The Unofficial 'CroMotor' Owners Tech-Tips Thread

[pucksterpete]

hi Doug

I have been running a cromotor at 100v for the last 2 years I'm 215 pounds. in the summer it has been nothing but great it's been ran in the extreme heat in the rain in the mud I do not have any test results as far as numbers but it's still going strong nothing's burned out knock on wood so if I had to get another motor for another bike it would be a cromotor. check out my thread

 

[Dougt]

hi Doug

I have been running a cromotor at 100v for the last 2 years I'm 215 pounds. in the summer it has been nothing but great it's been ran in the extreme heat in the rain in the mud I do not have any test results as far as numbers but it's still going strong nothing's burned out knock on wood so if I had to get another motor for another bike it would be a cromotor. check out my thread

I have no doubt that the cromotor is one of the best motors out there (that doesn't require extensive modification to use), but it is also one of the more expensive and there is a long wait to get one. I would like to compare it to others, and the only way to objectively do that is using performance curves.

 

[Alan B]

It would only be objective if all measurements were done by the same third party utilizing well controlled testing. The performance data from motor manufacturers is rarely directly comparable to the level of accuracy you would need to have a really dependable result. Good luck getting data accurate enough to do that.

Or just buy one of each and compare them, or find someone else who already did.

I thoroughly enjoy my Cromotor, but I suspect that any motor of similar diameter and magnetic width will have adequate performance for an excellent ebike grin (regardless if it is a few percent better or worse), so find something that doesn't have such a long wait and start having fun!

Best of Luck,

 

[ridethelightning]

i recently got a second crov2(i think) for a friends bike. but it seems to have extra meat on the disc side shoulder of the axle, causing an annoying offset.
the end result dropout width on the axle is about 153mm, but with this extra long axle shoulder, it leaves the motor off-centre by maybe 15mm or so.

has any one come across the different versions of the v2 and perhaps know what the measurements are?

ill have to get it machined off i think if im going to get it into the 151mm dropouts i have...with the disc and torque arms..

 

[madin88]

yes there are two different axle versions available so better ask before buy one. i believe the longer one was made for the greyborg frame.

 

[Jackrabbit]

I've got a bit of a problem fitting the brake disc to my Cromotor V3, the white plastic part that surrounds the axle protrudes past the rotor mount, preventing the disc from sitting properly. I've looked at pictures of other motors and this doesn't seem to be the case with them. Has anyone else had this issue? if so how did you resolve it?

 

[madin88]

on my brake rotor i have filed the curves flat and also the bolt heads to have enough space between

 

[striker54]

I've got a bit of a problem fitting the brake disc to my Cromotor V3, the white plastic part that surrounds the axle protrudes past the rotor mount, preventing the disc from sitting properly. I've looked at pictures of other motors and this doesn't seem to be the case with them. Has anyone else had this issue? if so how did you resolve it?

Don't worry, put the rotor in the motor and start bolting the screws and you will see that the rotor will install very well. In my cromotor when I was trying to install i also thought that it will not fit, but I give a try and start to bolt the screws and in the final it worked ok with a very tight fit in the plastic.

 

[striker54]

Another solution to install the rotor is here (check the video): http://endless-sphere.com/forums/viewtopic.php?f=2&t=65958&p=1004598&hilit=qulbix#p1004598

 

[AndyG73]

On the subject of rotor mounts, I wasn't happy with the standard Cromotor spacer so I made up an alternative. Its probably been done before, but I thought I'd throw this version into the mix too. It works well.
Uses only 6 bolts - straight into the cromotor outer case.
Lipped on inside to centre up on motor.
Lipped on outside to keep the disc centred.
Chamfered internal edge to give wires plenty of room.
Same disc off-set as the standard Cromotor spacer.
Needs a modified disc to work (enlarged centre hole and Cromotor PCD bolt holes).
:? And you'll need a disc with a good solid centre.
But with regen, the rear discs sees very little wear, so I've only had to source / modify just the one disc (and a spare).

PS. I know the welding sucks and... there is no torque arm, but the dropouts are holding up just fine (even with serious amounts of regen)!

 

[madin88]

good work Andy. looks fine!

 

[Jackrabbit]

Thanks for your replies. How do you remove the white bush? Does it just pull out or do I need to remove the side cover?

 

[Jonboy]

Just pulls out...

 

[Doctorbass]

Some questions about the Cro...

.. Cromotor are availlable in version 26x3T and 20x4T right?

The 26x3T is 12.9kv
The 20x4T is 9.3kv ?

Look like the most popular one, the 4T have better copper fill (80 total strands per tooth) and the 3T have 78 strands..

http://velomastera.ru/shop/show_cat.php?catid=5&grid=2

Also some axel are M14 and some are M16? and some have 12mm while some have 10mm thick?

Would be great to have a official thread about all the existing availlable version of the Cro..!! and all differences...

Velomaster.ru have these versions: http://velomastera.ru/shop/show_good.php?idtov=501072&grid=2
50mm brushless motor magnets. Motors rear 158mm (can be converted to 138mm). Power: 3000W nominal, real long-term 6000Vt and to 20000Vt briefly to 30seconds. / Weight motor: 10kg / There rim 17 inches (Moto) - chrome / s frivilom. Motor 3-turn works well on small and on large voltages. There are two versions - 4x20 and 3h26 (72V @ 680RPM and 72V @ 930RPM respectively) clearance from the cap to the rotor plane 18mm. (Avid BB7 compatible) 154mm dropouts without freeways. With single-speed frivilom - 156mm. With trёhskorostnym - 158mm. /


.zelenavozila.com/ have these versions:
http://www.zelenavozila.com/#!cromotor/c1ger


and greybordusa.com (Zombiess owner) offer these versions: http://greyborgusa.com/product/the-cromotor/

Doc

 

[Allex]

Doc I don't think velomastera have the Original cro.
They call it "Kro-moto" Not "Cromotor" So it could be a QS205, the progenitor of the Cromotor
See:
http://endless-sphere.com/forums/viewtopic.php?f=31&t=59432
And:
http://electrotransport.ru/ussr/index.php?topic=19666.0

 

[madin88]

to me one looks like original cromotor (with bolt mounted part for freewheel) and the other like normal QS motor.
i like the strong axle design of the QS where the wires coming out, but probably this is 12mm and not 10mm wide version..

 

[ewinters]

Is a vertical dropout better for a cromotor? I wonder because the heavier hits on the axle will come from the road, and on a vertical dropout the beefier line of the axle will be aligned with such forces.

 

[Rovi]

Hello,
I want to use the cromotor V2 for the drag track (Quatermile).
I´ve heard that there will be different versions available (5rpm/V up to 16rpm/V).
The 16rpm-version has no good acceleration but a fantastic top speed.
I got the information that somebody has destroyed this version by increasing the current.
So I decide to use the standard version 9,5 rpm/V.
I also will use a 21" x 2,15" Motorcycle rim with a 90/90 21" wheel because I do not trust the speed over 100 km/h with bicycle wheels.
I already red the comments here and found a trace of the motor regarding voltage level, current and top speed.
What do you think about the Kelly controller 14406E? He can handle over 200A at voltage level of 144V DC for 1 minute and also you can put up to 180V Battery supply on it.
Well I hope to get the 402m in 20 seconds.
I also found a LiPo battery (5000mA/h) with a continuous c-rating of 45 (225A) for 60 seconds and hope to get two runs.
I do not know which top speed I will reach at the end but I hope to be on the right side with my calculation.
Is somebody here who can approve my thinking?
Thanks for your help

 

[littleskull99]

^ sounds like a recipe for a hot motor. I would defo use a small wheel. "Volt up gear down" has served me well in rc and ebikes.

 

[Longshot]

21"???? For real? Go with a 17" tubless michelin so you can deflate a little for traction and not break your axle or burn out your motor.

 

[Longshot]

You need amps, not volts. Amp up and gear down.

 

[zombiess]

I had a 18KV Cromotor in a 14" MC rim and it accelerates just fine, even on 75V. It just needs some amps fed to it. Should work well in a 16" as well, just watch the tire height, shorter is better.

For what you would like to do, a larger motor than a Cromotor would be more appropriate. They can be sourced for about the same price as a Cromotor. John in CR has a motor which would work well.

 

[Longshot]

Yeah, check out the youtube video Of john in cr. Great motor, its just heavy.

 

[Scott]

The quarter mile is really long. I just about top out in the 1/8th of a mile at 122v (load) and 120 amps.

I would like to say that a higher top speed even if the acceleration is "slow" could possibly be faster. I gain less than 4 mph in the last half of the quarter mile.

 

[zombiess]

Drag racing is all about the 60' time. You need as much acceleration from a dead stop as possible. On a 13sec car, 0.1s faster in the quarter can be worth 0.2 to 0.3 in the quarter. The slower the vehicle, the more this applies.

MPH is not as important as you think. I have seen 7 sec passes at 80 mph.