my second build!

Discussion in 'Motorized Bicycle General Discussion' started by Johnc123, Dec 7, 2012.

  1. Johnc123

    Johnc123 New Member

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    Hello everyone I'm back after awile I want to build another bike and the bike I think I'm gonna use is the thruster fixie 700c and I'm stuck on engines I really would like to use the bgf rb80s or the dax f80 and the bgf is only 139 then the dax engine is 260 with shipping. I talked to Duane on the phone and he claims the dax f80 is made in the USA and has all grade A bolts and hardware do you all think this is true should I go with thedax motor or the cheap bgf please let me know thanks
     
  2. bigbutterbean

    bigbutterbean New Member

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    I would not use the fixie unless you plan on upgrading the brakes. At least two members of this forum have had serious accidents due to the shoddy brakes that come with that bike. As far as what engine to go with, I dont know if the Dax engine really is made in the usa or not, but the bgf engine is cheaper, and I have been pretty happy with my bgf engine.
     
  3. Johnc123

    Johnc123 New Member

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    Thanks for the reply! What exactly is wrong with the brakes? Luke what will I need to I'm prove onthem? And I will pry go.with a bgf since its so cheap!
     
  4. bigbutterbean

    bigbutterbean New Member

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    I honestly dont know exactly what is wrong with the brakes on that bike, I just know they are terrible. Rim brakes (the type where the rubbr pads rub the rims to stop you) are not the best setup for a motorbike to begin with. if you are going to go with rim brakes, I recommend v-brakes at the least. These are the type where the brake arms are welded to the side of the fork, rather than bolted to the fork crown. I hope you can understand what I mean by this. Other options for brakes are disc or drum. All of the setups I have described would require a different front fork. I recommend just getting a different bike with a better type of brakes.
     
  5. OblivionsKey

    OblivionsKey New Member

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    My sprained wrist, torn ligaments, road rash and cuts say DONT GET THE 700C THRUSTER! Oh and both tires are busted too... If I had landed differently and hit my head thatd been it for me. The brakes are garbage.. The tires are narrow and overall the only MB worthy thing is the frame which was easily mounted onto.
     
  6. Wickedest1

    Wickedest1 Member

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    As with any vehicle, smaller tires mean less traction and grip on the pavement...and to me that itself equals disaster. And as with anything you get what you pay for...but my first kit was a bgf kit and I put 1700 miles on it when she died.
     
  7. turbo1889

    turbo1889 New Member

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    In my mind a decent set of V-brakes with high end pads (quality pads make a huge difference with any kind of rim brake) is the minimum level of brake quality I will accept for a motorized bicycle that is heavier and capable of going faster then a pedal only bike. On low powered electric builds where the motor doesn't put out much more then the human pedal power puts out I'll accept less then that but those are the exception not the norm. I prefer disk brakes with high quality free floating mechanical calipers most of all, either 180mm for standard duty or 203mm for heavy duty applications.

    On my primary commuter 1.6hp Robin Subaru 35cc 4-stroke powered motorized bike I'm running a front 180mm disk brake with the original caliper with a quality free floating caliper on standby on the shelf in my shop for the moment the cheapo caliper the bike came with starts showing the slightest signs of trouble or when the pads it came with wear out and on the rear a set of generic Shimano V-brakes with the best quality pads that my LBS sells. The only reason I’m even using V-brakes on the rear for it is because the Staton-Inc axle mount kit I’m using with it doesn’t allow for a disk brake to be used with the motor drive sprocket on the left side of the rear wheel and some kind of rim brake is the only kind of rear brake that can be used with that set-up.

    On my commuter electric powered motorized bike I'm running 203mm disk brakes front and rear with high quality free floating mechanical calipers. That bike is my highest performance motorized bicycle I have and has enough power to pull the front tire off the ground and burn out the rear tire in a rolling wheely half way out into the intersection if I ram it full throttle from a dead stop when the light turns green. 1,400watts (barely below the 2hp legal limit for my state) on a "Brute" rear hub motor that is wound for high torque instead of high speed on a 48V system with the battery weight mounted low on the rear axle packs a heck of a wallop for low end torque.

    For my medium weight long tail electric assist cargo bike I’m running 180mm disk brakes front and rear with the high quality free floating mechanical calipers. Since that bike is using only a 360watt 24V system that drives through the chain right along with me pedaling and doesn’t go much faster or weight much more then it would with pedal power only and just lets me more easily haul groceries and stuff home on a bike the smaller disks work just fine for it.

    For my heavy hauler low-boy front flatbed cargo bike that I just built using a hybrid dual power set-up with a mated 1.1hp Robin Subaru 25cc 4-stroke and a 500watt 12V permanent magnet motor/generator unit I have both 203mm disk brakes with the quality calipers and quality V-brakes with high end pads mounted front and rear with double cable pull brake levers on both sides of the handle bars with the brakes adjusted so that the disk brakes grab first and then the V-brakes as well if you squeeze harder. Right side lever runs to the rear disk brake and the front V-brake and the left side lever runs to the front disk brake and the rear V-brake. The reason I rigged them that way is for redundancy so if one brake lever were to break in half or something I could still safely stop. The reason I’m being so careful with that one is because I built it to be able to haul hundreds of pounds of weight on the front flatbed, we are talking a 1/4-ton bicycle pickup truck that can really haul its rated load in cargo if necessary.

    I also have another electric assist bike that has a small electric gear motor and battery pack rigged up to it that has a whole lot of torque but at slow speed just to help out with climbing hills and the rest of the time on the flat you can go faster just by pedaling only and the motor is geared down so much that it can’t keep up with your pedaling unless your going up a hill. The whole system weighs less then ten pounds including the batteries and everything and on that bike I only have those brakes that came before V-brakes that work like V-brakes but use a triangle shaped loop of cable hooked to the two side levers being pulled straight up from the middle and not even with the best pads but it falls into the category of a bike with just a hill helper motor and not a real motorized bike. That little motor sure comes in handy on the hills though.

    I'm also looking into putting a "commuter booster" friction drive set-up or similar on a drop bar road bike with the narrow tires and if I do so I'm going to want to buy a bike with at the bare minimum quality rim brakes. Also, looking at getting a "bumble bee bolt-on" and putting it on a laid back cruiser or chopper type bike to have as a loner m-bike for when someone else wants to go riding with me and they don't have a motorized bike of their own so I don't have to loan them one of my good bikes and worry about them hurting it. I'll probably end up buying a cruiser bike frame that has mounts for rear V-brakes and then swapping out the stock front fork for an after-market universal triple tree chopper fork with disk brake caliper mount.

    Long story short, I’m overkill on brakes for my bikes (and I didn’t even get into the pedal only bikes just the ones with motors). But it is also true that so far I haven’t been in any wrecks because my brakes weren’t good enough either.


    P.S. = For those wondering how I ended up with so many m-bikes and e-bikes I did my first build (the one with just the hill climber helper motor) and then I started using it to get me back and forth all the time and hardly driving a full size vehicle at all and took all the money I saved and put it into the next one, and then the next one, and then . . . . You get the idea. WARNING You Can End Up Spending All the Money You Save On More Bikes, And More Motors, And More Improvement Parts, And Riding Gear, etc . . . . And In the End Don't Save Any Money And Possibly Spend Slightly More And End Up With A Shop Full of Bikes !!!
     
    #7 turbo1889, Dec 9, 2012
    Last edited: Dec 9, 2012
  8. Nashville Kat

    Nashville Kat Active Member

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    I think I know what the problems are with the wal mart fixies- several in fact, but I don't think you should blame either caliper brakes or the 700 wheels per se.

    And my opinions are born from 14 years racing USCF and my own experiences building and riding a couple of motor bikes with 700c wheels.

    I've toyed with the idea of building one of those up, by price alone, because it already has the 700 wheels and they are often the cost of this bike or more when you want to find some separately.

    I'm not sure if the people here who've built them and crashed have tried to use the fixie gear- A VERY BAD IDEA, and I have to wondrer if anyone is foolish enough.. You HAVE to use a freewheel- in fact I prefer and always use a freewheel and two calipers brakes-

    but rule # 1 should be- you MUST use a dual brake handle to control both- it's just to hairy all the time trying to work the clutch and a brake handle there om that side.

    Second mistake with this bike and it's diamond frame, and perhaps a lot of mountain bike builds is that 1. The frame is very short, and that makes it very responsive- it veers quickly especially if you haven't done a whoile lot of regular cycling otherwise,

    but I think the bigger problem stil then is that the short frame and the straight bars really get a rider too far forward- a sudden stop or braking tends to catapault you forward and you lose even more control as that progresses and go over forward-

    I started building one ten speed diamond frame- a schwinn travelller and found that the short top bar put the tank in the way of peddalling- defeating largely my purpose, and instead of staying with the bike which seemed to handling responsive with the motor, I built up a cruiser with light wheels- and now think I have the formula for what I want at least- a bike that rolls and peddles well-

    yet I also tend to ride it much like a bicycle and not a motorbicycle- I don't come racing up to intersections or stops and expect to bear down on the brakes and get stopped- I like to roll into it much more- in fact I shut the motor off all the time and coast up to the next stop- it saves a lot of wear on the brake pads-

    but the point is it's still really a bicycle and you have to respect the limits- it doesn't make it unsafe necessarily to have caliper brakes and narrow wheels- but you have to respect the limits of it- and it helps to have had a life of cycling experience-

    the cruiser frames keep my weight well back unless I want to get forward, and I use BMX bars that allow me to do that, and that are very perpendicular with a good horizontal grip that doesn't lean me forward like this fixie.

    and many wil say- wear a helmet- I always use a cycling helmet unless I have a couple of stocking hats on in the cold. I wouldn't be here now if it weren't for a very well-padded Kucharik hairnet back in '78 and an unfortunate head-on with a Chevy Impala at about 55 mph (me, not her) in a race.

    I alo like to have a rim with straight sides- not "aero" as many 700's tend to be- because the brake pads dO get a better grip on those then- the rim doesn't angle away from them

    and I personally ride tires that are 32 mm wide or about like a 27 x 1 1/4 vintage ten speed bike- although most people with no racing experience might feel more comfortable with tires 38 or wider- I think the Wal mart thrusters are about 38mm--

    and at that width you really need a rim that's one inch wide (25mm RIM, not tire) to be able to mount it- so that precludes many road bike rims that measure about 3/4 of an inch wide- I had a 38 wide tire on a narrow rim and it mounted and stayed on, buit I did notice that the tire "swayed" especially in a turn, because the tallness of the profile was too much then for the narrow width- 38 is the normal cut off, and the there's even another cutoff at a wider length I'm not sure where- probably about 48mm or so, you'd have to go even wider than a one inch wide rim, and you find those on some mountain bikes or comfort bikes with 700c wheels.
     
  9. KCvale

    KCvale Well-Known Member

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    Beside all the good advice Turbo gave you above first things first...

    There is no such thing as an 80cc motor, they all measure 66cc displacement unless they do magic to make the bore and stoke numbers more..

    There are no 2-stroke small motor manufactures in the USA, unless you look at super expensive Italian made Morini's and the like they are all made in China.

    DAX may be stripping cheap bike motor kits and putting in better parts but new 2010+ EPA reg kits like the Skyhawk's already come with them and better kit parts to boot for less.
    I just scored a 48cc 2011 Skyhawk kit from gasbike.net for $172 delivered with their Thanksgiving sale, and a pair of 66's the holiday before for less as 48's are more expensive for some unexplained reason other than 48's are legal most places and 66's are not.

    I get all the e-mail ads and pounce on the Skyhawk holiday deals but just have to laugh at the others I get.

    Just my advice, take it or leave it, but when it comes to building top quality motorized bikes for a living I don't take shortcuts on anything and that has paid off in spades.
     

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