Techniques for Mountain Back Roads

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

  1. Square4

    Square4 Been here awhile

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    I wanted to start a thread about how to ride steep, rutted, stony, ledges on mountain roads. I have not done much of this on three wheels. I find that when I am on these roads they always slope away from the mountain and as such I find that when going with the cliff to my left I lower the sidecar with my tilt control and when going with the cliff on the right side, I raise the sidecar so that it is running level. I find that this helps out a lot but still have some problems regarding tire pressure. I am running all tires at maximum cold pressure on the bike because if I do not do this I get excessive wear from time spent on the road. However, when riding on the rougher stuff this high pressure makes all of the tires hard and they tend to bounce off of everything. I think it would be a benefit to lower the tire pressure for all three wheels. I have a car tire on the rear of the bike and on the side car and they are r15/165 tires. I run the bike tire at 42 psi and the sidecar tire at 36 psi. I was thinking that lowering the tire pressure would improve handling and reduce the jarring from hitting these obstacles. I think that this would provide better control but have not done experiments to assess the amount that the pressure needs to be dropped to achieve improved control. I was wondering what experience others have had with tire pressures for these mountainous road conditions?
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  2. chiba

    chiba elitist BMW snob

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    I don't do a lot of off-road riding, but one of the best pieces of advice I ever got related to doing light off-roading (gravel roads, packed dirt, fire trails, rutted roads, rocky roads, etc) was to lower the tire pressure.

    I don't see why doing the same thing on a sidecar rig would be a bad thing. I obviously don't know anything about your tires, but still - 42 psi sounds high for the front tire no matter what - maybe that's your rear (car) tire though? I keep my rear (car) tire at 38, which is what the manufacturer recommends (on the sidewall). I run my front tire (Metz ME880) at 36 and my sidecar tire at whatever it says on the side (I can't recall the # right this second). If I was going to be riding all day on roads like you describe above, I'd probably drop 10 lbs of pressure out of each tire.

    You might think about adjusting your shocks as well - after all, their whole job is to absorb those bumps!! Dial back the preload & soften up the rebound a little.

    I'll trade a little handling & feeling safer for a little tire life any day.
    #2
  3. Abenteuerfahrer

    Abenteuerfahrer Deaf on Wheels

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    Front Metzeler Tourance at > 36. Rear Vredestein M/S > 36-38 when offroading; 40 on the slab. Sidecar Vredestein M/S always at 36. The sidecar car tire pretty much acts like a snowboard skimming over inclement terrain if not too loaded. Whether low or high psi doesn' seem to matter. It's the bike that matters the most!

    Most all roads on the Mtn' slope away from the Mtn' and you and I use the tilt to correct the lean and make it level. How about going the opposite direction where you cannot use the tilt; do you body lean all the way over (hanging over the sidecar) to assist your lean or do you pack the sidecar with lots of ballast to counter this sometimes dangerous lean. Just curious!

    cheers...
    #3
  4. Square4

    Square4 Been here awhile

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    Abenteuerfahrer wrote:
    How about going the opposite direction where you cannot use the tilt; do you body lean all the way over (hanging over the sidecar) to assist your lean or do you pack the sidecar with lots of ballast to counter this sometimes dangerous lean. Just curious!

    The only thing that I have in the sidecar unless I am headed into the back country to do some overnight camping is my normal supply of tools in the trunk, so the sidecar is lightly loaded. If I am going up hill I will shift my weight to the high side but when going down hill there seems to be better control. Going up hill the rear wheel is searching for traction and moves around to do this and going down hill, momemtum seems to help and one can just roll over things in a more controlled manner.

    For tires I have a K60 Scout on the front at 42#, an Arizonan on the rear at 42# and Federal tire on the sidecar at 36#. This is a great combination for the asphalt but do not like the abrupt bouncing on the mountain roads. I am thinking that the next time I get to ride some mountain roads which will be in mid June, I should just plan on finding a stretch of road that I ride then adjust tire pressures, ride again and keep repeating this until I find a combination that provides the "best" compromise of tradeoffs between protectilng the tire/rim and giving the smoothest most controlled ride. When I am bouncing around, I do not feel like I am in control so a tire that is softer that rolls over things might provide better feedback and feeling in control. The down side is that a softer tire is more vulnerable to damage if things are hit at speed.

    Any thoughts that others have found that work for adjusting tire pressures will be informative and any other techniques for riding these mountain roads will be useful for me as well as other readers of this thread.
    #4
  5. ag_streak

    ag_streak Tiene Ruta Cuarenta?

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    You didn't mention if you're running tubed or tubeless tires. Offroad bikes (with tubes) run as little as 6 or 8 PSI, but you can't do that with tubeless. Considering the greater weight of a sidecar and tug, I would think somewhere between 18 and 22 PSI would provide some of the improvements you mentioned without too much risk of pinch flats on tubes or or losing the bead on a tubeless tire.

    I am not an expert on this. I don't even play one on TV, nor did I stay at a Holiday Inn Express last night... :deal
    #5
  6. Square4

    Square4 Been here awhile

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    In response to Ag_streak all of the tires that I run are tubeless. Not sure how that impacts tire pressures but I am sure it has an effect and probably limits how low in pressure that one can use.
    #6
  7. Mr. Cob

    Mr. Cob Howling "Mad", Adventurer

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    Howdy Square4,

    Running low tire pressure with tubeless tires OFF ROAD is an invitation to a FLAT. If you hit a rut, rock or other obstacle at an angle chances are your going to pop the bead of the tire off the rim of the wheel, unless you have a way of re-seating the bead of the tire your going to have a hell of a time re-inflating it. My advise if your going to do this carry a can of starting fluid with you and learn how to reseat the tire beads using it.
    #7
  8. Square4

    Square4 Been here awhile

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    Dave; I kinow that you are more of an expert than I am regarding sidecaring off road. I was wondering what tire pressures you have used? Do you run yours at the maximum? If not, to what extent have you backed off from the maximum and not had any problems?
    #8
  9. Mr. Cob

    Mr. Cob Howling "Mad", Adventurer

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    Howdy Square4,

    I am hardly an expert at anything other then doing stupid stuff and so far living to tell the tale. :lol3

    Seriously, on my Ural's I run full pressure on and off road ALL the time. The Ural tires have tubes in them so theoretically I could run lower tire pressures but doing so would endanger the tire and make handling very difficult.

    With the weight of a sidecar rig even if it isn't heavily loaded the stresses on the tires are much more then on a similar two wheeled motorcycle. The sidewalls of the tires on a sidecar equipped bike have MUCH more stress on them then does a motorcycle, when the sidecar rig turns the sidewall of the tire tries to roll under and off the wheel rather then follow the curve as a normal bike does when it is "leaned" over.

    Having the tire at full pressure also protects the wheel from damage, this is especially true if a person has "cast" wheels, spoked wheels will absorb a lot more shock then will a cast wheel. Yes there are a few times when dropping the tire pressure a "bit" might help but then on a tubed tire one must worry about the tire spinning on the rim and ruining the tube, this is not a problem with a tubeless tire but if the pressure is low enough the tire could slip on the rim or the bead may break either way causing a flat tire.

    My Beemer hacked GS has tubeless car tires on the pusher and the hack, this size tire and wheel on the hacked GS may allow safe pressure lowering within reason. However as I NEVER plan to abuse my Beemer the way I regularly treat my Ural's its something I'll never have the occasion to experiment with. So my advise would be if your going to experiment with lower tire pressures have the needed tools and skill to either change tubes or re-seat the bead on tubeless tires.

    As a long time driver of a highly modified Jeep I would often lower the tire pressure to 5pounds or less on 44 inch tall tires however these tires were equipped with implement tubes. Some of my friends who could afford the setup ran "bead locks" on their tubeless wheels and could also run very low tire pressures, still from time to time a flat tire would result from over zealous activity, NOT that I would ever participate is such anti-social behavior.

    Get the proper tools and skills, try out different tire pressures on different types of terrain and report back to us how it works for YOUR rig, we can always learn, this is YOUR chance to educate us. :deal
    #9
  10. ag_streak

    ag_streak Tiene Ruta Cuarenta?

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    I think we're all in violent agreement here! :freaky
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  11. jeffygs

    jeffygs Been here awhile

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    So please, I wanna here about the starting fluid way of seating a bead. maybe a video!!!!:D
    #11
  12. Mr. Cob

    Mr. Cob Howling "Mad", Adventurer

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    Howdy jeffygs,

    Ask and you shall receive.........

    I chose this video because these guys have some credibility but in this film they left out one VERY important tip and just barely touched on another at the end of the film.

    Tip ONE, remove the valve core BEFORE using the stating fluid, this is to prevent blowing the tire off the rim.

    Tip TWO, the starting fluid is only used to seat the bead it is NOT used to inflate the tire, you must have a means to pump air into the tire to re-inflate it to the proper pressure AFTER the bead is seated and the valve core reinstalled. And now on with the show.

    <iframe width="560" height="315" src="http://www.youtube.com/embed/vdYCsMn4xK8" frameborder="0" allowfullscreen></iframe>
    #12
  13. Billtr96sn

    Billtr96sn Flange Furtler

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    You tube some Icelandic offroaders and how the reseat their tyres using easy start, lighter fluid, hairspray anything like that will work.
    #13
  14. ag_streak

    ag_streak Tiene Ruta Cuarenta?

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    Didn't find the tire inflation, but the first Icelandic Offroaders video I clicked on was Thread of Awesome material! :freaky

    <iframe width="420" height="315" src="http://www.youtube.com/embed/LKpWGy1slVs" frameborder="0" allowfullscreen></iframe>
    #14
  15. Billtr96sn

    Billtr96sn Flange Furtler

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  16. Billtr96sn

    Billtr96sn Flange Furtler

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  17. DRONE

    DRONE Dog Chauffeur

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    Square4--

    I have a rig like yours--1150GS with a DMC car--and I have a car tire pusher. I run less pressure than Mr. Cob and Abenteuerfahrer. I do go on dirt roads fairly frequently usually fully loaded with camping gear on multi-day trips. On my Vredestein Snow+ pusher, I run 26 psi and I think that's fine for both paved and dirt roads. Not only do I like the traction and the ride, but I'm getting pretty even wear. My logic here is that my 4000 lb SUV rides nice on 4 tires at 30 psi--that's 1000 pounds per tire. So why can't my car pusher tire ride nice at 26 psi with a load of about 650 pounds? It's an important distinction that this is a car tire and not a motorcycle tire.

    I run with 26 psi in the sidecar tire - Vredestein K60 Scout - not much load on that tire and no reason to make the ride super hard for the monkey.

    I run with 30 psi on my Vredestein K60 Scout front tire. This is the trickiest tire. I agree with Mr. Cob that you don't want to go too soft on this tire as you don't want to bend a rim or pop the bead. And it takes a lot of abuse up front there carrying about a 400 pound load and hitting all the rocks and ruts that I hit. But I don't really want to run it higher because I like the steering and braking performance on pavement at 30psi.

    I carry a compressor and a tire kit on board, BTW. And Ride-On tire sealant in all 3 tires. Not that either will save my ass every time, but they might save my ass some of the time.
    #17
  18. Abenteuerfahrer

    Abenteuerfahrer Deaf on Wheels

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    Hola Drone....

    Well, me thinks the SUV has 4 tires equally evened out..vehicle weigh distribution pretty even....30 psi each while on a sidecar me thinks 60% is ballasted toward the rear of the pusher tire..thus a bit more psi there !! ? Maybe BMWzenrider can chime in with his scientific analytial thoughts regarding tire loads recommended for the pusher!

    Cheers...
    #18
  19. Square4

    Square4 Been here awhile

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    Drone; your tire pressures are much lower than what I have been running. For the pusher tire, when I first started running the car tire I put in 32# because it is a typical value for car tires and after a few thousand miles the tire had a very obvious wear pattern with excessive wear on both sides of the tire tread that is typcial for an under inflated tire. I ended up trying some higher settings but when on the asphalt I had to get to 42#s to not have underinflated wear pattern. Part of this may be the tire which was a Federal and perhaps it had soft sidewalls soft tread or a flimsly tread belt that created this wear pattern. When I put on the Arizonian I just put it at the max and only have several thousand miles on it but it is wearing as expected for a pusher tire (slightly higher wear on the right or sidecar side of the tire). Based on your experience, I will try lowering the pressure and track the wear pattern. It would be great to run a lower pressure for smoothing the ride but I do not want to do this if the wear pattern is wrong. I will lower the pressure and measure the tire tread depth across the tire at a marked location and then check on the tread wear. I suspect that I will need to put on 1000 miles in order to see any difference that I can measure accurately. If I do not see any change, then I will lower the pressure and continue the same monitoring process.

    What experience have others had regarding tire pressures for both asphalt and fire road travel? How have you determined what is the best tire pressures to run?
    #19
  20. BMWzenrider

    BMWzenrider The Road Scholar

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    Square4,
    Changing the inflation pressure on your tires can indeed alter the handling and ride.
    To give you my personal opinion of what a safe inflation pressure would be for your rig, I would need to know the weight being carried at each wheel, the exact tire size being used there, and your goal. (max safety margin against tire damage, max traction, max wear, etc...)

    you have not mentioned exactly what your rig is, or the sizes of the tires.
    However, it sounds like you have a R1150GS/DMC rig, yes?
    You mentioned part of the size on your pusher tire, but not the profile spec.
    I do know that most of the 4valve GS guys are running a 165/80-15 tire, so I will go based upon that assumption.

    -----
    From my work in the tire industry I know that you can derive a load/inflation table for any tire given some information about the size/construction/etc.
    For a typical passenger car radial tire with a profile of 50% or better the equation looks like this:
    L=K*P^0.5*Sd^1.39*(Dr+Sd)
    There are separate formulas for low profile tires, bias ply, motorcycle, heavy truck, etc...

    When a vehicle manufacturers list the recommended inflation pressures for their product, it is arrived by: Taking the max. GVWR, divide by the number of tires supporting the load, and then finding a tire which will safely support that max. load at a chosen inflation pressure.
    They then post a single inflation number on the door post or in the manual.

    Many cycles have multiple recommended inflation pressures depending upon when ridden solo or with passenger/luggage.
    This is because adding passengers/load on a relatively light vehicle like a motorcycle can so dramatically change wheel loading, and the manufacturer and tire maker knows that the grip/wear/handling of a tire can change dramatically if you are over or under inflated for the given wheel loading.

    -----
    What does this mean for our sidecar rigs?

    When you put a car tire on a motorcycle or sidecar, the odds are pretty good that the tire is technically 'overmatched' to the loading of that wheel position.
    Even when my heavy rig is fully loaded for a trip (and with my fat ass in the saddle) my pusher tire's static wheel load is only around 650-lbs.
    The max load rating of the 165/60R15 car tire that I use in the summer is 900-lbs, or about 28% higher than required.
    If you overinflate tires by nearly 30% you WILL notice that they are noticably too hard, don't grip well, and will have classic overinflation wear down the center of the tread in short order.

    The 165/80R15 tire size has a typical max load rating of 1,200-lbs!
    If your wheel loading is anywhere close to mine, that means leaving that tire at max rated inflation pressure would have it WAY too high for the load on it.

    -----
    Tire manufacturers actually have complete load/inflation tables available for every tire that they make, so that vehicle designers don't need to go through the labor of picking a tire size, and then going through all the formulas to see if it will support the load and at what pressure.
    They just go to the tables for the size tire they are considering and can easily look up whether the tire is suitable, and at what pressure.

    However, if you call up Bridgestone, or Kumho, or any tire manufacturer and as a consumer and ask for the load/inflation table for a tire you will get this reply: "XYZ tires always suggests that you consult your vehicle owners manual or contact the vehicle manufacturer for correct inflation pressures."
    Their way of covering their butt so they don't get sued.

    -----

    Luckily, I know both the formulas used by the manufacturers to derive the tables, and the right magic words to usually be able to get the techs at the call center to just read me the load/inflation data from their charts... :wink:

    And here now for your viewing pleasure....
    The load/inflation data for a typical 165/80R15 passenger car radial tire.

    Tire: 165/80R15
    Pressure .. Load
    (psi) ....... (lbs)
    ---------------
    22 .......... 794
    23 .......... 833
    24 .......... 864
    25 .......... 882
    26 .......... 926
    27 .......... 950
    28 .......... 970
    29 .......... 1003
    30 .......... 1047
    31 .......... 1061
    32 .......... 1080
    ....
    35 .......... 1199
    ----------------

    Some of you may have already noticed that the load capacity vs. pressure is non-linear. (also that there are a few pressures not listed near the upper end, where the loads are already much higher than most sidecar owners will be at.)

    The tire industry usually calulates these published loads with a 10-12% factor of safety, and the numbers generally don't need to be derated for heat/high speed unless you are doing something extrordinarly fringe.
    Although part of the reason for this data is to prevent heat build-up in the rubber from cyclitic flexing. So if you are planning on going really fast in the desert, I would run a slightly higher pressure than absolutely needed for your load to reduce sidewall flex, tread squirm, and heating.

    As Mr.Cob has pointed out, there IS a practical limit on how low you can go.
    Yes, on extremely hard cornering a tire can lose seal with the bead if underinflated too far, but that is pretty uncommon, and takes some serious abuse to acheive.
    That is because most wheels designed for radial tires have a "safety bead". It is that hump that makes it harder to break the bead on a tubeless tire than for a tube-type tire/wheel. The safety bead is there to help keep the bead in place in case of a deflation while rolling down the road, so it works pretty well at low pressures as well. But it is not foolproof.
    For my 'spirited' riding on some pretty tight twisties I have run my pusher tire as low as 24-26psi(cold) without problems. And we are talking cornering speeds/forces which were making the front tire visibly roll in according to the photo someone took of me. (And it was at max sidewall pressure!)

    Another consideration is compressive deflection of the tire when hitting bumps/ruts/etc. The risk of pinching the tire flat against the rim and doing damage to the wheel in extreme cases.
    One thing that you have to factor in is that when you compare a typical motorcycle tire to a car tire there is a WHOLE lot more contact patch resisting that compression and there is generally more sidewall to absorb that force as well. The sidewall on a 165/80-15 tire is around 132-135mm tall. The sidewall on the stock GS rear tire (150/70-17) is only around 105-110mm tall. A 1-inch advantage in sidewall height for the car tire, and a whole lot more 'crush space' before you reach the rim as a result.
    So the danger of pinching down from lower inflation is usually not as great with an automotive tire as it is on a narrower bike type tire.

    Inflation pressure even influences the puncture/cut resistance of a tire.

    -----

    Probably LOTS more info than you really wanted, but hopefully you and others will find something in there of value.
    If not, just remember what it cost you... :wink:
    #20