Using 16/17/18/19-inch moped rims on large DD hubmotors

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spinningmagnets   100 GW

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Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by spinningmagnets » May 03 2015 5:30pm

There are several similar-subject threads, But I feel this is specific enough that it deserves it's own thread, due to its recent popularity.

The trend for off-road is to get the motor out of the rear wheel (LMX, LR big block, Raptors new mid drive), but for whatever reason, when someone wants a high-powered E-bike for the street, the large rear Direct-Drive (DD) hubmotors remain popular (Cromotor, MXUS, Crown, 35mm-40mm width stator hubs that have been ventilated/oil-cooled, etc).

These hubs are heavy, so...trying to save a few ounces by using a bicycle rim is being seen less and less. (I also recommend full-suspension at any speeds over 30-MPH / 48 kph, due to pothole hits).

There are benefits to using a higher voltage and a fast Kv of motor, and then mounting the hub in a smaller diameter rim. Due to the way that bicycle vs moped tires and rims are measured, a 16-inch moped tire/rim is very similar to 20-inch bicycle tire/rim (2.25 – 16 moped tire has a 20.5″ OD). A 19-inch moped rim/tire is similar to a 24-inch bicycle. Motorcycle / moped tires are very durable and flat-resistant, where bicycle tires are usually lighter for a given width of tire.

The problem that has drawn more builders to moped rims lately is that...heavy-duty bicycle rims have a limit to how much of an angle the spoke nipples can have when they are seated in their rim-holes. It is very desirable to have at least a one-cross pattern to the spokes, as opposed to a radial pattern.

Moped tires can be easily and cheaply found in widths as narrow as 2.25, to over 3.0-inches. Here is a link with a lot of info on moped tires/rims: http://www.myronsmopeds.com/category/parts/tires/

From ES member Kent,
left: Yescom hub (28mm wide stator) in 26-inch bicycle rim/tire, 19 lbs / 8.6 kg
right: Crystalyte H35 (35m wide stator) in 19-inch moped rim/tire, 28 lbs / 12.7 kg

Image

Mattyciii's rim, showing how the spoke holes are angled on his rim, allowing the spokes to be at a much bigger angle than a bicycle rim.

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For those builders who are interested in this, I hope for this thread to become a collection of links to parts that have proven successful.

As an example, the Kinaye Motorsports bike uses a: Hutchinson GP1 17" x 2.25" street tire, outside diameter is 21.5". The rim is a 17" X 1.6" moped. If you like this, but don't want to build one yourself, John Rob Holmes has built many of these.

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edit: from ES member relanium. The pic below is a 16-inch moped rim, and that is the smallest size I would recommend. With tire mounted I believe the outside diameter of the tire is 20.5-inches. Motor is the MXUS-3000, with the common spoke flange ERD of 231mm.

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"19 inch moto rims vs 26 inch bicycle wheels" (38 pages)
http://endless-sphere.com/forums/viewto ... =2&t=55458

"16/17/18/19 inch rims," 7-pages, JRH
http://endless-sphere.com/forums/viewto ... 31&t=35442

"Using 17/19 inch moped rims on large hubmotors"
http://endless-sphere.com/forums/viewto ... =2&t=69104

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by spinningmagnets » May 04 2015 6:54pm

Some members have expressed concerns that threads like this encourage builders to construct unsafe builds that far exceed the legal speed limits in many jurisdictions.

My opinion is that: these E-bikes are being built, whether the information on them is scattered about or indexed here. I encourage anyone who wants to build a powerful E-bike to research the local laws, and to always use high-quality and strong components that are capable of safely operating at the power levels and speeds you are designing for.

The only reason to choose one of the heavy hub motors listed, is to use a high power-level, since a lighter and less expensive hub can provide any modest power level that is commonly found. If you choose to design a high-powered E-bike (1400W-6000W) you should give serious consideration to the possibility of adding lights and turn signals, and possibly filing for a legal moped/S-pedelec license and registration.

Off-roaders are migrating to mid-mounted motors, but the future of hubs on street bikes is enduring. if you ride the streets in a wild and unsafe manner, it can draw bad attention, and possibly lead to legal crackdowns that can have a negative effect on E-bike commuters who are riding safely. Please don't ride like a jerk.

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by Hillhater » May 04 2015 8:36pm

Forget the nanny worriers SM! There are many good reasons to use small strong rims with bigger hub motors, and it isn't always for speed.
Anyone living with a hill on their bike route will know that a big hub is needed to give reliable climbing power without overheating, and those hubs are heavy which gives regular alloy bike rims a hard time when any obstical or kerb is met.
Small ER rims help the torque factor , reduce the speed, and strengthen the build.
I don't need to go fast, but I sure don't want to pedal up those hills ! :wink:
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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by teslanv » May 05 2015 10:05am

My take on "Faster-than-legal" ebikes is this:

You can have power and choose not to use it. You still have accelleration and torque, which are perfectly legal up to a certain speed.

Why do people buy a 100+MPH sports car if they cannot legally drive it on the road?

Lamborghini
Ferrari
Bugatti
Pagani
Aston Martin
McLaren
Koenigsegg
Saleen
Shelby

Ebikes deserve an equivalent high-performance option. 8)

P.S. - We are working on a DOT-compliant lighting kit, and agree that these high-perfromance ebikes should be registered and properly licensed as "Motor-Driven Cycles"

http://www.wsp.wa.gov/traveler/docs/che ... _moped.pdf
Last edited by teslanv on May 06 2015 1:04pm, edited 1 time in total.
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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by cal3thousand » May 06 2015 12:15pm

Very nice compilation! I would agree with TeslaNV with the points of discretion of the driver to control speed and attitude.


SM:
One thing that I noticed, Kent's image shows the 26" tire as uninflated, skewing the image towards 'less difference between the sizes' than reality.
Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Planning on posting questions or buying anything on this site? Put up your country (at minimum) on your profile. This is a worldwide forum and we haven't reached clairvoyance.

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by spinningmagnets » May 18 2015 9:22am

I want to give credit to the pioneers who spent time, effort and money finding out what the good info is for the rest of us. John Rob Holmes / JRH of Holmes Hobbies has been the driving force. Not only to find out what works, but to special-order parts that didnt exist before, and that serve the high-powered ebike community.

"11-15ga custom spokes" (16 pages, JRH)

http://endless-sphere.com/forums/viewto ... =1&t=16218
_________________________

"19 inch moto/vs 26 inch bicycle wheels" (38 pages, Mattyciii)

http://endless-sphere.com/forums/viewto ... =2&t=55458
_________________________

"16/17/18/19 inch rims" (7-pages, JRH)

http://endless-sphere.com/forums/viewto ... 31&t=35442
_________________________

"20-inch rims with motorcycle tires"

http://endless-sphere.com/forums/viewto ... 16&t=18511
_________________________

Here is a pic of a large-diameter hub in a small-diameter rim using a radial lacing (what this thread hopes to help builders avoid), pic courtesy of Cowardlyduck.

Image

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by teslanv » May 18 2015 11:00am

A Little Moto Rim porn from a recently completed Customer project:

Rims are Holmes Hobbies MMP 19"x1.6"
Tires are Heidenau K34 19" x 3.25" Motorcycle Tires
Rear Motor is a MXUS 3000W 4T
Front Motor is a 35mm DD Hub, original to the bike, relaced in the Moped Rim.
Total System Power = 4500W as programmed with LiPo (18S Multistar batteries).
Design Speed = 40 MPH commuter. Easily exceeds this.
Torque off the line is Obscene. :twisted:
My first foray with the CA V3 was a success as well. I was able to set-up multiple profiles so the customer could keep his Rear-rack-Mounted 13S-20Ah Battery (Not shown), as well as use the new 18S LiPo battery.

Total Weight including the rear rack battery is 128 lbs.

Image
Image
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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by markz » Jul 20 2017 8:08pm

Thought I'd bring this old thread up again. Dunno why, but I thought there needed to be a bit more info in this here thread.
Tire-Size-Conversion.gif
Moto Tire Chart
Tire-Size-Conversion.gif (29.98 KiB) Viewed 2466 times
tire-width-chart.gif
Bicycle Tire Chart
tire-width-chart.gif (8.1 KiB) Viewed 2466 times
Also this website, rim to tire fit on moto rim.
https://ridewrightwheels.com/pages/moto ... ment-chart

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by drewid79 » Nov 10 2018 4:42am

Hello,

Realize this is sort of an old thread, but I am trying to figure out what type of hub to use for the front wheel in the case of using a 17" moped rim with 12g spokes. I need one that works with a disc brake, but what I find accept 14g spokes, or don't list the size at all. Any advice would be greatly appreciated. Thanks!

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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by efMX Trials Electric Freeride » Nov 10 2018 10:56am

drewid79 wrote:
Nov 10 2018 4:42am
Hello,

Realize this is sort of an old thread, but I am trying to figure out what type of hub to use for the front wheel in the case of using a 17" moped rim with 12g spokes. I need one that works with a disc brake, but what I find accept 14g spokes, or don't list the size at all. Any advice would be greatly appreciated. Thanks!
what front fork are you using, 20mm thru axle? if so then you can use most any heavy duty dh hub that fits your forks and brakes.. you can drill the hub spoke holes out a little if needed or use Holmes moped nipples to fit to the rim.. or you could get a motored bike hub such as denzel or motoped, etc ready made for larger diameter spokes.. example :
http://www.eastgem.net/hub.html
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Re: Using 16/17/18/19-inch moped rims on large DD hubmotors

Post by kaning » Dec 16 2018 1:58pm

Hi all,
I've been reading a lot for my wheel set up and although radial pattern is not desireable would this set up be safe/good enough?
I live in the netherlands, so i would use the bike as my daily commuter in smooth regular roads.

Motor: Mxus 3k Turbo
Bycicle Rim 20'' (double wall) : https://classic-cycle.com/all/1103/alu- ... wall?c=406
Tire 20''x3.0 : https://classic-cycle.com/all/2402/tire ... wall?c=326

Using radial spoke pattern.

Total weight rider + bike no higher than 250 lbs or 115 kg (will be less for sure)
Also, any tip on the recommended type of spoke for this? Thank you!

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