Stabilize Front Fork

Discussion in 'Bicycle Repair' started by birdmannn101, Dec 27, 2013.

  1. birdmannn101

    birdmannn101 Member

    I need to know which front fork or springer fork would be the best to stabilize my front end? I'm running the HF79cc on a Huffy Nel Lusso with a Surmey Archer front brake hub. All suggestions are appreciated... Dan
     

  2. butterbean

    butterbean Well-Known Member

    If you can find a hydraulic fork with. 1" threaded steerer tube, you can't beat it. I'm running suzuki hydraulics with a worksman front drum, way better than solid forks or rim brakes by far. Even better than bicycle suspension forks. The forks I got are sold out, so you'll have to look around.
     
  3. wheelbender6

    wheelbender6 Well-Known Member

    A cantilevered springer fork would increase your wheelbase and slow the steering a little. Is that what you mean by stabilizing the front end?
    [​IMG]
     
  4. keatonx

    keatonx Member

    You say the springer would increase the wheelbase, so they must have more offset(rake). That would make the steering quicker, but less stable/twitchier at high speed (because the increased offset/rake reduces trail, and less trail=less straight line stability).

    Read this and you'll see what I mean-
    http://calfeedesign.com/tech-papers/geometry-of-bike-handling/

    You can probably find a springer with not that much offset(rake), but I can't imagine it being much of an issue anyways. I'm putting a 8hp rotary engine on a BMX, and BMX's are very twitchy/unstable at high speed (8hp=SPEED:devilish:). So I know I definitely am going to have an issue with stability. I'm going to adress this by moving the axle slots in the front fork back to reduce offset/rake, and maybe make a spring loaded steering dampener (something like this)-
    image.jpg
     
  5. birdmannn101

    birdmannn101 Member

    Butterbean, Are you running forks like these which are selling Ebay right now?
     
    BigBlue likes this.
  6. birdmannn101

    birdmannn101 Member

    Wheelbender6, the springer fork might be one option. My problem is the instability that Keatonx talks about in his post but I don't see how one small spring would stop the wheel vibrating in the fork. Without having someone with the same problem who has fixed it, I would lean more towards Butterbeans suggestion of using motorcycle front forks. Have you two tried those type of forks? I am just afraid of the forks giving out on me at 40 MPH and picking myself up off the roadway ... Dan
     
  7. BigBlue

    BigBlue Active Member

    Those Suzuki K-10 forks is what a lot of builders have used. They use to be sold by BMI Karts, but are sold out. $99.00 for the 3/4" handlebar clamp is what BMI sold the forks for. Might want to grab a pair before they're gone. Interesting that both sellers are in Ohio.

    Chris
    AKA: BigBlue
     
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  8. butterbean

    butterbean Well-Known Member

    Yes, I got my K10's from bmi for $37 plus shipping, which came to $53. I was unaware that they were selling again. I know someone bought them from bmi in bulk, so they must be reselling at a higher price. I would pay $150 for these forks if I needed another pair, because they are worth it.
     
  9. butterbean

    butterbean Well-Known Member

    The K10's added about 4 inches to my wheelbase. They also added a bit of rake. The key to stability for me at least was in reducing the travel. They come with about 5 inches of travel. I needed to reduce the amount of travel by about 2.5 inches just to keep the bottom tree from hitting my tire. I dumped the oil that came in the forks and added 6 ounces of 10w30 to each fork. Keep in mind I'm a bigger guy, so it took more oil for me. I weigh 285. A smaller person would probably not need as much oil, so I suggest adding an ounce or two of oil at a time and checking the travel until you are comfortable.
     
  10. HeadSmess

    HeadSmess Well-Known Member

    IMHO, if you cant ride it no hands without it getting the wobbles...look for a better designed frame. theyre meant to be enjoyable to ride, not a struggle, and not a pant-soiling experience either!

    rake, trail, steering tube angle, wheelbase, they all interact and play a part. increase rake, reduce trail, but by increasing the steering angle, trail returns...but then the wheelbase is lengthened and and and ad nauseum.


    quadratic functions, anyone? with no guarantee that the answer is actually correct...

    bmx forks on an old 20" cruiser made it rather sketchy. reduced the rake, which increased the trail. already a rather steep steering tube. well.... im glad the bearings have flogged out cus now i have to cut the steering tube out and replace it :) and im not currently riding it, another godsend :jester: had a really unnerving habit of just falling out from under... and was definitely a keep both hands on at all times type bike... id have stuck with the orig forks but they had those silly lil 8mm hole, squashed tube dropouts typical of the era... just a tad flimsy.


    one exception... my old postie bike. that thing would shake violently no hands, but would still hold a perfect line, even through corners. freaks out the people driving in front when what appears to be a motorcycle doing death wobbles comes up behind them :) (the headlight waves madly side to side along with the front wheel)


    by violent i mean it would hit the stops HARD. faster oscillations than was physically possible if you tried it yourself. around about 60 degrees to either side... never had anything else capable of doing that!



    that spring would do doodly squat. its barely in tension where it is, is only a light gage spring, and would require a LOT of rotation before it added appreciable tension. really requires a long arm on the fork part to increase the movement.

    worst case scenario, get a REAL damper off a motorbike. a damper dampens oscillations. a spring springs and bounces...


    personally... i cant ride a moto with a steering damper. feels all wrong, like the bearings have been overtightened...
     
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