage. Speed is all relative too, 30mph can feel pretty scary fast in the right terrain. On a flat, wide, paved surface, 30mph doesn't feel very fast.
This was our inside joke about the 'proper' pedaling position, it reminds me of this:
http://www.southparkstudios.com/clips/153058/it-beats-dealing-with-the-airline-companies
Bonus points + + + for not editing out the crashes !
You have done one excellent job of building that machine, light, fast and durable ( so far :lol: ! ) , I love it !
Geared hub, off road , if that motor holds up for a season without killing gears the way you are riding it , i want a rig just like that one next !
Thank you!
I plan on putting a front hub motor (and another 10Ah) on it to ease the strain on the rear motor. I did not create the hub motor, so i am not very interested in finding the limits of it ($ the hard way $), I just want to preserve it enough to test what I did build, the chassis. Two motors will ease the strain in the transient and from a dead stop conditions and low speed hill climbs, without adding too much unsprung weight to either wheel. The crystalites weigh more than the motor and batteries together, (1 BMC + 72v 10Ah, < 20lbs), so even though they may be more robust the weight penalty was too great to keep it within the target weight at the outset of the design. I will use independent throttles and configure it so each motor to be able to draw off an independent 10Ah pack for hills and acceleration, then allow the rear to draw off the whole 20Ah pack for long distance, steady state riding. So the front will only be used when needed.
I think this single motor setup has been holding up well, although I know it is running well above its limits. However it only sees the high power levels for short bursts, and I try to ride it sensibly (ie: not flogging the throttle when climbing hills with rocks, esp. at lower speeds, no WOT starts w/o pedaling). You get a feel for when to let off the throttle, the motor kind of lets you know when it doesn't like it. I try not to pull more than 3000W for more than 10 seconds, and I don't let it get too warm.
etard:
Awesome Video! Any chance of letting me know where those trails are? Some serious single track there! Looks like your bike is taking a good beating without too much problem. Congrats, but are you sharing with your partners? :lol:
Yes, that was one of my group partners with me at Del Cerro park in Palos Verdes. I got to take it home because I conceived it, paid for it, and put in the extra work to make it happen. That being said, It could not have been done without them though, not in >4 months at least.
vodka:
with this bike u definitely raised the bar for off-road e-bikes, thanks for sharing your amazing build. Just one thing, I'm not sure if you consider it as bicycle or motor bike. if it's a bicycle, it has definitely the disadvantage
of having no seat post so you're not able adjust for optimal riders position. As you can see on your Photo, this is probably not a very efficient position for pedalling
thank you! I posted that photo specifically to demonstrate the comfortable riding position.
As I mentioned in response to JohninCR's question about the pedaling position:
"The crank position works great. It was designed to have a more relaxed seating position, like a motorcycle where i can sit almost straight up, as opposed to the hunched over mountain bike position. I am 6'2" and the way it pedals for me when sitting feels more like a beach cruiser, if I need to pedal hard I just stand up. It has 5 speeds, but I usually just leave it in high, which is 34/14 I think. While this position compromises pedaling efficiency, the motor is there to back you up, so I don't feel like I have sacrificed anything at the expense of comfort. The seat also feels safer, without that danger zone in front of your seat..when you are off-roading, it is not if but when you fall, and that area in front of the seat on bicycles looks like like an accident waiting to happen, a bicycle vasectomy kind of accident..so I like how the MX style seat provides padding in that area."
Since it was a clean sheet design, the uncomfortable MTB seating position was one of the first issues to deal with.
It is not purely a bike, it is not purely a motorcycle, it is a hybrid of both, somewhere in between. That was the intent, so (in my opinion) there was no reason to compromise comfort for this drawback of pedal only bikes. As JohninCR mentioned somewhere else on the forum, I too have most of my fun at lower speeds when riding a dirtbike, especially after breaking my leg 2x in the last 3 years (not from riding dirtbikes btw). Since then I have lost some of my interest for high speeds (and crashing at them) unless I am in a cage. Speed is all relative too, 30mph can feel pretty scary fast in the right terrain. On a flat, wide, paved surface, 30mph doesn't feel very fast.
This was our inside joke about the 'proper' pedaling position, it reminds me of this:
http://www.southparkstudios.com/clips/153058/it-beats-dealing-with-the-airline-companies
Ypedal
100 TW
shock load on geared motors have proven problematic in the past, ( like hard landings. ) , time will certainly tell but so far so good !! 
Spacey
100 kW
Amazing bike, I would not be able to ride on the cliffs though like in your video as I would be too scared of driving off the cliff....on purpose....it's an odd thing but I scare myself that I might just do it in a fleeting moment of madness. It's also why I don't go on roller coasters lol.
dpearce
1 W
great vid and great effort with the bike, watch out for landing with throttle on, gear killer.
The hub should last for a while if you baby it some, but wheres the fun in that?
Thank you all for the compliments. I participated in the Society of Automotive Engineers (SAE) Baja collegiate design series for 4 years, I think we broke everything that can break in the drivetrain, which taught us to avoid shock-loading whenever possible. I always land with the throttle off, and try not to load it up over rocks, and just coast over rough stuff with momentum and minimal or zero throttle. If I hadn't been doing this I think I would have stripped the gears by now. I don't think I baby the motor by any means, but the fun being conservative with it is having it last for a while, and not have it relegated to just being a heavy bicycle with no motor power. Where is the fun in it if you can't use it because it is broken? hah
I think you can have the same amount of fun while not babying it, but just by being conscious of shock-loading situations and avoiding them when possible (sometimes it is not..I get nervous when others ride it and don't have any sense about that). Right now I am more interested in the limits of the chassis.
Thanks!
The hub should last for a while if you baby it some, but wheres the fun in that?
Thank you all for the compliments. I participated in the Society of Automotive Engineers (SAE) Baja collegiate design series for 4 years, I think we broke everything that can break in the drivetrain, which taught us to avoid shock-loading whenever possible. I always land with the throttle off, and try not to load it up over rocks, and just coast over rough stuff with momentum and minimal or zero throttle. If I hadn't been doing this I think I would have stripped the gears by now. I don't think I baby the motor by any means, but the fun being conservative with it is having it last for a while, and not have it relegated to just being a heavy bicycle with no motor power. Where is the fun in it if you can't use it because it is broken? hah
I think you can have the same amount of fun while not babying it, but just by being conscious of shock-loading situations and avoiding them when possible (sometimes it is not..I get nervous when others ride it and don't have any sense about that). Right now I am more interested in the limits of the chassis.
Thanks!
dpearce
1 W
hey no worries, I did not take offense, I was just rambling about my experiences with shock loading, and letting you guys know how I have been treating it. What part of the gears broke, did the teeth strip? Have you ever felt the clutch slip?
Thanks-
Thanks-
Ypedal
100 TW
The Sun gear is what started slipping on mine :
( eZee motor, but similar to the BMC in many respects )
http://ypedal.com/ezee.htm
But damn, that bike looks slick !!!.. 8)
( eZee motor, but similar to the BMC in many respects )
http://ypedal.com/ezee.htm
But damn, that bike looks slick !!!.. 8)
HAL9000v2.0
10 kW
What a nice build!
I like it!.
I like it!.
o00scorpion00o
100 kW
Hi dpearce,
That's a really nice build, congrats. and thanks for sharing. I loved the videos!
Has anyone ever tried an external controller gm magic pie? it will only go to 24 mph @48-52 volts, but it really has amazing torque. I am pulling 40 amps and it accelerates like a rocket! I wish I could try it @72 volts+ It's worth serious consideration. It is a good bit bigger and heavier though, but there is no gears on it to kill.
I had it @80 amps with the modded internal controller, it was amazing, but it died, so I rewired it for an external controller and now use a 40 amp infineon. The controller or the motor only gets luke warm no matter how steep hills I climb!
Funny enough though, now I am wanting to change it for a smaller lighter free wheeling mac 500 whenever cellman gets the new gears. :wink: As now I really want to exercise more and the drag on the pie is a killer!
Any way keep up the good work and keep us posted as the miles clock up.
Mark
That's a really nice build, congrats. and thanks for sharing. I loved the videos!
Has anyone ever tried an external controller gm magic pie? it will only go to 24 mph @48-52 volts, but it really has amazing torque. I am pulling 40 amps and it accelerates like a rocket! I wish I could try it @72 volts+ It's worth serious consideration. It is a good bit bigger and heavier though, but there is no gears on it to kill.
I had it @80 amps with the modded internal controller, it was amazing, but it died, so I rewired it for an external controller and now use a 40 amp infineon. The controller or the motor only gets luke warm no matter how steep hills I climb!
Funny enough though, now I am wanting to change it for a smaller lighter free wheeling mac 500 whenever cellman gets the new gears. :wink: As now I really want to exercise more and the drag on the pie is a killer!
Any way keep up the good work and keep us posted as the miles clock up.
Mark
Green Machine
100 kW
All that beast is missing is some 8" travel bicycle forks..double crown.
You can find on ebay sometimes for less than $400 just buy used.
You can find on ebay sometimes for less than $400 just buy used.
dpearce
1 W
More 'field testing' of the project:
[youtube]iOk_cD1b9SY[/youtube]
The one way bearing in the BMC motor sounds like it is starting to fail, it slips a little and makes an awful noise when loaded over rough stuff, but still works fine if you are careful not to give it too much power over rocks and steep bumpy hills. No big surprise as it is receiving 6 times the rated power over rough terrain.Took it apart and secured the ring gear to the hub motor case to prevent it from becoming the next weak link, and just received a V3 clutch assembly (thanks Ilia) to replace the second generation one that failed. I don't think it is the pressed in piece spinning inside, shown as one of the weak links here:
http://ebikessf.com/V2-vs-V3-clutch
The moise it makes sounds like the one way bearing actually failed. Ill have to take it apart after I replace it, to see what happened. Still works enough to ride for now, and holding up enough to test the bike as a whole.
[youtube]iOk_cD1b9SY[/youtube]
The one way bearing in the BMC motor sounds like it is starting to fail, it slips a little and makes an awful noise when loaded over rough stuff, but still works fine if you are careful not to give it too much power over rocks and steep bumpy hills. No big surprise as it is receiving 6 times the rated power over rough terrain.Took it apart and secured the ring gear to the hub motor case to prevent it from becoming the next weak link, and just received a V3 clutch assembly (thanks Ilia) to replace the second generation one that failed. I don't think it is the pressed in piece spinning inside, shown as one of the weak links here:
http://ebikessf.com/V2-vs-V3-clutch
The moise it makes sounds like the one way bearing actually failed. Ill have to take it apart after I replace it, to see what happened. Still works enough to ride for now, and holding up enough to test the bike as a whole.
dpearce
1 W
[youtube]14b2uN-EWDQ[/youtube]
etard
100 kW
You gotta stop posting those videos, or we are gonna get a huge influx of mid westerners freezing their arses off right now! :lol:
Man, those brakes sing, that doesn't annoy you?
Long flowy single tracks, I love it!
Just curious, what would you expect this bike to cost if you could build like 25 a year and still make it worth your time? Have you done a cost analysis?
Man, those brakes sing, that doesn't annoy you?
Long flowy single tracks, I love it!
Just curious, what would you expect this bike to cost if you could build like 25 a year and still make it worth your time? Have you done a cost analysis?
wojtek
100 kW
awesome video! great singletrack and you got some pretty good MTB riding skills! RESPECT
kfong
100 kW
Great videos, make me want to move out west. Excellent build! I notice you are running the same motor as I am but at 72volts. From what I have read, that V2T hasn't held up at those voltage levels. Keep us informed on how it holds up. I've been running mine at 40volts and have not had any issues. Hopefully this year I will get around posting vids as well. The max speed I'm getting is 20-21mph, which is all I need for the single track trails here in Mi. What is the max. speed you are seeing at 72volts? I am running with the V3 clutch and composite green gears. At those voltages I'm thinking a 9C would be more durable for your setup.
My brakes squeal just as much, when I replaced the rear one last year. The rear rotor was roughed up by one of the pads that was not mounted correctly, it actually fell off in the trails. I was tempted to replace the rotor to see if it would stop the noise but since it works I just left it. The Avid brake pads really need to be snapped in good, I'm sure other are similar.
My brakes squeal just as much, when I replaced the rear one last year. The rear rotor was roughed up by one of the pads that was not mounted correctly, it actually fell off in the trails. I was tempted to replace the rotor to see if it would stop the noise but since it works I just left it. The Avid brake pads really need to be snapped in good, I'm sure other are similar.
Beavinator
1 kW
- Joined
- Aug 17, 2010
- Messages
- 362
I can't even believe how cool that bike is! That ranks right up there with the Stealth Bomber in my opinion. Maybe even a bit cooler because of the carbon fiber. You really amazed me. A lot of people have ideas about building a bike like this but you actually saw the project through and that really impresses me. Good job!
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