Moto Guzzi V85 TT

Discussion in 'Moto Bellissima: All Other Dualsports' started by cabanza, Nov 7, 2017.

  1. Grinnin

    Grinnin Forever N00b Supporter

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    What @DesmoDog said is that while moving and turning, any tilt sensor that relies on gravity will always think the bike is upright.

    If you lean off the bike a lot in Valentino Rossi mode, my sentence above isn't precisely accurate, but a tilt sensor would think the bike is tilting opposite of how it's actually tilting.

    The adaptive headlights require a gyroscope or other non-gravity-based tilt sensor.
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  2. lamotovita

    lamotovita DAMN SNOWBIRD! Supporter

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    Try ignoring the mpg readout on your meter and calculate it the old fashioned way. My MPG went way up when I did that.
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  3. Pbro63

    Pbro63 Been here awhile Supporter

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    @DesmoDog said "It seems to me this switch would only work if the bike isn't moving when it leans.

    When you are underway, the resultant force works through the contact patch of the tires up through the Cg of the bike. If you're straight up and down so is the force, if you're leaned over, so is the force. The mercury won't move aside from other forces like bumps."

    Also @Grinnin said "
    What @DesmoDog said is that while moving and turning, any tilt sensor that relies on gravity will always think the bike is upright.

    If you lean off the bike a lot in Valentino Rossi mode, my sentence above isn't precisely accurate, but a tilt sensor would think the bike is tilting opposite of how it's actually tilting.

    The adaptive headlights require a gyroscope or other non-gravity-based tilt sensor."

    ----------

    This may be true, but consider the design of the switch has a rather big puddle in a narrow rice grain style tube and with the relative heavy density / weight of mercury it would seem that there would be no issue with centrifigal forces or road irregularities (The switch can be mounted on it's side or upside down and still works in the exact same manor). Also the trigger angle would be quite a ways from TDC (top center) so as the bike falls / leans into the turn the circuit would activate at an angle of your choosing based on trial and error. One would not want it to trigger near TDC (too soon) as that would result in the light not helping (ie pointed too high) and the possibilitiy that the forces you mentioned would be in play. There are similar designed switches using ball bearings which I think would be totally inefective for the reasons you stated since they do not share the same properties as mercury. Alas the summation that a gyroscope is required might be correct but then where would the fun and challenge be in not trying a simpler and doable for the layman solution?

    As to safety concerns the mercury is held within a tube that is held within a secondary heavy-duty see-through palstic housing. I'm a member of the school of "fuck it, I'm doing it anyway" because if everyone lived on the principal that the 1% chance something could go wrong there would be no motorcycles to ride amongst other things. Also consider that up until recently that thermometers were/are mercury held in delicate glass tubes that people put in their mouths!
    The impetus for this post is for someone if so inclined to try this out to see if it works and share the process and their findings. I will be giving it a go at some time in the future as well. :D
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  4. Pbro63

    Pbro63 Been here awhile Supporter

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    PM me
  5. hasselman

    hasselman Motorcycle learner (since 1981)

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    I'm not as concerned about the regulations as about the costs for carriage pigeons or snail mail from Canada to Finland.

    Prob63: Thank you for your kind offer. After checking some e-commerce sites, I've come to the conclusion that it's cheaper to ship across Siberia than The Arctic. For the postage charge of 2 units from Canada to Finland, I get 20-40 switches from China.
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  6. DesmoDog

    DesmoDog Desmo was my dog. RIP big guy.

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    Yeah... that's not really how physics works...
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  7. Pbro63

    Pbro63 Been here awhile Supporter

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    ... with the relative heavy density / weight of mercury it would seem that there would be no issue with centrifigal forces
    I stand corrected, of course there would be counter forces involved but is it enough to make it flow uphill? What kind of forces are involved in riding a mountain road at night? GP Kenny Roberts G forces? Yah that would be an issue, typically the main forces are deceleration and acceleration while the actual forces pushing away from the turn are based on speed through the turn which may not be as great as one thinks, again its all relative. for instance if the stock set up of lights has a nice wide spread then the cornering lights could have a higher threshold ie steeper lean sensor angle that would better counter opposing forces. So in my professional opinion it may or may not work or it may work most of the time or just some of the time. :hmmmmm
    That is what is intriguing about this, that one wouldn't really know until one tries and the level of success has many variables.
  8. RedHawk47

    RedHawk47 Adventurer Supporter

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    Lots of interesting physics going on with that mercury switch. The mercury's movement is limited by the tube it is in, but is not constrained within the tube.
    An object in motion travels in a straight line unless a force acts on it.
    If you lean the bike while moving forward, without turning, the mercury move to the uphill side, trying to maintain it direction of trave, and then succumbs to the force of gravity.
    But if you are leaned and turning the centripetal force will want to keep the mercury in the uphill location.
    However, this is complicated by the probable fact that you countersteered to initiate the turn (which you do instinctively without being aware of) which would slap the merc to one side and then to the other.
    Boy, isn't physics fun? There are probably other factors that I haven't even thought about.

    Dan
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  9. davidji

    davidji bike curious

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    Down from on the motorbike points to the tire contact patches and the line between them. Else the bike would tip over. A simple tilt switch won't see the bike as tilted when it's leaning in a turn. Fasten a bubble level to your tankbag if you like and see what it does when you're leaning in a turn.

    If you want to study something to understand this better, what comes to mind is to learn to draw (or at least understand) free-body diagrams with objects and the forces acting on them, if they aren't clear to you now. It often takes people some time to adjust their thinking.

    Next, the leaning section here should make it clearer. Look at the diagram to the right. Down from center of mass of the bike is the thick line.
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  10. Grinnin

    Grinnin Forever N00b Supporter

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    For both mercury switches and bubble levels, the vibration from engine and road will cause a LOT of random noise.

    If you can smooth it out to eliminate the noise, then "down" is always centered (left/right) through the motorcycle.

    That's why you don't have to put a foot down to lean the motorcycle in turns. It remains balanced left/right no matter how much it's leaned. When it's not balanced, it falls over and your 150Lbs will have trouble keeping its 600Lbs from hitting the pavement.
  11. DesmoDog

    DesmoDog Desmo was my dog. RIP big guy.

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    If you lean the bike without turning, you haven't changed it's direction of travel. The liquid will flow to the lowest point with no trip to the other side first. You haven't turned, gravity is the only force acting on the liquid when you leaned.

    No, the mercury will not move to the "uphill" location, it will stay centered. The whole point of the bike leaning is to keep the force going through the contact patch of the tires. Do you feel yourself getting pushed to the side when you turn a bike? Neither would the mercury.

    Ok, here I'm starting to assume things but the countersteering makes the bike lean, it would not slap the mercury to one side any more than it slaps your body to one side. It doesn't turn the bike left before it goes right, it leans the bike right as you turn right. Think about the center of gravity and what it does, not just the contact patch of the front tire. Yeah there's gyroscopic forces going on when you ride and now we're getting away from what a switch will do but the gist of it is the countersteering isn't going to make the bike zig left before it zags right.

    It's been too many years since I studied this sort of stuff to recall all the details of what the bike is doing but the bottom line is a mercury switch would do a horrible job of controlling a light on a motorcycle.

    "So in my professional opinion it may or may not work or it may work most of the time or just some of the time." Yeah, that pretty much describes the possibilities of what could happen. If that's your idea of success then I'd agree the switch would certainly kinda work, or not, some of the time. Maybe. Kinda reminds me of an old Honda I had, actually...:-)
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  12. DesertPilot

    DesertPilot Long timer

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    As a physicist (Caltech, MIT, 30 years at NASA), I'll note that there's an easy way to see what a mercury switch will do. Hang a pendulum from the top of the winsdscreen. Take a GoPro movie of what happens in a turn. Or what doesn't happen, as the case may be...
  13. Torquemada

    Torquemada Been here awhile

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    You know it’s a motorcycle thread when it occasionally devolves into subjective realities in perception of the laws of physics and near-earth orbital mechanics. Atom, mercury, banana, bowling ball.
  14. Grinnin

    Grinnin Forever N00b Supporter

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    Starting and stopping the motorcycle will send the pendulum swinging fore and aft. Then air turbulence will push it side to side. Before long it's going everywhere.

    Maybe a weight on a pivot with some motion damping. Pivot should allow only side-to-side swing, not fore-aft.
  15. jrt

    jrt Been here awhile

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    And helium-filled tires. Don't forget that!
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  16. RedHawk47

    RedHawk47 Adventurer Supporter

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    Hey, what do you know -- we agree on something!

    This is what I was going to suggest next however, you don't have to take it on the road - you can do it in your garage. Just lean the bike as if you were taking a corner.

    Dan
  17. stokerel

    stokerel Been here awhile

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    Life would be a lot simpler (and less fun) if physics of a static object would be identical to one of a moving object :) especially a two wheeler taking a curve.
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  18. Pbro63

    Pbro63 Been here awhile Supporter

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    Let's see if someone can get a prototype of any type going.! Went out for a long night ride to test the new mounts for the bar mounted fairing. Road through some very winding dark streets and found myself observing the behavior of the headlight at various speeds and angles. The fairing was very solid , took it up to triple digit speed on the freeway. Used some Slipstreamer hardware to attach to the bars along with some aluminum bar stock for the tie rods. Wasn't sure how to tie it into the fairing so I used cotter pins. Temporary ? Permanent? Another style vs function dilemma. To me it fits with the steam punk / flat track functionalistic ethos. It makes going between the large and small fairings or naked easy. After a test ride I'd like to move the base mounting point in the plate an inch higher for better wind coverage. And a half inch inboard to better match the screen`s contour. For this first iteration just used the existing holes which were darn close to perfect.

    IMG_20201123_221051762.jpg IMG_20201123_220959578.jpg Screenshot_20201124-014454.png IMG_20201123_233327835~2.jpg
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  19. JohnD01

    JohnD01 Been here awhile

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    Installed a local 'Meerkat Mufflers' 20201124_141310.jpg DeCat pipe today, Should keep the heat down during the Australian summer.
    Good sound too through the std muffler.
  20. DesmoDog

    DesmoDog Desmo was my dog. RIP big guy.

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    :lol3

    Ok, now you're just yanking people's antlers!