barber111

I'm in Montana. 6'6" tall, 250#, 57 yrs old.

My little brain says..

1. to buy an XL economical fat bike from BD or similar.
Then go about getting motor-kit-hub-wheel-battery. whatever, once I have the bike to go from.

My riding will ALL be on dirt roads, at 15mph top end "needed" speed. So, my first questions are.....

Do I go with MID or HUB (rear) ??

Luna has got the rear fat kit with a wheel laced in it. That seems good to my ignorance.

I understand I'll be throwing 1,000 bucks at it. I just don't know what to get..

Lets start there.

Thanks, Barber

barber111

I would also like pedal assist.

Barber

Doc_Wui

Have done what you want to do, except I started with a fatbike from Walmart ($99) with rim brakes that didn't work. Should have gone with a bikes direct model.

Geared 500W Bafang motor from China with 175mm axle. Similar to Luna's offering. I run it with 36V - 52V batteries that I put in the rack bag. Controller is the Luna 25A unit. About 22-24 mph withe Veeco Speedster tires on asphalt, but 15 mph is my preferred speed. For casual riding, the geared motor will work.

Tires are a big expense, but I wanted to save weight and have specific tread pattern. The Speedsters are for the street and cost $140/pair. I have Veeco Snowshoes, also $140/pair, for winter. Original knobbies were 8 pounds heavier.

For winter, I tried out 2WD. I bought an hub motor and spoked it myself. Then I moved the bottle battery from another ebke I own to the frame, as shown in 2nd picture. The front motor electronics is in the blue bag. Battery for the rear motor is still in the rack bag. Bike weighs about 65 pounds in this shot. It pulls nice thru 3" of virgin snow, but I came home sopping wet and got sick.

Probably threw $1600 into this project. I also spent 100 bucks on a front derailleur.

I'm now back to rear wheel drive only. Bike is closer to 50 pounds. I get away with small 4AH and 6AH batteries in the bag as I only ride it about 10 miles when I do ride it. No good place for a fatbike here in the suburbs and I feel like the guys who drove Hummers here in the 1990's.

Doc_Wui

You will have to ask Luna if their 25A controller has pedal assist. I don't believe their "R&D" guys know how to pedal.

I prefer to ride in pedal assist myself. My bike is quite pedal friendly too, with 21 gear combos and smooth tires.

barber111

Thank you.
I was just assuming 750-1000W. The $1,000.00 figure I thru out there was for the conversion, bike excluded. More is always good, no ?? I'm just asking and trying to learn..

Thanks again, Barber

speedy25

There's a new Bafang hub drive out there with a torque sensor in the BB. Make their system MUCH better than the cadence sensor models. Poke around for one of them from the Chinese market.

-SP

barber111

Thanks people. That gives me something to chew on with the puter.

Thanks Barber

Doc_Wui

Bike excluded, $1000 should cover battery/motor/ electronics. The Bafang gear motor for me was $340 plus $500 for battery/charger.

I had the second motor, plus replacing most of the bike parts which kicked up my spending.

That new mid drive Bafang only fits certain frames. If you want torque sensor plus mid drive, there's the TDSZ2 kit which comes in a milder tune than the BBS02, but fatbikes have 100mm wide brackets for the pedal assembly (also called a bottom bracket or BB), and TDSZ2 may not be available that wide. Standard BB widths run 68mm-72mm. Why ar fatbike BB's so wide? The tires are wide, so they need to move the front gear over an inch to clear the rubber.



When I did my fatbike, 100mm wide BBS02 units were close to $1000, so I went rear motor.

barber111

Excellent info Doc. Thanks, Barber

Rick Imby

I built up one of my old 26" mountain bikes. It has high end wheels (about $400 when new) and a high end ($600 when new front shock). Disc brakes are an absolute---

I went with a mid drive Bafang BBS02 from Luna with a $500 battery and I love it. There was a little bit of bs getting the battery to plug in---I went with a Dolphin but would go with a Bag battery instead---more options to mount---rear rack or in the triangle.

I am not as fond of a Fat bike for several reasons. Flat tires are a nightmare, tire availability is small and they are really expensive.

I'm 200+ and 63. I rarely use the throttle---I don't need it---but I love the pedal assist.

I have been using mine as an all around town and cruising bike some trail use---I live in Missoula and have beaten the fastest Strava time on a 17 minute paved hill climb by 2 minutes---however I very rarely use full power with my setup.

With your height you are going to have trouble finding a bike to fit---

I use mine for exercise and to get where I am going faster. I have about 1k miles on mine.

I started with a 30t front cog and then bought a 42 tooth---the 30t is too small for normal cruising but works well on steep trails.

Beware of fat Bike Wheel sizes---thru axels and 142mm or 148mm width are going to make it impossible to get a hub motor.

Good Luck

Rick Imby

I have ridden both cadence sensor and torque sensor a lot and have not felt the difference was worth paying for. I don't get the big plus some people feel about torque.

I use my bbs02 for pedal assist just to get there a little faster. rarely use my throttle.

barber111

Thanks Rick.. LOL... I plan on rarely using my pedals.... lol

Barber

Rick Imby

So you are building an electric motorcycle/bike.

That would get me leaning more into the mid drive. Mid drives allow the electric motor to be more efficient. Electric motors like to spin fast, you can keep it humming with the gearing in a mid motor.

Keeping the motor at higher rpms allows your motor to be much more efficient---less heat better battery power efficiency.



I would go with the Aluminum 42 tooth cog for the Bafang BBSO2 because you can get a much better chain line with the 42 than with the 30t.



I would go with a mid drive on a bike with a cassette hub---important---
Cassette hub wheels have much stronger axles than freewheel hubs---important with your weight.


If you go with a wheel motor be careful about being sure it will fit the dimensions of your frame---This is especially critical with Fat bikes

Other things to watch for---Bottom bracket width on some Fat bikes is different too. Be sure to order the right Bafang mid drive for your BB.

I don't like the Fat bikes--personal opinion---yes I have had a couple without motors and I still have one.---Flat tires are a nightmare, tires extremely expensive, rolling resistance much higher---lower battery mileage---bikes are significantly heavier--They are awesome in Snow---but snow riding kills your bike quickly.