Is it possible to Motorize a bike with coaster brake?

Discussion in 'Motorized Bicycle General Discussion' started by T Rock, May 6, 2010.

  1. T Rock

    T Rock New Member

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    I have a huffy that im trying to install an engine on and im having a problem with the rear gear and the coaster brake. I bent the coaster brake to clear the heads of the bolts for the rear gear and now the rear wheel does not spin freely, whats the deal? Having a real hard time trying to get the rear wheel adjusted properly. Any help would greatly appreciated...Thanks...Tom
     
  2. psprat496

    psprat496 New Member

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    IMO scrap the whole coaster brake and get yourself some V-Brakes at least. I think it's a must with these motorized bikes. The coaster just isn't as practical.
     
  3. Large Filipino

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    I used machine bolts on my sprocket on MOOP2. It holds well but I'm also very easy on that bike because it ONLY has a coaster brake.
     
    #3 Large Filipino, May 6, 2010
    Last edited: May 7, 2010
  4. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The sprocket is probably touching the dust cap! Trim off the edge of the dust cap & put it & the sprocket back on. ;)
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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  6. T Rock

    T Rock New Member

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    After reading your blog about trimming the dust cap, I think that is my problem. I will give it a try before going to a hand brake set-up. I will be getting a front and rear hand brake set-up in the future, but just wanted to get this thing running. Thanks Bikeguy Joe
     
  7. T Rock

    T Rock New Member

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    Thanks for the info, will be trimming the dust cap and giving it another try
     
  8. KCvale

    KCvale Active Member

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    Coaster bikes make the best MB's in my opinion.
    All you have on the handlebars is the throttle, clutch, and front brake.

    Put the bolts on the sprocket going through to the inside of the wheel, not sticking out to the outside.
    And yes, the dust cover can be an issue.
     
  9. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Do not just throw away the dust cap!! Trim the edge & put it back on. It's very important for tightening the brake arm back down!!!
     
  10. silverbear

    silverbear The Boy Who Never Grew Up

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    Coaster brakes on vintage bikes seem pretty good in my opinion. I don't know about the new ones. A brake up front is essential even if you ride at very moderate speeds. If the chain derails or breaks, there's nothing to stop you. A caliper brake up front is OK, drum it better, disc (I'm told) is best. I'd keep the coaster brake and add the caliper brakes you have ordered. Unless you're screaming around trying to set land speed records it should be plenty good. The faster you go then the faster you need to be able to stop.
    SB
     
  11. bairdco

    bairdco a guy who makes cool bikes

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    i love coaster brakes, because i've used them forever and know how to maintain them, and i know how they work, inside and out.

    the newer one's are pretty cheap, and taking them apart for re-greasing scares a lot of people away, but it comes down to preference.

    my bikes have all been vintage builds so far, and the coaster is the way to go to keep the look and style i want.

    also, if you search the coaster brake you have, you can probably find a site that shows you how to rebuild it.

    as far as it not fitting right with your engine, that's a common problem and an easy fix. the dust cap is the biggest hassle with them, but after you fix that, hopefully you'll have no more worries.
     
  12. Whizzerd

    Whizzerd New Member

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    It may not look real cool, but I've gone to a mtb shock fork w/ v-brakes on the front and coaster on the rear. Personally, I think properly adjusted v's work better than the drum. Probably the best and most costly would be disc front and rear. If I had a shift kit and traveled 40+ mph you betcha there'd be discs on the bike.
     
  13. Easy Rider

    Easy Rider Santa Cruz Scooter Works

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    Yes its possible but there is a down fall to having one. My first bike had a coaster brake and I loved it for cruising but if you ride fast (in the 30's)...beware. A bunch of us were racing down a street and had to brake quickly. Well to make a long story short, my lever clamp snapped and jacked up my frame when it spun around. Also, coaster brakes aren't good for windy roads or quick stops. Ask Dean, I slammed into him a few times. lol
     
  14. T Rock

    T Rock New Member

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    I trimmed the dust cap and now it works great, the wheel spins freely and no binding, Thanks for the help guys. I found out that basically the dust cap must fit through the center of the rear sproket, if it dose not well then it aint going to happen and binding will occur.
     
  15. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Right on!
    .............
     
  16. KCvale

    KCvale Active Member

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    I read a very informative and detailed web page about coaster brakes.
    Overhauling a Coaster Brake Bike

    I have noticed that newer Beach Cruiser coaster bikes seem to have a weak coaster brake, so I went looking for why and how to fix it.

    Turns out it is a matter of gear ratio, not the brake itself.

    Coaster bikes tend to be geared a little high so you can get up to a fair speed without gears.
    But this means it takes more effort to get them started.
    The reverse is also true, it takes more effort to apply sufficient braking force.

    The simple solution for a better coaster brake seems as easy as just lowering the gear ratio a bit by swapping in a rear sprocket with one or two more teeth.
    It's a fairly easy job, and the sprockets are only about $15.

    Since the vast majority of the pedaling you do is low speed, it would seem to be a win win, especially on the those days when the motor is stubborn to start and you have to keep pedaling to turn over the motor.

    I am aware the pedal chain will need to be longer, that is not an issue for me, I already size the pedal chain to match the drive chain so I don't need to use any tensioner.

    Has anyone already done this?
    If so, how many more teeth? One, two, maybe even 3?
    I suppose it would depend on the current gear ratio, but a little trial and error won't hurt ;-}
     
  17. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The gear ratio of the sprockets has nothing to do with the problems of modern coaster brakes... The problem is that they can over heat & lock up.

    I totally agree with Baird, older coasters seem to work much better than modern ones.
     
  18. Alajoyn

    Alajoyn New Member

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    Great response on this issue!
    On my tandem (85lbs w/o riders)(390lbs w/me & wife) I reverted back to the original HD coaster brake and a front and rear caliper. I can hammer down safely using all 3 from a nominal speed of around 22-24mph nicely and not over use any one system. I did R/R the coaster with cleaning and new grease before reinstalling it. The cost of converting to disks wasn't worth it to me.

    These guys are giving you great advise.

    Robert
     
  19. bairdco

    bairdco a guy who makes cool bikes

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    kc vale, you're right. i've had this argument with people before about gear ratios and coaster brakes. the smaller the ratio, the better the brake works.

    i had an old bike with a 52tooth front sprocket, and switched it down to a 36, without doing anything else to the bike and the brake went from barely stopping to locking up effortlessly.

    it seems odd, because you figure all you need to do is pedal backward and it should stop, so gear ratio shouldn't really affect it, but it does.

    i still don't know why exactly, but i know that it's true.

    also, it's very true about older coaster brake hubs working better and lasting longer than new hubs. as long as they're not worn out from age and use. compare an old bendix 76 to a KT or hi-stop, and there's a world of difference.

    there's a new hub called a "velosteel" which is based on the 50's Sach's Komet hub that's supposed to be the best around right now. i'm gonna lace one of those up soon and try it out.
     
    #19 bairdco, May 9, 2010
    Last edited: May 9, 2010
  20. happycheapskate

    happycheapskate New Member

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    I like coaster brakes on motor bicycles. Mine is working quite well. I have a front caliper brake too.

    I removed the dust cap, and installed the cog over the hub there, backing up against the spokes. The cog is held in place by the given bolts and nuts and one rubber washer and moon clip set, just eliminating one of the washers of the conventional setup.

    The dust cap was flattened to fit back into place under the coaster brake arm, against the cog with a little grease under there.

    I've been using it half a year. PS its a Hi Stop and it works fine.



    HOw the coaster brake increases power with lower gears:

    The use of a bigger rear cog (pedal side), or smaller front cog, gives the crankarm larger leverage over the internals of the hub which push out the brake shoes into the hub to brake.

    It is a similar effect as you would have by using a longer crank arm.

    If you can find 180mm 1 piece cranks (BMX shops), they will not be as comfortable to most riders, but would give much more pedaling and breaking leverage.
     
    #20 happycheapskate, May 9, 2010
    Last edited: May 9, 2010

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