Thinking about building a Fat-Tire E-bike.... need some help

OK so please forgive my noobness, I've been reading the boards, and I'm trying to settle on a setup before I start ordering a ton of stuff that doesn't fit / work.

I'm thinking about building this bike:
http://www.bikesdirect.com/products/motobecane/fat-bikes/fat-bikes-boris-x5-fatbikes.htm

Wanted to get a 72V10AH 24s Lipo battery + HT3525 high torque hub motor and run 40A controller.

Question #1 ....... where can I find a rim that will accommodate the HT3525 in the rear of the bike? The rear hub on the bike now is 170mm.

Question #2 ....... any suggestions on a good 40 Amp controller?

Question #3 ....... do you think 4" fat tire bike with no suspension will be comfortable riding at 30-35mph on the streets? I wanted to get fat tire setup to give me some cushion as well as ability to go over crazy bumps in the road.

Thanks in advance!!!!

You will need spacers for the 170 mm width. Easy to do. Lyen controller is what I prefer. Sensorless. Fat bikes are a little tricky.
I would put a Cro motor on it. They already close to that wide. How are you thinking of mounting battery?

Personally, wouldn't use that bike if it were free. Aluminum sucks for hub motor and i don't like the triangle shape. I'd much prefer the Mongoose Dolomite with a steel frame at less than half the price.

Your rim is on the original wheel, if it's 36 hole.

No, at 35 mph it will not be comfy. For that you need a good full suspension bike. Yes, the fat tires will absorb some rough road, but I would not trust them at 35 mph with 15 psi. You will still be hammered by a bad man hole cover or pothole at 35 mph.

Get a clue folks, fat tire bikes are made for cruising in the sand or snow. not hauling ass. A fat tire bike might be wonderful with a motor that goes 25 mph, but not for 35 +.

For a rear motor, you will need to find one with a very long axle. A rear motor can be run as a front motor, fitting the wider than normal front fork.

I agree with dogman. I ride the Boris X9 fat bike and it is a pleasure at 12-25mph on trails but it is not built for speed on those low pressure tires. It is not electrified, just stock, (lighter). If you want a bike that will go 35+mph get a good downhill bike with superior brakes and suspension. Brakes are most important. It is not speed that kills, its the sudden stopping.

-rich

OK thanks for the info ....

as far as the rim being on the original wheel.... unfortunately, not... the bike comes with 32h ..... i looked at the mongoose dolomite and counting the spokes, it looks like it has 36 hubs, so that could work. I'll keep looking for 36 hub bikes to simplify things.

i'm still really wanting a fat bike but i'll look more for suspsension bikes as well....

I need to find a source for a good 36 hole fat bike rim. So let me know if you find one. I get this constantly on the EBK chat, and some have 32 spoke wheel bikes.

DO build your fat bike, just go for more sensible speeds. My idea of an ideal fat bike build would be a much slower wind DD motor, and 48v. 20 mph ish. But with the slow wind, it could tow trailers, or just grind through deep sand real nice.

Fat bike is a willy's jeep, use it to off road ride. For hauling ass, get the Subaru rally car equivalent bike.

http://www.niagaracycle.com/search.php?search_query=dhl

Thanks, I'm real interested in a fat bike too, but I want one with suspension. Frankenbike a steel mongoose frame with a custom rear swingarm?

Removable dropouts that allow using a 135mm rear hub? I'd be happy enough with a 2.5" front tire on a normal fork. I just want the float of a 4" tire on the rear wheel for sandy arroyos.

So many dreams, so little money.

Waiting for the Bafang BB to come out fitting fat bikes wide BB shell. One guy is doing a custom adapter, but $$$$!

I think because of the explosive popularity of fatties, we are going to see more competitively priced electric kit options made especially for them, be it 100mm bottom bracket or 170-190mm rear dropout width. Wise companies would consider 30-40 amps as a starting point since these bikes are well suited to snow, sand, and very loose terrain (i.e. pumice).

My dilemma is the line between electric assist Fatbike and more sturdy framed Motoped with fat tires. One is going to be a heavy beast (relatively speaking :wink: ) and handle the jump to roadway speeds (40mph roads & 60mph highways).

IMO, fat bike tires will always perform best under 20 mph. At 40-50 mph, I wore out a bike tire in 40 min once. Looked fine from the outside, but inside all the cords were cooked. Like a ball of string inside when I took off the tire.

Moped dot rated tires for the homemade flyweight motorcycle.

melodious said:

I think because of the explosive popularity of fatties, we are going to see more competitively priced electric kit options made especially for them, be it 100mm bottom bracket or 170-190mm rear dropout width. Wise companies would consider 30-40 amps as a starting point since these bikes are well suited to snow, sand, and very loose terrain (i.e. pumice).

Click to expand...

I agree. While searching for something else, this, I came across this: http://www.ebay.com/itm/Fat-Tire-El...d=100034&prg=10942&rk=3&rkt=8&sd=151437749256

Sorry for the long link. I don't know the code for hyperlinking.

I had never seen a kit for a fat bike before. I think it is a front kit though.

If you're willing to pay $810 for a 700W motor kit in a 26x4" rim I'll come out of retirement and build you a 1000W kit for $800.
http://en.wikipedia.org/wiki/There%27s_a_sucker_born_every_minute
just delete everything in the url starting at the first ?
http://www.ebay.com/itm/Fat-Tire-Electric-bike-Kit-26-x-4-48Volt-1400-W-Max-Made-in-USA-Whole-Kit/281424741800

wesnewell said:

If you're willing to pay $810 for a 700W motor kit in a 26x4" rim I'll come out of retirement and build you a 1000W kit for $800.
http://en.wikipedia.org/wiki/There%27s_a_sucker_born_every_minute
just delete everything in the url starting at the first ?
http://www.ebay.com/itm/Fat-Tire-Electric-bike-Kit-26-x-4-48Volt-1400-W-Max-Made-in-USA-Whole-Kit/281424741800

Click to expand...

Listing indicates Busetti motor. If that's the same Busetti found on the forum I'd wanna know more specifics about it.

How many fat bikes have you built Wes?

You can read all their hype here.
http://www.busettii.com/

... still pricing out / sourcing components.... I'm leaning more towards the single speed Bullseye Monster:
http://www.bikesdirect.com/products/gravity/fat-bikes/fat-bikes-bullseye-monster.htm

Will need rim/hub to be mounted on motor and someone to lace it... trying to figure that part out now.... I've emailed a few people.

Will be using 72V10AH Lifepo4 battery and running 40-55A for 3-4KW power.

If the tires are too "knobby" and not street slick enough I'll get these Surly 26 x 3.8 tires:
http://surlybikes.com/parts/wheels/black_floyd

If I feel the ride needs more suspension I'll switch out the seat for one with springs and if need be consider getting a front suspension fork for fat tires. In Cali there aren't too many potholes, etc... luckily the roads are fairly smooth. I guess we'll see how it rides and go from there....

I'm probably not going to go 35-50mph that often (if it can go that fast with 3-4KW).... I just want to go that fast if I feel like it... or have the power to accelerate fast off the line. Yes, I will commute to work with it... but that commute is only 1.25 miles each way I live in Hermosa Beach, CA and I also plan to play in the sand and trails, etc... plus everyone here has a beach cruiser and I think this will fit in nicely with the beachy vibe / lifestyle.

If your going to try slick tyres also consider Vee speedster 26 x 3.5, I ride a Surly Troll semi fat my rims are Halo SAS 37mm wide so not the full on fat rim sizes.
At speed downhill on tarmac over 30 mph (no thanks !) the bouncy nature of black floyd was scary, the speedster is much better if a bit smaller and can be inflated to between 8 and 36 psi, my fork is the standard troll fork.
I rode down a steep local country lane at speeds touching 40mph the other day, handling was stable and felt safe I run it at 30psi on tarmac and 18psi on trails.

Hey dogman, apparently Weinmann makes a 26 X 4 Double wall fat tire rim in both 36 and 32 hole. Pretty cheap too. Here is a link to a sold one on ebay but I know Amazon has em:

http://www.ebay.com/itm/Weinmann-Rim-Alloy-26X4-0-DHL80-36H-Black-/131282728378

I plan on using these on my next project. Their main web site does not list them oddly but I remember somehow backing into a different section of their site when I was researching this and found the specs. Maybe you can figure it out.

Bikewagon has them on their site (Mountain, wheels, rims, weimann). I've used this company repeatedly, and found them to be excellent. Additionally, the rims ship for free from them, not $9.99 like ebay.