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Thread: Classic 1984 R100CS with High Speed Sway

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  1. #1
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    Classic 1984 R100CS with High Speed Sway

    I have a 1984 R100 with 15,000 miles. I am the second owner and bought the bike in 1999 with 3,500 miles.
    For years I have been running Metzeler Lasertec tires with no problems or swaying at high speed (75 mph +).
    Two weeks ago I changed out my Lasertecs that were put on last fall with less than 1,000 miles to try out the new Continental Classic Attack Radial Tires. I am experiencing swaying at above 75 mph. Logic would say check the head tube bearings. They have been replaced years ago and still feel good.
    The new Conti Radials do have a more rounded profile than the Lasertecs.

    Has anyone had a similar problem and solution to swaying at high speed?

    Ted
    Richmond VA.

  2. #2
    Administrator 20774's Avatar
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    Ted -

    These tires are pretty new and I haven't heard much experience with them. What tire pressures are you running? Are you running metric sizes or inch sizes. There may be an issue that the pressures need to be different than what you might normally run in a bias ply tire.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    I have the 100/90-19 on the front and 120/90-R18 on the rear. I put 34 lbs in the front and 38lbs in the rear.

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    I wouldn't hesitate to up the air pressure in the front at least a couple of pounds and retry your road test...see what happens. What's the cold inflation pressure on the side of the tire?

    I looked at Continental's website and of course they don't mention any specifics. On their FAQ page they list recommendations for their racing tire. 2.1 BAR (cold) and 2.25 BAR (hot). That's 30 and 33 in psi. Not really what I would have expected.

    I guess my recommendation is to try pressure a couple of psi either side of what you run now...see what happens.

    Could also be that the new tires have unmasked a differet problem, like weak springs in front, worn rear shocks, slop in the swingarm bearings.

    When you have the front tire off the ground and gently push the handlebars to one side or the other, do the bars move slowly by themselves to the stop. Or do they clang off the stops (too loose) or stay where you put them (too tight)?
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    By "swaying" do you mean a gentle back and forth that feels mildly disconnected or do you mean a fast oscillation?

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    The handlebars move smoothly from side to side while up on the center stand. Not too fast and not too slow.
    The front forks have Race Tech Gold Valve Cartridge Emulators and Springs that were installed three years ago. At the same time the rear Ohlins shocks were overhauled.
    I will play with the pressure and check out the swingarm for any play.

    Is there a way to check for alignment of the wheels?

  7. #7
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    The swaying is fast enough to be unnerving but not fast enough to have the handlebars slapping the tank. I did have my steering dampener on max just to make sure!

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