Building Another Bike

Discussion in 'General Questions' started by Masor, Jan 20, 2011.

  1. Masor

    Masor Member

    I'm building a new bike to replace my old bike (Frame cracked everywhere. Weak bike!!). I'm building it from scratch and putting my SD Stinger engine on it. I've built a few bikes before, but never put engines on them. I want this one to be sturdy and safe. Does anyone know a good strong kind of STEEL I can build my bike out of?

  2. DuctTapedGoat

    DuctTapedGoat Active Member

    Well, it depends on the unknown unknowns and the known unknowns. IE - all the variables that can't be taken into consideration reasonably, weight and diameter of tubing, high and low weight for balance, to gear ratio and motor size.

    Just make sure you make SUPER clean cuts and thicker welds. And honestly, you're going to want to find a nice basic middle ground between heavy/strong and light/weak.

    Look at how the motor is assembled, what parts are being stressed at all, and put in reinforcement plates if you're worried about it.

    Personally, I use rusted out 25 dollar thrift shop bikes. It all hits 35-40 in the end after it's tuned...
  3. sfhellwig

    sfhellwig New Member

    Well the KIND of steel isn't really going to be a choice unless you mean build it like buy all the tubing and make the frame on a jig. If you are working with existing bikes there are only a certain number of materials used in the industry. If I'm not completely correct, I'm sure someone will add the right details.

    In the early days I believe it was all high-tensile steel. And until the last 10 years or so the only thing a department store bike was ever made out of. I'm not sure when the bike industry started using 4130 chromoly but this is the "good" steel. Just as strong at a lighter weight, this is what a good bike shop bike would be made of. Low end models were called tri-moloy meaning the front triangle was chromoly and the rear stays were hi-ten steel. Then good bikes starting being aluminum, titanium and eventually carbon fiber. Cheap bikes seem to skip the chromoloy stage and go straight to cheap aluminum. Not really that light and surely not as strong (maybe just bad welds). Non-aluminum department store bikes appear to still be the same small diameter hi-ten steel tubing.

    In my short time here it seems people avoid aluminum as it does crack under repeated stress unlike steel. If you are going to chop frames look for upper level bike companies to get the chromoly. Otherwise when motoring a bike the weight difference between hi-ten and chromo seems negligible. Otherwise consult someone with experience to make sure weld locations are in reinforcing areas, not stressful areas. Then make sure the welds are good, whether you're doing them or a professional. All it takes is one bad weld to "ruin" a frame as you already know.

    I personally am working on a cut and stretch of a chopper frame. As suggested here my butt-welded piping will be plugged with smaller diameter piping. This seemed to be acceptable to those that commented and I hope to find out real soon if this method is strong enough to trust. When in doubt, over-engineer. You know, the whole safe versus sorry thing.
  4. Masor

    Masor Member

    Thanks for the info, I'll try to find out what will be the best for my bike.
  5. retromike3

    retromike3 Member

    steel is real

    I build bike frames as a hobby and I like steel tubes. The frame tubes I like are True temper. they are made in the U.S. and they are a superior product. I would recommend buying a manual called "the Paterek Manual" they will give you the steps you need to get this whole thing going. Including the jigs you need and all of the materials to start building your frames.

    What I did on my current build was to modify a old steel mountain bike frame I got by changing the rear dropouts But, what I first was to get a longer front fork to take the squirrelly out of the ride. Next was to swap out the old vertical dropouts and replace them with track type. the reason for that was that way I could get the chain tension right on the motor side without having a take up wheel. I also welded a derailleur hanger on the side that still has the freewheel because I still like to shut the motor down and go into "stealth" node and for that gears are nice.

    When my motor died a while back I striped all of the motor stuff off it and made it my daily rider. I set it up with a lower chainring in the front (it only had one before ) because I really liked the way it rides.

    I recently got s new engine so its back to gas for me and maybe a bit more speed. Next step is to get my S.B.P. tuned pipe mounted correctly witch might require modifying the pipe so it will fit on my frame. (another thing that is helpful to know how to use a torch.)

    Last edited: Jan 22, 2011