Mongoose 20" FAT build

Hi folk

To not pollute anymore the 20" thread where this insane idea has been generated, I start this new thread about the conversion of this little big WM bike...

I'll start resuming the bike measures..

Wheels:
ETRTO 406x93(100)
Tires:
(20"x4" 1/4")
100mm wide
556mm high
front dropout: 135mm
rear dropout: 175mm
ISO disc mount: yes


Frame:
100mm BB shell
175mm rear dropouts width
whelbase: 924mm
BB to ground: 250mm
Axle to Ground: 280mm
chainstay: 380mm
chainline: 73mm
toptube (virtual): 490mm
toptube (actual) 475mm
Seatpost Dia: 1 1/8
Seatpost min: 580mm
headtube angle: 69°
headset: 1" threaded
headtube lenght: 117mm
Dropout style: welded, 10mm vertical
Dropout mounts: ISO Disc mount (LH), derailleur hanger (RH)

fork:
dropout width 135mm
Axle to headtube (lower edge) 355mm
trail.: 90mm,

weight: 17.5 Kg

Click to expand...

And the Ideas about how to restyle/upgrade it:

Bar: BMX 9"
saddle: BMX
Brakes: hayes So1e
Longer seatpost
Derailleur/shifter Sram x7 short cage + revo
Sinz Short isis crankset + gigapipe 100
Bmx pedals
Better headset.
Legal hubmotor candidate: XiongDa 2 speed
Medium power candidate <750w geared scooter hubmotor (suggestions?)
Extreme hubmotor candidate: Minimonster or higher power, non-bike standard motors.

I could try my astro 3220 drive on it with a longer jackshaft assembly....as I plan to do on the 26" fatbike I have.

Click to expand...

than I'll repost the pictures of what I've made actually and the "forkpost" idea (just the first fit with a road front hub forced under a super comfortable royalgel saddle, A front axle alone with an old style saddle clamp opportunely spaced should do the job, it also elevate the saddle just the bit needed to avoid the legs to touch the fork's end.




I would try with a legal hubmotor first, I have a BPM but the axle length is not enough, I'm looking for <750w alternatives and among the few that should fit in term of axle I found the XD, and since the 2 speed version is tempting me in any case, I'll try with it unless you have any concern about, or any better alternative in this power range to suggest

I Agree with Cwah that This little thing Is calling for a Minimonster or a similar scooter size motor, but the Bike is so short, And I have My Astro 3220 MP6 Freeride bike, when I want true power and a true Bike....
Having the time and the interest wouldn't be that hard to make a similar frame but with an extended wheelbase and chainstay, and a properly armed dropout for the Minimonster's torque.....

.

TroySmith80 said:

lol, a fork used for a suspension seatpost, there's something i've NEVER seen before!!

Are those scooter tires? Pretty interesting bike, i'll be curious to see what you do with it. Put a link here to your build thread please. Is the frame Aluminum or steel?

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No, these are formerly bikes tires, rims, tires and tubes are easily available online and are the same as a Schwinn Stingray, Haven't found decent offroad tires for it, nor in the 16" scooter size.....The Frame is Steel

the x-treme xb600 hub motor fits the wide dropout of the Schwinn occ should be about right for the mongoose fat bikes,
its a little smaller in profile with the original rear tire though theres a place selling 500 watt kit for the Schwinn occ as well
lil more pricey though, and I think the a2b hub motors are close to the dropout size needed for both I have some trike kits that
would fit the rear dropout, they were custom made for the wide dropout of the schwinns I been wanting 1 of those fat bikes
for the parts to transfer to a Schwinn chopper seems like the 5 speed setup and disk brakes would swap over

Thanks for these info, I would like to keep the rear disc brake working, that's the big problem, a drum brake is the only alternative option, but means adding weight and a bad look...
Is the Occ mounting disc brakes? disc brake system of this bike is terrible as any component other than the frame an the wheels, that are anyway cheep china pinned rims with no eylets. tires smell like a rubber's factory even after a 2 weeks of use and a shampoo! Derailleur is 7 speed SiS (nothing to do with the 20+ Years old SiS I have on an old bike).
Definitively there's nothing I can think to transfer from this bike to another other than fork/wheels/Hubs

Dude, that thig is freaking Nuts! I love it!

SO finally got the XD 2 speed motor, It is a drum brake version with a screw on adapter for 6h 44mm ISO rotor mounts.

There is also a solid DTSwiss version (ARAI) of these adapters...they fit standard 1.375 threads.

The spacing is at about 166mm and the wheel is perfectly centered!!

All functions seems to work perfectly on the bench....I'm using the Lishui controller+ KM5S display combo, the 2 speed switch works well....

Now I've to decide the rims and eventually the type of grease to replace the factory one.

Rims: flange spacing on the hub is 52mm, but the holes in the original rim (and in dhl100 rims) are 64mm spaced, that leads to an outlaced wheel.
The DHL80 and the DHL101 have more centered holes....that should be better for this job.
Have you guys any advice about rims or in lacing the wheel? the plan is to use 1Cross with 133mm 13g plain gauge spokes (DHL-80-101)..I've good experience in lacing wheels, but not with hubmotors....

Any advice about suitable greases to be used for the gears is welcome too

I'm not picky about the brand, as long as the grease is synthetic, and it is made for a cars front wheel bearings, because disc brakes get very hot. Synthetic grease does not harden in freezing weather, and still works well far above 100C /212F

Ok, got it, many thanks....
I will try one with the class of grease that you suggest, and maintain the other with the stock grease,
that should give us useful comparative data...

If you're using Windows you can open your pics in the Paint program and rotate them 90 degrees to the right.

Dauntless said:

If you're using Windows you can open your pics in the Paint program and rotate them 90 degrees to the right.

Click to expand...

Oh! yes sorry for that....I know it , I was out of time but wanted to post these pics...

Edit about the Bike

The Original rims (single wall pinned 100mm) have 62mm spaced holes
The DHL100 (double wall pinned 100mm) have 50mm spaced holes
the DHL 80-101 should have similar spokes holes at about 20-25mm

So I will give a try to the DHL100...

Update:

View attachment 2
I've laced the wheel with PG13g spokes 2 cross and the wheel was not able to stay centered for more than few Kms. So I'm trying now with alpina 2.5mm Moped spokes, again, 2crossed. I've enlarged the rim's holes for the 5mm nipples. Spokes result a bit bended due to their strange (and not so good) offset, especially the internal ones (external head); in fact this wheel has a virtual flange spacing of only 2mm due to the 50mm distance between L and R holes and the 52mm hub flange spacing. I've made some Kilometers pedaling with this lace and everything seems ok, surprisingly....
Best thing is to obtain a new DHL101 rim that has more centered holes and lace 1crossed or use 80mm rims that have centered holes too. I may also try 1 cross with the same 2.5 alpina's or radial, even with 3mm spokes, I want a true 0 maintenance rear wheel. The whole rear wheel weight is 7.2kgs including freewheel, rotor, tire and tube.

I will like to use the bike mostly with PAS for the first test phase, This will be a legal bike, an option should be a thumb that works only when the PAS sensor signal send pulses, that is legal here.
I'm interested about the system reliability, the forgiveness of the whole bike in fact of wheels and axles (yet bended the stock rear axle and BB spindle ) the climbing/pulling ability.
I will test it with 10s and 9s lipos first, than I will try overvolted setups.

Only 2 kms made right now with a 9s 5Ah zippy compact. Shifting seems perfect, speed is a bit over 30kph in High/full charge. Noise is normal.

I've re-greased the other motor, that has been a challenge, at least for me, I'll try this one with the stock grease first.
Final Bike will be full Black, maybe with only rubbers and rim sidewalls in the stock yellow-orange tint, and, since I will bring this bike with me next Eurobike show, I will stick in an ES logo, this time, same as for my MP6 Astro Bike.
Ah!, maybe I will need a volunteer, because I think that only a single bike is allowed for each visitor..... :wink:
Stay tuned.

I've made 100km with this stupid bike and I'm pretty happy with it and the motor.
It tops out at near 35Kph with throttle, it can climb a 2digit grade, It is the opposite of what I've considered a Bike during my life, and still remain that
But I have to say that is an interesting short-commuting thing, especially for our historic and gas-limited center-towns, or as a small tractor puller.

I started this build without thinking a lot....there was the option to get this bike from WM to Italy with only a little more overpricing (280$), found the XD as wide enough among the legal (or so) Hub in the market with the 2 speed experimantal feature too (240$), used only spares components from my garage ...except for the rim(50$) and spokes ($1 each); well, the X0 shifter and the X7 derailleur are deluxe spares, while the old Ritchey thread to clamp stem is a vintage beauty, but you can get new and reliable parts instead for cheap.
Juice comes from some 9s and 10s ZippyCompact 5Ah i got at liquidation price from the EUwarehouse some time ago.... 55$ each shipped 8).
The KT controller I have has a 27v LVC...while the lishui has 31-32 one. At 9s the bike still works fine.

Anyway, It is a very low budget electric stupid bike (all costs are including shippings and taxes for my particular case)



[youtube]XUb5UiFXBy8[/youtube]

But......what about a more elegant, slightly longer and taller frame made to be lighter and stronger and made with some e-side care and details? I've some request for this from local shops and rental shops.
It could cost the frame only as 1 or 2 Massifs....but than, one could even think about some true power on it.... :wink: If I could source a matching, acceptable, steel fork, the job should be really feasible.

I've yet to find any Ebike build, no matter what power levels, to be stupid. It's good to have different arrows in your quiver, as they say. :wink:

What kind of range are you getting in mixed terrain that the bike is suited to?

melodious said:

I've yet to find any Ebike build, no matter what power levels, to be stupid. It's good to have different arrows in your quiver, as they say. :wink:

What kind of range are you getting in mixed terrain that the bike is suited to?

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I can do 25 Km in auto mode with PAS only and an average 3 of 5 level assist, with a 9s 5Ah battery, that's in flat.
about half of that in mixed conditions with hills. The bike climbs like a tractor in low speed. I think it stall without pedal at say 12% grade, but it is so highly geared that adding just a bit of torque with the lowest pedal gear allows even 20% hills. I'm keen to test more the 700c bike with the other motor, I'm waiting for a cool 36holes 29" rimset and a 36h front hub for a definitive setup, than I could start a new thread on that.....

I have one of these bikes as well and probably going the rc motor route on it. I think I saw in another thread a post by you about getting some better rims for it. I have pretty fair skills in some areas but my knowledge of whats available bike parts wise is somewhat limited. Whats the likelyhood of finding a rear disc brake type hub of the same width as this for building your own rear wheel. One of the factors that led me to get this bike was the fact that it had disc brakes front and rear and would lend itself to left side drive. Also curious if there is a front suspension type fork that would fit a tire/wheel of this width.

I just saw something on a bike parts site about some BMX rims that were designed to be cross laced. This is where the spokes go from one side of the hub to the opposite side of the rim from where they would normally go. Wondering if that could be done on a rim not specifically designed for that.

I just bought this bike used on craigslist. Not sure exactly how I'm converting it yet but will start a thread for it.