Techniques for Mountain Back Roads

Discussion in 'Hacks' started by Square4, May 28, 2012.

  1. Abenteuerfahrer

    Abenteuerfahrer Deaf on Wheels

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    BMWzenrider..

    I remember now that the tire pressure/weigh ratio was once posted by you somewhere but lost neverthless.

    Thanks Karl for posting it again.

    So Drone you're basically doing a-OK ....:D.

    Cheers...
    #21
  2. BMWzenrider

    BMWzenrider The Road Scholar

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    Static weight distribution on a hack setup is definitely asymetrical, just like everything else about them.

    what I have typically gotten with my current rig when I roll it across the scales is a distribution of:
    Front wheel: 30-35%
    Pusher wheel: 45-50%
    Sidecar wheel: 20-30%
    (these percentages are with my 'wide load' occupying the driver's station, just like it would be running down the road.)

    The percentages move a round a bit based upon loading, driver's position on the bike, and even the position of the camber control.
    I have put just one wheel on the scale deck (rear or sidecar) and cycled the camber control from full-left to full-right and can watch the numbers on the scale move, up to 30-40 pounds of weight transfer between the two wheels depending upon load, load height, etc.
    Interestingly, I DID try the same thing with just the front wheel on the scale. No change.
    Shifting your body around can make a noticable shift in weight distribution at each wheel as well, but it is still harder to influence the load on the front wheel from anywhere on the seat where you can still be in control of the rig.

    So while you may get relatively close by just dividing the weight of your rig my three, it won't be as good as getting on a platform truck scale with one wheel at a time.

    Not necessarily very 'scientific', but I like gathering data, even if it has limited usefullness. :D
    #22
  3. DRONE

    DRONE Dog Chauffeur

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    That's what all my girlfriends say too! :evil

    My wife . . . not so much. :huh
    #23
  4. Square4

    Square4 Been here awhile

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    BMWzenrider;

    thanks for all of the information. My rig fits right into what you described. I am running on my 2002 R1150 GSA and the sidecar a 165/80R15 tire. I loaded my sidecar and saddle bags with the loads that I would be taking on a long trip and had the following loading numbers: Sidecar 340#, Front 440#, Pusher Wheel 730# and a total on the scale of 1470#. Now most of the time I do not run that loaded but got these numbers so that I could get shocks that would be capable of handling these loads as needed for long trips. I think that proportionally they come out pretty close to the distribution that you described with 23% on the sidecar wheel, 30% on the front wheel and 47% on the pusher wheel. Now most of the time I do not run with the sidecar loaded to max or the saddle bags with much in them. However, when I was running 32# in the pusher wheel I had a significant under inflation wear pattern on my pusher wheel. This does not seem consistent with the data that you presented regarding the loading capacity at this pressure. At higher pressure the tire wore as expected with both edges of the tire wearing fastest. That was the basis for the original question. If the tire had weak sidewalls would this make it tend to sag on itself and cause wear on both edges of the tire? Is it the tire? Will going to other tires improve this? The original tire was a Federal and it was down to the wear bars in just over 5,000 miles.
    #24
  5. BMWzenrider

    BMWzenrider The Road Scholar

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    Ok, I am a little confused.
    Typical overinflation wear is faster wear in the center of the tread.
    Underinflation causes the edges to wear faster.

    [​IMG]
    http://blog.tirerack.com/blog/where-the-rubber-meets-the-road/how-tire-pressure-impacts-tread-wear

    Also, most sidecar setups have the bike leaned out (to the left in the USA), which leads to more wear on the side of the pusher tire that is farthest from the sidecar. And in an earlier post you mentioned that the shoulder closest to the sidecar is wearing faster on your rig.
    How is the setup on your rig? Does it pull to the right?

    ----------

    When I had a 165/80-15 tire on my rig I kept it at around 26psi.
    From what I remember, that pressure produced even wear on the tire.

    My current summer tire is smaller, and I run with the rig unloaded at 26psi for a load rating on the rear wheel of 698-lb. Same result of fairly even wear other than the differential wear caused by the lean-out.

    So I don't really know what to say about your rig and the observed tire wear patterns.
    Sorry...

    ----------
    If it were my rig, I would opt for a tire pressure that gives enhanced traction and ride before worrying about treadwear. Keeping it in the safe zone, of course.
    Even with the 'spirited' riding that I enjoy, I am still getting 15-16,000 miles out of each summer tire (~6,000mi for my winter rubber).
    So, once you have the car tire conversion, the cost per mile of the rear tire is pretty low, so I would gladly trade some wear for better grip/handling.

    Of course, that is just my opinion. You have to do what makes sense for your situation.
    #25
  6. Square4

    Square4 Been here awhile

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    BMWzenrider;

    It was late last night when I was sending my last response and see that I stated something incorrectly. So I want to clarify it.

    AT 32 # I got under inflated wear pattern oon the pusjer tire.

    At 42# I got what I consider to be more typical wear with slightly more wear on the side of the tire nearest the sidecar. I have a tilt control so it is set up to be adjusted to run in a neutral mode. I have been told that this tire wear pattern is normal because of the effects of the sidecar on the tire during accceleration and braking.

    I hope that this clarifies my observations, sorry about the confusion.
    #26
  7. BMWzenrider

    BMWzenrider The Road Scholar

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    Ahhhh... Drunk posting to ADVrider... :freaky
    :lol3 :D
    #27
  8. Square4

    Square4 Been here awhile

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    Actually what happened was that I wrote it and was reviewing it when I got interrupted. When I got back to finish my review I forgot where I was and messed it up. I just went down to the John Day Rally put on by the Oregon BMW club. I tried running 34 #s in the pusher wheel and 32# is the sidecar wheel. It handled nice and I put on 50 miles of forest service roads with lots of puddles, holes, drainage ruts and rocks. It handled well so I am going to do more testing to further evaluate tire pressures. I think I need to find out what works best for some "standard conditions" that I want to use as a gauge for how to set up tire pressures. I need something local for this so that I can run tests and go over and over these conditions at different pressures as well as speeds to understand how they impact handling and then run what I think is the best and see how the tire wears.:clap
    #28
  9. Abenteuerfahrer

    Abenteuerfahrer Deaf on Wheels

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    Currently running 32#-front Tourance; 28# pusher; 28# sidecar......good ride on pavement and off road...comfy with the overall Hyperpro shocks on the motorcycle and Progressive 200/350 on sidecar. (carry a pair-just in case).

    Now I don't slam-bang the rig through the worst roads....easy does it.. ! Ain't racing a la Moto offroad...always make sure that the pusher is in/on the best lane of travel disregarding the sidecar pretty much :rofl.

    Cheers...
    #29
  10. YOUNZ

    YOUNZ Been here awhile

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    What's your opinion on using a so-called "space saver" tire as a pusher on a rig. It would seam they need to be pretty tough, for what is required of them.:ear
    #30
  11. Bobmws

    Bobmws Curmudgeon At Large

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    Every one of those I have had in a vehicle limited the top speed (maybe 50mph) and total miles (maybe 100) for using that tire. I also seem to recall they are fairly expensive, you'd do better with a bike tire.
    #31
  12. Pete-NZ

    Pete-NZ Been here awhile

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    Getting back to the question... Away from the tyre thead its turned into...

    The best way is have a passanger that works.. the sit still sack of spud type
    passanger in the bath tub style side car are good for easy flatish road type tracks..
    Once you go onto rough trails with offcampers / deep ruts etc you require a mobile
    passanger in a car that lets the passanger move...

    If you do have a tub car with a dead weight passanger and/or gear the best option
    is a leaning car.. The car to most exstent works as a independant unit going
    up/down over bumps/holes with next to no effect on the bike and will quite happerly
    run along a offcamper while you still ride the bike verticaly.. changes in direction are
    still made by leaning the bike regaurdless of what the car is doing..

    I took the slideing limiting strut of my dirt leaner & replaced it with a fixed strut
    well what a mungal of a thing it was on any other that level flat ground.. & the
    steering got noticably heavyer...

    A couple of other good points with a leaner a leading link front end is not required
    steering weight dosn't change on the road you ride it like a normal bike just lean
    and it goes around the corner...3 bolts remove the car takes me all of 15 minutes
    to remove it or put back on..

    So to the question... Techiniques for rideing back roads... with a leaning unit
    its not a lot diffrent from a solo bike... With a fixed unit you need a passanger
    thats just not there for the ride..
    In both cases you have always got to be aware there is a car..
    #32