Electric Motocross Bicycle build (Tons of big pictures)

[dpearce]

Thank you all for the compliments!

Whiplash:
Absolutely AWESOME! I can't wait to get mine going! You need a solid R/C motor in that thing so it can really haul! How many watts are you pulling with that setup? I may have seen it but don't remember..

It has a 72Volt battery pack drawing 50 amps, so there is around 3600W going into the motor.

etard:
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?

We are considering producing a small quantity of these kind of bikes, and possibly a frame and swingarm kit that do-it-yourself types could finish with their choice of components.
If we use a chromoly frame we can make them for around $7500US.

That would be for a similar configuration to this one, and with many upgrades available such as a front hub motor for AWD, up to 30Ahr of battery capacity, and a built in charger.
We are working on a revised model based on what we have learned from this one. Carbon fiber is very expensive..and of course we can do that too, but it is much more labor intensive. I am most familiar fabricating with metal, it is easier to do in quantity and is much cheaper.

We can build a chromoly frame/swingarm kit for around $2300, nothing is set in stone yet though.

If anyone is interested PM me.


kfong:
What is the max. speed you are seeing at 72volts?

It will do about 27/28mph or ~45kph right off the charger on flat ground, no pedaling, 200lb rider. It pulls hardest from around 10-20mph.

beavinator:
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!

Thank you!


More testing results..Here is a picture of the old planet gears and one way bearing, if you look closely you can see the crack in part of the bearing that was causing it to slip. There is only one that the picture shows, but there are actually 2 more cracks that are harder to see. The new one looks a lot stronger, it is all one piece in that area. I'll keep putting miles on it and we will see how it holds.

[kfong]

Great last video, definitely shows off it's potential. First time I've seen blue BMC gears, it's usually the hard green ones I have on my BMC or the white nylon ones that quickly turn to peanut butter. Do you have any info on these gears? They look like they are holding up to your higher voltage. Are you limiting the current on your setup at all? Above 40amps seems to be it's downfall.

[Mark_A_W]

I've welded my old (failed) freewheel solid, including welding the pins that hold the gears.

The BMC V3 freewheel is playing up, after 2000k's at 30 amps.

The green gears are fine however.



Just weld the freewheel up. If you have a decent torque arm you could then do regen as well.

[Mark_A_W]

Oh, and the video is frikkin awesome!

Had my heart beating when you were fanging it down that hill

[GCinDC]

that drop at 0:45 is spectacular! i'd love to see a close up/slowmo of that! looks like 8 feet!

awesome rig.

[Garrick_s]

Where are those trails ?!?!?
Is this in So Cal some where? do tell please!
I want to do that drop too!!! fun stuff indeed!!

PS - I had my clutch plate go out too.
Same "Older" clutch style (per Ilia at EbikeSF) - Older V1 style.
Mine had the blue gears too (which were stripped in the first 100 miles).

Great work on the bike.

[kfong]

Are the blue gears simliar to the white ones then? My green ones have been holding up, but I'm not running them at high power levels. Only 40volts at a limit of 35amps. Runing the V3 clutch on a 600w V2T

Where are those trails ?!?!?
Is this in So Cal some where? do tell please!
I want to do that drop too!!! fun stuff indeed!!

PS - I had my clutch plate go out too.
Same "Older" clutch style (per Ilia at EbikeSF) - Older V1 style.
Mine had the blue gears too (which were stripped in the first 100 miles).

Great work on the bike.

[wojtek]

Ilia said that modern V2S are holding up pretty well, he hasnt had a single complaint yet after 1 year of selling them. That V3 clutch was major improvement

i am also about to replace the old clutch on v2 to the new one. once done, i will be selling my bmc v2 perfectly laced to the most beautiful 26'' Mavic rim in the world

ex_729_disc.jpg (14.77 KiB) Viewed 1564 times

Are the blue gears simliar to the white ones then? My green ones have been holding up, but I'm not running them at high power levels. Only 40volts at a limit of 35amps. Runing the V3 clutch on a 600w V2T

Where are those trails ?!?!?
Is this in So Cal some where? do tell please!
I want to do that drop too!!! fun stuff indeed!!

PS - I had my clutch plate go out too.
Same "Older" clutch style (per Ilia at EbikeSF) - Older V1 style.
Mine had the blue gears too (which were stripped in the first 100 miles).

Great work on the bike.

[Alan B]

Really nice job!

[dpearce]

Update:

Finally Toasted the BMC V2-T, although I think it was avoidable.



Looks like some solder melted...

This motor has taken a lot of abuse, and I was beating on it pretty hard up until when it failed. I think it could have lasted many more miles if I didn't start going overboard with the wheelies, especially while going uphill. Overloading it repeatedly at very low RPMs to help pop the front wheel up, while climbing a hill, that's what did it in. I was also testing the limits of hill climbing before it happened as seen in the video below, so heat soak probably contributed. The way I normally used it it never got too hot, and a wheelie here and there didn't seem to hurt. About 20 in a row going uphill apparently does. In trying to find the balance point, I have done many more wheelies than that back to back on flat ground before and it seemed to handle it fine, but perhaps it was slowly building up to this.

I am going to try out the V3 next and see how that holds up to the abuse. Hopefully I will be able to fix this BMC V2-T. After the final wheelie that killed it, the motor would barely, if at all turn, and only once I got it to keep spinning under no load by starting the spin by hand, then I stopped it, throttled again and nothing.

Also we will soon be selling high performance electric mountain bike frame kits. They will be similar to the prototype's frame, but refined based on what we have learned testing it and based on feedback it has received. We recently won a competition at the university that gives us seed money and in kind services to jump-start our business, so keep an eye out for our products or contact me for further details. Ill have some better videos up soon as well.

http://www.ElectricMotocrossBicycles.com

[Ypedal]

Excellent video ! Might be the camera making it look more deadly but some segments of those trails look like they could hurt if you slipped off the path !! hehe..

I"m surprised the motor lasted as long as it did ! those geared motors are not built for this type of rough stuff..

[kfong]

Ha ha, that fall looks like a lot of my mishaps. Those trails look like a blast to ride. I'll have to post some of my trail rides this year.

The solder mess actually looks promising. The phase wires look in tact and not darkened. I suspect the heat just melted the solder and the hall effects let loose. Try resoldering it back. That has been a fix for many who overheated to where the heat melts the solder joints. Clean up the solder blobs though, you don't want those to create shorts later.

How did the gears look? I plan to abuse mine more this year with jumps. So far mine has been rock solid on 40 volts. If your gears look good after what you have been putting it through, mine should have no issues.

[Green Machine]

i have had nothing but bad luck with the v3...just had my 4th one leave me in one year.

My v2 600's are rock solid but only cranking 30 amps through them.

[Green Machine]

Congrats man on the press coverage and the 10k prize well deserved.....i hope you make a go of it...i believe you should atleast make an attempt of making a living of building and riding ebikes..i do believe its your calling. Just a word of advice someone gave me when i got out of college...helped a lot...just do what you love..dont worry about money it will follow. Sounds cheesey...but i always found that to be true.

It sucks your finishing college in this dog awful economic situation our forefathers left you...but it seems you may have a fun out.

When gas hits $10 a gallon....people will come a looking for products like yours...watch.
E

Student-designed bike to hit market
By Brianne Schaer
Staff Writer
Wednesday, April 27, 2011

A student-designed electric motocross bicycle will be on the market as a result of three Cal State Long Beach students who won the university's 2011 Innovation Challenge.

The prize included $10,000 to further develop the product and create a business plan. It also included important connections in the business world.

Mechanical engineering students David Pearce, Rogelio Rosas and Dan Southard worked together to build the bike, which is unique to the United States.

"There's nothing really out there that has the capabilities of our electric mountain bike," Pearce said. "None of the [electric bikes] had the performance we wanted."

The team's high-performance bike has the capabilities of a dirt bike and the practicality of a mountain bike. It is lightweight and powerful, capable of going uphill and over difficult terrain due to its heavy-duty suspension. It is also silent and emissions-free.

"Electric vehicles are pretty much the future," Rosas said. "So we wanted to build something that was innovative and fun."

The teammates were friends before embarking on the project.

"It was natural for us three to be in the group because we had chemistry and we all had experience," he said. "We all had experience and got things done."

A strong work ethic was essential in order to complete the project in a reasonable amount of time.

"The main difficulty was the time," Pearce said. "It was a pretty ambitious project to organize everything and make sure everything got done on time."

Another difficulty the group encountered was the lack of precedence in the electric motocross bike market.

"It really hasn't been done before, so we had to pretty much start from scratch," Rosas said about designing the bike.

Using the prize as a springboard to market and sell the bike, Pearce hopes to begin selling the bike as soon as next year.

He described their business plan, which focuses on starting small.

The bike will first be sold in a kit containing just the frame and the suspension so that the customer can personally build the bike. Then, later, the complete bike will be available on the market.

Pearce, who was not sure whether his team would win the contest when they originally entered, said he was glad to have won.

"We knew we had project potential," he said. "But we had no idea we would win. We put a lot of hard work into this project — we didn't just get lucky. We also had a lot of faculty support."

The College of Engineering and the College of Business Administration sponsored the Innovation Challenge.

© 2006 – 2011 Forty-Niner Publications

[danimal]

Thanks Green Machine for showing some of our publicity. I'm Dan Dave's partner on the project. We are hoping that will be the case, making e-bikes for a living is something we aspire to.

Just a quick update on what we have been up to with the project. We have been out riding and testing the EMXB and have started work on a new bike coming soon.

Here are some pictures from our most recent test ride:



Here is a link to the slide show: http://s616.photobucket.com/albums/tt24 ... =slideshow


The ride was great, but we did run into some issues with the BMC V2. It makes a strange whirling noise when the throttle is pulled hard, it seems something is loose inside like a spinning gear. The upside is it still works fine, it is just making a weird noise. The V2 deserves some credit though, this hub motor has been through a lot of abuse as you can see in the photos. We will be taking it apart for inspection and get back with more later.

[danimal]

Green Machine:
FYI this is another article for anyone who's interested, the picture is awesome the camera guy really knew what he was doing with the cool blurred background:
http://www.presstelegram.com/news/ci_17971132

Kfong:

Thanks for the advice! Dave re-soldered the connection and the motor worked fine again. The gears also looked fine upon inspection, no visible indication of wear.

[Whiplash]

Awesome bike, looks like the hub is working, but I am guessing it will be a limiting factor very soon!

[Green Machine]

Ridiculous pictures.

You guys are really doing it right.

Good luck i think you guys are right on in so many levels. For example its so rare to get some one on one of these high powered electric bikes who can actually ride them properly.

Keep it up.

Check out stealth bikes USA for how good video and photo coverage can be...there is a reason stealth is taking over the high end ebike market. They could use some competition.

[etard]

Gnarly drop, where are all the hubmotor naysayers that said it couldn't be done? Best of luck to you guys and thanks for bringing ES along for the ride.

As for price, you would have to sell the motocross bike for the same price as a high end DH rig for me to consider it, which would be somewhere between $5-6K. I would be almost as happy with CroMoly especially if I ever wrecked it and needed to repair it, CF may get you in trouble if you were to provide a warranty with the EMX.

You guys should bring that thing out to the Fontana Winter series. It's a pretty popular race series with a well known DH section.

[kfong]

That's great to hear you are up and running again. Also good to know the BMC is holding up to your abuse. It hasn't let me down yet and they now have stronger purple gears if the green ones don't hold up. I love how quiet these motors are, and they have proven to be trail worthy in my daily use. I even bought an extra one for a second trail bike.

Green Machine:
FYI this is another article for anyone who's interested, the picture is awesome the camera guy really knew what he was doing with the cool blurred background:
http://www.presstelegram.com/news/ci_17971132

Kfong:

Thanks for the advice! Dave re-soldered the connection and the motor worked fine again. The gears also looked fine upon inspection, no visible indication of wear.

[dennyt]

This is incredibly awesome. Just yesterday I was dreaming of building a downhill bike with a V2T in the back and 72V, and here I see you've far outdone that. Thanks for blazing the trail & sharing the info as you learn!

[dpearce]

Follow the build thread of our new EMTB build here:

viewtopic.php?f=15&t=32950



We should have some videos of both these bikes in action very soon.. We will also be building these frames for the DIY'ers who want to build their own electric mountain bikes.

[Timma2500]

Awsome build, i love it! An ebike C.F. frame is something i've wanted to do for ages after getting my C.F. EPX TerraShark normal mtb frame.
I'll be keeping an eye on your future frame building and new thread!

Bloody nice trails your riding too, your a lucky bugger!


Paul

[korpin]

these things still available?

[korpin]

i saw website anybody order one?