Axle trying to leave Dropouts when Tightening

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hias9   100 W

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Axle trying to leave Dropouts when Tightening

Post by hias9 » Sep 21 2019 9:39pm

I have installed a slightly bigger hub motor on my slower bike today.
When tightening the M14 nuts, at about 30Nm of tightening torque, the axle begins to leave its position.
So when reaching about 50Nm of tightening torque, the axle will still be inside the dropout, but has already moved by a few millimeters downwards.

I will make torque arms for this bike later anyway, but I am just wondering why this is happening.
It‘s a 135mm dropout aluminium frame which I strech by a few millimeters to fit the motor. On each side is a washer inside the dropout.

markz   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by markz » Sep 21 2019 9:56pm

Yeah its happened to me lots of times.

Lets see now, I hold the wheel and kinda tighten one side, do the other side the same. Go back to original side, hold wheel and tighten it as hard as you can. Same with the otherside. I like to eyeball the tire that its in the center, but yes its happened lots of times as I get lots and lots and lots and lots of flats. Rear hub motor.

I see you stated a washer on the inside of the dropout, I've done the same as my dropouts were getting rounded in the slot.
Just hold it as you tighten it! Eyeball that the wheel is centered on both the chain stays and seat stays.
Good 2 Go!

hias9   100 W

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Re: Axle trying to leave Dropouts when Tightening

Post by hias9 » Sep 21 2019 10:34pm

Yea, that‘s exactly what happened.
And it also happened on my other bike, but at higher tightening torque and the axle did not move that much.
Maybe it happened because I could not hold and tighten at the same time cause I have a broken arm at the moment.
Instead I was putting my weight on the saddle while tightening, but that didn’t help.

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MadRhino   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by MadRhino » Sep 22 2019 1:33am

Now that you are using bigger motors, it is time to make proper mounts. You can’t just put the motor wheel in your bike’s dropouts and hope that you can tighten the nuts enough to hold it.

Your motor axle must not rely on axle nuts to secure its position. In fact, you know that your mounts are good when you could ride safely with axle nuts missing. Pinch dropouts or through axle dropouts plates each side, is the way to secure a big hub.
Make it fool-proof, and I will make a better fool.

hias9   100 W

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Re: Axle trying to leave Dropouts when Tightening

Post by hias9 » Sep 22 2019 9:29am

For my fast bike I have 10mm thick stainless steel torque arms on both sides water cutted.
No problem at all at 22S and 200/450A.
This is just for a 2KW (14S, 40 battery amps) city bike, which I used to ride without TAs. (only TA washers)
Motor was overheating when riding hills, so I went to a slightly bigger motor.
I will make TAs for this bike as well now, but I am just wondering why the axle is now moving while tightening.

dilkes   100 W

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Re: Axle trying to leave Dropouts when Tightening

Post by dilkes » Sep 22 2019 11:55am

MadRhino wrote:
Sep 22 2019 1:33am
Now that you are using bigger motors, it is time to make proper mounts. You can’t just put the motor wheel in your bike’s dropouts and hope that you can tighten the nuts enough to hold it.

Your motor axle must not rely on axle nuts to secure its position. In fact, you know that your mounts are good when you could ride safely with axle nuts missing. Pinch dropouts or through axle dropouts plates each side, is the way to secure a big hub.
Where do you get through axle dropout plates and are they a universal fit or specific by frame?

hias9   100 W

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Re: Axle trying to leave Dropouts when Tightening

Post by hias9 » Sep 22 2019 2:02pm

I design them using a 2D CAD software and have them water cut out of 10mm stainless steel.
On the left side it´s fixed to the IS2000 brake mount. On the right I drilled a hole and cut a thread.

Here is a picture of the left side:
Image
Last edited by hias9 on Sep 22 2019 2:15pm, edited 1 time in total.

john61ct   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by john61ct » Sep 22 2019 2:05pm

hias9 wrote:Here is a picture of the left side
Here's what your pic renders to from here
Screenshot_20190922-150453.jpg
Screenshot_20190922-150453.jpg (53.37 KiB) Viewed 501 times

hias9   100 W

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Re: Axle trying to leave Dropouts when Tightening

Post by hias9 » Sep 22 2019 2:07pm

I am trying to fix this. Where do you upload your pictures?
edit: It should be working now.

john61ct   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by john61ct » Sep 22 2019 4:11pm

hias9 wrote:I am trying to fix this. Where do you upload your pictures?
edit: It should be working now.
Yes, but years from now may not.

Direct upload to this website is best, may need to reduce resolution / filesize.

I use Imgur, been around a long time, unlikely to disappear nor to hold your images ransom like those scammers at PhotoBucket did a couple years ago.

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MadRhino   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by MadRhino » Sep 22 2019 5:35pm

I make them with 1/4 carbon steel using hand tools: angle grinder, drill, files.

Here they are 2.5 inch extended, 1 inch down. The Alu mounting plates were professionally welded and the swing arm aligned/heat treated.
7A21C960-EC94-495C-AEFE-4198AD17CBCB.jpeg
7A21C960-EC94-495C-AEFE-4198AD17CBCB.jpeg (80.81 KiB) Viewed 474 times
Make it fool-proof, and I will make a better fool.

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E-HP   10 MW

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Re: Axle trying to leave Dropouts when Tightening

Post by E-HP » Sep 22 2019 7:08pm

MadRhino wrote:
Sep 22 2019 5:35pm
I make them with 1/4 carbon steel using hand tools: angle grinder, drill, files.

Here they are 2.5 inch extended, 1 inch down. The Alu mounting plates were professionally welded and the swing arm aligned/heat treated.
That's cool!! When you do tire maintenance, do you remove those six bolts and keep the motor mounted to the dropouts?

markz   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by markz » Sep 22 2019 7:51pm

Pffffffffffft @ CAD this or 3D printing that.

Home Depot 1/4" steel 4"L x 1.5 or 2" wide
Hose clamps
Angle Grinder

As you can see, I slipped my steel on the inside of the dropout.
Not the best picture but you get the idea.
No fancy wimpy looking arched ta's



edit: better pic
PS I miss my mxus 3kw :( pedaling is not my forte. If you notice it, a year if not longer. Riding everyday!
ta2.jpg
Last edited by markz on Sep 22 2019 8:06pm, edited 4 times in total.

john61ct   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by john61ct » Sep 22 2019 7:52pm

cannot tell at all what I'm looking at.

Please post a high res shot if you get the chance one day

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MadRhino   100 GW

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Re: Axle trying to leave Dropouts when Tightening

Post by MadRhino » Sep 24 2019 1:04am

E-HP wrote:
Sep 22 2019 7:08pm
MadRhino wrote:
Sep 22 2019 5:35pm
...
That's cool!! When you do tire maintenance, do you remove those six bolts and keep the motor mounted to the dropouts?
Yep. I cut the tie wraps holding the wiring and brake hose, undo the chain tensioner and put the wheel horizontal on a stool beside the bike. Mounting a new tire takes about the same time as with a plain pedal bike. I find important to build with quick service in mind, because I ride a lot of mileage thus replace tires often.
Make it fool-proof, and I will make a better fool.

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