Motor axle is too thick for dropout, what should I do?

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DasDouble   100 kW

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Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 08 2018 2:15pm

Hey guys,

I ordered a motor for a friend of mine some time ago from QS motors a QS 1000W 135mm 205 35H V1 for a standard mtb bicycle. Now a problem occoured: the axle of the motor is 0,65mm too thick for his dropout (10.25mm axle and 9.6mm the dropout).

Now the question is: How to solve that problem? Maybe grind it down a bit so it fits? He´s going to push about 4kW (Adaptto Mini-E Controller) with it, so maybe it could brake because of that weakening? :?

What do you guys think?

Secondly: The cable rubs on the brake rotor. Normally that shouldn´t be a problem at all as you just have to lead away the cable downside the axle so it goes through the dropout and doesn´t have to get bended towards the rotor, right? Has someone also have had such issue before?

Thanks for your help!

Regards, Elias
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Re: Motor axle is too thick for dropout, what should I do?

Post by amberwolf » Mar 08 2018 2:32pm

There've been a lot of posts about filing dropouts with different techniques, to make hubmotors fit them. Not everything in this list is relevant, but even just the first few probably have enough info for you to do it.
https://endless-sphere.com/forums/searc ... mit=Search


For the rubbing, if tying the cable down to the frame doesn't hold it out of the way enough, you might have to use spacers on the rotor and/or frame and/or caliper to make this happen.

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Re: Motor axle is too thick for dropout, what should I do?

Post by teklektik » Mar 08 2018 3:32pm

DasDouble wrote:
Mar 08 2018 2:15pm
Maybe grind it down a bit so it fits?
You situation is pretty normal. You want to file the dropouts not the motor shaft.

Some hints... see:
https://endless-sphere.com/forums/viewt ... 7#p1145413
https://endless-sphere.com/forums/viewt ... 4#p1359674
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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 22 2018 3:16pm

ANOTHER PROBLEM:

The cable seems to get damaged by the brake rotor. I guess the following video of my client should explain it in the best way: What should I do against that?



Damon from QS said I would need such washer for the cable, but where could I get that from?
14554586940.jpg
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"..the crazy kid exploring hipower ebike world ^^"
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Re: Motor axle is too thick for dropout, what should I do?

Post by Marin » Mar 22 2018 4:43pm

DasDouble wrote:
Mar 22 2018 3:16pm
ANOTHER PROBLEM:

The cable seems to get damaged by the brake rotor. I guess the following video of my client should explain it in the best way: What should I do against that?



Damon from QS said I would need such washer for the cable, but where could I get that from?

14554586940.jpg
The motor cable is meant to go between the disc and dropout, mine had to go downwards, really not much room there but cable zip tied to frame to keep away from disc bolts. Might only be 1 or 2 mm clearance.

Different motor has wire exit out of axle which has other issues.
Marin ex-rental hybrid with 48v bionx...sold
Specialized hardrock with magic pie 4-5
Lunacycle with l/r mid drive coming soon
Kona Caldera with QS 30H (maybe), and phase runner
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Re: Motor axle is too thick for dropout, what should I do?

Post by spinningmagnets » Mar 22 2018 4:48pm

Thick axle is good. File the frame, and then add thick torque-arms.

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Re: Motor axle is too thick for dropout, what should I do?

Post by John in CR » Mar 22 2018 8:27pm

DasDouble wrote:
Mar 22 2018 3:16pm
ANOTHER PROBLEM:

Damon from QS said I would need such washer for the cable, but where could I get that from?

14554586940.jpg
Fabricate one or incorporate the same in clamping torque plate.

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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 23 2018 8:26am

I texted him I could send him such self built spacer to get a plus of 5mm. This is what he replyed. Do you agree with him?

"Although in principal it looks like it would work on a steel frame but it is a custom alloy frame and is not designed to bend plus is heavily braced around the chain stays to account for a wheel with a motor of a given high wattage.
Opening the frame up by 5mm is something I would prefer not to do as the frame was built with 135mm O.L.D in mind and not 140mm O.L.D. (over-lock-nut distance)
Plus in addition the wheel will need “dishing” to accommodate keeping the track between front and rear wheel and central to the chain stays.
"

Im running out of ideas. He wants to send it back to me to germany to modify it somehow, but I have no clue what I could do about that to solve that problem. :|
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Re: Motor axle is too thick for dropout, what should I do?

Post by John in CR » Mar 23 2018 9:32pm

Something is wrong. Either QS shouldn't be calling it a 135mm motor, his frame isn't 135mm between the dropouts, or he has something taking up extra space on the other side, because there should be more space than shown in the pic to bring the cable harness out safely so the brake disc doesn't cut it.

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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 24 2018 4:57pm

You can already see on the picture that the construction of the motor itself is a disaster - isn´t´it? You can clearly see that the cable gets in contact with the freaking brake rotor. Is this normal? I don´t think so. What can I do about that? Buy a different motor?

Do you guys know some good 130mm hub motors I can use for him instead??? Seems like Im gonna have to buy a smaller one for him. :cry:
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"..the crazy kid exploring hipower ebike world ^^"
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-Overtake Porsche with own Ebike: ✔
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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 24 2018 7:33pm

I figured out that the crystalite h3540 serie could be a good option as it has got a beter cable solution and is also 135mm long.

Any experience with that?
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Re: Motor axle is too thick for dropout, what should I do?

Post by teklektik » Mar 25 2018 9:22am

DasDouble wrote:
Mar 23 2018 8:26am
This is what he replyed.

"Although in principal it looks like it would work on a steel frame but it is a custom alloy frame and is not designed to bend plus is heavily braced around the chain stays to account for a wheel with a motor of a given high wattage.
...
the frame was built with 135mm O.L.D in mind...
"
Although that QS motor has issues of its own and may not reasonably be used with 135mm OLD dropouts, the bigger problem is that the swingarm was sized to 135mm in the first place by/for someone who doesn't seem to have ever mounted a motor.

Putting a steel axle in an aluminum frame typically is going to require at least a washer in each side to distribute the force when tightening down the axle nuts to avoid sinking the shoulder into the aluminum. This may not be necessary for motors with substantial axle shoulders to the threaded part, but it's a common problem. Another common issue is the need to put a spacer on the freewheel side to clearance the freewheel/chain from the dropout. Again, this isn't always necessary, but it's not uncommon. To build up a custom frame for exactly 135mm really doesn't make any sense since the odds are that even with a 'proper' motor, the chain stays will need to be sprung a bit to accommodate these commonly required extra bits and pieces.

CustomSwingarm.png
custom swingarm - a missed opportunity

This shot of the tiny axle shoulders on the QS motor shows the need for some help be usable in an alloy frame. Washers may work, but axle spacers with a shaped hole pick up more of the shoulder surface.

qsMotorAxleSnafu.jpg
tiny shoulder needs washer/spacer in any case
qsMotorAxleSnafu.jpg (218.88 KiB) Viewed 911 times

If we look at the Xlyte motor, again there is a tiny axle shoulder and perhaps the need for a spacer for the freewheel (as shown on the axle). That spacer is certainly not part of the axle "135mm" specification.

freewheelClearanceIssue.png
small shoulder needs at least a washer - maybe that spacer for freewheel clearance
freewheelClearanceIssue.png (248.76 KiB) Viewed 911 times

Anyhow, the point being, there is a bit of responsibility for the situation to spread around here and the swingarm guy had an easy option to address common mounting issues with a bit of extra spread but has instead adhered to the industry 135mm standard that creates at least minor issues for many if not most motor installations. A little extra unneeded spread can be easily filled with a washer or two.

To try to fit that QS motor, I would go to a standard 5mm spacer and relieve the section near the flat side of the axle - this is 90 degrees away from a standard "C-washer" which would not work here. Maybe something like this with the notched side against the cable and the remaining solid bit against the dropout. If the owner won't accept any chainstay spring at all, he may be in a bit of pickle regardless of the chosen motor unless he goes to a motor without the QS cable issue and clamping TAs to eliminate the need for axle nuts and an inside washer on the brake side.

axleSpacer.png
axleSpacer.png (47.69 KiB) Viewed 905 times

This is an awkward situation - hope your client will be a little flexible with working this out since the whole swingarm thing is a bit of a mistep (IMO).
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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 25 2018 1:09pm

Thank you Teklektik for your long reply.

"We" are now going to get a crystlite motor as it seems like it has a better cable fitting then the QS and then Im gonna have to sell the QS to someone who maybe has got no problem with opening his frame a tiny bit. Waiting for a reply of 4 people I have contacted via email if they can sell me such crystlite for this guy.
Do you think a 7 speed freewheel would fit on that crystlite? Or will it be too big then?
Thanks guys so far..

Elias
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Re: Motor axle is too thick for dropout, what should I do?

Post by amberwolf » Mar 25 2018 9:48pm

As Teklektik noted, it's just as likely that the frame will need to be spread for the new motor as the last one, for a freewheel spacer, and shoulder washers on both axle ends as well.

Whatever motor you put in there, the frame will probably have to be spread enough to accomodate shoulder washers, and possibly freewheel spacers.

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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 30 2018 11:23pm

Alright, I will have to sell this motor, he threatens me with the lawyer.. I will have to buy the Crystalite H4065 instead.

Is anybody interested in buying this QS 1000Watt H35 motor, laced in a black 24" wheel? I would thank him really much.
"..the crazy kid exploring hipower ebike world ^^"
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-Overtake Porsche with own Ebike: ✔
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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Mar 31 2018 1:16am

In case I order a new Crystalite H4080 for him, is it possible to cut some material away from the axle so it fits for his dropout? From 10mm to around 9.6mm?
"..the crazy kid exploring hipower ebike world ^^"
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-Overtake Porsche with own Ebike: ✔
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Re: Motor axle is too thick for dropout, what should I do?

Post by SlowCo » Mar 31 2018 6:08am

If you have such trouble fitting a hub motor why are you doing this as a bussiness? With "customers" like the one you described you won't make any money...

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Re: Motor axle is too thick for dropout, what should I do?

Post by DasDouble » Apr 01 2018 8:40am

SlowCo wrote:
Mar 31 2018 6:08am
If you have such trouble fitting a hub motor why are you doing this as a bussiness? With "customers" like the one you described you won't make any money...
I made this just once as I thought building an ebike kit is an easy job, but I didn´t expect that 2mm of steal could do so much trouble. Everything worked out, the battery, the controller, just the motor is a problem here. I thought thats easy money as Im familiar enough with electric bikes..
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