Looking for advice on Swingarm extensions.

[Apoc232]

Recently I bought custom swingarm for my Project Bike, 230mm Dropout.



I bought a QS275 6inch wide, 17inch diameter, hub motor.


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Here is the dilemma.
Despite asking for at least 12-14inch swingarm to fit my hub motor. The swing-arm measures barely 9-10inches from axle to base. They measured the entire length of the swingarm, not from the axle .

My hub motor can barely fit inside of it, and that's without the tire attached too it.


Talked to representative from the store, and they say the cannot offer a refund, since the specs they offered was correct. And in my hubris, I never bothered to confirm my exact point I wanted. It's whatever, I only payed a hundred for it, so im not that worried to get a refund. And finding another swingarm to fit a 230mm dropout is insanely hard. So I rather not go through the hassle of returning it.
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Here is my solution:

I'm thinking of just getting a swingarm extender to make room for the tire. Everything else fits fine, its just the length from the base, to the axle, is too short ( Roughly 10inches ) and I need something minimum 14, to be safe.

However, since the swingarm I bought was not listed as a main product. ( They basically had to search in the back to find one that matched my description ), there is no blueprint online with the specs listed.
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So here are my questions:

• What do I need to look for when ordering a swingarm extender?
• Are there certain shapes that I need to matchup, or can most of them fit inside the hole made for the axle?
• If there are certain shapes that fit, what size should I measure?
• Are there any universal swingarms extenders that can adapt to most swingarms, or do I need to also get it custom made?

A more clear picture of the swing-arm im working with. Any advice greatly appreciated

 

[99t4]

Who is the vendor?

 

[gromike]

Could you move that transverse piece forward? Maybe cut it out and fabricate another transverse piece.

 

[Apoc232]

Who is the vendor?

Sorry for the late reply. It was some chinese vendor from alibaba ( Hefei Hongzheng Motorcycle Parts Co., Ltd )

 

[Apoc232]

Could you move that transverse piece forward? Maybe cut it out and fabricate another transverse piece.

Sadly, its welded together, so not really.

 

[99t4]

It was some chinese vendor from alibaba

Sorry about that. Won't be the first non-responsive ali*.* vendor refusing to stand behind their product.

Thanks for sharing, hopefully a future prospective buyer will see this and shop prepared.

 

[bananu7]

I'm thinking of just getting a swingarm extender to make room for the tire.

The extenders you posted are for swingarms that use sliding axle blocks, not dropouts. Your swingarm has nothing to support that piece.

I think your best option would be to lasercut two sheet metal pieces and weld them flat to the swingarm's flat sides, to create a new set of dropouts further down. I'm afraid that fabricating and welding such extensions would itself cost way more than the $100 you paid for it in the first place - with no full guarantee that it wouldn't just bend and/or collapse catastrophically.

I think you need to accept the loss here and find a new swingarm that would fit better. No idea how the rest of your frame looks, but used minibike swingarms are plenty and cheap, and could likely be easier to adapt for a dropout axle.

 

[Apoc232]

I think you need to accept the loss here and find a new swingarm that would fit better. No idea how the rest of your frame looks, but used minibike swingarms are plenty and cheap, and could likely be easier to adapt for a dropout axle.

Any advice on where to find one with a 230mm dropout? Maybe I should just look for one from a used harley bike?

 

[bananu7]

You'd need to look around. The length you want is actually quite short, i think a full-sized bike might be too big.

MotoTec Mini Bike 60v 1500w Rear Swing Arm-Mini-Bike-60v-150

mototecusa.com

 

[Apoc232]

You'd need to look around. The length you want is actually quite short, i think a full-sized bike might be too big.

MotoTec Mini Bike 60v 1500w Rear Swing Arm-Mini-Bike-60v-150

mototecusa.com

Thanks for the advice. I am still looking around, but have yet to find a swingarm with a 230mm dropout Center pivot width . even on the site you listed, ( stock unavailable anyway ), they dont list the dropout size.

Edit: I should probably note. This is not a minibike. This is a conversion of an old kawasaki 1985 vulcan.

Edit 2: Moments after writing this comment, I decided to look at kawsaki models instead. And I think I found one that might work for me. Thanks for the advice on all that helped me. I think using the term "dropout" wasnt helpful. ( link to site with a list of sizes for those who might find it useful )

 

[bananu7]

Yeah, "dropout" is typically used to mean open axle access, with an axle fixed in the hub and sliding into the swingarm, rather than being fed through an eye opening. Of course a "traditional" swingarm could be cut away to accommodate geting the axle in, but i'd be concerned about the strength afterwards.