Snow Handling Questions- Mtbr.com
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  1. #1
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    Snow Handling Questions

    My questions are for those who ride their fat bike in the snow. I've only ridden in the snow a few times and want to compare my notes to other's experiances.

    1. packed trails vs soft snow over road/packed base - Does the bike steer better on packed or loose trails? I've noticed my steering is very squirrelly and typically slides sideway when cutting through 6" soft snow.

    2. What other factors will affect handling? Snow temperature / consistency? Wet snow is slipperier than light fluffy snow? How about air temp? How about the base? Riding on loose snow over packed snow? Loose snow over concrete or dirt?

    3. Steering on snow difficult if your weight is too high and back? I'm using riser bars on my bike, and I'm thinking the extra 1" of rise is causing front tire to lighten enough to loose control while steering in snow. The bike was designed for flat bars, but I had a nice carbon riser laying around. Should the handlebar be higher, lower, or even with the saddle hight?

    4. Front tire pressure? Lower than rear? I'm thinking the front should be a little more squishy to help grip the snow during turns.

    I'm headed next weekend to try some groomed snowmobile trails up in the mountains. It should be medium to hard packed groomed trails. I'm hoping to have more control while riding than last weekend's ride.

    I'll figure this all out over this winter, but I want some feedback from you seasoned veterans of countless winter riding.
    "Riding is about rhythm and flow. It's the wind in your face and the challenge of hammering up a long hill…" - Gary Klein

  2. #2
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    Think of the front tire as a rudder except when riding on packed or a few inches powder over packed. Substitute packed for any firm surface.

    I find that steering with your hips is beneficial. I run the front lower than the rear. Keep in mind what temperature you fill the tires at compared to what temp you'll be riding at. 5psi is as low as I've gone on the front. You can smack the rim if you hit a step with it.

    For those snowmobile trails you could have 20psi and have decent control. I'd probably run 7-8 psi front and 12-13 psi rear. Overfill the tires before your trip so you can adjust tire pressure for elevation and temperature on site.

  3. #3
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    You're thinking too much. The pugsley won't mind subtle differences of 1" of rise on your handlebars, it weighs 40lbs!

    Adjust the tires for the conditions, the softer the snow, the less psi you should run. I liked keeping my pressures pretty even. If you're doing any uphills, the back can't be too hard, or you'll spin (loose or hardpacked). Too soft and you'll find yourself with lots of side to side instability on the hard packed stuff. Like Schmucker said, start high and drop as needed.

    Hard packed will always be faster. With loose snow, you will have to do the work of compressing the snow yourself, which isn't easy. The loose stuff is fun on the downhills, but be wary of hidden rocks/stumps/bumps.

    mikE

  4. #4
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    Quote Originally Posted by tswg
    You're thinking too much. The pugsley won't mind subtle differences of 1" of rise on your handlebars, it weighs 40lbs!
    mikE
    Who has a 40lb pugs? my wife's el cheapo build is only 34. racerti posted pics of his 29.5 lb 907. now i'm thinking to hard...about leaving work and riding my bike

  5. #5
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    There are a bunch of reasons why I think the front end pops too easy in snow.

    1. front end in ultra light. Drilled fat shebas, titanium fork, carbon bar, etc...
    2. 1" riser and 25mm of headset spacers, places handlebar just higher then saddle. I've lowered handlebars, by moving one 10mm spacer above stem.
    3. 9:zero:7 have different geometry than a Pugsley. Headtube is much longer, so you don't need so many headset spacers. They also designed the geometry around flat bars, used to dangle junk off when racing across alaska.
    4. I ended up using my granny gear to cut through the deeper sections. This added more torque to the bike, and popped front tire a bunch.
    5. Snow was wet, but not packed. Front tire was packing snow as I rode. I think snow acted like a little ramp, until my weight would press it down.
    6. rear tire pressure was way too low. Tire sidewall was crushing when I pedaled. I learned about inside temperature vs outside temperature. Also my tire pressure gauge isnt very good. I need to pick up a digital one from autoparts store.
    7. Climbs were not steep at all, less than 5% since I was just tooling around my community. However, I did have the most problems during the little climbs I did.

    Options:
    a. adjust stem down 1", using spacers.
    b. replace riser with flat bar off my singlespeed.
    c. get tire pressure undercontrol
    d. add sand bags to frontend to make it feel like a Pug.
    "Riding is about rhythm and flow. It's the wind in your face and the challenge of hammering up a long hill…" - Gary Klein

  6. #6
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    ......or just trade in the 907 for a pugs

  7. #7
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    Try strapping some of your day trip gear under the h bars. That should weight the front end down.

    Snow conditions can vary so much, getting rid of the riser is pretty easy thing to do, but maybe give it a few weeks and you may find handling is more favorable in different conditions.
    Also, riding in snow is often a slow, choppy, messy, challenging experience, so the handling characteristics you're experiencing might just be the nature of riding on snow.

  8. #8
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    Just do it...

    You are worried too much about tire pressures...Quite simply, use enough air to get the job done, it doesn't really matter if the pressure is exactly 4.7 in the back and 7.012 up front...who cares what the pressure is...The biggest question is, are things working? Do you feel you have more rolling resistance because of floppy, underinflated tires or from overinflated tires punching through the crust? As the saying goes, when in doubt let air out. It doesn't say, when in doubt let exactly 4.6% of the current psi out of the front and 7.62% of the current psi out of the rear...you are thinking WAAAY too much...just ride, man.
    If Huffy made an airplane, would you fly in it?

  9. #9
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    Quote Originally Posted by damnitman
    You are worried too much about tire pressures...Quite simply, use enough air to get the job done, it doesn't really matter if the pressure is exactly 4.7 in the back and 7.012 up front...who cares what the pressure is...The biggest question is, are things working? Do you feel you have more rolling resistance because of floppy, underinflated tires or from overinflated tires punching through the crust? As the saying goes, when in doubt let air out. It doesn't say, when in doubt let exactly 4.6% of the current psi out of the front and 7.62% of the current psi out of the rear...you are thinking WAAAY too much...just ride, man.
    I use a torque wrench too. I must be a monster....
    "Riding is about rhythm and flow. It's the wind in your face and the challenge of hammering up a long hill…" - Gary Klein

  10. #10
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    Do you...

    ...calibrate the torque wrench?
    If Huffy made an airplane, would you fly in it?

  11. #11
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    On snowcat rims I just let out air until traction and flotation are close to optimum, or a little more if the rim bottoms too much or gets too squirrely. Haven't a clue what psi they are, don't really care.

  12. #12
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    I'm a geek, and messing with tire pressures is fun for me. I don't have a lot of experience, so reading what others have concluded is very helpful. I like this thread!

    Quote Originally Posted by damnitman
    ...calibrate the torque wrench?
    I use a 2nd torque wrench kept in a padded case in my tool cabinet to "calibrate" my disposable $10 harbor freight torque wrench/hammer/pry bar against periodically... And I'm going to quote tire pressures in my reply. Yes, when it doubt, let air out, but it is nice if when we say how squishy we found it should be, we can quote something that others can compare to that isn't subjective, like, say, PSI.

    Quote Originally Posted by Schmucker
    Think of the front tire as a rudder except when riding on packed or a few inches powder over packed. Substitute packed for any firm surface.

    I find that steering with your hips is beneficial. I run the front lower than the rear. Keep in mind what temperature you fill the tires at compared to what temp you'll be riding at. 5psi is as low as I've gone on the front. You can smack the rim if you hit a step with it.

    For those snowmobile trails you could have 20psi and have decent control. I'd probably run 7-8 psi front and 12-13 psi rear. Overfill the tires before your trip so you can adjust tire pressure for elevation and temperature on site.

    I have only a few hundred miles on my snow bike, most of them in summer, but I have decided 20 psi is overkill for any conditions except pavement, and I can't be bothered to pump past 16 psi or so even then.

    I've (happily) run the rear as low as 4, and the front as low as 8 psi in summer conditions. In winter riding, I kept the front higher than the rear as it seemed to offer better control (don't recall pressures), but lowered the rear to 5 psi over the course of almost ever winter ride (couldn't convince myself 5 psi was really safe for the rims and tubes over logs and stuff.) As I lowered pressure, I got better flotation, and surprisingly, better handling.

    This is on Endos mounted to 100mm rims. Snow/trail conditions were mostly warm, mealy spring snow, and tight, technical, deer path singletrack.

  13. #13
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    Quote Originally Posted by racerxti
    I use a torque wrench too. I must be a monster....
    Same here. Even own a few of 'em. Including this little beauty:



    - Another Freak

  14. #14
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    Quote Originally Posted by rocwandrer
    I'm a geek, and messing with tire pressures is fun for me. I don't have a lot of experience, so reading what others have concluded is very helpful. I like this thread!



    I use a 2nd torque wrench kept in a padded case in my tool cabinet to "calibrate" my disposable $10 harbor freight torque wrench/hammer/pry bar against periodically... And I'm going to quote tire pressures in my reply. Yes, when it doubt, let air out, but it is nice if when we say how squishy we found it should be, we can quote something that others can compare to that isn't subjective, like, say, PSI.




    I have only a few hundred miles on my snow bike, most of them in summer, but I have decided 20 psi is overkill for any conditions except pavement, and I can't be bothered to pump past 16 psi or so even then.

    I've (happily) run the rear as low as 4, and the front as low as 8 psi in summer conditions. In winter riding, I kept the front higher than the rear as it seemed to offer better control (don't recall pressures), but lowered the rear to 5 psi over the course of almost ever winter ride (couldn't convince myself 5 psi was really safe for the rims and tubes over logs and stuff.) As I lowered pressure, I got better flotation, and surprisingly, better handling.

    This is on Endos mounted to 100mm rims. Snow/trail conditions were mostly warm, mealy spring snow, and tight, technical, deer path singletrack.
    I've been running my endo's 9psi front , 10-11 psi rear, year round, this seems to be the compromise between getting good grip, easy pedaling, plenty of cushion without the annoyance of a pinch flat. I'm a clydesdale rider (225 lbs).
    2010 Surly, Curry "Pugs"
    Surly, Gray "Pugs" R.I.P.
    2010 HARO, Mary SS
    Kona "Deluxe" roadbike

  15. #15
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    apples and oranges...

    to use a standard such as psi you will also need to standardize the tire / rim combination being used, the ammount and location of gear lashed to the bike, the weight and riding style of the rider as well as the type, depth, and density of the trail, At 10 psi in my Endo's on 100's, you could more easily go where you would have issues at 5 psi in Endo's on Marges...When I'm letting air out I usually let it go 'till just as I hear the tube pull away from the carcass...I figure that is just enough of a difference to allow the tire to flatten out and make an easier transition to the changing trail conditions...When I air up I usually don't pump less than 100 per tire with a Master Blaster frame pump...just do it till it feels right...
    If Huffy made an airplane, would you fly in it?

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