My build. Frankenstein.

Discussion in 'Photos & Bicycle Builds' started by Fatandre, Feb 11, 2014.

  1. Fatandre

    Fatandre New Member

    I have started a build and will be building a fast bike. Thats the plan so far.
    I have finished the frame and bought the fork.
    I got a brown Brooks seat
    I want to put a fast engine into this so your help would be well seen.
    I decided to go with a 2 stroke and will build some slowly.
    If you have any ideas please let me know and tell me what you think.

    This is how the frame looks, bit I will be running different wheels.

    [​IMG]
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    This is the fork

    [​IMG]
     

  2. bluegoatwoods

    bluegoatwoods Well-Known Member

    Well, you've certainly got a fine frame for this job. Roomy and sleek.

    I'm feeling kinda jealous.
     
  3. FurryOnTheInside

    FurryOnTheInside Active Member

    That frame has a seriously long wheelbase! :D Especially the chainstay length.. It should be very stable at high speed and not be prone to the dreaded speed wobble. (I'm planning on using the Surly Disk Trucker myself so this is definitely something I approve of) Really looks a great frame for fast road use. Plenty of room for a jackshaft behind the seat tube too. :) So much room in the front "triangle" though, are you planning an in-frame gastank? Fork is pretty cool too, I like the disk brake mount, very interesting.. forks usually compress when the front brake is used (while moving) but this arrangement would do the opposite.
     
  4. Fatandre

    Fatandre New Member

    Just so you know. Those wheels are 24" but I will be mounting 26"
     
  5. FurryOnTheInside

    FurryOnTheInside Active Member

    I guessed that. Its still lonnnggg though :):)
    Did you fabricate that frame yourself from scratch?
    How will you mount a rear brake, and what type of brake are you going to use?
     
  6. Fatandre

    Fatandre New Member

    The frame is a custom made one.
    Friend did it for me.
    I will be having drum brakes on the rear for now and disc brakes as I have a disk brake mount on the front fork.
     
  7. Fatandre

    Fatandre New Member

    I bought those tires and this seat

    [​IMG]

    [​IMG]
     
  8. Fatandre

    Fatandre New Member

    I was wondering if I should go for a 4 stroke.
    What do you think?
    Can they perform well? I want to cruise comfortably lets say 50-60 mph

    Here is one pic. More to come

    [​IMG]
     
  9. battery

    battery Member

    50 60 mph on a single speed bike? good luck getting it started. it will take quite the hill. but I would think a 2-stroke would be better as they are lighter and produce most power at high rpm's. I wouldnt call 50 60 mph riding comfortably. white knuckling it would be more appropriate.
     
  10. battery

    battery Member

    if you plan on hitting 60 I highly reccomend some suspension and some lightweight steel bead 1.1 tires. and ultralight tubes aqlong with lightweight reliable very well balanced rims.. DONT GET A FLAT! the heavier the tire and even more so the wider the tire the more likely you will be to encounter those speed wobbles. if you havent encountered them, DONT!
     
  11. battery

    battery Member

    in my personal opinion with a single speed, go with the 4 stroke. they hae more torque for climbing hills without effort. and will get you going from a stand still much better.
     
  12. FurryOnTheInside

    FurryOnTheInside Active Member

    It's my understanding that a larger (more trail) and heavier (more mass) front tyre will make it harder for the rider to induce speed wobble (at the same speed, all things being equal and all that)

    EDIT: Oh it's this thread! :D With the chainstay length being SO long, speed wobble will only be easily induced by going very, very fast indeed and holding on very very tightly, because the centre of mass is so far forward of the pivot point (rear axle).
     
  13. battery

    battery Member

    yes everything would have to be equal. but perfect. the wheel is light and flexible. the tire is as well. at very high speeds the large rim being only slightly out of balance will vibrate and cause wobble. but this is just my thinking. dont take it for fact. hopefully someone here can science it for us.
     
  14. FurryOnTheInside

    FurryOnTheInside Active Member

    AFAIK speed wobble comes from the rider overcorrecting, and geometry etc can only change how easily the rider induces it, for the same speed.. or change the speed at which it's the same ease of inducement, if that's a word. That's what I meant by all things being equal.
    When a rider gets into a wobble and high sides himself off the bike, the bike often then recovers and continues to roll, WITHOUT wobbling, until it eventually turns and runs off the road.
     
  15. battery

    battery Member

    you are more correcter than I sir. here is wiki defonition. I still highly reccomend good light weight tires with steel beads though at that speed. Wobble or shimmy begins when some otherwise minor irregularity accelerates the wheel to one side. The restoring force is applied in phase with the progress of the irregularity, and the wheel turns to the other side where the process is repeated. If there is insufficient damping in the steering the oscillation will increase until system failure. The oscillation frequency can be changed by changing the forward speed, making the bike stiffer or lighter, or increasing the stiffness of the steering, of which the rider is a main component.[2] While wobble or shimmy can be easily remedied by adjusting speed, position, or grip on the handlebar, it can be fatal if left uncontrolled.[4] Since shimmy frequency is independent of bike speed, gyroscopic effects "are clearly not essential to the phenomenon."[2] The top five influences on wobble have been found to be lateral stiffness of the front tire, steering damper, height of bike center of mass, distance of bike center of mass from rear wheel, and cornering stiffness of the front tire.[3][5] An academic paper that investigated wobble through physical experimentation and computer modeling concludes: "the influence on wobble mode of front tyre characteristics, front frame inertia and chassis stiffness were shown. In particular, it shows that [by] increasing front tire inflation, chassis stiffness, and front frame inertia about steering axis and decreasing sideslip stiffness of front tire, wobble mode damping is improved, promoting vehicle stability."
     
  16. battery

    battery Member

  17. FurryOnTheInside

    FurryOnTheInside Active Member

    I've never heard it put quite like that! but it's a very over-discussed topic on bike forums.. and I'd personally not take much notice of computer modelling since riding style can't really be included, except that bit about shifting centre of mass forward when you go fast.
    IMO the most important thing is to relax. If you hit a bump don't grab on tight, don't make your knuckles white, don't stiffen your elbows, panic, overcorrect, or anything else like that, just ride. I like to grip the bar with just two fingers of each hand, right by the stem or the middle of the crossbar on a BMX bar, for best aerodynamics.. and I've been clocked at over 45mph doing this on a 24" wheel BMX (freestyle frame, short-ish but very stiff FYI) :)

    Fatandre's bike is so long that it's probably all moot. High speed stability should be very good.


    You can get steering dampers (not dampeners, that means it makes things wet! ;) ) for downhill/hucking mountainbikes but there's really no need for road riding.
     
    battery likes this.
  18. battery

    battery Member

    I hae only had the wobbles once in my life on two wheels. It was on an old bmx when I was a boy going down a very steep hill. but with my new 29" and high gearing I do plan on hitting speeds of 60mph. I will have to invest in some slicks beforehand and get to know the roads well beforehand.
     
  19. FurryOnTheInside

    FurryOnTheInside Active Member

    Oh yes we've all done it as a kid. Usually getting up with our hands burning like hell from hitting the road and having no clue as to how the heck that happened! xD
    I agree with you about steel beads, IMO just for their tendency to not roll off the (same sidewall depth) rim if and when they go flat.. but less important than making sure it doesn't go flat! :p Stiff front tyre sounds good though IMO more benefit from "stiff" being also heavy which provides enertia (which you can regard as damping).

    60 should be dead easy! :) Got a nice heavy suspension fork? No rear panniers or light rear panniers? I'd not worry too much about it.. road cyclists do 60 often enough. :)
     
  20. Fatandre

    Fatandre New Member

    So my problem now is just picking the right engine for my bike.
    I do not plan on racing, but riding this bike. I want to be able to do 40 miles in one trip just for fun of it.
     
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