Bicycle Fabrications MissingLink Budget DIY DH Build

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Solar DH
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Bicycle Fabrications MissingLink Budget DIY DH Build

Post by Solar DH » Dec 31, 2016 6:00 pm

This is my solar DH bike and first ebike build. I made a lot of mistakes along the way, but it didn't cost much and I learned a ton. The frame is a 2012 Bicycle Fabrications MissingLink(TM), co-designed by Hank Matheson and I. Hank did most of the fabrication. You can see more on the MissingLink in this Dirt Rag article - ... -platform/
I started the ebike conversion in June of 2015 and had it running in about 3 weeks, but it took a year to get fully sorted. I burned one motor twice and one controller. This bike is not high power or long range but is enough to help get me up the hill nearby.

Parts, mods, and rough costs:

2x Unite MY1016 24V 350W brush gearmotor $104
timing advanced ~12 degrees $0
2x Yiyun 36V 500W controller $23
12s HK Lipo, 3 x 14.8V, 222Wh $100
precharge circuit, fuse, switch $5
larger brushes and modified holders $6
high temp brush board $5
high temp ceramic/ss bb, epoxy potted in brush cover $8
cooling holes in motor and controller $0
2x 24V 40mm fans in series, 1 for motor, 1 for controller $4
filters and screens from automotive air filter $0
shunt mounted inside controller box $10
volt and ammeter to motor $10
pack voltmeter $8
stator temp gauge $5
Dicta crank freewheel $12
12t generic Ebay motor freewheel $5
diy freewheel adapters $15
8s motor chain $0
SBP 170mm cranks $25
square taper bb $10
40t chainring $20
custom upper chainguide $0
custom 9 speed 11-44 cassette, 44t chainring pinned to 34t $0
modified derailleur $0
total ~ $375

Advancing the timing was the key to the motor surviving higher power. I figured that out last of course. I wouldn't recommend this build unless someone was a glutton for punishment and or on a budget. It has been a fun and cheap education though.
IMG_0032c.jpg (147.31 KiB) Viewed 1125 times
IMG_0034c.jpg (142.79 KiB) Viewed 1125 times
Last edited by Solar DH on Apr 04, 2018 2:25 pm, edited 2 times in total.

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Re: Build 1 - Bicycle Fabrications MissingLink + $50 Motor

Post by Dauntless » Dec 31, 2016 9:18 pm

2D suspension. Interesting, but is it overkill? You what they say about it being the extra part that breaks.

Are you saying there are 2 motors in front of the crank? Maybe the picture doesn't show. But why not just a bigger single motor?
Any sufficiently advanced technology is INDISTINGUISHABLE FROM MAGIC!
- Arthur C. Clarke

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Re: Build 1 - Bicycle Fabrications MissingLink + $50 Motor

Post by Voltron » Dec 31, 2016 9:54 pm

I think what he is saying is that the cost list shows two motors because he burned one up... not two at one time on the bike.

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Re: Build 1 - Bicycle Fabrications MissingLink + $50 Motor

Post by motomech » Dec 31, 2016 11:30 pm

Nice looking bike!
Not included are the costs of caring for the LiPoly, which can be considerable. Of course if you already were set-up for it, those costs can be amortized.
Speaking of LiPoly, that's a very sm. pack. My experience is LiPoly doesn't last very long when it's being dis-charged deeply.
I was able to hide 4000mAh's of 12S in a home made water bottle;
100_0107.JPG (89.08 KiB) Viewed 1089 times
And there is another 10,400mAh's in the frame bag for a total of 14.4 Ah's.
My point is, a decent sized pack can be fitted w/out becoming too ubtrusive.

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, Crazy Bobs run ghetto tubeless. 25 mph. Mean Well HLG-320H-54A ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 14S LiPoly elifebike 9-FET 20A controller. 23 MPH. ... 8#p1237928

Solar DH
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Re: Build 1 - Bicycle Fabrications MissingLink + $50 Motor

Post by Solar DH » Jan 01, 2017 6:29 pm

Dauntless - this is probably the simplest form of 2d suspension, with fewer parts than a lot of current 1d designs. The swing link on the shock pivot is only for lateral stiffness, not part of the 2d system. We also have a two shock version (being updated) with a discrete link that is equally minimalist. These are single pivots at heart although our 2d system can be used in 4-bars, etc. We prefer fewer parts though for just the reason you state. This bike has been abused now for 4+ years and is going strong.

Yes, just one motor on the bike but I eventually purchased two after blowing the first one, twice. I used only the rotor from the new motor so I have a spare gearbox, stator, and brush assy. I tried to repair the first rotor (threw a comm. tooth) after it overheated badly. It worked for awhile but overheated and blew again since I hadn't done the timing mod yet. I also took out the first controller in the mayhem. I installed the new rotor but before using it I put in the bigger brushes, ceramic bb (cage melted in the original bearing), cooling mods, and gauges. The magnets seemed fine so I left the stator. On the workstand I could now see into the motor through the brush holes and at known voltages. The arcing got heavy starting at ~29 volts, which is when I realized I should look at the timing.

motomech - thanks! Likewise on your stealthy build. I had to look twice. What cells are you using? You are correct I left out:
charger $20
balance board $12
battery monitors $12
I am a totally new to lipo so these were all incremental costs. Also forgot I puffed one hardcase along the way, and had to settle for a softpack sandwiched between two plastic plates (hardcase were sold out). This brings the cost to about $375+$44+$35 = $454. I thought it seemed low at first.

I had no idea how much battery I needed until I could do a whole ride without blowing something. I can now do the main loop from my house on a little more than half the charge, about 120~130Wh. Not sure if that is considered too deep. It's been interesting to compare to my second build with a BBS02 750w. I can do the loop on a little to a lot less than half charge on that bike. I pedal as much as possible and mainly use assist on the steeps I used to have to push up. I have gotten used to the charging hassle and like having fewer batteries to manage, but have definitely lusted over a bigger (Ah) and more user-friendly pack. I use this pack on three bikes.

A few more pics -
brush side.jpg
Visible is the fan switch (from a '90's light system), air filter element (from a car filter) over brush holes that the fan draws through, and spare chainguide bracket that came in handy for a motor mount. Also the controller with fan in the back drawing air over the fets through its own filter. There is a screen (from the same filter) over this fan for protection.
brush side.jpg (151.05 KiB) Viewed 1017 times
drive side.jpg
Motor fan, good old muffler clamp, diy fw adapters, and custom upper guide that is essential. I can't go 100 feet down the trail without it. Also a random heat shield from the parts bin that made a nice fw rock guard, and the holes matched. Looks like the half link needs some attention.
drive side.jpg (164.96 KiB) Viewed 1017 times
55.5-56 lbs as shown all up, ready to ride. Slightly over my goal of 55 lbs max. I wear a camelback with spares and tools (not batteries) with this bike.
lh.jpg (126.05 KiB) Viewed 1017 times
motor V, A, temp.jpg
Motor V, A, and outside temp. I started with 1, then 2, then 3 guages. Need to make a better mount but it works for now.
motor V, A, temp.jpg (52.72 KiB) Viewed 1017 times
pack V, full tank.jpg
Pack V, full tank. These gauges all run on the same 9V battery but if all are plugged in at once the bike blows up, and I draw the line at one 9V battery.
HA ~61.5 deg, SA ~71 deg, WB 48.25", CS 17.0, BB 13.75"
rh.jpg (116.23 KiB) Viewed 1017 times
Happy New Year!
rh2.jpg (126.29 KiB) Viewed 1017 times

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Re: Build 1 - Bicycle Fabrications MissingLink + $50 Motor

Post by Sillyhead » Feb 01, 2017 1:21 pm

what speeds does this bike get up to?

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Re: Bicycle Fabrications MissingLink Budget DIY Build

Post by Solar DH » Feb 04, 2017 4:24 pm

It's geared more for climbing than high speed but I'm guessing with 34-11 gearing and 2.5" knobbies maybe high 20's on flat ground? I built it mainly to climb this hill so I wouldn't have to shuttle or push:

This is the steepest part on my local test loop and the motor was drawing 1600W+ here, 40V+ x 40A+. I was trying to do a temperature test but the sensor came loose and dropped back closer to ambient. It still gets hot but doesn't burn up, which is nice. With a small pack and motor I go easy on it everywhere else.

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Re: Bicycle Fabrications MissingLink Budget DIY Build

Post by Solar DH » Apr 04, 2018 12:57 pm

I'm bad with updates. Last year I did a double motor swap, putting the BBS02 from my Superlight on this bike since it was the better DH bike. The BBS is now a a third bike. There is great DH riding in my town. Backyard roadgap test, got a little close to the camera guy:

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