Chainline How to Align?

On a whim, I bought a stealth bomber frame. See:

https://www.ebay.com/itm/Electric-Bicycle-E-Bike-Frame-Kit-Electric-Bicycle-Bike-Frame-For-Stealth-Bomber/223999637065?hash=item34276b3649:g:V5YAAOSw9htejOax

Or

https://www.ebay.com/itm/Electric-Bicycle-Bike-Frame-Kit-Stealth-Bomber-Electric-Bicycle-eBike-Frame/223609867251?hash=item34102fcbf3:g:HHAAAOSwg9hdOWpv

The rear wheel dropout spacing is 177mm. That seems like an odd size. Playing with that... it's probably +/- 10mm. The bottom bracket for the preinstalled crank is only about 100mm at the frame with a square JIS crankset.

How do you get a reasonably close chainline from the crank to the hub motor?

Only interested in single speed to keep it an eBike.

Thinking about the QS205 hub motor, but that's 150mm dropout spacing. Can you just use spacers to place it in the right spot?

Thanks!

Oh wow, that's a really bad stealth knockoff. They keep getting worse. They're even cheaping out on the paint quality.

Honestly, rather than dicking with a knockoff of a knockoff of a knockoff, i would send that puppy back since you bought it from a California seller... who also sells flag poles, bed frames, chalk markers... they're obviously just moving low quality Chinese merchandise and could not tell a proper bicycle part from a potato.

So it's a knockoff. I'm not sure how you can see the quality from an eBay listing? But you are absolutely right, the seller isn't going to be any help.

I have no basis for comparison. But after inspecting the frame on arrival, while certain it's not the same quality of the original, it's actually better than I expected for the price.

I don't believe stealth sells their frames. Especially not through some small time ebay seller that sells completely random things. A stealth bike costs $10k. So it's pretty unlikely the frame itself goes for $250.

This is what a real stealth bike looks like:



If you look closely at the eBay listing.. the seller has a picture of their stealth frame photoshopped over one of stealth's product photos. You can tell it's an obvious photoshop because there's a dramatic difference in texture and also resolution.

..that's probably because they cannot figure out how to assemble it into a working bike either.



The stealth knockoff frame pictures show a lot of irregularities in their manufacture. The paint job that was reminiscent of someone's first rattle can garage job was the first hint for me.

You're lucky you bought it from a USA seller and don't have to pay $240 to return it to China for a total of a $10 refund.. which is usually how it goes when you buy Chinese knockoffs.

The eBay seller I bought from buys anything they are willing to gamble will sell for a premium after buying in sufficient quantity to reduce the shipping costs. Before shipping in quantity, this is $130 frame. There are several builders in China using this exact frame to build entire eBikes for $1200-2200, before shipping, depending on the details of the build. So it can be built on. But it's certainly not a "genuine" Bomber frame.

In my case, I built my first conversion based on a hard tail MTB. It actually turned out pretty nice. But I had more fun building it, than riding it. This build is so I can have a real battery storage spot without using a bag, clean up the wiring, and get stronger moped wheels/tires and more torque. I ride a touring BMW motorcycle for longer distances, but for around town, I'm hoping to get 40 mph where everything isn't stressed to the limit.

I see this frame as a possible way to accomplish that. Will it? Time will tell.

Back to the question at hand...QS Motor normally sells the 205 with 150mm spacing and room for a single gear. My dropouts are about 175mm. QS also sells a 175mm version for fat bikes, that has room for a multi speed freewheel. But it moves the centerline of the lacing pattern by quite a bit. So, to simplify the question....can I use the 150mm version with spacers? Would probably take 10mm, 5 on each side by compressing the dropouts and 15mm, using 7.5 mm spacers on each side?

For single speed, the chainline should be close to perfect.

This will undoubtedly screw up the spacing for the disc brake caliper. But I can add spacers there as well?

I have a pretty good understanding of the electrics, but not the mechanics. It would seem this will work, but unsure about how it loads the axle and brake not being flush with the frame?

Hopefully someone can help with these questions.

A 175mm motor with a ~7 speed freewheel would give you a working chainline at at least one of the gears.. a better choice than trying to add half an inch of disc brake spacing. :thumb:

a 150mm hub might align the chain correctly or it might be an expensive mistake that can't be sent back to China. You'd have lots of spacers on the axle and disc brake which is far from ideal.

I've seen these stealth knockoffs on those chinese bikes and the resulting built bike is in the 100lbs range and looks like a dirtbike even if you use bike tires due to the very tall and thus wide stanchion fork required to support all the weight. It's the perfect thing to get police attention on, hehe..

..and those frames i've seen were first generation stealth knockoffs.. this eBay one looks like a copy of a copy.. and using even lower quality metals.. hence the shipping weight comes out to 50lbs. ( versus a regular aluminum full suspension bike frame coming in at 5-10lbs )

A full suspension mountain bike frame can handle 40mph pretty well and the resulting build would be like 40lbs lighter and not be on the radar of lawmen.. I've personally built up a nice dual sus MTB bike to 60mph and never felt uncertain riding it until i got beyond 40mph. Worth considering.

I haven't been able to find a diagram yet of the 175mm motor. But I'm assuming it's exactly the same as the 150mm version with space on the opposite side for 7-9 speed freewheel. So that requires lacing the wheel 25mm off center. The lacing on the motor is only about 40mm spread. So I'm not sure that would work? You can see the drawing here:

https://www.alibaba.com/product-detail/QS-Motor-3000W-205-50H-V3_62020109349.html?spm=a2700.icbuShop.41413.10.125873f1YntkAR

I could probably spread the dropouts for the 273 motor, which most diagrams show at 190mm with one gear. See that here:

https://tzxiya.en.alibaba.com/product/62069652056-810528558/QS_Motor_8000W_273_50H_V3_E_Motorcycle_Spoke_Hub_Motor.html?spm=a2700.icbuShop.41413.39.125873f1YntkAR

But that motor is heavier and overkill for my application. But if it fits?

Open to other motor suggestions....

On the dual suspension MTB, barrier #1 is price for a decent frame. And barrier #2 is a place for all the batteries and electronics for a clean install. I'm not terribly worried about the law, I have very gray hair and will have the default mode of the electronics limited to lower speeds. I just don't see them going out of their way to hassle me.

Aligning chainline: Front = Longer chainring bolts and washers to space chainrings.Rear = Cassette spacers and remove unneeded cogs.

A QS205 150mm motor fits fine in this frame - I've built 4 of them.
The frame quality is pretty good, though the seat bracket needs lowering to the lower holes and 2 new holes need drilling. Also the headstock bearing will need upgrading by 1000 miles.
The axle slots are also too deep for the 205s axle thickness so you will need to shim it (hacksaw blade fits well) to stop axle rotation slop.
There is enough lateral flex in the swinging arm to add large washers and tighten everything to bring the chain into line on a single speed sprocket. The wheel will still be pretty central.
Add a 150a controller + 84v battery and 50mph + is easy - all for under $2000
Here's one I made earlier:

Thanks for the help everyone! @Jonno, those pictures are worth lots of words. If you happen to know the specs on the bearings, I will order a set before I install. Sure I will run into more questions as the project moves along.

Feel free to PM me with any further questions - battery build etc

Jonno