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  1. #1
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    Back tire skidding

    This was a new one for me. I went on a ride yesterday and hit some parts of the trail with loose rock. After awhile, out of nowhere, my back tire started skidding every time I'd make a climb or take a switchback. The big thing I noticed when it was happening was when I'd sit down and my weight shifted to the rear wheel.

    The only thing I could think of why it was happening was the back tire pressure may have been too low. I noticed about halfway through the ride that it seemed to be a bit down. Not too bad, it wasn't flat or anything. I'll take a look at it tonight to confirm psi, but I'm guessing maybe around 25.

    I'm going to check the tires more thoroughly tonight, but overall just eyeballing them yesterday they seemed fine.

    Just wondering, do you think the tire pressure probably was the culprit? Need to have a little more air in them hitting the loose rock? I've heard the low psi makes it hard to ride in gravel, but didn't think that much about a halfway gravel trail.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  2. #2
    Fat-tired Roadie
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    I actually think bigger, lower-pressure tires are better on almost everything, loose rock and gravel included.

    A skinnier, higher-pressure tire may perform better on stable, hard-packed surfaces, and they're better on pavement. As long as it's concrete or asphalt - not chipseal. And if it's winter or you're someplace dirty and there's a lot of grit on the roads, little tires can get a bit scary.

    Strange that it happened more when you weighted the rear wheel. That's what I do to correct traction problems.

    With poor traction, it's all about smooth power delivery, and for me that means a high cadence. Maybe you'd be better off a gear or two lower?

    What do you weigh? I like 25 psi in my tires, which are relatively little 2.1" models, but I weigh 155 lb. If I weighed more, I think I'd have some pinch flat and wallowing problems.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
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    I weigh 190.

    The gearing didn't seem to be the problem. It was doing it whatever gear I put it in. Ended up screwing my ride a bit because I started losing confidence in the bike.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  4. #4
    Fat-tired Roadie
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    Do your tires wallow at all?

    If not, it's probably not the equipment...

    You had a thread about rooty climbs the other day - this is your Nishiki, right?

    Are they the original, or period tires? If so, I'm going to be a gear whore for a second, and tell you that new tires will actually make a difference. If you're not worried about speed, just get some big tires with a big tread. They'd be marketed as "trail" or "all-mountain" probably.

    EDIT: Actually, a bigger difference than a good suspension fork. And so much cheaper.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  5. #5
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    Nope, don't wallow at all.

    Tires are Panasonics. I'll have to check them out tonight to get the model. Can't remember off the top of my head. Not sure if they are original or not since I bought it used. They seem to still have a good tread on them.

    I've thought about going to tubeless, but then I kind of balk on trying to upgrade it too much because I start wondering if I could use the money for a better bike.

    But if it keeps this up while I'm riding, I'll go ahead and front the money for new tires. Less expensive than a new bike.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  6. #6
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    Panasonic or Panaracer?
    Last edited by jeffj; 06-21-2011 at 12:46 PM.

  7. #7
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    Panaracer.

    Duh.

    Sitting at work and doing too many things at once.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  8. #8
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    Just looking at tires. I might need some new ones. And they aren't as costly as I thought. Just general upkeep of the bike anyway.

    Now I may need to post up what a good set of tires would be. Just looking at WTB Dissent. Kind of liked those.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  9. #9
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    Which model tire?

    Panaracer is a division of Panasonic, but it should say Panaracer on the tire.

  10. #10
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    Panaracer makes some good tires. The Fire FR is a monster grip tire, but the side knobs protrude so far that they sometimes will tickle your chain in the lowest granny gear combo. The 'regular' Fire XC is decent too in many conditions.

  11. #11
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    Are you climbing in your granny gear? I always had traction issues in my granny before I yanked it.
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  12. #12
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    Maybe too high of a cadence so your just spinning out.

    Panaracers are the shizzz, I have Rampages on my front they are so slick.
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  13. #13
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    If your tire has to dig through the gravel to something beneath than yes loiw pressure can make it skid out....

    The lower pressure causes the tire to ride over the gravel...."marbles" and skid....

  14. #14
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    Yeah it was pretty low. Down to about 20psi. I just pumped it up and I'll see how that goes. The model tires are Panaracer Smoke Classic.

    The knobs are getting a bit rounded. I think i do need to invest in some tires soon.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  15. #15
    Fat-tired Roadie
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    I didn't like the Smokes very much.

    I think the Dart - the matching front tire - kicks ass. And I think the WTB Velociraptor rear, which is a fairly equivalent competitor for the Smoke kicks ass. But those weird alternating bars and the way the tire cornered were not very cool.

    If the Raptor came in a 2.3", I'd have to get another set, for the winter.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  16. #16
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    I'm wondering if I may have found the problem.

    I went down to the garage yesterday morning, felt the back tire and felt it was almost flat. I've had probs for weeks with the tire pressure going down on it. So, I took it off, looked at the tube and then went ahead and put a new tube in. While I was airing up the tire, the head on my pump broke. Took it to the LBS and they replaced the head. I told him I've also seem to be having some issues with the pressure gauge on it, he took a look, used some of his gauges and came back and said my tire gauge was off by 12 psi.

    Wow, freaking 12. I came back home, found out my front tire was at 20 psi. My back tire had been running a little lower, so I'm thinking my back tire could have been anywhere from 10 to 15 psi. I'm really surprised I wasn't hitting the rim. I know lower air pressure is supposed to get more traction, but running that low could have made the tires way unpredictable.

    Riding it this morning to see if it rides better.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  17. #17
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    Quote Originally Posted by Rocklion View Post
    I'm wondering if I may have found the problem.

    I went down to the garage yesterday morning, felt the back tire and felt it was almost flat. I've had probs for weeks with the tire pressure going down on it. So, I took it off, looked at the tube and then went ahead and put a new tube in. While I was airing up the tire, the head on my pump broke. Took it to the LBS and they replaced the head. I told him I've also seem to be having some issues with the pressure gauge on it, he took a look, used some of his gauges and came back and said my tire gauge was off by 12 psi.

    Wow, freaking 12. I came back home, found out my front tire was at 20 psi. My back tire had been running a little lower, so I'm thinking my back tire could have been anywhere from 10 to 15 psi. I'm really surprised I wasn't hitting the rim. I know lower air pressure is supposed to get more traction, but running that low could have made the tires way unpredictable.

    Riding it this morning to see if it rides better.
    I don't know how you did not feel it when you set off the bike would feel all squishy when you are riding. Did the back wheel feel like it was flexing in turns ? If so the pressure was 2 low:

  18. #18
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    Wasn't squishy. I could have been running it about 20 with it going down on me at points while at the trail. I really didn't feel it flexing. But then again, to be perfectly honest, I don't know if I knew what that would feel like if I did feel it.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

  19. #19
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    Quote Originally Posted by Rocklion View Post
    I really didn't feel it flexing. But then again, to be perfectly honest, I don't know if I knew what that would feel like if I did feel it.
    It's a good thing to learn the difference between the feel of a properly inflated tire that is skidding/loosing grip vs. an underinflated tire wallowing on the sidewalls. The feeling of the skid is...well, the feeling of the tire sliding over whatever surface you're on.

    The low pressure wallowing is for me a very different feeling. The bike will slip from side to side a bit, but the tread is still hooked up so when you've slipped as far as the sidewalls will allow the sideways movement stops and everything is still pointed in the direction you had intended. I've described the feeling to my riding buddies as being "greasy." Not sayin' that means anything to anybody but me, but it's the words that were coming out of my mouth at the time (after the well timed "oh fawk!" of course.) It's always a little disconcerting to me but it happens so fast that it's over before you know it, and it's a sure sign that I'm going to be doing a little trailside work as soon as I find a good place to stop.

    My early riding days were primarily on the road, and you'll get the same effect, but with a much smaller safety margin since the tire volumes are much lower, and if the tire is leaking air the amount of time you have between "greasy" and "faceplant" is much shorter.
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  20. #20
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    Well no doubt in my mind now it was something to do with tire pressure. Just got back from my ride and the bike was like a stallion. The tires gripped fine and I could definitely feel a difference in the bike's performance. Much faster. Also climbed better.

    Amazing to me what a difference.
    You're not one with nature until you eat it.

    Bike: 2011 Diamondback Overdrive 29er

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