Help! Stripped gears in a Cute Q75

How can I find replacement gears for a cute Q75?

The gear is helical on the bottom with straight gears on top.
There is an insert or bearing inside of it.

I stripped the top portion. (It is not very obvious from the pictures)

I asked the supplier BMS Battery when I ordered the motor if they could
get replacements (in the hopes of finding the part before a crisis)
and they said they don't have them.

Any ideas on a source for these?

Thanks

I can't help you with the gears, but t cold you tell us what conditions caused the gears to strip: motor rpm, battery voltage, controller amps, rider weight, wheel size and miles to failure? That will help others decide on wether the motor has the capability to meet their requirements.

If you can't get the gears, you could buy a bare motor and swap the cores to avoid building a new wheel.

Bascially I changed my P1 to 160, and I went to test the thing out.

I mistakenly believed that with the p1 @ 160, the controller motor mismatch (motor rated to 200 W, cotroller rate to 250w)
was not on issue. In order to test and see if the P1 was corrected I applied full throttle to the wheel without assisting at all.
(which I would never normally do)

I weigh 200 lbs, the battery and other accessories on the bike weighs probably 20lbs + the bike.
The RPM is the 200 variety. I was on nearly flat ground, slight uphill.

I did not note the Watts displayed on the meter at the moment it did that, but before changing the P1 full throttle would briefly display
something in the range of 320 watts before the system sped up.

Hmm, thanks for the info. Guess you have to be careful with that little motor.

I've never seen replacement parts. For $79, I just ordered a spare motor when I got my pimary, as a bare motor is pretty cheap.

This place has replacement gears for Bafang. You could ask if they have access to Cute gears, as they do sell them:
http://www.greenbikekit.com/bafang-8fun-bldc-hub-motor-nylon-gears-replacement.html

Welcome to the world of “unobtainium” with regard to these internal geared motors.

Forget Greenbikekit, BMS Battery or any of those vendors. If you do elicit a response they’re more likely to say “yes, gears we have” and send you whatever gears they have laying around.

I dunno everything or why people call ‘em “Cute” but the factory who makes these Q motors - “Aikema” - http://www.aikema.com.cn/En_CoProfile.asp

I emailed and after exchanging pictures and caliper measurements a nice employee eventually sent me correct replacement gears for an older Q128H but it was a major PITA to arrange payment. The factory doesn’t have PayPal or a system to sell to individual customers, etc.

And what the good man d8veh said above is very true. There’s many variables influencing reliability with these motors. Keep things more pedal than motor and you may realize a long service life.

But turn ‘em up a little bit either speed, power, long extended run times or some combination of the 3 and you'll wind up with the situation you’re facing now.

I kinda have a problem when folks say “it’s only $80 buy a spare." Well, don’t get your hopes up because shipping can easily be another $60-$85. Even if/when you buy 2 motors at the same time it doesn’t save you that much shipping.

In my experience, any way you slice it they’re $140-$200 motors delivered to USA.

Browsing the Aikema website it appears many of the motors have evolved but still retain the old model names. Be very careful if buying one in the hope of swapping internal parts/components.

Thanks so much for the Aikema info!

Although it would be best not to make to many inferences from email with a language barrier as well but
when I emails BMS battery asking for gears it seemed like the attitude was "We don't make money selling cheap
gears."
I haven't even emailed them because I feel like they will prefer to sell me a new motor even if they had or could get them.

In Defense of the Q75, I still like it. Further more this happened after riding in a lot with the wrong P1 value occassionally making a
terrible grinding noise, which I now wonder if was one tooth stripping. I rode it on a long climb often in temps >100F and hauling me up
a long grinding climb. I think it would have kept doing it for a long time if I had changed my p1 and not abused the poor thing the way I did.

I wouldn't mind buying another motor, but eventually it will fail also and what am I going to do with two dead motors.

Ykick, how did you find that website?

I searched for the Cute and Tongxin Cute a ton and never found anything.

abecrizer said:

... but eventually it will fail also and what am I going to do with two dead motors.

Click to expand...

Bookends :lol:

The "Cute" name is only used by BMSBattery. Other resellers use different name and designations. They appear to be identical to Aikema motors, but I believe that they're clones and not actually made by Aikema. When the Q100H first came out, I visited Aikema at the Shanghai show to ask them about what the difference was. BMSB were in sight of their stand. They hadn't a clue about it, and when I pointed to BMSB and told them that the Q100H was on the stand, they said it wasn't one of their motors and didn't look happy. BMSB have at times sold genuine Aikema motors, which were black and had Aikema labels on, so a bit of a mystery.

@ykick – thanks for the good info. That is great.

Bummer that you have so many problems with them. I run mine about 40 miles a day and after 3 years they are going strong. Although I run them at 25mph, I’m just using the stock power levels (36v 15amp).

Although I have had them shipped for free (GBK agreed to put one in my box without charging me extra shipping), the bare motors are $110 from elifebike and $114 from GBK (including shipping).

The Q75 compared with the Q100 has a smaller rotor and stator, but the gear side of the motor is the same as a Q100 and the gears are similar, so the chance of failure should be less because the torque is a lot lower. The internal gear ratio is nearly the same as a Q100H (13.4 vs 12.6). It looks like the difference on the final gear that failed is 21T compared with 23T on the Q100. The fact that it's a small motor therefore can't have anything to do with the gear failure.

I emailed Aikema. Will post what I hear.

Need some advice,

I emailed Aikema with a brief text and the picture with measurements attached below,
they emailed back next time the sun was up in their time zone.
I was really suprised impressed by the quick turn around. The message was brief:

"Dear Eric,
Where do you come from?Where you buy 75SX?thank you!"

I replied that I was in the USA and that I got the motor from BMS battery.

Since then nothing. Which is fine, 3 days is a vey reasonable time to wait for a reply,
but it is in contrast to the initial quick turn around.
They could be looking into it, or their email could have indirectly meant:
"Go talk to the people you bought it from."

I could just be patient, but if they can't help I need to start with a new plan, and the sooner I do that the sooner
my deal will work agian. What do you guys think?

I would be tempted to just buy the gears from BMSBattery, Elifebike, or Greenbikekit and see if they worked.

The problem with BMSBATTERY is last time I checked, they had a ridiculous minimum shipping charge of $50, which is why I tend to use one of the other two options.

Ok so maybe persistence paid off.

Aikema never emailed me back after the initial one I mentioned.

The person at BMS battery I bought the stuff through never emailed me back either.

I emailed the general BMS batter contact and got a response from a different sales person.
The looked into it and saw they can get me the gears. $20 a set. We will see what comes in the mail...

I did order a 2nd motor too.

At long last I got my gears.

I emailed the Aekema folks, one response, then nothing.
Emailed the original sales person at BMS battery who sold me the stuff. No response.
I would much prefer to hear NO than to feel ignored, though I must give every one who responded even once credit
for being willing to help me at all considering I cant email in Mandarin.

So I emailed the main BMS battery email. I pretty much figured I was out of luck but decided to try it.
I got a reply from sales11@bmsbattery.com "Suga Wu" who helped me out big time tracked down the gears
confirmed they were the right ones.

It took several months but I finally got the gears, they fit and look identical to the old ones.
I did take some time to clean all the old stripped nylon sprockets out of the works. I hope I got it all,
since that could jam and break the whole thing again.

The gears were $20 USD each, plus shipping. I got 3 sets so I gave 2 spares now.
I purchased a 2nd motor to tinker with.
I am considering using it as a light weight mid drive option.

Thanks to everyone for your help and advise.
In the mean time I rode with no motor and I think I got stronger. I hope to do the ride without
assist a few times a week so I can continue to improve me time.

Congratulations. As papa said "Patience is a virtue".
Of course then he would remind me I was very short on virtues. :?
I hope that was $20 each per set.

Yeah $20 per set, pretty expensive actually considering a new motor is less than $100, but I consider it a
reasonable fee for tracking down something that is apparently a weird part.

How much they ding you for shipping and transaction fees, if any?

Well the shipping was $68 USD, no transaction fee.
But that was for a motor and several sundry items little hidden wire brake sensors, PAS sensor, throttle AND the gears, all told $184 of other stuff.
The motor itself is fairly dense after all.

Ah, and here is the key to this transaction. Nothing motivates BMS Battery like telling them that if they can make good on a defective part(In my case, a charger), that you will make another order(also a motor in my case), so they can be shipped together.

motomech said:

Ah, and here is the key to this transaction. Nothing motivates BMS Battery like telling them that if they can make good on a defective part(In my case, a charger), that you will make another order(also a motor in my case), so they can be shipped together.

Click to expand...

Excellent motivation.

Yes indeed but that being said: When I contacted them at the first time (the sales person I bought the kit from
at first) I was clear that I would order more stuff if they could help with the parts, and I got no response what
so ever to that one.

When I sent the email which finally got me the gears I did not use that as a bargaining chip.

How did you open up the motor ? Does the plate on the side without the wires unscrew with normal threading ?

Yes that side does unscrew.

You take the screws out of it (the connect the shell to the freewheel inside).

I drilled 3 holes to match the same patter in a piece of wood, with a large hole in the center for the axle.

Then I put 3 bolts of the same thread through the holes I made into the body of the motor (if you dont
see threaded holes through the holes in the cover, turn the axle until you see them). Then you unscrew, Lefty loosy.

See page 2 for pictures.