Versus Weapon X, Middrive BMC V2 and 22s a123 Prismatics

[kfong]

This is the start of my new build. Yikes up to 6 now, not counting the two I built for friends.

If you’ve been following my builds, you know that I’m really into trail riding, mostly single track. My BMC build was down for repairs this year. I lost over a month, mainly lack of time to work on it and a waiting game for a rear shock that went bad right after the install. It’s now running with a cheap fox vanilla coil spring. I’ll see if I like it over time. The good thing about coils is there is little to go wrong.

This started my quest for a new backup bike. It had to be better than what I built and had to be a bit different as well. I started looking into building my own frame or purchasing a custom one meant for ebikes. The components I wanted on this bike took that equation out of the picture. It looked cheaper to just get a good DH bike and convert it. I liked Doctorbass choice of the Team DH and was looking for that version as my next bike and actually had an 06 model I almost picked up, but it had less room for the battery. Browsing through ebay, the Versus Weapon X caught my attention. It had all the components I wanted in a bike and had enough room for a 10ahr pack, so I made a bid on it and was surprised I won. The only downside was the size of the bike. I would have preferred a medium, but I rode it yesterday and it passed my ride test. The only issue is the stand over height is going to be a ball buster for me. I rarely need to put my feet on the ground when trail riding so its all good.

Some interesting features that made me want this bike. Very high BB, 16” this means there is 12” of ground clearance. Log jumping won’t be an issue. Needle bearing pivots, this bike is build to take a lot of abuse. I compare it to a Clydesdale next to my Motobecane. The floating rear brake is nice, 888 fronts and fox rear are superb. Large brake rotors for serious stopping power. I plan to put batteries in the triangle as well as the front of the bike to increase my range. This bike was built to jump, 9 inches of travel for the rear and 7-8” for the front. Big Maxxis tires. I knew it was going to be a beefy bike, but the down tube is ridiculously wide and over built, much like the rest of the bike. I don’t think I will be breaking this frame; it will end up breaking me.

Some things not so great, only one front gear. I like a larger range for my trail riding. Especially during break downs. The rear axial is going to be a challenge to mount the BMC to. I will need to CNC mounts for this. The bike is over 50lbs already so it’s going to be a heavy ebike. The handle bar is the biggest I’ve come across, 28.5” wide. Nice for ebike accessories, but sucks for narrow single track. I’m not sure what I plan on this part of it, but obviously the bike is meant for a wider type of trail riding and won’t turn as well due to the geometry. This is all fine with me since I have my Motobecane for that and I didn’t want a duplicate ride, just as long as I can get out in the woods.

It’s been raining all day today and will be the rest of the week, so outdoor pictures of the bike will have to wait. This bike will be my winter build so don't expect much progress for a while.

[nicobie]

You weren't kidding when you said you would break before the frame did!

Is that extra bar to reinforce the rear brake mount? Reminds me of the torsion bars we used on drag cars to help prevent wheel hop. Very nice.

BTW, were you able to get any use out of that toasted BMC-S I sent you?

Nick

[kfong]

Yeah, this bike is impressively built. I can't even wrap my hand around the down tube. I will post pics of it side by side with my Motobecane when the weather clears. It's like comparing a gorilla next to a monkey.

That bar is what is needed for a floating brake. It locks the brake to the frame rather than the suspension. It's suppose to improve braking, but will complicate the motor install.

I took a look at the motor, will try to fix it and use it as backup parts. It will allow me to be more aggressive with the new motor. I picked up a second BMC motor when there was a sale on them this summer, it had dual phase leads and updated clutch. It was meant to be a backup, but I realize I need two trail bikes now, so I'm not waiting on repairs. I plan to run the bike at 50volts. 12S or even higher since this new bike can easily handle any speed I want to push it to. As long as I have one reliable ebike for the trails, I can have fun experimenting with the other. There is an area built by the metro park for mountainbike trials, but turning into more of a bmx playground. Big ramps, looking forward to taking this beast on it.

Didn't know yours was a speed version, I will have to try to duplicate the windings if I end up rewinding it.

You weren't kidding when you said you would break before the frame did!

Is that extra bar to reinforce the rear brake mount? Reminds me of the torsion bars we used on drag cars to help prevent wheel hop. Very nice.

BTW, were you able to get any use out of that toasted BMC-S I sent you?

Nick

[oatnet]

Nice frame, I look forward to seeing what you make with it.

-JD

[GCinDC]

*subscribed* I came so close to bidding on this very bike! I look forward to seeing it's progress.

[bzhwindtalker]

AMAZING bike!! Thats one hell of a frame!!

[kfong]

Thanks for the comments, the weather is still overcast so no pics. I was able to ride it a little more around the block, I'm really impressed with the floating brake setup. You really feel the stopping power right away. With a regular full suspension, especially ones with long travel. You get a spongy feel when braking. The back brake feels more effective than the front, but is easy to lock up. I doubt that it stops better, just responds better. The front when stopped, you feel yourself plunging down into the shocks, so the delay is noticeable. Definitely a worth while addition, but a real pain to keep. It's threaded into the axial with a large bearing for isolation. This axial is larger than my hub motors axial! This means I will have to make one similiar that threads onto the BMC's axial or do away with the floating setup, which at this point I would like to keep.

After studying it a bit more. The best approach seems to be replacement of the two rear most sections with custom CNC parts. I lucked out on this design, since most bikes are one piece rears. This will allow me to integrate the torque arm and create pinch clamps as well, making it easier to change out the tire.

[kfong]

Finally, some clear weather. Here is some eye candy. The frame is so way overbuilt on this bike. Check out the massive swing arms. It all adds weight though.

weapon lt.jpg (127.91 KiB) Viewed 2050 times

weopon rt.jpg (122.84 KiB) Viewed 2050 times

weapon rt1.jpg (126.79 KiB) Viewed 2050 times

I thought I would put a side by side comparison of the Beast against my other bikes. For those of you who have no idea what a DH bike is like.

Here is what I consider a Heavy weight division against a Middle weight. I thought the Kona was a tough ass bike but looks sadly weak in comparison. The Kona will have an RC setup when done. It's toughness comes from having mostly BMX parts. It was designed for jumps and terrain parks. A very tough bike to break.

weapon VS kona.jpg (100.6 KiB) Viewed 2050 times

Now the Heavy weight against the Light weight division.
As you can see, the Motobecane looks like a weakling in comparion. Still this is my choice for single track riding. Light and nimble. This is pretty much your standard mountain bike frame. The Beast will be used for speed and Jumps and the Kona with the RC will be used for BMX parks.

weapon Vs motobecane.jpg (101.33 KiB) Viewed 2050 times

Hopefully, this rounds up my ebike collection.

[kfong]

With all my break downs this past year on my Motobecane, I'll be glad to get this one running next year as a backup. My big concern is using Lipo's. I plan to install them in the triangle frame on this bike as well as up front in the forks. I have been avoiding Lipos, until this year. I now have a plan that I'm comfortable with on how I want to charge the packs, but need to get boards sent out to implement this.

For those who are actually doing a lot of trail riding with Lipos, have you had any issues I need to be concerned with? I'm worried about all the pounding and possible abrasion they will encounter. I plan to balance charge each time to avoid any surprises like I found recently on my Konions. This will force a safety check during each charge, since I will not be able to visually inspect them each time. With all the vibrations and pounding of trail riding, I want to reduce all possible problem areas. I will be making a custom battery holder like I did with the Motobecane build, as well as a fiberglass cover. This time around I plan to use nomex as part of the shell in case of fire and vent holes to direct it. I plan to have the battery tied down as secure as possible with a thin layer of foam for impacts, but mainly as a cushion between the frame and pack.

[sn0wchyld]

With all my break downs this past year on my Motobecane, I'll be glad to get this one running next year as a backup. My big concern is using Lipo's. I plan to install them in the triangle frame on this bike as well as up front in the forks. I have been avoiding Lipos, until this year. I now have a plan that I'm comfortable with on how I want to charge the packs, but need to get boards sent out to implement this.

For those who are actually doing a lot of trail riding with Lipos, have you had any issues I need to be concerned with? I'm worried about all the pounding and possible abrasion they will encounter. I plan to balance charge each time to avoid any surprises like I found recently on my Konions. This will force a safety check during each charge, since I will not be able to visually inspect them each time. With all the vibrations and pounding of trail riding, I want to reduce all possible problem areas. I will be making a custom battery holder like I did with the Motobecane build, as well as a fiberglass cover. This time around I plan to use nomex as part of the shell in case of fire and vent holes to direct it. I plan to have the battery tied down as secure as possible with a thin layer of foam for impacts, but mainly as a cushion between the frame and pack.

for me, its early days, but so far so good. Im using these http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=15521 inside a padded pvc case. Had a small crash the other day where the bike slid/bounced down a rocky embankment on its side, but didnt seem to have effected the batterys or cases at all. Im bulk charging 90% of the time too, just using some temp probes and some 8s monitors to let me know if anything is getting messy (high temp alarm + delta V and High V alarms). Im planning on balance charging every 10th cycle or so, so I can monitor if any of the cells IR or capacity changes dramatically. Afgter seeing the abuse that the more modern lipos can take im not tooooo worried, im more 'very cautious'. the IR+temp+capacity should tell me if any cells are going bad, particually since I cant see if these are getting puffy .

Id say just pad them fairly well, so they cant move due to vibration or shock, and then make sure the case can take a few knocks. abrasion shouldnt be an issue if you keem em from moving, so build a tight fitting case (or use plenty of padding). And temp probes are a good idea, since you'll be able to see if any packs are warming up excessively compared to their neighbours, a good indication that something isnt right (unless you've just parked it with one side in the sun).

[kfong]

It's my third season trail riding. My konions have held up exceptionally well, even after dropped from the rear rack a few times. I will be avoiding any rear racks with this setup. The vibration finally did the battery in the frame in, even though they were secure. It's a very harsh environment. I even had a couple of the mounting bolts that held the battery shear on me, luckily the other 4 bolts held. I usually get several hard crashes a year, and numerous small ones. I've gone over the handle bar several times, that usually gets the bike rolling. During those 3 seasons i've broke 2 frames, bent wheels, lost spokes, countless flats, went through 5 rear racks and one brake handle, and currently down due to a punctured brake line. I would stick with konions if I could, but it won't give me the voltage or power density I need for this build.

I plan to add fuses and I like your suggestion of temp gauge for the battery. I won't be able to visually inspect these packs so I need to put in as much safety measures as possible. One concern I have is how the bottom cell will hold up after repeated compression. With konions you have a metal case that gives it structural support. Ideally I would have each pack in a compartment, but realistically they will be stacked two high. The very bottom cell well bear all that weight. With a good jump, that repeated pressure has me worried. I might have to go with the hard cases as you did, but they don't come in 6s.

[Kris B Krunch]

Any updates on this build?

[kfong]

Been too busy with my other builds. This one won't be started till late spring, but by then I might be riding too much to get around to it. It was meant to be a backup for the Motobecane. I just installed a new rear shock on that bike today. Ordered a brake rebuild kit today as well. Trying to get that bike done since spring might be early.

[kfong]

I've had all winter to think about this build. I was planning to put a BMC hub motor on it but was undecided about how to install it on such a custom rear frame. It looked like a bit of machining was needed to do it correctly. When I saw Tench's middrive hub motor setup and between Whiplash reviews and Tench's, it sold me on the design. I will be going middrive with this bike.

This would solve a few of the things I was concerned with. The install should be easier, I won't have to deal with the floating brake and it will allow me to keep the bike mostly intact. The use of gears should allow me to have lots of torque and give me more speed. Going middrive should protect the gears on the BMC. Fortunately I have a bottom bracket height that is unusually high on this bike, so there isn't much concern with the motor hitting things. Seems like the bike was destined to be a middrive all along. Balance will be better as well. Already placed an order for A123 prismatics. Going all out with 72volts or will tone it down depending on what I like for the end results. The only part I have to compromise on is battery placement. It looks like they will be placed in front, mounted on the forks. I would prefer them in the triangle, but the dimensions of the prismatics are just too wide. I can build a 12S 10ahr lipo pack for the triangle later if I need better handling.

Oh, the best part none of the noise associated with an RC build and all the benefits.

[kfong]

Not much to update but I've been slowly getting parts for this build. Thanks to John Holmes, I have 22 a123 prismatic batteries for this bike. Looks like I will follow j3tch1u's clamp setup instead of going with the pcb route. I've also decided 22 lbs all up front would hinder my dh bikes performance. Instead I plan to break it up into three sections, with some up front and on the side of the bike using custom molded fiberglass cases. Hopefully by fall I will be up and running, hard to get much done with the warm weather.

I currently need to mill down the BMC motor so it has a smaller profile and figure out how to install a gear or left hand freewheel onto the motor. A normal freewheel would be rotating in the wrong direction.