Author Topic: Cheap Electric fatbike  (Read 95745 times)

TEX_SUP

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Re: Cheap Electric fatbike
« Reply #75 on: September 05, 2016, 06:27:05 PM »
I am leaning back towards the Bafang.  The primary reason is the enclosed gearing.  I didn't like the look of the exposed 2nd chain the cyclone kits. 

My primary interest in this bike would be to replace my current Surf-Mobile.  This would involve some beach riding in hard to soft pack.  I am getting comfortable that the 1,000 Watt BBSHD Bafang should deliver the goods in a more hermetically sealed package.


If reliability in a beach environment is a concern Mongoose has a simpler version called the Beast.  No cables, no derailers, etc.  We have two of them that we have ridden on the beach several times a week for the past two years with virtually no reliability issues.   

I took the frame out of the box and put in sealed bearings, lower gearing (for soft sand), rust resistant chain, lightened the wheels, and lighter tires.  Run 15 psi for the street and hard pack or 4 psi for messing around in the dunes.

If you have an electric motor what do you need gears for anyway?

Brakes might be an issue though.


PonoBill

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Re: Cheap Electric fatbike
« Reply #76 on: September 05, 2016, 06:46:46 PM »
Gears are nice. Derailleurs stand up nicely to sand and junk because they're coarse and simple sprockets to begin with. If you want to get fancy you can use an Alfine internally geared rear end as I did with the three wheeler, or go wild and use a NuVinci hub, though in theory they're only rated for 350 watts.

The Mogoose beast uses a coaster brake. I don't know how that would work out with the Bafang--probably OK, but I like the disks. You don't need a sealed bottom bracket because you're tossing all that away.

I recommend cheap and cheerful with the Mongoose (on sale for $179) and if you really like it and want to gpt fancy, all the electric stuff can move to a more spendy bike later. I have to say that building my Trek--about $2k worth of bike--has been three times more difficult than building the Mongoose. Everything was a bit of a struggle. Getting the sprocket to line up with the derailleur has taken all kinds of fiddling, and I still can't get first gear without the chain popping off.  Zero problems with the Mongoose. Something to be said for the robust nature of cheap, clumsy parts designed to be assembled by K-Mart employees.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

JP4

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Re: Cheap Electric fatbike
« Reply #77 on: September 06, 2016, 01:07:57 PM »
In my continued effort to keep my 17 yr old son from driving and endangering us all, I've been pushing the electric fatbike idea on him. We've talked about 50cc scooters, but they're super slow anyway, gotta have insurance, yadda, yadda...
Question, especially for you PB since you know the hills around here. Will the standard Bafang conversion give him enough power to, say rip up the hill from the skatepark (next to Safeway)?
He's only 120 lbs.
He'd be riding it mostly to the high school and down to the waterfront for work.
He's going to be paying for it himself, so I don't want to sell him on something he's but going to be stoked about.
JP

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GOTWAVZ

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Re: Cheap Electric fatbike
« Reply #78 on: September 06, 2016, 01:22:53 PM »
In my continued effort to keep my 17 yr old son from driving and endangering us all, I've been pushing the electric fatbike idea on him. We've talked about 50cc scooters, but they're super slow anyway, gotta have insurance, yadda, yadda...
Question, especially for you PB since you know the hills around here. Will the standard Bafang conversion give him enough power to, say rip up the hill from the skatepark (next to Safeway)?
He's only 120 lbs.
He'd be riding it mostly to the high school and down to the waterfront for work.
He's going to be paying for it himself, so I don't want to sell him on something he's but going to be stoked about.
JP

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Yes, easily! I'm 205 lbs and I have a nice size hill near my house on the way to the beach, it's not a problem. It's comical.  If you get the advanced controller you can also set a max speed for him. I set my sons to 20 MPH, which give me some solace, otherwise he's pegged at 32mph.  Of course im assuming your mating this to a 52 Volt battery which I listed in my build.
HB, CA, Oahu, HI
JK 7'-8' x 28"x 4" = 99L
JK 7'-10" x 41/4" = 106 L
Joe Blair Gun 8-10" x 28 x 4 1/4
198 lbs - 5'-9"

JP4

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Re: Cheap Electric fatbike
« Reply #79 on: September 06, 2016, 05:55:55 PM »
Thanks GOTWAVZ. I'm promoting it as basically an electric scooter that just happens to have pedals, so I don't want him disappointed if it can't whip uphill without pedaling.
Hood River is only 4-5 miles across at it's widest point but is very hilly, so I think this will be a great way for him to get around.

Like Beasho, I'm looking at BikesDirect for the starting point. I've bought a few things from them before and the service is good. Looking at the Boris X9 with front suspension so he has something nce to cruise around on.
 
http://www.bikesdirect.com/products/motobecane/fat-bikes/fat-bikes-borisfs-x9-bluto-ltd.htm

JP
« Last Edit: September 06, 2016, 06:10:45 PM by JP4 »

PonoBill

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Re: Cheap Electric fatbike
« Reply #80 on: September 06, 2016, 10:03:33 PM »
Major overkill for what you're trying to do, seriously. Why spend a thousand bucks on a nice bike that you then strap 15 pounds of motor and 30 pounds of battery to? You bike guys are the worst gearheads. Covesurfer had a mild coronary because I put bar ends on my Trek. So very 1990.

Anyway, the Bafang HD will take him up any hill Hood River has without pedaling. But don't go bonkers on the bike. Suspension is unnecessary on a fatbike. If you want to go all gearcrazy get some lighter tires for the Mongoose, but seriously, just buy the cheapest fatbike you can find with Derailleurs and discs (at $179 I think you're good with the Walmart Mongoose) and get 'er done.  Your kid will love the thing, and if it falls apart in two years you do something different, and just transfer the electric bits.

Scooters suck toads. I wouldn't put my worst enemy on one. I bought my father in law a Honda Pacific Coast to get him off a scooter.

Bring the thing up to the shop and I'll help you stick it together. It will take about three hours, max.

Oops, $187. You waited too long. Seriously, there will be NO DISCERNABLE DIFFERENCE between the thousand dollar bike and the walmart special, and the Walmart bike is an easier build.  https://www.walmart.com/ip/26-Mongoose-Dolomite-Men-s-7-speed-All-Terrain-Fat-Tire-Mountain-Bike-Navy-Blue-Red/29741123

If you want to get all crazy, get the hitch for $249. It has lighter rims:
https://www.walmart.com/ip/26-Mongoose-Hitch-Men-s-All-Terrain-Fat-Tire-Bike-Red/42248079?action=product_interest&action_type=title&item_id=42248079&placement_id=irs-106-t1&strategy=PWVUB&visitor_id&category=&client_guid=87d7f7fe-c4bb-467c-bedf-14e32d66173a&customer_id_enc&config_id=106&parent_item_id=29741123&parent_anchor_item_id=29741123&guid=b69c6c43-fcfd-4cf2-9a84-a9dfbecf8019&bucket_id=irsbucketdefault&beacon_version=1.0.1&findingMethod=p13n
« Last Edit: September 06, 2016, 10:16:54 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

JP4

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Re: Cheap Electric fatbike
« Reply #81 on: September 06, 2016, 10:40:21 PM »
Thanks PB, I knew I was gonna hear about wanting too fancy a bike, but I'm a bike geek, what can I say? Covesurfer and I used to spend ridiculous amounts of money to win meaningless old man bike races. It's funny I'll balk at spending $2-3k on a new sup, but that would only buy about half a mid-range mountain bike these days. We used to drop $1k on a set of wheels that would be next to worthless in a year. Dumb.
I'll check out the Mongoose.

1tuberider

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Re: Cheap Electric fatbike
« Reply #82 on: September 07, 2016, 06:56:29 AM »
I find my 500 watt evelo is a great commuter. I cruise around town at 20 mph. Hills do slow it down a little, but still
plenty fast when compared to no assist. The evelo does give up to 750 watts on demand. I have had the bike up to 26 mph a few times. Nuvinci hub is how I control speed and power. I highly recommend it. But as PB mentioned they are limited to 350 watt. So far no problems. The evelo came with a 2 year warranty.

My 1000 watt fat bike has limited top speed due to tire bounce. It is used only on sand. I rarely take it up to pas3, I mostly stay in pas1 as I have a 31 tooth front sprocket and a nuvinci hub. Plenty of gearing for soft sand. I can rooster tail when peddling. I do not like speed on the sand as it is bumpy and hard jolts to the frame. My battery housing cracked due to the jolts. This is where a front suspension would help. The fat tires are great for absorbing rocks and in many ways is better than a suspension. But when it gets rough and your cruising 15 mph and hit a wash out that is hard to see, you get jolted and the fat tire adds to the jolt.

When I build the 3000k bike, it will be built to handle the extra power. Failure of frame at 30mph due to fatigue of being beat is something I want to avoid. I did do some research in this area and decided to stay away from a mild steel frame.
At slower speeds it would probably be ok, but I would be looking for cracks before the ride. 

The e bike is evolving. I expect the market is going to satisfy all types of needs. 

PonoBill

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Re: Cheap Electric fatbike
« Reply #83 on: September 07, 2016, 09:47:26 AM »
The power and torque of an eBike is not a huge problem, even when it's up in the 2KW range because it's delivered continuously. Even a kids bike needs to be able to handle a lot of torque when the rider stands on the pedals. Make that a 250-pound oaf standing on 6" cranks and it's 125 foot pounds of torque at least, That's about double the torque of a 100 watt motor (about 50 ft-lbs). Weight is the issue--hanging even a light motor from the bottom bracket applies twisting forces during jolts that the frame wasn't really designed for. But still, consider that the 250 pound oaf could be standing on the pedals during the jolts and it seems that any bike that could handle the average American man could handle a motor and battery.

It's kind of amazing that a little bike chain and lightweight sprocket system can handle a big man pounding away at it, but it can. A smooth running motor doesn't stress the system nearly as much, even though it can provide a lot more power.

I think offroad eBikes are going to get a lot stouter because they create an opportunity to whale the living daylights out of a bike, but when I watch what people already do with pedal bikes I think the strength required is already available. But for general street riding and moderate off road, I don't see much need for added strength.  We'll see, it looks like GotWavz is using his pretty hard, and I'm abusing mine in Maui. Now that I've written all this I'll probably find myself carrying the broken bits back from canefield ride some day soon.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Beasho

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Re: Cheap Electric fatbike
« Reply #84 on: September 15, 2016, 04:33:29 PM »
Maybe not so cheap.  Here are the list of electronics on the way ~ $1550.

This is going to be the step up from my current electric bike.  Take my top speed from 20 mph to 30 mph and extend workable range to 5 miles from current 3 miles.  Range is more a function of time than battery limitation.  Beyond 3++ miles its just more effective to take a car.  I don't like using my car and haven't had to in the past 6 years.  This should also add to the adventure since the beach now become traversable.   More to come.

1tuberider

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Re: Cheap Electric fatbike
« Reply #85 on: September 16, 2016, 06:50:51 AM »
Beasho I get closer to 10 miles of range on the beach with soft sand. You should see more for street.
I have the 52 v bottle battery. My daily use of commuting bike ranges from 6 to 16 miles. I have not run out of power
and its a smaller batter.
 
For gearing I used a 31 t front sprocket. It gives lots of low end power and hill climbing ability. The bafang motor likes to rev. I also find my gearing is used for speed or power.  Once use to it, its very efficient. I am not interested in high speed on a bicycle. Over 20 mph and your breaking Calif law for one thing but braking is not like a motorcycle and I find cars not respecting my right of way. They speed around you and then turn right causing you to brake at speed.
 
It looks like your setting up a fat tire bike with the 100 mm bottom bracket. If you find the tires not the best choice for street, I believe the house has street wheel tire sets for fat tire bikes. I gave up on using mine for the street and just bought a better style bike for commuting.

I am not trying to get a quiver of bikes, but like boards they all have their strengths and weaknesses. Now get that bike
built and give us a report and compare it with your hub motored e bike.

Unless you have the bicycle tools, Luna has the tools needed to make the motor nice and tight. They are worth having.

Cheap is relative. Your going to have a great kit that can transfer to another bike. Most e bikes available cost more than your kit and some 7 times the price of your kit. I am not an advocate of cheap anything. I think you get what you pay for. You do have a great kit.

PonoBill

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Re: Cheap Electric fatbike
« Reply #86 on: September 16, 2016, 07:53:03 AM »
Looks good. I like bigger batteries, but that's just because of the way I use my bikes. Long rides. I also suggest a smaller sprocket, though the big 46T one gives lots of speed. I have a 30T on my new Trek and it required a change in the way I ride. I was getting it into top gear on the flats, cranking the motor to five for assist, and going balls out--generally 35 MPH. Now I'm dropping to 1 for assist and doing 20. Saner, and the battery lasts forever. The other advantage is you won't have to lengthen the chain to suit the much bigger sprocket. I think the stock Mongoose sprocket is 32T.

You'll probably have to shim the Bafang crank housing to the Mongoose frame. I don't remember what I did in Maui. It's worthwhile to get a snug fit with solid metal though it will work with something funky, like plastic shims. I used a piece of steel tubing I cut off a trailer jack foot that was still little too small for the Trek BB, so I added an aluminum shim. PIA. You can buy converters meant to convert the various standard bottom brackets for using cassette crank shafts--not much in the way of standards in the bike world.
« Last Edit: September 16, 2016, 08:00:49 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

covesurfer

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Re: Cheap Electric fatbike
« Reply #87 on: September 16, 2016, 10:28:59 AM »
Pono, don't forget about building one with me this winter in Maui. Cheap = Good for me. First of all, I totally don't need one, I don't have room for one, and it's better for me to pedal than coast. That doesn't mean I don't WANT one. Just sayin'


PonoBill

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Re: Cheap Electric fatbike
« Reply #88 on: September 16, 2016, 11:55:18 AM »
Sure. Stick a board rack on it and it's a good replacement for a car--everywhere but on Maui, where if the tourists don't get you the texting locals will.

I took my truck to the Dalles this morning to have it serviced before the long road trip to the PPG. Stuck the ElecTrek in the back to ride home. The Odometer reads 41 miles for the trip, which included a few side excursions. Odo and speedo are probably not quite accurate, though I did calibrate for the tire diameter.  I did 17MPH average on the four climbs -- Rowena Crest, State Road, Twin Tunnels and 13th street. I got lazy on 13th street because I just had breakfast (Egg River) so I did it on throttle only--16.5 MPH. the control panel shows 2/3 of battery capacity is left. I doubt the accuracy, I'm tempted to run it back to the Dalles without charging and see how it does, but I don't feel like pedaling up seven mile hill without assist.  Going back on the back road to get a change of scenery.

I'm no longer sold on the 30T sprocket. It's nice to be able to pedal assist when you're doing 30+ on the flats. A little speed on a long ride is a good thing. I can do 34mph (indicated) but it's all throttle. the lower gear ratio means I can't pedal fast enough to add any power.

I'm going to try something in between. I don't want to use my lowest ratios on the derailleur because the front sprocket is moved too far out--the chain is straight on the ninth gear (10 speed hub) which makes for an extreme angle to first. It's usable, but I wouldn't want to put a lot of strain on it. If it gives me too much trouble I'll ditch it and put on a Rohloff. 

Gotta love big batteries though. This one from Lunacycle is what I'm using--20AH, 52V 1040watt hours.  http://lunacycle.com/batteries/packs/52v/triangle-52v-panasonic-pf-18650-20ah-pack/

the one I'm building is bigger, fills the whole frame, but it's cheap chinese LiPos that vary all over the place in capacity, so who knows what I'll get out of it. As my battery build chops improve I'll do one with good batteries.



The climb up to Rowena Crest is substantial. I passed a lot of lycra this morning, none of them were happy to see a dipshit wearing levis, sitting up straight, blowing past them a double their speed. No wonder they hate electric bikes--cheater!!

Back at the shop. 41 miles, still got battery left. If I were being conservative I'd probably have a hundred mile range, but that would be all on the flats, lots of pedalling, and no blitzing up long climbs or 30+ mph throttle only shots. And I'd have to pump up my tires. I forgot that I'd let most of the air out to do some dirt stuff yesterday. I just checked the rear tire--8 pounds. No wonder it was so loud.

I have no idea what the battery capacity meter really means. Could be about anything.

Beasho, this is a good article to read, though you're a bit on your own with the Mongoose because the bottom bracket is non-standard. I've found the Mongoose is about the easiest bike to add a Bafang drive to, even if you have to shorten the non-chain side of the BB. Very few interference problems and the chain lines up in the middle of the derailleur. https://electricbike-blog.com/2015/11/19/get-a-bigger-hammer-bbshdbbs02-installation-problems-fixes-for-non-standard-bb-intrusive-chainstays/
« Last Edit: September 16, 2016, 12:52:11 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Bean

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Re: Cheap Electric fatbike
« Reply #89 on: September 16, 2016, 01:01:37 PM »
Holy Crap PB, 1040wh, that's a big-ass battery!

So, to put it in perspective (mostly for me), 1040wh is more than 10 times the battery capacity, in watt hours, that the FAA will allow you travel with.  The Onewheel battery is 130-140wh and the Boosted board is 99wh or 199wh depending on the chosen battery pack.

 


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