My dream bike

[motomoto]

I did a thread a while back entitled "Another DH Project" which resulted in this build.



This project was to get my "feet wet" in electric bikes. I learned a ton of stuff and think
my next step is to build a bike from the ground up.

Lately I have been obsessed with this bike that was put on the internet briefly.



It has a lot of the characteristics that I want in my build. Mine will have
a longer wheelbase and some kind of motorcycle type seat arrangement.
Here is a mockup of that.



I know it is weird, but that is just playing around with the idea. On the bike that
I have, I find that it cannot be ridden standing up as the bike tries to shoot out from
underneath you. You have to be sitting down when the throttle is applied and one
seating position isn't enough for dirt riding.

Another thing I want is covered battery panels on each side of the bike that can
be easily removed and replaced with a panel of fresh batteries. There is nothing
worse than not being able to ride when you have just gotten warmed up with the
first ride and are just getting into it. I major complaint about electric bikes. You
don't want to sit there and have to charge batteries for 2 hours when you want to ride.

I was thinking after watching this video of a Zero electric bike, that all you need
is a race course with 10 mile loops and some quick change batteries and you could
have some bitchin' electric races where you cover 50 miles.

[youtube]PHKXP_YA40s[/youtube]

 

[POPS]

Hi Moto

Very impressive build.

Do you have any other stats. on the Ebay bike.

Price, motor, Batts, Etc.

Looks lots like a Greyborg.

Rick

 

[motomoto]

I have no data about the bike. I hope someone can find out something about it. I will
keep looking. I would like to see it in action. 12K is a lot of power!!

 

[POPS]

It's A dream bike to me too with perfect stats.
I hope you find some more about it.

 

[kfong]

Nice bike, haven't seen that one. Curious about the power plant. Looks to be a midrive setup with a custom gearbox. Hard to tell how wide the body is, that's a lot of battery capacity to put into a frame. I wonder what chemistry he is using. Frame looks custom as well.

 

[motomoto]

For all we know, all the numbers they are posting, might be what they are 'shooting for'.

I don't even see a motor, let alone a 12Kw motor. 12Kw should do more than 55 mph.

3kwh of battery is 45 plus pounds. That is possible at 90 pounds, if there was nothing
else adding weight to the bike.

I just see from the picture they did a lot of things right. Like having the swingarm pivot
right at the chain line, so there is minimal suspension distortion from the chain pulling.
The suspension is done correctly from my perspective. There is a lot of weight on the
front of the bike from where the batteries are placed but it might be a good thing. My
bike is too light for the power and wants to flip over backwards, and also wants to
shoot out from under me if my ass isn't planted on the seat. So the weight should mellow
things out.

 

[Green Machine]

That bike is presumably using a modified optibike motorized bottom bracket and is the personal project of Optibike owner's son Nicholas Turner. There are no indications that this bike will be in production by otpibike...it's essentially an optibike home build.

 

[kfong]

Yeah, I thought that middrive setup was a bit too custom for the average builder. I wonder if they are using the factory gearbox. It would be great if they sold just the bottom bracket gearbox setup. More pictures if anyone has any to post would be great. They really should produce a custom high power setup like that, I'm sure they would have buyers. I'm slowly acquiring the skills and tooling to do my own gears. It would be cool to build custom bottom bracket gearbox and frame. I'm sold on the middrive designs.

 

[Miles]

Hmmmm... 12,000 Watts @ 100rpm = 1146Nm at the bottom bracket.....

 

[Green Machine]

It probably runs in the family to exaggerate performance numbers .

 

[bzhwindtalker]

12kw offroad on bike transmission components is not going to work well very long, especially with small chainrings! I am breaking stuff all the time on only 2500w (4000 peak)
Chains, sprokets, derailleurs... Tensile strength of a typical bike chain is about 1200kg if I recall? Multiples speeds are kinda pointless above 5kw anyway, excepted if you want to go over 40 mph and do 10mph trials riding on the same bike.

1200N.M at the bb sounds like an awfull lot of torque, my guess is that this much torque would just break all the sprocket teeth right at their base haha

 

[Miles]

Tensile strength of a typical bike chain is about 1200kg if I recall?

1200N.M at the bb sounds like an awfull lot of torque, my guess is that this much torque would just break all the sprocket teeth right at their base haha

1200Nm on a 100mm dia. chainring would be about 2500kg force on the chain......

 

[bzhwindtalker]

Yeah something is wrong on those specs, they look appealing, but they are not working. This is why my bottom bracket spins to 250rpm and only drives 30t, and I broke some chains going full blast on the low gears. I just can't imagine the mess 12kw would make of a bike transmission set

 

[full-throttle]

Tensile strength of a typical bike chain is about 1200kg if I recall?

Ultimate tensile strength under ideal conditions for a new 1/2" x 1/8" (track) chain. Multi-gear chain is weaker and any misalignment reduces the strength

I'm only 65kg, yet snapped half a dozen chains in sprints. Both new and used, but mostly used. Including a crushed roller

Perhaps the decimal point is missing in the spec - so it should be 1.2kW, same as the highest power Opti

 

[nonlineartom]

I can identify that charger as being a 2KW BMS battery alloy shell bulk charger

It also looked like he's using Avid BB5 cable brakes. You need big hydraulic breaks if you really are pumping out 12Kw. Those BB5's will be toasted in minutes if there really is 3KWh of LiPo going 55mph.

Also looks like a 24fet controller on the frame there. Guessing she is pretty wiiiiide

 

[POPS]

Just 1 comment on the Vid.

The guy rideing the Zero is one hell of a rider.

Rick

 

[motomoto]

12kw offroad on bike transmission components is not going to work well very long, especially with small chainrings! I am breaking stuff all the time on only 2500w (4000 peak)
Chains, sprokets, derailleurs... Tensile strength of a typical bike chain is about 1200kg if I recall? Multiples speeds are kinda pointless above 5kw anyway, excepted if you want to go over 40 mph and do 10mph trials riding on the same bike.

1200N.M at the bb sounds like an awfull lot of torque, my guess is that this much torque would just break all the sprocket teeth right at their base haha

I have a bit of data on the chain and sprocket situation. Yes, 12k through the drive system is pretty crazy. I am building a slipper sprocket for the sprocket that
drives the chain to the rear because you don't want to approach the tensile strength of the chain at any time, not even for an instant.

I think if you gave the chain and drive system that kind of protection, you could do some amazing things with less than 12k. On tight trails an electric downhill
bike is faster than a 450 dirt bike, and I ride dirt bikes almost every weekend. Here is an example.

[youtube]KqBy1R7IMGE[/youtube]

 

[full-throttle]

Here is an example

Are you saying Gee would be faster on LiPos? :lol: