mounting a hub-motor, torque-arm, .. man thats hard work

[kraeuterbutter]

first problem:
motor is ~11,5cm wide, the steel fork only 10cm

that does not seem much, but man:
try to bend it apard and insert the wheel with only 2 hands.. impossible

tried it with the help of my girlfriend -> impossible as well (with the wheel inside, iam not strong enough to bend the fork far enough apart..

so i bought two "ratchet tie down"..
i planed to bend the fork with the ratchet between two cars were i mount the strap

befor i tried it this way:
i made two nooses, for each fork one
then i lied on the ground, with one feet in one noose and two arms in the other noose
and so i bend the fork apart,
my girlfriend was then inserting the wheel/hubmotor standing above me int he up-side-down bike

question:
is it always that hard to mount a hub-motor ????

-----------------------------

next problem:
the axel of the hub-motor is not round, but a little bit flat (thats normal i think)
BUT: it does not slipp in completle into the fork..
there is 1-2mm missing
this results, that the torque-washer,
i mean this thing:

does not fit 100%
because the axel is not 100% inside the spacing of the fork..
so the little nose/arm of the torque-washer is not resting between the spacing of the fork but it stands over it

so: should i use a file/rasp to make the spacing bigger ?
what do you suggest ?

and how should i screw the thing together ?
besides the torque washers,
what should i mount from these parts ?

the black ring between torque washer and nut ?

thx for help...

at least iam having now the connectors and parts for soldering the controller to motor, breaks, pedelec-unit, switch, battery....

 

[Tiberius]

Hi kb,

It sounds like you and your girlfriend need to get it further in.
Can you post a picture?

Nick

 

[flecc]

Hi kb,

It sounds like you and your girlfriend need to get it further in.
Can you post a picture?

Nick

The mind boggles.
.

 

[kraeuterbutter]

my English is not that good, but i think this sounds a little bit funny..


hmm... maybe i should go to my girlfriend instead of sitting here in front of the internet..

for getting the wheel deeper in the fork-spacing ( i don´t know how to call it):

i have no camera here in the moment..

 

[kraeuterbutter]

here a little, very bad drawing:

the axel does not slipp in fare enough

what do you suggest..
more pressure (press it in) or gentle hammering on the axel does not help

its maybe 1/2mm that causes the problem..
i think i will have to grind the fork

 

[flecc]

Yes, I would grind or file the fork a little to get the spindle to seat properly.

You may need to add a shaped torque arm with a clip onto the fork leg. An anti torque washer may not be strong enough and it's locking tongue could expand the fork opening and crack it apart.
.

 

[kraeuterbutter]

hmm..
where can i get such an "Torque-arm" ?
from which company ?

 

[frank9755]

Normally a DIY item I'm afraid. Check Flecc and Jeremy's past posts for guidance and pictures. If its for a front motor there may be a ready-made one available. There was a thread on endless sphere about it recently.

Out of interest, does anyone know a supplier of torque washers?

Frank

 

[john]

Yes, I would grind or file the fork a little to get the spindle to seat properly.

You may need to add a shaped torque arm with a clip onto the fork leg. An anti torque washer may not be strong enough and it's locking tongue could expand the fork opening and crack it apart.
.

File it a little at a time and keep putting the axle in just on the side you are working on to check that it fits. It is important to get a snug fit and easy to overdo it or get the shape wrong.

If you have strong steel forks then you are probably OK without a torque arm, weaker alloy forks would probably need one.

 

[kraeuterbutter]

Hello again...

so, i managed to make some pictures..
sorry about the Quality, but the display is broken on that camera, so i make pictures without knowing the settings of the camera

it is a steelfork,
about 15-16 years old

here you see the torque-washer -> the little torque-arm does not grap between the fork-mounting-spacing


at least: does the fork look robust enough to you ?
robust enough to try it with this torque-washer alone? (of course: each fork-side one washer)

i don´t have a 1200Watt 72Volt endless-sphere-i-can-not-have-enough-power motor inside

it is rated 180Watt (@24V) - 250Watt (@36Volt)
with 500Watt peaks

i will power it with 9cells, so 33Volt nominal, ~31Volt under load

the wheel is slightly bigger than 26" because i use Big Apple Ballone tires
so think no murder-torque to the axel to be expected ?!?

 

[john]

That fork looks strong enough to me. Actually I don't use a torque arm in my alloy forks and haven't had a problem although you probably have a bit more torque than me.

Make sure you do the nuts up tight though.

 

[Chris_Bike]

That steel fork will take a bit of abuse, but the lug on the torque washer MUST engage the slot fully.

I was going to reply yesterday about springing your forks (though you seem to have done this). I would use a long threded axle or bar (usually available from DIY stores/bricolage) and simply use nuts on the inside of the fork to bend it outwards so that you achieve a permanent change of shape. I've used this method sucessfully on the rear triangle of a frame.

 

[kraeuterbutter]

thx..
so iam a little more pacified...

Chris:
that sounds easy, to bend the fork apart the way you do it...
wondering why this didn´t came to my mind...

at least, i didn´t want to bend it permanently, because i was afraid overstressing the fork

i mean:
when i want to bring it from 10cm to 12cm i need to "overbend" it to 15-16cm so that it remains at 12cm after i would remove the long threded axle

i have not much experiences with working on bikes, or welding (and for that konwing how strong a welded fork is)
i was just driving bikes all my life.. not working on them..

so my fork is still under tension.. when i remove the wheel it will go back to 10cm

well, i will trust you and the torque washers after filing the fork a little so that the torque-washers can engage the slot (fully - we will see if fully is possible)

wondering, why there are not torque-arms seperatly buyable ??
i mean: it should be possible to make such thing that fits than virutally any bike

 

[flecc]

wondering, why there are not torque-arms seperatly buyable ??
i mean: it should be possible to make such thing that fits than virutally any bike

The fork ends tend to vary considerably, and some bikes use rear motors with different torque arm needs. Given the fact that it's only the higher power motors/weaker forks that tend to need them, and the market is so small anyway, making a range for various designs isn't viable really.
.

 

[Tiberius]

Looking at your pictures, two things occur to me.

Is the motor touching somewhere else, for instance on the inside of the forks?

You could make a torque plate. This would be a flat piece of steel 2 to 3 mm thick, with a 10 mm slot to fit over the axle, and suitable hole to bolt it to the mudguard fixing hole on the forks.

Nick

 

[kraeuterbutter]

Tiberius,
thats an idea i had too...

two problems:
1.) how make a 10mm Slot ?
(i have a fretsaw at home )
ok.. i have a friend who can maybe do that
maybe he can "erode" it (i have not understood it 100%: its a fine conductor, running like a saw but with electricity... the steel is than "burned" away by an "light-arc")

2.) the fork is not flat..
what i mean with that: (man, its difficult to explane what you want, when you don´t speak the language good enough)

maybe you can see it here and i need no further words:
http://www.kraeuterbutter.at/Bilder2/Radnabenmotor_Vorderreifen/Montage/DSCF1967_3.jpg

to solve this second problem: a normal standard-washer would be needed, to make the fork at all positions same flat..
i would not be able to mount that arm on the inner side of the fork, there it also not flat..
so when, than on the outer-side

 

[kraeuterbutter]

this idea came to my mind, first time i saw the torque-washer and my fork..

question:
would it be strong enough, when the plate for the 10mm slot is on one side (of the slot) open ??
i mean: thats the same like the fork is made..

but otherwise making would me much harder i think..

 

[Tiberius]

That is exactly it. It can go on the outside.
But on the torque plate the 10 mm slot does not need to be open at the end; it is better if it is closed.

Nick

 

[kraeuterbutter]

yeah.. question is, if it is easy to make it when it is closed...

maybe it has to be done in 2 parts..
so its easier to machine it,
and afterwards screw the two parts together, quasi a "door" for the slot

 

[Tiberius]

Kraeuterbutter,

Um zu 10 mm Schlitz machen, man kann dieses nutzen.
Maximat V10 Lathe/Milling machine
Hergestellt in Osterreich.

Oder eine Feile.

Nick