Will a typical 80cc Chinese motorized bike kit work on a fixed gear bike?

Discussion in 'General Questions' started by AidanC, Jul 18, 2013.

  1. AidanC

    AidanC New Member

    If I were to mount a motor from one of those cheap chinese motor kits onto a fixed gear bike, would the engine drive the pedals?/is there an easy way around this?

  2. jaguar

    jaguar Well-Known Member

    the fixed gear bikes I had always had a coaster hub so that the wheel didn't force the pedals. They were the kind of hub that allowed you to move the pedals backwards to actuate the brake inside the hub.
  3. bluegoatwoods

    bluegoatwoods Well-Known Member

    This isn't my area of expertise. But if we're talking about a true fixed gear bike, then yes; the engine will propel the pedals.

    I don't think that type of bike can or should be motorized.

    Sorry about that. But the good news is that you can get a bike that is right for the job cheaply enough.
  4. jaguar

    jaguar Well-Known Member

    the only single speed bikes I've ever seen without a coaster rear hub were those little $50 bikes for 4 year olds.
    So unless you have one of those then NO it won't move the pedals.
  5. retromike3

    retromike3 Member

    I think it can be done but, its killing the idea of a fixed to start with. The neat idea of a fixed it that is very simple. if you add a motor and extra drive train that weighs more than the bike you start with, then you are violating the KISS design concept (Keep It Simple Stupid)

    Mike Frye AKA Frye Bikes
  6. LR Jerry

    LR Jerry Well-Known Member

    There are lots of true fixed gear bikes out there which aren't a child's bike. It would be way to dangerous to motorize one of them. You don't even want to go down a really steep hill on a fixed gear bike.
  7. BigBlue

    BigBlue Active Member

    If your bike is a fixie, it doesn't have a freewheel hub and will cause your pedals to rotate. You can use a flip-flop hub and put a freewheel on the rear hub, so the pedals don't rotate.

    AKA: BigBlue
  8. HeadSmess

    HeadSmess Well-Known Member

    theres no reason why you cant, a bike is a bike. you just have to live with the legs constantly going up and down. if its what you have and ride, are used to the way fixies ride, go for it. corners and all that sort of stuff. fun :)

    ive got a few coaster hubs here. one or two that DONT have back brakes simply so us BMX freaks can ride em backwards without the pedals playing silly buggers. fairly easy to modify so they do this, without buying the real ones. our "bowl" or "swimming pool" was actually a dam. hard to keep the vert ,erm...vert!

    i also have a bendix kickdown coater hub. two speed hub gear with coaster brake. awesome :) little back pedal changes gears, big one hits the brakes :) this should be chromeplated and mounted to a plaque...

    but, back to the fixie. personal taste. its not a huge drama to get a new wheel, either :)
  9. KCvale

    KCvale Motorized Bicycle Vendor

    A fixie is typically a 24" or smaller BMX style trick bike, you can pedal forwards and backwards (no brake), cool for riding your bike under like 5MPH like a unicycle.

    Chances are you wouldn't fit a motor kit in the thing anyway so a moot point as you don't see many 26" fixies.
    In the rare event you have a 26" fixie bike a motor would fit in then just have your local bike shop swap out the fixie hub for a $50 HD hub with the motor drive sprocket and a band brake mounted on it.

    Don't confuse the 'non-free-wheel' descrition meaning the pedal sprocket is like your fixie, it freewheels but doesn't have a coaster brake, it has that band brake.
    The description is because they offer a freewheel on the motor drive sprocket for pull start motors that don't need to be bump started as well.

    For most just the perfectly mounted sprocket and band brake are worth the money and what is going on a repair customers Huffy with a trashed rear hub.
    Last edited: Jul 25, 2013
  10. Jeckler

    Jeckler New Member

    Quite a few companies are making fixies in 700c, so it's in no way limited to 24" and below. A quick search reveals a lot of them come with flip-flip hubs too.
  11. KCvale

    KCvale Motorized Bicycle Vendor

    Just a generalization and a moot point, the point is an MB will beat your legs to death with a fixie.

    A flip flop wheel might seem ideal but it's not, even if you could find a big enough sprocket to screw on to it the threads are the wrong way for left side drive, it would spin right off when you hit the power.
    And you still don't have a brake unless the bike has C or V rim squeezer brake mounts.
  12. Jeckler

    Jeckler New Member

    Sorry, I was misunderstood. I didn't mean using the flip flop to run a drive side sprocket. I meant to use it so the pedal side would freewheel and doesn't beat the crap out of your legs at 30MPH. :) The OP could still use the rag joint for the drive side. Or a sprocket adapter if it fits the hub.
    Brakes are a whole other issue.
  13. KCvale

    KCvale Motorized Bicycle Vendor

    Sure that would work, just take the fixie sprocket off to maybe fit a rag joint sprocket but for what a flip-flop wheel is worth you could sell it to get the $50 for the killer MB hub is all as buying an $80 hub adapter for an improper hub to begin with is just a silly waste of money to me.

    On a a side note I ordered on of those $50 HD hubs with drive sprocket and band brakes yesterday to see if this Huffy is worth saving as it's hub is toasted.


    I have no clue what the motor status is other than it was poorly mounted but the frame welds seem good.
  14. Waleed

    Waleed New Member

    Might be, but fixed gears sometimes can be problematic at mounting the engine

    A few weeks ago, I decided to build a motorized bike for my friend. I initially planned on restoring an older mountain bike, but later found out there was too much work involved in that bike, and I'd rather sell it for parts.

    I ended up finding a good deal on a vintage schwinn cruiser bike for $20 (Had lots of surface rust, but most came off pretty easily). All I really needed to get the bike itself going without the engine was a front tube.

    I expected the most difficult part to be mounting the sprocket on the rear tire around the hub, which is usually what I find difficult to get true. The coaster brake also makes it harder to mount the sprocket, it was mounted backwards so the brake arm can clear the chain properly. So I took it to a backyard motorized bike dealer I knew, and he charged me $25 to do it. The hub feels alittle loose though, but it rides fine.

    The most annoying problem I faced was trying to mount the engine. The stock front sprocket was pretty large, and wouldnt clear the engine. I ended up getting a bmx sprocket(Should have thought of it earlier and saved myself the headache), and shortened the chain a little(Which I need to do again and take off the masterlink lol), and it made it easier on me.

    Point being if u ignore the long story, is that it might be possible, but you'd likely have to get another crank, and the coaster brakes would be alot less effective if u tried to drive the chain side, and brake at the same time.
  15. Jeckler

    Jeckler New Member

    Let us know how that works. I'm curious myself as I've only seen a band brake in person once and it was crap. It may have been the cheap chinese scooter it was attached to as well though. :)
    Did you get the freewheel version?
  16. Waleed

    Waleed New Member

    I honestly think the best thing might be disc brakes. At least on the front and typical v brakes in the back. Coasters also work well, but they take getting used to. Which reminds me, I need to try to find a front caliper and a front wheel with discs
  17. KCvale

    KCvale Motorized Bicycle Vendor

    It is a 2-stroke bump start so no I didn't order the freewheel drive side sprocket option for pull start engines ;-}

    I have used many a band brake wheels and seen this exact one on the Grube GT2 (whatever) bicycle I build. They are somewhere between a side pull C brake and V or disc in my book.
  18. HeadSmess

    HeadSmess Well-Known Member

    pffft, disc brakes, thing of the past!

    what you need are these :jester:


    rod brakes, ha ha. favoured in china and india...

    v brakes and cantilevers setup correctly are simple, fuss free and work well enough to flip the bike with one finger... there are tricks in setting them up, just like everything else.

    even decent caliper brakes work well, though the cheap pressed steel ones are useless. once again, setup.

    it always amazes me how many different brakes they tried before somebody thought of v-brakes.... simple and effective.

    my gripe with disc brakes? parts. i know i can always get plain old pads for caliper brakes.

    whereas my shimano discbrakes... new pads are NA. sort of makes the brakes useless, not being able to source new pads...

    to me they are bling. look cool, but arent 100% necessary.