The Unofficial 'CroMotor' Owners Tech-Tips Thread

[shorza]

Can anyone please tell me the length to the axle on these?

It must have an axle length 205-210mm for me to be able to get the nuts on outside my 140mm dropouts and torque arms.

[Alan B]

The Cromotor freewheel threads are too long for the White Brothers freewheel. What is the best remedy?

[cassschr1]

I don't see why thats a problem. Is the motor to wide now?

[Alan B]

If I use a spacer on the freewheel it will require extra dropout width. I need to get some numbers.

[alex77roma]

I have the avid rotor and already made the same modify, but I don't find the Magura Gustav.
Are there any alternative silm rear disc brake to Magura Gustav for fitting the cromotor in a 135 hub with?

If you have only 135mm of dropouts and still want to fit some torque arms inside, you can use the following disk rotor adapter mod:
-remove original adapter,
-get avid g2c2 203mm rotor
-get magura gustav M rear brake for enough clearance
-dremel a bit of avid rotor to make it fit and screw it up INSTEAD of original adapter

here is your additional ~5mm clearance for torque arms with CroMotor and 135mm of dropouts!
and some pics:

[GCinDC]

I have the avid rotor and already made the same modify, but I don't find the Magura Gustav.
Are there any alternative silm rear disc brake to Magura Gustav for fitting the cromotor in a 135 hub with?

from here.

...Like many rear hub motors you can run into caliper clearance issues, but I managed to get a Hayes Stroker Ryde on the back of my custom bicycle by using a 203mm rear disc. This larger disc allows the caliper to stick up high enough to not rub on anything but it’s a tight fit due to this particular caliper being very wide compared to others such as the Avid Juicy brakes I’ve run.

i wonder if the magura mt2, mt4, etc would be good. i believe kepler said they've got 17mm of clearance from disc to edge.

[Olly3012]

I have just purchased a croMotor and was wondering what the ultimate controller available for this I have 30S2P lipos 111V-126V with 30C cells, I don't care about mileage at all just want maximum power any suggestions cheers.

[Emoto]

If you have only 135mm of dropouts and still want to fit some torque arms inside, you can use the following disk rotor adapter mod:
-remove original adapter,
-get avid g2c2 203mm rotor
-get magura gustav M rear brake for enough clearance
-dremel a bit of avid rotor to make it fit and screw it up INSTEAD of original adapter

here is your additional ~5mm clearance for torque arms with CroMotor and 135mm of dropouts!
and some pics:

Andreym Good to see this mod, are you using regen, how long have you been using it like this.any problems yet

[Alan B]

Nice technique! May have to do that myself.

[binlagin]

Unfortunatly I snapped my Cromotor axle yesterday after a heavy acceleration from a dead stop. I had made some room for larger phase wires... but apparently I shaved to much down .

Now I have to figure out if it's even possible to replace. I have no idea where I can source a replacement axle and/or how to install it.

[fractal]

Unfortunatly I snapped my Cromotor axle yesterday after a heavy acceleration from a dead stop. I had made some room for larger phase wires... but apparently I shaved to much down .

Now I have to figure out if it's even possible to replace. I have no idea where I can source a replacement axle and/or how to install it.

That sucks! Could you weld it back together? Finding a replacement that fits could be a challenge!

[Doctorbass]

Unfortunatly I snapped my Cromotor axle yesterday after a heavy acceleration from a dead stop. I had made some room for larger phase wires... but apparently I shaved to much down .

Now I have to figure out if it's even possible to replace. I have no idea where I can source a replacement axle and/or how to install it.

did you used single or DUAL strong torque plate? ( one on each side)

Doc

[gensem]

Unfortunatly I snapped my Cromotor axle yesterday after a heavy acceleration from a dead stop. I had made some room for larger phase wires... but apparently I shaved to much down .

Now I have to figure out if it's even possible to replace. I have no idea where I can source a replacement axle and/or how to install it.

Go to a machine shop and ask for a new one... btw why did you have to use larger phase wires?

[binlagin]

I'm using the Kiwi's drop outs for the Giant DH Team. They seem to be pretty heavy duty and have held up so far.

I haven't actually taken the motor out of the rear swing arm yet to get pictures and confirm 100% that thinning the axle is what truely caused the failure.

I've messaged Zombiess to see if he's able to get his hands on a spare axle. *crosses fingers*

Oh and Gensem why did I do this? I'm a noob and I thought those wires where to thin....

[gensem]

Oh and Gensem why did I do this? I'm a noob and I thought those wires where to thin....

They arent super thick either like 10awg tops.
But the deal is that they will not have to deal with constant current so it should be good for a lot of amps.
I ll find out it soon as im planning to run 160a main 240a battery on a cromotor.

[Emoto]

Nice technique! May have to do that myself.

ive got my motor and frame only atm, 135 dropout, and im thinking, i saw your thread and you have less to work with, but i have a couple of ideas that will work.
finding a disc that has enough materal to re drill the pattern is one thought

[hillzofvalp]

I haven't set up a rear brake yet over 800 miles.. Regen is soo strong and I have a lot of trouble mounting the caliper.

Sorry to hear about the snapped axle! Makes me worry! Tell us about your regen use, wheel size, phase/battery current, etc as well once you catch your breath. So far the dp420 and .5" thick dropouts have held up... But I'm quickly being deterred from bike frames for this type of power.

[binlagin]

I've made a post with more detailed information about my failed axle here:

viewtopic.php?f=6&t=36090&p=611756#p611756

[Emoto]

I haven't set up a rear brake yet over 800 miles.. Regen is soo strong and I have a lot of trouble mounting the caliper.

Sorry to hear about the snapped axle! Makes me worry! Tell us about your regen use, wheel size, phase/battery current, etc as well once you catch your breath. So far the dp420 and .5" thick dropouts have held up... But I'm quickly being deterred from bike frames for this type of power.

Yeah regen being strong i can imagine is handy in you situation , but i would like to fit a rear brake,removing the adapter is a good aproach. ive got a dh frame and the swingarm is quite strong [i may modify it/ wider] would'nt be confident in a normal frame.

[Emoto]

I've made a post with more detailed information about my failed axle here:

viewtopic.php?f=6&t=36090&p=611756#p611756

Ive just received mine, on first inspection i thought this was the obvious weak point, and now im a bit worried, as you can see the phase groove machining is quite deep only leaving 12.1 mm is this normal.

[hillzofvalp]

I found it a bit questionable as well. That's nearly worse than m14.. Which would be something like 12mm of solid metal. Your measurement minus 1 mm of thread...

[nicobie]

I wonder why they don't put the groove on the same side as the axle flats?

[Emoto]

I wonder why they don't put the groove on the same side as the axle flats?

Nicobie, your absolutely! right.
My other problem is the groove machining should not pass the shoulder and therefore weakening the shaft

[hillzofvalp]

If they put on the axle flat side, the wiring harness wouldn't come out where the dropout channel is. for most frames this would present an issue.

[hillzofvalp]

My other problem is the groove machining should not pass the shoulder and therefore weakening the shaft

I agree, but it still conflicts with the design constraint of getting the wires in line with the axle slot. Don't they do it this way on other brands, too?