0.0 Is this a CRACK?!

Discussion in 'Motorized Bicycle General Discussion' started by Mr. Minecraft, Jun 15, 2012.

  1. Mr. Minecraft

    Mr. Minecraft Visionary

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    Could you give me a check list of things i should look for?
     
  2. tooljunkie

    tooljunkie Member

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    yup,re-read from first post.i got all-knowed-up about wat to look for in respect to a welded frame.
    i definetly would not go for a bamboo bike,they would be a little tough to hang a motor on.
     
  3. Mr. Minecraft

    Mr. Minecraft Visionary

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    Da **** is a bamboo bike XD
     
  4. Ibedayank

    Ibedayank New Member

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  5. KCvale

    KCvale Well-Known Member

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    (just shakes head) There are plenty of brand new great bikes for a big powerful motor under $200, they post them in the paper where the brand new 3/4 ton 4 wheel drive pick-ups for $2,000 are.

    Seriously, learn from your first mistake, double your bicycle budget and don't shop in a department store and get a good solid bike, you'll be able to build and rebuild on it for years.

    Giant and Raleigh make great bikes just under $400 that will hold up for years if you don't do something like drill the frame for the front mount or some other such foolishness.

    Just my opinion but I build a lot of lot of high end custom bikes, usually shifters, and nothing beats starting with a really great bike.
     
    #45 KCvale, Jun 16, 2012
    Last edited: Jun 16, 2012
  6. Pilotgeek

    Pilotgeek New Member

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    I have a Dynacraft 26" mountain bike. It's surprisingly thick aluminium for being a cheap bike, and I've never had issues with it showing any signs of stress or damage after almost 1800 miles. I think I may have just gotten lucky on it, as all the welds are really well done and it seems thicker than usual. Everything else on the bike has been upgraded around the frame (bearings, wheels, etc).

    Also, buying an expensive bike isn't a guarantee for a frame that will hold up either. Bike shops often sell the same bikes that walmart does, and I'm pretty sure the bike shop doesn't fill the frame with some sort of magic sprinkles or something to make it better. It's better assembled, but the frame itself is the same. A high-quality name brand like Giant or Trek will carry a better frame, but in the end, NONE of these bikes were meant to have an engine slapped on them.
     
    #46 Pilotgeek, Jun 16, 2012
    Last edited: Jun 16, 2012
  7. 2door

    2door Moderator
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    Going back to the first post of this thread and examining the photo the OP provided, I find it hard to believe that he has a steel frame. That looks like an aluminum weld to me.
    Heliarc has a destinctive look to it and I say it's aluminum. I want to see a magnet stuck to it.

    As far as "cheap bikes", "Department store junk"...I had the opportunity to closely inspect the frame of a $700.00 Felt Cruiser and realized that in every detail it was identical to one of my "cheap" Target Schwinns that sold for $150.00. I questioned the bike shop employee who was trying to sell me the Felt and told him the frame was the same. He finally agreed with me and said, "Yes, the frame is the identical frame on the Target Schwinn but everything else, bearings, brakes, rims, crankset, is upgraded which explained the difference in price. Now, you decide what you want to pay for a bike if frame integrity is your only issue.

    Tom
     
  8. fx-2

    fx-2 New Member

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    Well if it can't be done I guess I did the impossible . Over the years shorted an lengthen more than a few . I built crane carrier , dump trucks an other special equipment for power line . There a few tricks but it is done all the time . The ones you CAN"T weld are the aluminum frame you just replace the frame rail . Dan
     
  9. Ibedayank

    Ibedayank New Member

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    [​IMG]

    this welding is MIG not tig/heliarc the guy that done it is called ZTfab can be found on
    http://weldingweb.com/showthread.php?t=30845

    the black Bike is a 1996 Diamondback outlook tig welded steel frame

    the other.. aluminum frame Next -Avalon


    Can't judge a book by its cover when the guy holding the Miggun really knows what he is doing

    A great weld is a great weld no matter the method used and a poor weld is just one that needed to be ground out and redone.
     

    Attached Files:

  10. Ibedayank

    Ibedayank New Member

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    wrong again.... some are made from a type of spring steel that is why you CAN NOT weld them. you can not weld spring steel and have it hold
     
  11. 2door

    2door Moderator
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    Maybe you should go back and read my post. I said, "the photos the OP provided".

    What does that have to do with the one you put up? The bicycle frame shown in the OP's (Original Poster's) pictures were the ones I was referring to.

    As far as the "the guy holding the mig gun" I'll venture to say that since I started welding, back in the late 60s, I have enough experience to perform as well as critique a weld. Be it steel or aluminum.


    Tom
     
  12. Ibedayank

    Ibedayank New Member

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    2Door

    What I see is a very COLD weld with not enough gas flow. and some serious pitting.
    By the looks of it just used the arc to melt the filler rod and not using the base metal to melt the filler rod as it should be done. Do you agree?


    [​IMG]


    after looking at the website the only alloy frame comes in silver and black only his is red
    http://firmstrong.com/product_1.htm

    looks like it broke right behind/at the seat post
     
    #52 Ibedayank, Jun 17, 2012
    Last edited: Jun 17, 2012
  13. Mr. Minecraft

    Mr. Minecraft Visionary

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    Sorry if I forgot to add information.

    Yes it did break at the seat post. Here is an interesting thing... The crack around the one bar is definitely a crack, but I could not see the second one. When we got to the autonomy shop, we looked again in full sunlight and still could not see anything. I believe that was sy a well Placed shadow.
     
  14. Ibedayank

    Ibedayank New Member

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    look at your first post I can see both cracks the one thru the tube cross ways and the one that runs thru the weld in both pics not just one


    twist the frame and I am sure you will see it then
     
  15. silverbear

    silverbear The Boy Who Never Grew Up

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    It seems to me you're waiting to hear what you want to hear... that it can be fixed easily and will be good to go. Some of the people here are very knowledgeable who are trying to give you good advice. And they are telling you to dump that bike and start with a decent frame. I've bought good vintage bike frames from the 1950's, made in America and well put together for $20.00 to $25.00, less than you're paying for your repair. Even on Ebay you can pick up a great frame and have it shipped to you for a hundred... and you have a sound foundation for a motorized bike.

    If you're not willing to invest enough to make a motored bike safe then you shouldn't ride it.

    And I wonder at selling a bike with frame issues to someone else. That frame should go to the dump in my opinion. How would you feel if that person got seriously hurt on a damaged bike you sold?

    Good luck whatever you do and stay safe.
    SB
    SB
     
  16. The_Aleman

    The_Aleman New Member

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    Any bike frame design that cracks/breaks at the cantilevers like that is an indicator of poor design - a bad copy of Schwinn's '55 design.

    Curved seatstays on cantilever bikes should be a warning. Look how Schwinn did it, their seat stays are almost straight from the dropout to the seat tube.
     
  17. KCvale

    KCvale Well-Known Member

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    I am no welder but if a good magnet sticks to the bike frame I'd think it had enough steel to weld. If not you have your answer.

    If you just want to move the bike for $200 post it up on Craigs and point out it needs a frame repair to be safe. You may just get a hobbyist that can fix it himself and get a bargain but either way you are off the hook as you warned them and was honest about the danger without repair.

    I build a lot of bikes on the $170-$220 Macargi beach cruiser frames, even a 49cc 4-stroke shifter on one, but I would never use one for a 99cc 4-stroke like you want to do.

    Department stores don't carry bikes like Giant or Raleigh for a reason, people that shop for a good bike don't go to Wally World to find one and their allotted space for bikes is filled with the cheap ****.
    That is just my observation in Phoenix, it could be different where you live.
     
  18. Sgt. Howard

    Sgt. Howard Member

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    Regarding welding- any steel and most aluminums can be welded assuming-
    1)The welder knows exactly what material he is dealing with &
    2) The welder knows how to deal with it.
    I am a gunsmith. I have had recivers welded back to rights by my tigman for many, many years. Several folks say don't do this- I have never experianced a breech failure, and I have practiced since 1975. If the welder can properly identify the steel he is working with, all is well. A car body man ought to know his biscuts here.
    Regarding 'cheap department store bikes'- I EXCLUSIVELY build on WalMart Huffys. I have not experianced a frame failure yet... and that's after seven builds and three sales. My customers rave about my bikes- some treat them rather rough- and I've had more issues with the China Trollop motor and it's componants than anything else... tires run a close second... the rims, frame and forks are without issue. A pricey bike can fail just as easily as a cheap one- the only brand that sounds better to me would be a worksman... and someday I will go there and do that.
    Mind you, I go through every bike- I inspect, dissasemble, clean, lube, re-assemble, adjust each machine before installing the motor. I do a minor re-wire of the coil ground lead of the magneto. The carbs now get the 'Howard Wedding Band' aluminum bushing to replace the nylon rubbish. The full electrical system is installed- head and tail, brake and turn, 6volt SLA battery with trickle off the white. PLUS the rather pondersome Howard hub mount is bolted onto the hub, useing the hard steel sprocket that comes with the China Trollop kit- I detest ragmounts- so the customer gets a rather thoroughly built machine.
    Time invested with experiance makes a difference.
    the Old Sgt.usflg
     
  19. wayne z

    wayne z New Member

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    My last 99cc vari-speed build is with a Cranny. I also tuned up the bike and wheels and spokes before adding a motor. Also added a suspension fork. Almost 300 hard miles on it now. No probs with any part of the bike so far.
    My first Preddy 2 speed, has over 1200 hard French Qtr. miles on a pre-Cranbrook Huffy frame. No frame probs with it yet either. Did finaly break a few spokes though, but I never tweaked it's wheels beforehand.
     
  20. KCvale

    KCvale Well-Known Member

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    Well Sarge we certainly differ on what a 'rather thoroughly built machine' means.

    With all due respect sir all I see is a guy slapping the cheapest motor kit on the cheapest bike he can find and sending it out with just a coaster brake.

    Rag joint sprockets serve a purpose, they provide a slight cush between the rapid RPM changes and 2-stroke motor pulses to the hub.

    Sure, those hub mount sprockets are easier as it's a 2 man job to do a rag joint right as it is an art to do right, my shop mate and I can have a rag sprocket mounted dead true in all 3 directions in 15 minutes with a 10mm socket equipped drill and a box end 10mm wrench these days.

    I guess what bothers me most is you are wiling to spend almost the cost of the whole bike on a $70 hub mount sprocket to make it easier for you but you won't spring $15 for a front C brake?

    Nothing ever leaves my shop with just one brake and most coaster brake bikes get front and rear C brakes on a dual pull handle and the coaster is a back-up brake. Depending on the bike I like to pull that 18T rear sprocket and drop in a 19T for $6 when we put on the rag sprocket on and brake. It makes it much easier to pedal start and as a bonus makes the coaster brake work better.

    It's not so much the frame on cheap bikes that fail (until a critical time like a pot hole) it's the rear hub.
    It isn't a matter of IF a huffy rear hub will fail, it's how soon. 40 miles or 400 miles because they will fail, you can bank on it, my bike bone yard is littered with Cranbooks they bought from a local guy that builds like you do.

    Even he has quit using Wally bikes and BoyGoFast motors since I opened up shop here and now competing with me using the same basic SKyhawk motor Macargi bike combo, just cheaper because he doesn't do any mods and only charges $50 a build for labor.

    Again Sarge I'm not trying to 'get in your face', it just sounds like you want to make a business building bikes and good for you, I have a blast and make money doing it from home, my only point is the market in my town at least is happy to pay $570 for a reliable safe quality bike and motor, and I don't have to re-build my new bike before I even start, they come good for $170-220 and even better in the $300-400 range for the high end shifter builds.

    Just a business tip for you:
    Set the bar higher than anyone else selling in your area with quality parts and see what happens for yourself, it sure as heck worked for me, I get as many $1000+ builds as I get $570 builds these days and repairing or usually replacing the bikes people bought from other 'cheapest way' builders in town ;-}
     

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