decisions on motor bike configuration

Discussion in 'General Questions' started by preventec47, Dec 29, 2013.

  1. preventec47

    preventec47 New Member

    I want to do a lot of road travel and need
    to be legal and as reliable as economically possible. ie need to be cheaper than store bought moped from name brand suppliers.
    I am drawn to mountain bikes because of
    their front ( at least) suspension and I think heavier duty brakes and frame etc that should hold up better to hitting bumps repeatedly etc.

    I had five more paragraphs but had to cut them because the post was denied ? ? ?

  2. preventec47

    preventec47 New Member

    ( rest of my post)
    What I have found are inside mounted engines that either drive the front sprocket*in which case it appears the pedals have to*always spin, or drive a supplemental sprocket at the rear wheel on the side*opposite of the derailures and other sprockets. In this instance, I believe
    the engine could drive the rear wheel
    and the rider could coast with the
    pedals. The drawback as I see it is
    that the rider could not shift gears
    by moving the drive chain to the
    various size rear sprockets.

    So does the ultimate correctly boil down
    to performance and how lazy the rider
    wants to be ? Is there an issue
    with reliability? IE I would only want
    to put the motor power to the rear sprockets if they could hold up to the
    extra stress. Have the rear sprockets
    been shown to be a weak link ?
  3. darwin

    darwin Well-Known Member

    Using a motor to drive a cheap cassette is not advisable, they barely hold up pedaling them.
  4. Fabian

    Fabian Well-Known Member

    With these parameters in mind you will need to do a bit of home engineering as well as installing the following components:

    mountain bike with front suspension, fitted with a Hayes V9 nine inch front disk rotor and Avid BB7 calipers at both ends of the bike,

    Sick Bike Parts shift kit, fitted with either a 4-stroke or 2-stroke engine; both engine types being reliable when set up correctly, but a 2-stroke 69cc engine produces more usable low and mid range torque than the 48cc,

    Jaguar CDI,

    CR Machine Manufacturing medium compression billet cylinder head,

    home made, anti chain suck system that (requires some fabrication skills) is "absolutely" essential from a reliability perspective,

    correctly jetted carburettor or an upgraded system using a Rock Solid Engines reed valve intake with Walbro style diaphragm carburettor,

    rear wheel gear system "specifically" using an 8 speed cassette with 11-34T or ideally an 11-36T sprocket combination (and most importantly, 8 speed cassette sprocket spacing), coupled to a SRAM X7 Twistshift mechanism mounted on the left hand side,

    9 speed chain driving the 8 speed cassette (an important feature to eliminate ghost shifting) and is much more tolerant of derailleur hanger misalignment, should the rear derailler suffer an impact,

    high and low range gears operated by the front derailleur (using the Sick Bike Parts optional 24 tooth and 30 tooth sprockets) allowing hill climbing ability up "any" level of incline, no matter how steep it looks,

    Sick Bike Parts 9 tooth and 48 tooth sprockets for the jackshaft to bottom bracket gearing ratio,

    trailer to carry spare parts and extra fuel as well as food and drink and electronic equipment if on a long trip,

    high power front lights, brake light, mirrors and indicators - a lot more important than most people think is necessary,

    thorn proof tubes filled with slime puncture sealing compound,

    optional Cane Creek Thudbuster suspension seatpost to save your backside from knocks and bumps,

    optional cylinder head temperature gauge and Exhaust Gas Temperature gauge to keep an eye on what's going on inside the engine; alerting you to either a potential fuel blockage or air leaks, if the instrumentation starts to show signs that the engine is running lean, thereby preventing heat related engine failure,

    optional pull start mechanism and centrifugal clutch mechanism if running a 2-stroke engine.

    Once all that is done, you can do this:







    and this:
    Last edited: Dec 30, 2013
  5. preventec47

    preventec47 New Member

    In order to decide between rear cassettes or internal
    rear hub gearing, has a consensus formed as to
    which rear gearing type has proven to best handle
    the extra stress of added motors ? Also, I was told that there were some heavy duty rear cassettes designed for tandems that were designed to be sturdier and stronger? Fabian, your setup is super impressive but I need 4 stroke and the sick bike parts website seems to imply that their jackshaft
    shift kit only works with 2 stroke engines. Can anyone confirm ?
  6. Fabian

    Fabian Well-Known Member

    They do 4-stroke kits:

    If i could be given a guarantee that an internal hub would hold up to the massive amount torque being pushed through it when the bike is fitted with low range gearing, it would be on my bike tomorrow.

    If i could be given a guarantee that an internal hub would still operate some of the gears even when a few of the others have smashed themselves to bits, it would be on my bike tomorrow.

    As an alternative system, the Nuvinci Hub is a great design but they do not warranty the hub if it's used in a motorised application, so i am figuring that it can't take the punishment of higher torque output when used on a motored bicycle.

    Although the chain and cassette and derailleur system has a lot of drawbacks, it has proven to be bullet proof when it comes to handling the extreme torque output of mega low range gearing afforded by the Sick Bike Parts shift kit and optional sprocket combinations.
    Even if you do bend up a few cassette sprockets, it still allows you to get home using sprockets that are undamaged, and, if you damage a rear derailleur and hanger, it can be replaced on the spot with a spare derailleur and hanger from your tool kit.

    If a hub mechanism fails 50 miles from home, you are screwed, because carrying a spare hub means carrying a complete spare (rear) wheel with hub attached - not a cost effective solution and it's not exactly a space economical solution either.

    Spare chain, spare rear derailleur, spare hanger and spare rear derailleur cable are easy to pack into a small box.
    Carrying a complete spare rear wheel is a logistical nightmare.
    Last edited: Dec 30, 2013
  7. bigoilbob

    bigoilbob Member

    A quick second to Fabian's advice, re Nuvinci hub. I have the beefier, 171 hub, with a developer's kit. Works for me, but my power is much lower and IM twisting a 20" wheel. FU run the numbers IM also at the top of my permissible torque.

    The only way a NV hub should be used in powered apps with anything bigger than a 20" tire is as a jackshaft. They ARE rated for up to 1000 r/m, which is 2-3* faster than most 26" wheels ever spin. Hence, the possibility 2 transmit more power with more speed/less torque, via deployment as a jackshaft.
  8. Fabian

    Fabian Well-Known Member

    I just want a Nuvinci Hub that can do the job. From what i understand the Nuvinci Hub is about as useful as female mammary glands on a bull when it comes to coping with the extreme torque being sent to the rear wheel via a Sick Bike Parts shift kit.

    I just "wished"; i just "so wished" that Nuvinci would build a proper hub capable of handling the extreme torque dished out by the highest levels of twisting force that can be produced when running the highest ratio gearing provided by the optional jackshaft sprockets in the Sick Bike Parts catalogue range.

    I really, really want a Nuvinci Hub that doesn't spew grease for 50 yards in every direction as it blows itself to pieces; transforming into scrap metal under a motorised bicycle configuration.
    It's so frustrating when all you want is a Nuvinci Hub but are unable to use it, because it's nowhere near as tough as what it could be, or should be.
    Last edited: Dec 30, 2013
    bigoilbob likes this.
  9. KCvale

    KCvale Motorized Bicycle Vendor

    Yes Sick Bikes makes a nice a 4-stroke shift kit for the HS 49cc and Honda 50cc engines, a great base for the engine with all the JS mounts and the needed parts, what is important is what does the initial gear reduction and clutch work from the engine out to the drive chain output sprocket, and how it relates to the jackshaft input sprocket.


    I like the HS 142F 49cc with 4G MB kit as it has everything and goes together well for direct drive and with the sickbikes 4-stroke shift kit, the rub is paying for all the duplicated and unneeded parts.

    In short the SBP shift kit eliminates the need of any of the following gasbike kit parts:

    Motor mount base and it's mounting hardware.
    Back sprocket, chain tensioner, and all their mounting hardware.
    Wider BB pedal axle, sprocket, bearing hardware, and special crank arms so the pedals don't hit the wider 4-stroke engine.

    What that leaves is the SBP shift kit with just the following needed:

    Engine with everything to make it run.
    Cent clutch (or torque converter) transfer case.
    Fuel system.

    The rub comes when you try to price out the above and it's like $20 difference between getting the whole gasbike kit or just parts so a no brainier for me, I build a lot of bikes and a 4-stroke platform, wide pedal parts and direct drive hardware comes in handy for things like this 79cc direct drive.


    As for the rear wheel gearing I find just a simple internal 3 to be perfect for anything with 2 -5HP, in short every engine has a much wider power band than a human pedaling and mor gears just make it harder to operate, for example on 7-speed shifters I only use the even numbered gears.

    Hope that helps.
  10. professor

    professor Active Member

    Preventer, you got some great answers.

    I ended up using some moped parts on the bike I concocted, and when one adds up the costs involved, or if you want to avoid a buckboard type ride, think about a real moped.

    I have a nice Honda 90 trail that has been in my garage for decades. It is neither fish nor foul- too slow for traffic- too fast for the curb/bike lane.
    So I built a motorized bike as a toy and my little jaunts around town.
    It does have full suspension!
    However, if I was into distance use, something more oriented for that purpose would be desired.
  11. HeadSmess

    HeadSmess Well-Known Member

    depending where you are...get the moped. youre in for the same total cost, possibly even LESS after the third engine, and well...if youre asking these kinds of questions, i (personally, no offense) feel that you, like a lot of the general population, will just get ANNOYED with a motorised pushbike.

    if you arent experimental, havent played around with these sorts of things before, and have extremely limited workshop facilities = completely stuffed when something, no matter how simple, goes wrong :( which it will. regularly. no matter what engine, supplier and or genius fabricator you have access to... its called murphys law. my engines dont DARE breakdown cus they know ill either fix em or melt em down for scrap... either way, they end up regretting it...

    if you want a hobby, dont mind the occasional push home, or even ringing a mate at 2am when its packed it in... sure. pushy.

    everyday use, get you to work on time every time, get you home in time for *insert fave show here*, doesnt need constant fiddling tweaking or TLC...moped. especially if you want to cover more than 30-40km each way.

    it does depend on where you live and what the rules there are. you might have to get even the pushy registered. you might get away with a 50cc motorbike without rego! etc etc.

    a brand new moped comes with at LEAST a years WARRANTY. any and ALL guarantees are void and null if you use a pushbike. frame, components, engine... purchase at users risk!
  12. HeadSmess

    HeadSmess Well-Known Member

    i just had to throw this one in...

    we had a dairy BUCK of particular good lineage that produced a litre a day... had two bags down below! only one came with dual spraybars, mind you ;)

    still, not exactly practical. sort of like using a mini to tow a caravan... funny to watch but you sure look stupid to anyone watching :jester:
  13. KCvale

    KCvale Motorized Bicycle Vendor

    I was all wow'ed and smitten with the NuVinci CVT so much between my shop mate and I bought like 8 Cadillac bikes that came with the N170S.

    For those that remember back to mid 2011 the SBP jackshaft was still pretty new and had the 3-part back base, and ** introduced the Cadillac Fleetwood beach cruiser that came with a NuVinci hub and rear disc brake.

    Amazon had them for $799 but we found them for $300 for most, $350 for a couple others which is was about just the back wheel cost so you got the killer unique bike for free.


    3 of those hubs failed before the motor was even broken in, that bike above failed within a dozen miles and no returns.

    Fallbrook Technologies came out with the NuVinci Developers Kit with automatic computer controlled shift back then when I got my 1st Caddy for the older larger hub and I finessed my way into them giving me a free Developers Kit hub and remote control to test with gas power if I posted the results on their no longer existent developers forum.

    I built Bad Mojo in February 2011 for Death Race in Tucson, AZ with that Dev Kit.


    Man I was in hog heaven plugging my bike into my PC and making all kinds of custom automatic shift tables for the hubs controller, creating a bike powered charging system for the my own on-board power system but I was sorely disappointed in the end.

    I have a 10 page forum topic about the ordeal on my site but the point is I think the whole theory of a fluid 'briefly changing states from a liquid to a solid when compressed' would be great if such fluid existed that worked.

    If you haven't seen the video of how the NuVinci works watch it here.

    Pay close attention to the part about how the fluid is suppose to 'stick' the rolling balls to the hub at 'microscopic tolerance'.

    I think the fault lies in Fallbrook not making their NuVinci hub designed for frequent fluid changes and making that 'magic fluid' reasonably priced and easily available as none of my failures ever leaked, made grinding noises or spewed parts, the fluid just quit holding.

    Anyway I wander again...

    I still have the whole Dev kit setup but I have no interest in resurrecting it, I put a nice simple internal 3 on Bad Mojo and as far as I know still cruising alone today and I have never seen an internal 3 fail yet.


    Then again I don't build for doing steep rutted dirt roads to a ski slope lift top pulling a big trailer either ;-}
    Fabian likes this.
  14. bigoilbob

    bigoilbob Member

    KC, 2 nitpic, the NV fluid really does what it says it does. Just not well enough 2 transmit enough useful torque 4 most MAB aps. And that's with the beefier 171 hub. God knows how puny the 360 hub is. But thanks lots 4 your larger points about MAB's 4 the rest of us. You helped me with my "odd" bike, and I'm sure many others as well.

    FYI, I sent another poster, who also has a NVDK, your way. I would have been lost without your advice on strengthening my circuit board, and so will he, unless he checks out your relevant pix.
  15. Fabian

    Fabian Well-Known Member

    @ KC - that's really interesting information. Do you have any knowledge if Fallbrook has any plans to make a stronger Nuvinci hub?
  16. KCvale

    KCvale Motorized Bicycle Vendor

    Ya, the controller board left a lot to be desired but I think the whole problem with the automatic shifter, especially with trying to put in so many shift points is trying to get the fluid to start hard under power and trying to shift it under power too.

    If you operate it manually and back off power when shifting the other hubs worked dandy, especially with an electric, but that being the case I found it just a cumbersome system to operate.
  17. bigoilbob

    bigoilbob Member

    @KC, per some of my old, old, posts, I made the shifter shift up automatically under near full input torque, and have done so almost every warm day for the last 2 years. The secret is beaucoup 12+ volt power, with 5-6 amps always available. But this is faint praise, as "full input torque" is certainly (and understandably) less then most MAB builders want. Making U correct as usual on the larger point of it being a cumbersome system to operate in a "conventional " mode.
    But all that being said, I think NV should have tamed the system for us by selling it as a jackshaft shifter, with a kit charging system for the controller. "Cumbersome", yes. High $, certainly. But worth it, in my view. I say this because (1) my shifter works just fine within permissible torque, and (2) if you run the numbers using max permissible torque (48 lb*ft.) and max permissible input and/or output r/m (1000), you could transmit over 4.5 hp starting out, and over 9 hp after input/output speed ratio rose above 1. These are theoretical and need to be cut back for a safety margin, but remain tantalizing.
  18. KCvale

    KCvale Motorized Bicycle Vendor

    In my case with auto-shifters it's a once bitten twice shy thing.

    I wanted a video of the difference between the sound of that Giant Suede with Dev Kit automatic above at the muffler shop before I had the glass pack for the the X-pipe put on and this is what happened during the 'before' video in their parking lot.

    In short I nailed it from a dead stop and as I started to make a gentle turn it auto-shifted at full RPM with some loose gravel in the parking lot, the back wheel flew out and I went down hard to the left trapping me under the bike while the jackshaft gear on the right caught my pant leg and pulled my leg in and did a 'chain saw' treatment on it.



    The whole gruesome story is here

    5 days in the hospital and well over $100,000 (that I am still paying on 3 years later) I was home with a nice pubic hair covered skin graft patch from my lower tummy on my calf and a 6" scar at my belt line, the surgeon told me to consider that part a free 'tummy tuck'.

    That bike got the name Bad Mojo after the guy working for me at the time thought it would be cool to do a brodie in the back yard after coming in from a test ride and he went down hard the same way.

    Call me a sissy or a scared old man but I don't want automatic anything on my MB, I want good easy to use manual brakes and manual shifting.
    HeadSmess and bigoilbob like this.
  19. bigoilbob

    bigoilbob Member

    Actually, can't agree more. Manual shifting has SO many advantages. I was just trying to stay legal, but now I think I was overcautious.....
  20. Fabian

    Fabian Well-Known Member

    That injury could have easily been prevented by a chain guard. Having said that, i hate chain guards because i like to see the mechanical parts whizzing around, hence my solution to design a chain guard that doesn't obscure the working parts, by drilling and tapping an M5 thread into the jackshaft and installing a transparent polycarbonate disk, as shown in the below photo and video.


    Last edited by a moderator: Dec 15, 2015