Another Stealth bomber (clone) build

Did you ruin a line or two of that lovely grassland?

shortcircuit911 said:

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@markz Lol no. There is a regional park by my house that has hiking and biking trails. I've been going there towards 6pm when there are fewer people on the trails. Never been much of a trail rider, but am starting to get into it.

I got a 12v brushless fan installed on the bike to help with the thermal issues I've been seeing. I won't have time to test until this weekend but I'm hoping to get extended run time on the bike before hitting the thermal protection limits on the controller. The only thing I don't like is how loud the fan is, but it'll have to do for now. Going to look into water cooling soon.

Fan: https://www.digikey.com/product-detail/en/delta-electronics/BCB0812UHN-TP09/603-1213-ND/2034820


Going to get a pack of these as well:
https://www.summitracing.com/parts/ufi-ufv-6?seid=srese1&gclid=Cj0KCQjw0brtBRDOARIsANMDykbwTSyIXDhngpagTGjWKST4RcLVkhtlHrjuW72Kz63aTf6JZy8GTuMaAof-EALw_wcB

Another solid day on the trails today, with video this time. Max power pulled was just under 14Kw and 90% of the video was uphill (steep and choppy). I had a fan in place this time and right when I came to the stopping point in the video the thermometer light on the dashboard changed meaning it was getting hot. I took a 3-4 min break and the light had already changed back to green and was ready to rip the entire ride. I really need new forks as the zooms are shit, a new tire is a must as well. More to come.

Video: https://youtu.be/7-ADTMlIMw4

Here's another video of the same trail, but this is the descend, so most of it is down hill. It was a nice reminder that I need to get a better front tire and possibly upgrade the brakes. The front forks of course will get upgraded, hopefully this year.

I have ordered a shinko 244 2.75-19-43 for the front. I'm hoping to get it mounted on the front for next weekend so I can test it out on the trails. I should be doing some riding back home over thanksgiving, so I want to get the bike as dialed as possible (on a budget) before then.

Tire: https://www.ebay.com/itm/123721699038

Video: https://youtu.be/fvWGIXNt72k

Shortcircuit911. Quality video....amazing scenery to. Would love to visit the states.

@choppa what's up man? How are you and the bike doing?


Well I pushed really hard to get a bunch of improvements done on the bike before hitting the trails this weekend. One of the mods/fixes was the front tire. I got the shinko 244 mounted (by a LBS) and daaaaamn that things is wide, a little too wide. The offset of the wheel in the forks makes the tires just too fat, if you don't have an angle grinder . About 20 min and a bunch of burnt rubber later, the tire fit!

So my worst fear came true today. I finally hit the trial on the bike with all the improvements, and it was running great. I was able to carve in turns better because of the front tire, and the front end felt a bit more stable. After going through my usual trial I decided to go a bit further to the end of the trail and all was good. On the way down I was hitting some decent regen, nothing crazy. As I was approaching the point where I usually head back I was rolling at about 10 mph, then heard a clank and rubbing and the rear end felt very wobbly, wtf. I laid the bike over and was horrified. The axel of the qs205 sheared on both sides of the shaft! 3 miles into the trail (where I entered). After much debate I decided to hide my bike and walk back (in full gear) to the entrance where my wife could meet me. I started making the trek and climbed the largest hill and was going down when I ran into a guy on a mountain bike. He could tell I broke down and was trying to help. He told me there was another entrance closer to where I broke down and walked back with me. Luckily the ranger station was about 1/2 a mile down a trail I've never been down and he went to get the ranger for me. She came about 5 minutes later with a truck and the guy who helped me load my bike up. She drove me to the street entrance where my wife could pick me up. She kindly told me ebikes were allowed on the trails if I ever get it going lol
Whew, this was a huge save because it would've been brutal walking those 3 miles in full riding gear then having to come back and some how get it out. Huge thanks to Pedro!


So I've secretly been planning to turn my bike into a swingarm mount drive system. The un-sprung weight of the hub really sucks off road and as a result of repeated abuse, left me stranded today. The hub motor never felt right off road and it's failure confirmed that they're not suited for off-road use. Time to call Lightning Rod's! Hopefully the conversion won't break the bank and I can start acquiring parts soon.

That sucks!

This just reminded me to check my dropouts..

Any pics from dropout side? I bet its not in "like new" condition . Seems from the nut pic that it has been turning back and forth for some time but hard to be sure. QS axle should be strong but everything fails if it has regen and some room to wiggle.

What can you do?. 12/14 mm drop outs

That's not alot of metal, for a massive amount of power, happens alot unfortunately.

As controller and battery technology moves on drop out foundations stay the same.

Wow sorry to see that bad news

Shortcircuit911

Hi,I'm good thanks..you? Though not that good buy the look of it!! that sucks about the bike and motor! Though I guess if its gonna do it then at least you weren't flat out on the road or somewhere and got hurt. I'm with mxer on that one,just don't know why the motor manufacturers arent improving on the whole axle/dropout bit? And I guess the frame manufacturers cant do much about it until the motor design changes? I'm still doing bike,though haven't done much on it for a few months,still got the electrics to do but the bike is back together as a rolling frame,with all the brakes and things sorted,and I'm finally happy with it. winter here now so time to start on with it again.goodluck with the new motor/build,keep posts and pictures coming.

@choppa, thanks for checking in and saying what's up.

ossivirt said:

That sucks!

This just reminded me to check my dropouts..

Any pics from dropout side? I bet its not in "like new" condition . Seems from the nut pic that it has been turning back and forth for some time but hard to be sure. QS axle should be strong but everything fails if it has regen and some room to wiggle.

Click to expand...

Pics below and yeah they were beat up. I was only able to find one side of the axle when I broke down. It's hard to say how long the nut was turning back and forth, but it didn't last long. M6 hardware was clamping the dropouts shut in addition to the torque arms being bolted to the swingarm with M6 hardware as well. I've been pretty good about checking bolts and dropouts, definitely checked before that ride, it was just inevitable.


I've been reading up a lot on Lighning Rod's Big Block setup and that looks pretty sweet. Unfortunately with timing I probably won't be able to overhaul my bike until next year. Will slowly start saving for this as it won't be cheap. Anybody want to buy a busted QS205 shoot me a PM (U.S residents only)?

I read this :https://endless-sphere.com/forums/viewtopic.php?t=82936
There was lots of good info in there if anyone is thinking of alternatives to hub motors. I'm convinced a chain driven big block will suite my riding style nicely. Will post when there is some progress.

Sorry to see the damage. It looks like you didnt have anything holding the wider part of the axle flats? (on the brake side) I only have one of the included torque arms holding that part, maybe it is time to upgrade..
I also put shims between the axle flats and dropouts to prevent the axle from moving, better dropouts would be a better solution..

@bjork possibly. I think part of the problem was that there was always some play between the torque arm and the axle.

Well it's been a while with no progress on the bike. Since it broke I basically drained the battery to storage voltage and let it sit. Over the holidays I placed an order with LMX out of France for some rear wheel parts. The plan is to go with lighning Rod's BB mounted under with swingarm, and to build a new wheel to drive the bike.

The parts I ordered from LMX are: Rear hub, sprocket adapter, 94t (219) sprocket, and some spokes. I ordered it right before Xmas and the parts showed up right before new years, lightning fast. I'm going to try and lcae the wheel myself and see how that goes, otherwise I'll take it to the bike shop. I also want to get another shinko for the rear as I think it's a better tire for the riding that I do. Hopefully I can get the wheel built soon then hopefully buy the motor in about a month for my b-day and we're in business! So much more to come

if you're going middrive, this doesn't really matter, but just for future readers or if you go hub again:

regarding the dropout picture below:


the clamp doesn't work as well as it could because there is no slot at the inner end. meaning, the only part that really can clamp down on things flat is the part near the clamping bolt.

if you instead add a cut (slot) at the end of the dropout like below, with a drilled hole as a crack-stop, it might help the axle be fixed in place better. it depends on the metal hardness, too, if either axle or dropout is much different in hardness from the other, then one will bite into the other. not sure if it matters if it is only surface hardness or requires the same hardness throughout the metal, but i know it is a factor.

Thanks for posting amberwolf!

Got the rear wheel laced up after the 3rd try which wasn't too bad. The only issue is that the spokes are too long. I got everything but the rim from them which I believe is the issue. They are using a different lacing pattern than I am so that is likely the issue. I took a spoke off my front wheel because it's from the same set as the rear rim which has a similar lacing pattern. The front spoke is 200mm and the spokes I got from lmx are 218mm. The plan is to get to the lbs and buy some stainless steel 12ga spokes so I can finish this wheel.

The next thing to think about it pedals. I don't plan to pedal but its nice having them because they make the bike look the part. I might just ditch them and go with pegs and make this thing completely what it is, a motorcycle. Another option is to make a spacer and have the rotor and drive sprocket on the same side which would allow me to keep the pedals, we'll see how it goes.

I started mocking up the wheel and getting an idea for what needs to be modded and fabbed. I'm thinking a bolt on extention to the swingarm that looks just like the end of a dirtbike swingarm. I can machine all the needed plates and hardware needed to make that happen as soon as I get the wheel sorted.

Hi, it seems you laced it as 2x but our wheels should be laced 3x to fit.
Best regards, Adam

Hey Adam, thank you so much for that comment. I looked up what you said and was able to get the spokes to fit in the wheel. I think you helped me when I placed my order as well, you've been super helpful. Thanks! I also want to say you guys have a great deal on those spokes, they're sapim and other vendors are charging $1-2 a spoke, you guys are crushing it. I wish I could afford one of your bikes or at least a rolling frame, you guys are one of the top vendors in my opinion. I will be back for more parts!

Well the wheel is laced and at the local bike shop to get trued up I also just placed an order for another shinko 244 and heavy duty tube for the rear wheel. They will be dropped shipped to the bike shop so I should be able to pick it up next weekend. I also made the spacer for the brake rotor and drive sprocket interface. The material is ldpe because the part is only serving as a spacer. I still need to figure out the right side of the axle to connect a sprocket to the hub for the pedals. I plan to run pedals for a while and see how things go.

I've marked up the swingarm where I want to modify it for the extension/conversion to chain drive. The plan it to add some extensions to the swingarm which will require trimming some of the swing arm to make it happen. It will also add the width to the rear, and the length necessary to run the big block motor. I have started machining the swingarm extensions for the custom axle I'm going to make for the rear. It will be like a traditional dirtbike swingarm and have about an inch of adjustment. I'm going to machine a piece to fit in the cutout and weld a 10mm hardened socket head screw to it. Once these things are done I will be ready to order the big block and I will hopefully be in the home stretch after that. If all goes well I can have all the fab done by next weekend when I pick up the wheel. I will need to figure out what needs to be fabbed to make the new caliper mount for the rear brakes when the wheel comes back and can be set in the new swingarm. Once that it done I plan to powdercoat the swingarm because there is some rust forming on it from my shitty paint jobs in the past(paint it came with was shit too). Then all is well

I'm really excited to see how the bike is going to handle. The major improvement is the rear wheel weight. When I get the wheel back from the bike shop I will put it on the scale along with the old wheel since it's in it's original condition, the difference should be huge. I have pulled the front end because I remember it feeling a little rough and sure enough, the bottom bearing was destroyed. Both bearings were destroyed when I tried to remove them, but they left their outter race in the headset which is unfortunate. The plan is to dremel out the outter race and get some sealed bearings for the headset and hopefully call that done. It would be nice to have some new front suspension eventually which would be the next major improvement needed to make this bike handle the way I want it to. Another thing I'm excited about it how well the motor should perform once tuned with the Mobipus. The big block only needs like 80 amp and the Mobipus can push 200A battery and 375A Phase so I plan to install a temp sensor and hook it up to the mobipus so that the controller doesn't kill the motor. When I was running the QS205 full blast in the trails I was pushing so much current through that damn hub to get around. It is going to be really nice not having to worry about the controller getting hot when riding. I will keep the same 3 speed switch for the new setup and play with the settings to get the 3 profiles setup to my liking. The gear reduction should hopefully make the front end come up much easier as I like to ride wheelies and hit jumps. More on progress soon.

Well I've been able to get quite a bit done since I last posted. I did all the cutting and grinding to the swingarm. I also stripped most of the paint to powdercoat after much more modding to the swingarm, more on this below. I also finished the machining on the rectangular tubes that will be welded to the swingarm. I also made a 160mm spacer for the welding process and machined the blocks that will locate the axel in the swingarm. I'm waiting on a longer bolt which will be the rear axel (M10 X 240mm socket head hardened screw) so I can tack weld the arms to the swingarm and bring it home for a test fit. There is a little bit more machining left on the tubes and they will be ready to weld, hopefully this will happen by the weekend.

I checked the shpping for the tire and tube today and they arrived at the bike shop today. I'm going to call him Saturday if I don't hear from him. I'm not in a hurry for it, but would like it this weekend to make more progress. I always let him call me because he is usually doing grunt work like putting moto tires on a 40lb rim on for me, instead of tuning up road and mtbs.

I found a sealed bearing headset kit on ebay which should be here on Friday. I already cut out the old outter races with a dremel and some pliers. The front end should be much robust and sealed from dust. It should all be back together this weekend.

So I brought the scale down to the garage and started weighing stuff. I put the old rear wheel (qs205) on the scale and it came in at a whopping 41lbs! I'm hoping the rear wheel comes in under 15lbs as the front wheel is 12lbs. After weighing a bunch of parts and doing rough math, the bike should be in the 100lb ball park, probably over by a few lbs. I'll get a final weight when the retrofit is complete.

*****UPDATE TO THE BUILD PLAN*****

After some research and talking to trazor here on the sphere (he has the open emoto thread) and he was saying the big block gets hot faster than the denzel 4500 which is a bit better. After reading that and Grantmac's suggestion of the QS 120 2 kw mid drive motor. After reading up on that, I'm sold! It is cheaper than the big block and it has way more torque (specs below) . I will have to go to 428 instead of the 219, but that shouldn't be a big deal. The real change is going to be like the swingarm. I plan to modify the front of the swingarm to look like the cyclone kits (pic below). This should take care of the ground clearance issue, move the drive sprocket very close to the pivot point of the swing arm, and balance the weight much better than it was. I'm hoping after this mod that the bike will be an absolute beast with the QS motor and the Mobipus at 100A (battery) and 375A (phase) with 6:1 gearing.

Hoping to make a lot of progress this weekend, keep you posted.

*****Sorry for the bad lighting in some of the pics, will get better ones soon.****

QS 120 motor:
https://www.aliexpress.com/item/4000076478471.html?spm=a2g0o.detail.1000014.31.3d6240f5GdQDk9&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.13338.128125.0&scm_id=1007.13338.128125.0&scm-url=1007.13338.128125.0&pvid=ed6e0398-86c6-4288-8069-dc1ed39bd3d0


headset bearing kit:
https://www.ebay.com/itm/JESSICA-1-1-8-Threadless-44mm-Bearings-Mountain-Bike-Headset-Sealed-Frame-Parts/173596262980?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Made some progress this week in a few areas. First, the headset came in which was really easy to install. I used some 3/8" all thread 2 washers and 2 nuts to compress the new cups into the frame. The sealed bearings are a slip fit which is really nice. The front end is back together and ready for action.

I was also able to get the swingarm mocked up for some fitment on the bike. I set the rear width with a spacer and some washers and just tacked the rear extensions on to make sure a few other things are ok. There is still a lot of work that needs to hapen to the swingarm to accept the new motor. I still haven't ordered the motor and probably won't until next month. In the mean time I'm going to laser cut some templates and start drawing things up in CAD. I plan to make a 'motor' out of the templates which will help me with placement and design. More on that soon.

The bike shop called me and told me he's having trouble with my wheel. When I laced it, some of the spoked had a lot of extra length and some had just enough. He was a bit confused as well and was going to reach out to Adam at LMX to see if he could help, hopefully he can get the wheel done soon as I need it to set the rear end. Hopefully this week, we'll see.

Hey Shortcircuit911,

I'm sure you're probably already aware but just in case you're not,
The QS mid-motors a really wide (see below link)

https://ae01.alicdn.com/kf/HTB1A5xeauL2gK0jSZFmq6A7iXXaQ.jpg

The link is to a QS138-70H but I believe the length is similar and only the diameter changes.

But as I said you may already know this.

Cool build by the way 8)

@chambers, thanks for the reply and kind words. You're right, it is a long motor but has so many pros. I'm going to make a mock up of the motor out of a template I made in solidworks so I can have a physical representation of the motor to see if it's something I want to pursue. Excellent observation! If the dimensions won't work I'm probably going to go with the original plan and get the big block, I see he's expecting some more in this week. We'll see how it goes.

No worries,

I'm planning on using the 138 in my build so it can definitely work just might take a bit of wriggling.

I agree the specs are hard to resist.

@chambers, dude just realized which build thread is yours, awesome start! That thing should be pretty sweet when you get it going, good luck with it all. You were right, that motor is just damn long. I made the mock up I've been threatening to make and just sat it on the swingarm and stared at it. Even with the wider swingarm and going chain drive on one side and brake on other (no pedals in the mix) and even then it still isn't going to work, there would be a huge imbalance because of the motor hanging off of the bike. Bummer.

So it looks like the Big Block is back at the head of the pack as far as options. I was looking at the cyclone motors and didn't like any of them, and the denzel stuff looks big and awkward with that huge flat plate used for mounting. If anyone knows of anything better that I've missed, let me know. Luckily Amberwolf bought my qs205 so that adds to the new motor fund. Hopefully I can make a decision and be able to pull the trigger in the coming weeks.

I still need to check in with the bike shop and see if the rear wheel is ready to go. Hopefully he gets it done this week but who knows, I really don't want to rush him. I was surprised he was having trouble, but to be fair it's a weird mix of parts that he doesn't deal with often/ever. We'll see how it goes.

shortcircuit911 said:

Even with the wider swingarm and going chain drive on one side and brake on other (no pedals in the mix) and even then it still isn't going to work, there would be a huge imbalance because of the motor hanging off of the bike.

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what do you mean by "imbalance"?

if you mean the weight/mass, i doubt it's going to make much difference, especially at axle-height. your own weight moving side to side and whatnot will make a lot more difference.

if you mean the looks, well....i suppose you could make a shell or something for the chaindrive side that looks the same as the other side, to symmetricalize it.

or is it something else?


pedal clearance....don't know about that part.

I meant both. The motor offset would shift the weight from the center of the swingarm which would likely affect handling. How much? I don't know. That offset was also going to affect the way the motor was going to be incorporated into the swingarm.

I really like clean lines and symmetry and that motor hanging off the side would kill me. I could make a cover but who knows if I'd be happy with the look. I would also worry about hitting the motor on something, especially if I eat shit. I really wanted that motor on this bike but I dont think I'll be happy with the end result. My next build will be ground up around the 2kw or 3kw version of this motor, kind of like @chambers build and the emoto.