motor for 120mm drop out hub drive?

chas58

chas58

10 kW
Joined
Mar 19, 2013
Messages
712
Location
Detroit, Michigan, USA
I have a single speed road bike which would be great for a hub motor. But, there is a catch:
- it has a carbon front fork
- It has a 120mm (horizontal) rear drop out.

It would be perfect for me if I could put a small motor in the rear, but most rear motors are 135mm wide. Now the BMS web page shows the technical diagram of the cute Q100 in single speed configuration (120mm width, accepts single speed cog/freewheel) that is perfect for what I need. I just can't find anyone who sells it. Anyone else find a 120mm single speed rear motor?

The other alternative is purchasing a new fork that doesn't match too well and putting a motor on the front, but I would love the stealth look (and ridability) of a Q100 in the rear of a single speed (where it just looks like a not electric geared hub).
 
I believe the HS 22 is the narrow version of Chrystalyte H motor.
I recall Ebike.ca used to have it. You should ask details via email.

I would not build with a hub motor on a light weight road bike.
You should investigate friction drive, or mid drive PAS.
 
I don't know about fitting a single sprocket onto various motors, but I think most hub motors are far less than 120mm wide.

To illustrate, em3ev.com has their direct hub kit setup to fit a 135mm with a 6 speed hub. The 6 speed hub is 32mm wide, so logically you'd guess that the hub is 103mm wide. You could probably somehow fit a single speed sprocket to it and fill in whatever gap you had remaining with spacers/washers of some kind. Maybe e-mail them about it or another vendor.
 
It should be possible to fit a 9c motor into 120mm. The critical thing to look for in the drawing will be the outside of the two bearing housings on the covers. Then you cut new axle shoulders into the axle at 120mm, with a hacksaw. The rim won't center right then, so dish it.

The smaller gear motors might be too wide. I'm not sure.

But I also agree, a light single speed screams for a friction drive, or at least a motor that doesn't weigh down a wheel.
 
bowlofsalad said:
em3ev.com has their direct hub kit setup to fit a 135mm with a 6 speed hub. The 6 speed hub is 32mm wide, so logically you'd guess that the hub is 103mm wide. You could probably somehow fit a single speed sprocket to it and fill in whatever gap you had remaining with spacers/washers of some kind.
Click to expand...

The problem is the axle. It has shoulders machined onto it at 135mm spacing, which would have to be machined to a smaller width after extracting the axle from the dropouts. it's not that straightforward.

My approach to the problem would be to leave the nice single speed bike unscathed, buy a cheap steel single speed on eBay and convert it to electric after spreading the rear end to whatever spacing does the job. There are simple chromoly single speed/fixed gear framesets on eBay right now for $150 shipped. Something like that would be much less likely to suffer harm from a hub motor conversion than a lightweight non-steel frame.

Getting correct chainline could be a puzzle. It might be preferable to use a multi-speed 5 or 6 speed freewheel with the larger sprockets removed instead of a single freewheel. If you can find an old-stock non-Hyperglide freewheel with full height teeth, that would be just the ticket.
 
Get another frame.
Adding dozens of pounds to a roadbike frame and going really fast on it is a bad idea.
They are not built for the task - they are built for lightness.
 
If you're willing to DIY you can even turn a front hub into a rear for 120mm dropouts:
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=37837
 
EDIT: that "adapter" shown below is probably 30mm, so just removing it made the hub too short. I replaced it with a bearing of the needed length and that fit fine. Alternatively installing the motor without any washers or that silver lock (as mentioned in the email below) nut will get you pretty close to 120-125mm anyway, so you don't need to use the bearing as a spacer.

I have finally figured this out, after having plenty of vendors tell me it can’t be done. With most of Asia running around on single speed motors bikes, there has to be a way.

I was tempted to hack away at a 135mm fork width motor, or modify a 100mm fork motor, but both of those options have alignment and durability issues.

So, here is the secret:
The Q100 is designed as a single speed motor that can be easily adapted to a muti speed cassette for a 135mm sized frame. There is a 15mm adapter added to the motor to convert it from a 120mm single speed frame to a 135mm multi-speed frame use. To use the Q100 as a single speed, order the 135mm rear motor, remove the 15mm spacer, and put on a single speed freewheel.

So, after getting lots of “no” answers, and gathering data, and rephrasing the question in different ways, here is the answer I have been looking for:

“Hi,
I checked again. 120mm is OK. You can remove a nut, then the size is 120mm.
于 2013/4/5 18:49, 写道:”

It is an interesting design. Wish me luck! ;)
 

Attachments

  • q100 GBK rear sm adapter.jpg
    q100 GBK rear sm adapter.jpg
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Hello all,

I am new in the forum. I am very interested in this issue since I am in the same situation (I've got a single speed folding bike with 120mm drop out) and this is the only piece of information I have been able to find.

Did you finally get that hub motor? If so, could you confirm that it fitted ok the 120mm drop out? Where did you get it? (BMSbattery, elifebike, greenbikekit,....)

Thank you very much.
Valeri
 
Yeah, there is no info on this anywhere, is there?

The Q100 is not very wide. It looks to me to be 130mm, or if you take the little silver nut off (which you don't really need if you leave the wheel on the bike), its down to 125mm. Either way, it will easily fit on a single speed 120mm frame with a slight bending of the rear fork. No problem at all for a steel frame, and even with aluminum, it takes very little pressure to give a 10mm spread. I went to the hardware store and bought a bearing with a 1/2" ID and 3/4" OD that was the same size as the spacers on the wheel, just shorter. Another alternative would be to drill out a 12mm nut (basically removing the threads) and use that as a spacer. But really, that little motor fits fine as it is.

the important part is the chainline, which is perfect with no adjustment. I am using a 16 tooth freewheel. 42x16 gearing I think it works great with a 201rpm Q100 on a 26" wheel at 15-18mph. (I assume you would need the 328rpm version for a smaller wheel).

So yeah apparently I have Endless-sphere's first single speed build, and so far so good.
 
EDIT - found your other thread and answered my questions!

Nice, is that your lace job or ???

Where did you buy your motor/controller?

Good info, gonna help me a lot in the next few weeks. Thanks!
 
Thanks!

Shipping (to US) alone on a wheel is $85 than just shipping a plain motor.
Total cost of hub: $80 + $51 shipping = $130
total cost of wheel: $115 + 135 shipping = $250

I got my stuff from GreenBikeKit. they put a spare motor in the box for no extra shipping charge (they can actually ship two front wheels for the price of one wheel, but not two rear wheels).

so by saving $135 in shipping, it made sense to have a local bike shop build the wheel for me.
 
Thanks chaos58!!!

So, If I am correct, you took off the 15mm adapter shown couple of pictures before, did you? And that was all?

Valeri.
 
It works fine without the adapter removed. The adapter pictured above is much more than 15mm. Probably 25-30, so you can't just remove it.

But that motor is pretty loose in a 135mm frame unless you use several washers. Don't use the washers and take off that silver nut, and you are probably down to 125mm. Either way, bending the dropouts a few mm wider isn't going to hurt anything.

I removed the adapter and replaced it by a bearing of the length I needed. I went to the hardware store and bought a bearing in the nuts and bolts section, ID=1/2", OD = 3/4"
 
hi chas,
i have 3 question re cute 100
1. what is threading on gear is it english or metric? can u put a 14t gear on it?
2. where did u get spokes
3. it is 36 hole so where did u get 36h rim

my target is my 700c road bike.
rafe
 
rafeh1 said:
3. it is 36 hole so where did u get 36h rim
Click to expand...

For real?
 
chas58 said:
EDIT: that "adapter" shown below is probably 30mm, so just removing it made the hub too short. I replaced it with a bearing of the needed length and that fit fine. Alternatively installing the motor without any washers or that silver lock (as mentioned in the email below) nut will get you pretty close to 120-125mm anyway, so you don't need to use the bearing as a spacer.

I have finally figured this out, after having plenty of vendors tell me it can’t be done. With most of Asia running around on single speed motors bikes, there has to be a way.

I was tempted to hack away at a 135mm fork width motor, or modify a 100mm fork motor, but both of those options have alignment and durability issues.

So, here is the secret:
The Q100 is designed as a single speed motor that can be easily adapted to a muti speed cassette for a 135mm sized frame. There is a 15mm adapter added to the motor to convert it from a 120mm single speed frame to a 135mm multi-speed frame use. To use the Q100 as a single speed, order the 135mm rear motor, remove the 15mm spacer, and put on a single speed freewheel.

So, after getting lots of “no” answers, and gathering data, and rephrasing the question in different ways, here is the answer I have been looking for:

“Hi,
I checked again. 120mm is OK. You can remove a nut, then the size is 120mm.
于 2013/4/5 18:49, 写道:”

It is an interesting design. Wish me luck! ;)
Click to expand...

Can this trick be used for a q100h too, in order to get a 120mm rear width with a single speed configuration? Or the q100h is different from the q100?
 
Just wanted to note, I recently purchased the Q100H from BMSbattery

Just wanted to show that yes the 135mm spacer can be removed easily with a wrench to fit 120mm dropout.

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qhQoJaqOzfx_lHbx1nRo1pQEYnDNlRwWMNbgtuxP-WDci1Rq-tPvoIHtVWdE1IVWz9FtR-Z72odF9src1KNVXeYeDXkhN8dt2X8G08shL4L9OX9LGUhZTjGd-2ASOF8AF_56p8bz8LVQAATctTYpaCPFhhi--Fk5wvp7s8XkzXn3WDACmZUD-MOwOwnbkdY-YPtQS_YfT7JoZOHcJoC7XTy6FaFXx3P11GOBvfk6lvAkcfqiKlQPczhlKKXdrnJEnlLd4Bo3yFDY6VO0lb5rjopY7EUkSWEBu7fOip3uS8zIkrfYPDjIC1HFbjpBzhszMlupNfuUOmov8Bvr6P1EwauFI6qCFonbBit9ixU10bKebZnfyEhKc0k16rUbOtG2ak0hsH0nP2L8oSPfdAG51p5UTRTeloozjhyfpJdQsGmoRQYB8XddC4qD1prdz0TQuLnZbAyav_mR1QNFmGg7lCyvhg2iZQeRPDe4I4jrGAdM-mJn519LgH0p_Hvfd2Pp9OO3tLGg3IPH61RMMWyPVJRJLAdVa6Qdd0A6VjFw9sqvL7QwlHqJc2nfPi06pWtT7pKYSMNcZUMUDWLyKAhPeDhYZoqHf1n5MK1JQbYS_3QPtMBmPQ=w920-h690-no


Still have yet to setup, but once I do I will make a post about it.
 
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