8kW E-Bike Qulbix Q76R 100lb trail beast

Discussion in 'Some Assembly Required' started by sailah, Sep 11, 2017.

  1. sailah

    sailah Lampin' it

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    Figured I would start a new thread. I've been posting in Electric Bicycles, Shiny Things forum but this is going to be quite a project and I didn't want to turn that thread into my personal build log.

    A bit of background. I've always wanted an E bike, thought they were cool. Since moving to MA my offroading riding chances are pretty slim. I live in suburbia and dirt bikes are frowned upon. I figured this would be a semi stealth way to enjoy the tons of bicycle trails we have. And before I get people screaming at me about riding this bike on trails, I don't plan on roosting up nice bike trails. This will be a general purpose cruiser, more for getting out and enjoying some wind in the face, and pedaling along too. I also like projects and for those that may remember some of my previous builds, I do like making things.

    I set out to find a frame and thought about converting my Trek 9.8 hardtail. But for a lot of reasons going with a purpose built E bike frame was a better fit. I wanted full-suspension, I wanted lots of capacity and cramming all those into a regular bike just doesn't work well. Plus nice downhill frames are expensive.

    Qulbix Q76R seemed like the slimmest, newest frame out there. Bought it a few months ago and been pecking away at it. The company is in Slovenia, so it's a bit of a ship but not too bad.

    Here's the frame as I got it. With the frame you get the swingarm, side panels and choice of seat. I went bicycle seat as a moto seat would probably be pushing my luck.

    20170819_113045.jpg

    The rear shock is a Marzocchi bomber 3.5x10 shock. Got on ebay and upgraded the spring.

    Built a jig to hold the bike as the rear hub motor is very heavy. The motor is a QS205 and is capable of huge power levels.

    20170902_191353.jpg

    I had some issues with the headtube not being round so I had to use a big vise with soft jaws and squeeze it back round. Installed the Marzocchi 380 C2R2 forks. Rims are 19-1.40 Pro wheel 36H F&R. Bought a Shimano Saint front hub and drilled out to accommodate 9g spokes. Planning on sending to Buchanans to have them custom make spokes for front and rear.

    20170910_092051.jpg
    20170910_111036.jpg
    #1
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  2. sailah

    sailah Lampin' it

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    So that's where I'm at now. If you want any more back story to anything, the Electric Bicycles thread has some answers.

    From what I gather I should be able to get about 60MPH and maybe 30-40 miles of range from this? I may be off on that but we will see.

    Frame & Swingarm : Qulbix Q76R
    Motor: QS205
    Fork: Marzocchi 380 C2R2
    Shock: Marzocchi bomber with Rock Shox 550 spring
    Rims: Pro Wheel 19-1.40 36H gold rims
    Spokes: Custom Buchanans 9g stainless
    Tires: Shinko SR241 2.75-19"
    Headset: Cane Creek zero stack 44MM
    Cranks: Race Face Respond with 83mm bottom bracket
    Battery: Custom pack 20S12P using Samsung 25R cells, 240 total. BMS undecided. Will be welding cells myself
    Controller: Power Velocity 18F controller
    Brakes: Shimano Zee hydraulic brakes with 203mm rotors

    Couple Youtube vids so you can see what I'm after



    #2
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  3. DakarNick

    DakarNick Swabee

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    Sweet
    #3
  4. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I'm liking this! What would a reasonable budget for this kind of build be?
    #4
  5. sailah

    sailah Lampin' it

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    I've been attempting to not add things up, thanks a lot!!:lol3

    Frame & Swingarm : Qulbix Q76R $1435 including motor below
    Motor: QS205
    Fork: Marzocchi 380 C2R2 $467
    Shock: Marzocchi bomber with Rock Shox 550 spring $150
    Rims: Pro Wheel 19-1.40 36H gold rims $176
    Spokes: Custom Buchanans 9g stainless $250???
    Tires: Shinko SR241 2.75-19" $72
    Headset: Cane Creek zero stack 44MM $40
    Cranks: Race Face Respond with 83mm bottom bracket $75
    Battery: Custom pack 20S12P using Samsung 25R cells, 240 total. BMS undecided. Will be welding cells myself $660 for batteries, maybe another $200 in cables, connectors, shrink, BMS
    Controller: Power Velocity 18F controller $350 includes $100 bluetooth dashboard to display on phone
    Brakes: Shimano Zee hydraulic brakes with 203mm rotors $300
    Saint front hub $30

    So I'm at $4205 so far.

    Off the top of my head I still need:

    Pedals
    Rear derailleur and freewheel
    Chain
    Tubes
    Seat
    Seatpost
    Rotors
    Charger
    Rewiring hi amp connectors
    Battery spot welder
    and probably a bunch of other stuff I forgot about

    So I'd say to build it like I'm building it, you're looking at maybe $5k? I wanted really nice components so I tried to go high end where I could. I bet you could get down to $3500 if you started using used stuff or got creative with recycling laptop batteries. I didn't want to do any of that. I wanted a potent bike, that almost could pass for a pedal bike. Something that I could commute 12 miles each way to work and have a blast, but could rip wheelies on command. I love that they are so light compared to a dirt bike. I should get pretty good range too if I planned it right.

    The videos above don't use the same motor I'm using. Rob in Sweden in video above has a MXUS 3K motor, mine is a lot more powerful

    Here's a guy with my motor, same voltage just different frame to give you an idea of acceleration and overall feel.

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  6. JimVonBaden

    JimVonBaden "Cool" Aid!

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    Wow, I can see why you were trying to avoid adding up the costs, but it sure will be a sweet bike when you are done with it!
    #6
  7. sailah

    sailah Lampin' it

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    Yeah you can certainly do a nice ebike for WAY cheaper, but that was not what this project was about. I was trying to build a Stealth Bomber clone myself, but smaller, faster and cheaper. Downgrading things like the fork, rims, using chinese spokes, you can cut corners all over the place.

    Probably the best bang for the buck is a Bafang mid drive, premade battery. You could probably do one of those for $1500?? But don't be mad when I roll past you on the back wheel at 30mph...:D

    I was headed in that direction and then scope creep set in and I decided to blow the budget apart
    #7
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  8. pennswoodsed

    pennswoodsed lizards,bugs and me

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    Holy hell ,you moved ? !? Nice project .
    #8
  9. Bt10

    Bt10 Been here awhile

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    What? No front hub motor?

    Looks interesting
    :lurk
    #9
  10. sailah

    sailah Lampin' it

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    Thanks. Yeah I moved to MA maybe 5 years ago?

    No front hub motor I don't think it's needed here lol
    #10
  11. scot_douglas

    scot_douglas Dirt Harley Lovin'

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    180nm of torque? You might as well take a dirtbike on the trails. :jack
    #11
  12. SteveAZ

    SteveAZ Long timer

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    With a hub motor that's the torque at the wheel, not before a transmission and drive line that increases torque by about an order of magnitude so it's more like a 20nm motor that's ahead of the torque multiplication *and* there are no gears so you're stuck in one. Since they are single speed, in order for a hub motor to have any giddyup at low speed they have to be monstrously over-sized from a torque (amps) standpoint and their maximum power is directly proportional to the speed...
    #12
  13. SteveAZ

    SteveAZ Long timer

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    A number of folks have experimented with hub motors on both the front and the back. In principal it sounds like a really great idea but in practice these bikes have such little weight on the front wheel that they provide very small benefit and are far less efficient so all you end up with is a lot less range with only very minor improvements in traction and control.

    I've yet to hear from someone who has done a two-wheel drive electric that thinks it's "worth it" beyond the enjoyment of the build process - like what a lot of this seems to represent to Sailah who clearly enjoys building.
    #13
  14. nuggets

    nuggets It's all my fault...

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    :lurk
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  15. JDUBinCO

    JDUBinCO Mass Centralized

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    I saw your post on shiny things, quite frankly, I love it!

    As you mentioned above a cheaper build would be with a bafang mid drive and a premade battery. The are lots of old DH bikes for sale here on CL, which I think would be a great platform if you found one with the right triangle to house the battery. It wouldn't be a wheelie machine like yours but it would give me a lot of opportunities to ride Moto style around home.

    Keep up the build, I'd love to see how it comes out!
    #15
  16. Salsa

    Salsa Been here awhile

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    With that kind of speed you need to make one of my double disc front bicycle front hubs. The pictures are of a later one , but the first ones were 2 front hubs cut and welded together to get 2 8" front disc brakes.
    Double Disc Front  Wheel.jpg
    Build a Hub.jpg

    Don
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  17. nuggets

    nuggets It's all my fault...

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    The shimano zee brakes would probably be a good choice for you. Quad piston and you can get pads with built in heat sinks. From $200 a set on the fleabay.

    [​IMG]

    [​IMG]
    #17
  18. Samtech79

    Samtech79 Two wheeled lunatic

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    That's rad. You might motivate me to build one...
    I had build a pretty rad moped a few years ago, with Ebike technology maturing as fast as it is... things are really getting interesting.
    http://garage.1977mopeds.com/build/Enduroped
    #18
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  19. sailah

    sailah Lampin' it

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    So I got the spokes from Buchanans they do such a nice job worth the premium for sure. Waiting on the front spokes and I can lace up the Hope hub I got.

    Lots of parts on order for battery and that's the next big project
    20170916_195818.jpg 20170916_201527.jpg
    #19
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  20. sailah

    sailah Lampin' it

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    What would you run for pedals on this? Thinking downhill platform pedals would make the most sense. That way you could just hop on and ride. I do have a pair of semi platform Shimano with SPD on one side on my Jamis bike. I don't ride enough to have a solid opinion.

    I bought a set of Zee brakes, most guys say you don't even need a rear brake with the regenerative braking from the hub motor.
    #20