Page 2 of 3 FirstFirst 1 2 3 LastLast
Results 16 to 30 of 45

Thread: A Study in Stability - Sidestand versus Centerstand

  1. #16
    Registered User
    Join Date
    Dec 2012
    Posts
    998
    Quote Originally Posted by Weasel View Post
    It wasn't noise from the huge truck with a load of steel, it was that it shook the ground as it went by. Another time, I had parked on the centerstand (I used to use the centerstand exclusively) and a terrific storm came and eroded the surface underneath my bike and over it went. I hauled it up and put it on the sidestand, and all it did was lean a little further, but didn't fall over. Gale winds have blown my bike over on the centerstand until I got wise and used the sidestand such that the wind blew in the same direction as the lean angle on the sidestand. Each will do things as they see fit and there are many variables to the equation. Do whatever works best for you with your bike(s).
    This proves that the issue of which stand to use, is MORE determined by the material under the bike, not the particular stand itself. The tests of Kurt, show that the centerstand itself doesn't take as much pressure to tip over than the sidestand at lease in most directions and assuming the same under-the-bike base material.

    For me, one of the critical issues is the oil issue in boxers. But, like Mike above, I will use whichever I think is best for the circumstances at hand. Loose ground, mud, gravel, asphalt softened by hot sun, and I will search for a place to use centerstand safely, and if that doesn't exist, I will go with sidestand, and if on any sort of unlevel ground, I will be sure to also put the bike in gear.

    Now...have I satisfied everyone?

  2. #17
    Superkraut typ181r90's Avatar
    Join Date
    Sep 2009
    Location
    NJ
    Posts
    377
    I love this forum
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1973 VW Type 181 Custom SOLD )

    http://symphonyofshrapnel.blogspot.com

  3. #18
    not so retired henzilla's Avatar
    Join Date
    Sep 2006
    Location
    between SanAntone & the Weird Place, TX
    Posts
    5,991
    Nice work Kurt. Been busy,eh?
    Some physics as you mention...and then a whole lot of peo's (personal experience opinions) still. All's good it seems as expected



    And to add my witty as usual input...

    I still prefer the first style below in most situations...have seen gale force or T-storm downdraft winds not care which way you chose or which way it was pointed, nor what sized bike. They all took a nap. Luckily, twice I can recall, I was parked next to anything larger than me when I was in that situation...on the leeward side if I guessed right or close enough to the structure my bike disappeared in the wall/wind equation The other guys didn't fare as well. My brothers Vision fared better than the KTM near it in MT one morning as we looked across the hotel lot from inside.

    three point stance.jpg
    Had a Sumo pic, but thought that might be a bit much, The NFL 350lb Lineman pic wasn't much better...but I wouldn't push either from the side. Both made me think 'Wing or LT

    attention stance.jpg
    A little too stiff and upright for me...looks like it would blow over easily despite possible rank/weight.

    Two point parade rest.jpg
    # 2 looks OK if needed, but I'd lower that flag a tad on a windy day


    I bet this thread can take us thru the thaw of 2014

    carry on... and park any way you like, I certainly don't care if you haven't gathered already.
    Steve Henson
    SABMWRA MOA Club#62's Flat Fixer/ current forum moderator
    It's not the breaths you take, but the moments that take your breath away-D.Dillon/G. Strait

  4. #19
    Registered User
    Join Date
    Sep 2007
    Posts
    532

    I just can't resist on this

    A number (a great number) of years ago at a rally in the Florida keys (Gator Rally I believe) a really, I mean REALLY BAD storm came through overnight and pretty much demolished the campground. Out of all the bikes found on their valve covers on the morning after none that I'm aware of were originally put on the side stands for the night. In my world when I park one of my boxer twins I use what ever method (side or center stand) works best for the situation at hand and I give some consideration to expected length of time the bike will be parked. I have two /2's that are regular riders and find that neither will start right up unless the bike is on the center stand regardless of how or when it was parked or if it was on the center or side stand. My air heads get the center stand treatment most of the time because the side stands are unreliable, flimsy and will knock the crap out of your shin with little warning if you so much as think about a quick dismount or hop on and ride, I prefer to take my time and use the center stand with those. My oil heads are well trained and do just fine with either although I do not like to load the 04 GSA and then put it on the side stand, I can just see that side stand bend and break with all that weight. The only Hex head in the stable is my HP-2 Enduro and it has no center stand but that OEM side stand mount is just plain garbage. It is so bad Woody's wheel works toke the time and made the investment to make a stronger, better replacement mount for the 2,900 or so machines that were built.

    Translation: Its your choice which to use but choose wisely my friend.

  5. #20
    Benchwrenching PGlaves's Avatar
    Join Date
    Oct 2003
    Location
    "Big Bend" TX
    Posts
    8,680
    Kurt,

    I followed what you did more or less but I can't replicate the math with a changed variable. Can you redo the sidestand calculation at a lean angle of 15 degrees. (I have a K75 )

    Also, assume I park with the sidestand down wind - what might it take in lateral force from the side opposite the sidestand - on firm ground - no sinking.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  6. #21
    Registered User
    Join Date
    Sep 2003
    Location
    Virginia Beach
    Posts
    704
    This may well become the new "oil thread"...

  7. #22
    rangerreece rangerreece's Avatar
    Join Date
    Aug 2008
    Location
    Enterprise, AL
    Posts
    178

    Three points of contact

    Just my thoughts,
    I would imagine friction at the points of contact would weigh heavily into any literal or figurative equation. On the side stand my three points of contact are the side stand and two tires. Center stand; front tire and the two contact points of the center stand that are closely placed. The "maintenance" stand always feels unstable to me. It is necessary to access the rear wheel maintenance area. The side stand always feels very stable to me. Two years ago my bike was hit by a golf cart at work, it was on the side stand, the right rear wheel of the golf cart hit the right side of the front wheel of the bike. The OEM rain cover was on. The front wheel turned left with impact. No damage to bike no toppling.
    2005 R1200RT
    BMWMOA # 143779
    "Positive Habit Transfer is no substitute for Situational Awareness."

  8. #23
    Registered User melville's Avatar
    Join Date
    May 2010
    Location
    Behind the Redwood Curtain
    Posts
    113
    Theory is all fine and wonderful, but how about some actual testing?

    How about a spring scale anchored to the frame at the rear of the tank to measure the amount of force ACTUALLY required to lift the bike off the stand? Checking from both sides, of course. While there is probably not much difference in tipover force required on the centerstand, on the sidestand is another story.

    We're certainly a nerdy bunch, no?

  9. #24
    No longer a member here
    Join Date
    Apr 2006
    Posts
    1,432
    Quote Originally Posted by melville View Post
    We're certainly a nerdy bunch, no?
    I predict it is going to get worse for many as soon as cabin fever spreads. This is just the beginning.

  10. #25
    Curmudgeon nrpetersen's Avatar
    Join Date
    Sep 2004
    Location
    minnetonka mn
    Posts
    608
    Kurt's analysis would be more complicated but more correct if the compliance of the front and rear suspensions is included in side stand performance analysis. On the other hand, the center stand isn't sensitive to suspension compliance.

    When it goes onto a ferry, I try to use the center stand. Otherwise it depends on the surface and static loading of the bike.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  11. #26
    Registered User
    Join Date
    Dec 2012
    Posts
    998
    Quote Originally Posted by melville View Post
    Theory is all fine and wonderful, but how about some actual testing?

    How about a spring scale anchored to the frame at the rear of the tank to measure the amount of force ACTUALLY required to lift the bike off the stand? Checking from both sides, of course. While there is probably not much difference in tipover force required on the centerstand, on the sidestand is another story.

    We're certainly a nerdy bunch, no?
    I think you are on to something!

    Before anyone reads any further, I think that Kurt's numbers ARE helpful when considering this ONE bike, based upon these assumptions. The numbers arrived at are relatively useful when considering THIS bike's leaning force and therefore the force necessary to "push" it back up into upright position (if on sidestand) or the force necessary to push a centerstand bike off center and over center to tipping point. I think it basically told us what we already knew, that the sidestand DOES provide a more stable overall position than the centerstand, but not that much so. But, when other factors are considered, such as ground density, or windage and direction, AND also the belief (or non-belief) of the oil situation concerning boxers, the decision to use either method of parking still resides with the rider who evaluates (and prioritizes) the situation at each parking time and chooses what he/she wants.

    Kurt,

    Can you provide us with the algebraic formula that you used to calculate the side forces? Did you derive your final data from actual testing on your bike in your garage? I.e. tipping it and then using measuring devices to see just how much force is needed to tip back up or tip to the point of T/O?

    Did you basically use these numbers:

    Total weight of bike
    Lean angle (theta per your sketch)
    Location of the center of gravity (assuming centered over tire patch left to right, and then measured height off ground)

    Could it be that you used some formula that was used for "leaning" forces while riding? I would think that they could be similar, as one can imagine the "forces" when actually leaning into a turn, for example and the "forces" needed to straighten it back up after the turn.

    Just asking....

    Thanks,
    jlc

  12. #27
    Registered User
    Join Date
    Dec 2012
    Posts
    998
    Quote Originally Posted by rangerreece View Post
    Just my thoughts,
    I would imagine friction at the points of contact would weigh heavily into any literal or figurative equation. On the side stand my three points of contact are the side stand and two tires. Center stand; front tire and the two contact points of the center stand that are closely placed. The "maintenance" stand always feels unstable to me. It is necessary to access the rear wheel maintenance area. The side stand always feels very stable to me. Two years ago my bike was hit by a golf cart at work, it was on the side stand, the right rear wheel of the golf cart hit the right side of the front wheel of the bike. The OEM rain cover was on. The front wheel turned left with impact. No damage to bike no toppling.
    What if the golf cart had hit the left side of the front wheel and forcing bike to the right? Would side stand have been as good in that situation?

    How about if the cart had hit directly from behind, pushing the bike forward? Or form the rear left, pushing the bike forward and to the right?

    Just to mention a few of the literally hundreds of situations that can occur. That is done simply to let us all know that we all must make our "decision" at the time we park our bikes. To one, one possibility may be higher than to another in a given situation.

    My biggest dislike is when bike is parked and someone comes along and decides he/she wants to see what it feels like by sitting on it - all without permission, and even maybe when we are not around and behind our backs! This is when I wire my bike for 280 volts and anyone who touches it gets all of them!

  13. #28
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    13,155
    Quote Originally Posted by jimmylee View Post
    Can you provide us with the algebraic formula that you used to calculate the side forces? Did you derive your final data from actual testing on your bike in your garage? I.e. tipping it and then using measuring devices to see just how much force is needed to tip back up or tip to the point of T/O?

    Did you basically use these numbers:

    Total weight of bike
    Lean angle (theta per your sketch)
    Location of the center of gravity (assuming centered over tire patch left to right, and then measured height off ground)

    Could it be that you used some formula that was used for "leaning" forces while riding? I would think that they could be similar, as one can imagine the "forces" when actually leaning into a turn, for example and the "forces" needed to straighten it back up after the turn.

    Just asking....

    Thanks,
    jlc
    Jimmy -

    I did think about testing to see how my answers compare. I envisioned a fish scale of sorts attached as suggested. It would be easy enough to perform the tests on my Reynolds stand setup, although if the correct answer is near 130 pounds, that's going to be a bit scary to do the test...even if it is just to get the bike to start moving. My stock centerstand is in the attic. As for testing on the sidestand, I'd have to wire the sidestand down and block the front and rear wheels so it doesn't move. I don't have any "built in" helpers, so doing it solo presents some problems.

    As far as considering other factors, yes, there's some simplification to my approach. I was just trying to get a general sense of the relative values. Bike with half fuel will have a different CG location and force vector; an R100 with the lousy/bent sidestand will have a different lean angle. But the scenario was basically a static situation...I don't think consideration of the suspension changes when trying to lean the bike over will change the results to a significant degree.

    Regarding the forumulae involved, I indicated it was Statics 101 for anyone getting an engineering degree. I took the published weight for the R100/7 and used sines/cosines/assumed angles to resolve the gravity vectory (474 lbs) into it's orthogonal components. It's easy enough to do this computation which then gives you more forces to work with. And, knowledge of angles (interior angles of a triangle sum to 90 degrees, etc.) let you determine other angles of my diagram quite easily.

    As for consideration of forces while turning, that would be another level of complexity. The gravity vector is always acting straight down. The radius of the turn and speed will identify a radial acceleration which then results in a force of the CG to move laterally. But that is resisted by the friction created by the tires and the contact surface. It's always amazed me how the MotoGP guys can go around a turn at 65 degrees lean angle at those speeds and not spin out. How in the heck does the tire do this? Well, as long as no other point of the bike touches the ground, if the vertical force at the CG is 474 lbs, then the sum of the vertical force at the two contact patches is also 474 lbs. That will be enough for the friction forces to do their job. But as soon as the rider touches a footpeg down or even puts too much weight on the knee puck, this transfers weight away from the two vertical forces at the tire contact patch, reduces the friction forces, and a lowside usually happens.

    But I digress!
    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!

  14. #29
    Registered User
    Join Date
    Dec 2012
    Posts
    998
    Quote Originally Posted by 20774 View Post
    Jimmy -

    I did think about testing to see how my answers compare. I envisioned a fish scale of sorts attached as suggested. It would be easy enough to perform the tests on my Reynolds stand setup, although if the correct answer is near 130 pounds, that's going to be a bit scary to do the test...even if it is just to get the bike to start moving. My stock centerstand is in the attic. As for testing on the sidestand, I'd have to wire the sidestand down and block the front and rear wheels so it doesn't move. I don't have any "built in" helpers, so doing it solo presents some problems.
    What you describe is exactly what I did when I worked for a company in their R & D department. Though we were not engineers, we would use the calculations told us by the various vendors (let's say for certain plastics, etc.) and then we would do actual testing using scales, hyd. pressure (gages) or air pressures. We also did lots of cycle testing - designing up a rig to put a part to test as similar to its actual designed use, and see how many repetitions it would go before failing. Often many of the same item were tested using various greases to see how each performed when lubricated differently. Also did under varying temp settings were possible.

    Rarely, however did the actual tests reveal the same numbers as did the calculations.

    To quote someone. "You done good!!"

  15. #30
    Aspiring Profligate jeff488's Avatar
    Join Date
    Apr 2007
    Location
    Nacogdoches, TX
    Posts
    794
    That does it. I have read this entire thread. I obviously need help.

    I am going to buy a 45 year old Puch 250 twingle for a Winter project.
    That'll do it, I'm sure.
    '04 Silver R1150RT "Big Oel". '05 Yellow KLR 650
    '00 Red Suzuki Bandit 600
    '65 Allstate/Puch 250 twingle
    "I just want somewhere to ride and food when I get there."

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •