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Custom Bicycle

Discussion in 'MEMBERS PROJECTS - POST YOUR PROJECTS HERE!' started by rwm, Apr 11, 2017.

  1. rwm

    rwm Active User H-M Supporter-Premium

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    I am planning a project to build a custom cruiser bicycle to ride to the craft breweries here in the CLT. (OK maybe other places too.) I am just in the planning stages at this point so no pics yet.
    I need to decide if I want to start with a donor bike that has a ChromeMoly frame or Aluminum. I can weld either although I am more proficient with steel. My question is bending tube. What kind or aluminum tube is best suited to bending and what do they use on bikes? I saw a frame that was 7075 but I always thought that was low strength and poor form-ability? What say ye?
    OK here's a pic:

    [​IMG]

    Robert
     
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  2. richl

    richl United States Active User Active Member

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    Harbor freight makes a low cost tubing roller that is in the 180.00 area. Get a 20% coupon and it's very affordable. You will be able to roll tubing that looks quite nice. Also take a look at a site atomic zombie for ideas on making fat car tire rims with bicycle spokes. Ratrod bikes is another site to get ideas.
    Tubing roller
    http://m.harborfreight.com/tubing-roller-99736.html?utm_referrer=direct/not provided

    Swag off-road makes a few acc for the roller, dies, hydraulic pump, electric motor.

    You can get pretty far without spending on all the equipment.

    Hth
    Rich
     
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  3. Rustrp

    Rustrp United States Active Member Active Member

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    7075 has tensile strengths in the mild steel range and is one of the strongest as I remember, without pulling the chart.

    Most quality tube bending taking place is done with a bender using a mandrel inside that follows the bending process. Without the mandrel you always get mixed results.
     
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  4. mikey

    mikey Active User H-M Supporter-Premium

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    7075 is actually a high-strength alloy and therefore difficult to bend (or weld). I believe frames made from this stuff are actually epoxied into brackets. I don't know much about bike frames but I thought the latest and greatest was titanium.
     
  5. ddickey

    ddickey United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Carbon is the latest and greatest for many years now. Titanium is probably the ultimate as it never fatigues but is heavier. That's the problem, people want the lightest no matter what. I've seen people pay big bucks to save 50-100 grams. My Ti frame was very nice but my favorite was an aluminum Klein. makes me sad to think it is gone as I sold it years ago.
     
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  6. Rustrp

    Rustrp United States Active Member Active Member

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    7075 or any of the heat treatable aluminum alloys are tough in their tempered stated but prior to heat treating they are probably one of the most forgivable and easiest to work and weld. All the cutting and fitting processes are easy on tooling and I'm not sure why so many folks think aluminum is difficult to weld. There's not much difference in the melting temps of the different alloys and using the correct filler metal is of most importance along with all the other thing a person should do to produce a good weld.

    I'm getting ready to weld up some frames made of 6061 extrusion and most of the welds on the inside I will MIG weld. Apperance isn't critical and it's easier to get the gun nozzle into some of the corners, and a lot faster than me fumbling around inside the frame TIG welding these up. I took about 15 seconds to run the bead and another 2 minutes to load it.

    With that said; Finding 7075 in an annealed condition to make one bike frame may be difficult.
     

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  7. mikey

    mikey Active User H-M Supporter-Premium

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    I have no problem mig welding 6061 but 7075 ... no, not so much. I think I would be reluctant to ride a bike if I wasn't confident in the weld integrity.
     
  8. Rustrp

    Rustrp United States Active Member Active Member

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    Weld integrity is always a question when the base metal is hardened/tempered, and there is no way to make sure unless the part undergoes heat treatment after welding. It's always a guess, so 6061 or 7075 may both end up with the mechanical properties of 5052 after welding, or close to it. 7075 has traits and characteristics that require heat treatment after welding and welding should only be done in a 0-temper state. Given that 0-temper isn't going to be available without special order then pre and post heat treatment is required. When life and limb is at stake, don't weld it. If one chooses 6061 based on strength then welds without pre and post heat treatment will result in reduced strength, although 6061 isn't as susceptable to cracking as 7075. Heating a part up and holding it at 400° is difficult to do when most will be attempting to do this with a torch, and there's no accurate way to measure the temp.

    To prevent welding on 7075 the industry limits the filler metals available to weld it. I never weld anything where the base metal is in question. It's easier to say no than have calls from attorneys at a later date.
     
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  9. rwm

    rwm Active User H-M Supporter-Premium

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    I think I hear you saying "Chrome moly!"
    Robert
     
    Last edited: Apr 12, 2017
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  10. mikey

    mikey Active User H-M Supporter-Premium

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    Yup, Chrome Moly is easily gas welded; good enough for airframe use, it is probably fine for bikes. Rustrp makes a good point. Welded aluminum will anneal with welding and needs to be heat treated if the hardness is important. On a bike frame, I would think it would be important but I don't have any experience with frames like that so I'm guessing. There is a member who does bike frames but I can't recall his handle.
     
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  11. richl

    richl United States Active User Active Member

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    i've built a couple beach cruisers, roach cruisers, customs, board track racers. Its how i got into machining, I am certainly not the person to talk to if you are looking for a traditional bike, but if you want something outside the box, i've hacked together a couple frames. Cro Moly is a good choice, easy to work with, strong, light, and forgiving. .065 ga is common, some go lighter, some heavier. .065 works nice in a manual tubing bender, I've used mine to make bends for the front forks, and the rear. The above mentioned harbor freight tubing roller makes nice sloping tubing that woks well for the main frame. With the use of a lathe of moderate size you can make your own custom head tubes to accommidate any head bearings...
    making rear rims from cars into bike tires is slick, motorcycle tires are rounder on the sides so they are easier to lean than the squarer profile of a car tire. something to consider when making a rim selection

    hth
    rich
     
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  12. NortonDommi

    NortonDommi New Zealand Active Member Active Member

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    Hello,
    I had a friend who used to make custom racing bicycles & he used 22ga. 4140, he reckoned lighter & stronger than Aluminium plus a breeze to braze/Bronze weld with Eutectic 16F. He used a vapourflux unit which sped things up & no mess. I use the Eutectic rods too with powder flux and it is great as you can get penetration through mating surfaces,(braze), let cool slightly then go back and build a fillet for maximum strength,( like Bronze weld). Purpose designed for light weight tube,(e.g. furniture, wheelchairs ect), and is redily available.
    A great site for insiration and help is Atomic Zombie.
    Cheers,
    Barry.
     
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  13. NortonDommi

    NortonDommi New Zealand Active Member Active Member

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    Just had a thought, most tubing can be had in different shapes for instance I use oval or a shape that is like a flattened round tube. Anything but square.
    Barry.
     
  14. rwm

    rwm Active User H-M Supporter-Premium

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    I just bought an awesome Harley rear wheel. Polished aluminum 5 spoke. It's 8" wide so I plan to mount a 240/40/18 tire.

    [​IMG]

    Next question: Richl- should I plan on lengthening the frame so the crank is in front of the rear wheel or can I make a wide crank set that clears the wheel on each side? I could widen the bottom bracket. I would prefer the look of the later if it is workable. Remember this is not a performance bike!
    Robert
     
  15. richl

    richl United States Active User Active Member

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    what you are doing with getting the rims and tires first is not a bad idea, this way you can flesh out the proportions of the bike before you start bending metal, As far as the bottom bracket, getting one of the older roller bearing and axle type allows you to lengthen it easily . The newer sealed bearing type limit you to a smaller size bottom bracket. Bottom brackets are best scavenged from recycled bicycles, though there is no reason you could not turn your own, remember one side is right thread, the other is left thread.

    I have never built one that did not weight in excess to 50 pounds, as soon as you start puttin motorcycle rims/tires on it the weight climbs fast. These are cruiser/cool machines not racers.

    rich
     
    Last edited: Apr 18, 2017
  16. richl

    richl United States Active User Active Member

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    2013-10-17 15.22.58.jpg
    These are just a couple random photos from my Dropbox. The beauty of these kind of bikes, there is no one right way to do them. Keep and eye on the head tube and the bottom bracket. If you have a lathe and mill you can make your own head tube, and but bearing to fit. Same with the bottom bracket.

    I haven't built one in a couple years, would like to do another this summer.

    Rich
     

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  17. richl

    richl United States Active User Active Member

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    As far as location of the bottom bracket, just keep in mind the path of the chain. There are ways around it by using a transition point and another sprocket dedicated to the rear axle. Again 2 good forums for ideas are atomic zombie and ratrod bikes. Than searching the web for custom bicycles. Surprisingly you will see some amazing engineering .

    Hth rich
     
  18. rwm

    rwm Active User H-M Supporter-Premium

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    Rich-- that's some nice work you have there. Ladder for a setup table is brilliant!
    What are your thoughts on a crank with the pedals set about 12" apart? Would that be workable. That would avoid the secondary shaft.
    Robert
     
  19. richl

    richl United States Active User Active Member

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    Robert, it's doable.... might be a tad bit uncomfortable to ride, I also wonder about the force applied to the shaft... I've done it with shorter bb, they were about 6" and had on 4" tires, the fat tire bike all had intermediate shafts.
    The ladder is a nice poor man's frame jig

    Rich
     
    Last edited: Apr 18, 2017
  20. rwm

    rwm Active User H-M Supporter-Premium

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    Who knew there were more than 7 common standards for bottom brackets?! Crazy. I think I have that one planned out though. I will make bearing carriers that screw in to the bracket and these will hold outboard press fit bearings. Then I can also lengthen the spindle to clear the rear tire.
    But how do you attach a freewheel cassette to a Harley wheel? That whole axle-bearing-cassette thing will take some engineering. Any ideas welcome.
    Robert
     
  21. richl

    richl United States Active User Active Member

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    I have never used a wheel like you are, but if I did, I would make up a hub, it would carry the thread for the casset than weld that to my hub. From there you have the mounting for your rim/tire. You can even make your own brake disc and one of the many bicycle disc brake kits.

    This is a 15" steel rim I had, I removed the steel center section and drilled it for spokes and spoked it up With bicycle spokes. The axle is a steell unit I purchased new for something like 5.00 dollars. Cut it up, welded a center tube to it. Than it was just a matter of mounting it
    IMG_20130209_124104.jpg

    Hth Robert

    Rich
     
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  22. richl

    richl United States Active User Active Member

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    The reason i started getting interested in machining was because building a custom bike requires a lot of custom metal fabrication and machining. A lathe and mill are a big plus
     
  23. rwm

    rwm Active User H-M Supporter-Premium

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    Great idea. I will do that. Working on getting a splined hub that I can weld to a plate and then bolt that to the wheel using the standard holes. I am thinking I will use HD bearings and use bushing to reduce the axle size. Maybe 1/2"?
    R
     
  24. richl

    richl United States Active User Active Member

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    Just keep in mind the human body is only good for about 1/4 horse power. Weight is not your friend

    Rich
     
  25. hermetic

    hermetic United Kingdom Active User Active Member

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    If yer riding round the breweries, best make it a 3 wheeler.............................
     
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  26. richl

    richl United States Active User Active Member

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    I will use HD bearings and use bushing to reduce the axle size. Maybe 1/2"?

    I am not sure it matters, depending on how you plan to address the sprocket on the axle, whether a thread for the casset, or welding on, you can do almost anything you want.

    Rich
     
  27. rwm

    rwm Active User H-M Supporter-Premium

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    I made a bearing installation tool and learned how to install wheel bearings. Then I mounted a tire for the first time with hand tools. I had trouble with one part of the bead setting. I let the air out and set that part first. Eventually got it set @ 60 PSI. Makes a beautiful sound.

    [​IMG]

    You can see the unfinished axle laying in the background.

    Robert
     
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  28. rwm

    rwm Active User H-M Supporter-Premium

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    So I am designing the bottom bracket which will require a 10" crank spindle. I was planning on using a ground shaft of carbon steel which is called "medium hard" Brinell 167. Will I be able to drill and machine that?
    Robert
     
  29. richl

    richl United States Active User Active Member

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    Still watching and loving your project Robert. Can't wait to see where you are going with this.
    No ideas on the machinability of your steel. I hope it works for you...

    Rich
     
  30. richl

    richl United States Active User Active Member

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    If I read the conversion chart correctly, that would place it around a Rockwell rating of about 87... that would put it up there.
    You do have heavy machines... right?
    Can you aneal and temper it afterward?
     

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