Page 1 of 2 1 2 LastLast
Results 1 to 25 of 28
  1. #1
    mtbr member
    Reputation:
    Join Date
    Apr 2010
    Posts
    54

    High Speed Instability on my Yeti 575

    I've been riding my 2011 Yeti 575 for about 1 year. As as my skill level gets higher I am riding faster and faster. On some of my recent rides I have felt the bike is unstable or wobbles at high speeds. This usually occurs around 20 MPH and higher. I have tried locking out the front, playing around with more air in the rear shock to no avail. Changing the handles bars from 680mm to 720mm has helped alot with the slower speed stability, but i cannot get past this 20 MPH barrier and feel comfortable. This happens on hard pack, shale, groomed gravel, anything involving what I think is high speed.

    Wrong tires, bike to small, geometry? What could be causing this?

    Small 2011 Yeti 575, I'm 5'5" 150 lbs geared up. Riding on Schwable Nobby Nic's

    Thanks!

  2. #2
    187
    187 is offline
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    196
    What air pressure are you running in your tires?

  3. #3
    mtbr member
    Reputation:
    Join Date
    Apr 2010
    Posts
    54
    Quote Originally Posted by 187 View Post
    What air pressure are you running in your tires?
    Last ride I was at 35 PSI, the nobby nics are 2.35 front and back. On the shale, it is very unstable at high speeds and choppy. I ride at 20-25% sag.

  4. #4
    187
    187 is offline
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    196
    It seems like your rebound may be too fast. I had a similar problem on a pivot fb and slowed the rebound a couple clicks.

  5. #5
    I'm with stupid
    Reputation: hitechredneck's Avatar
    Join Date
    May 2009
    Posts
    4,007
    On shale that is about the limit of what feels planted, Bikes are just like cars on dirt the faster you go the "looser" they get. The drifty feeling is something you have to get used to the faster you get. Also play with your rebound settings on both front and rear at the SAME TIME! put both at the middle setting and ride that spot. Then get off hike back up and add a bit of rebound or take some away of both at the same time so that it is balanced and ride the sport again repeat over and over till you get the rebound set up for your liking. Im almost willing to bet that it is set to slow and packing up.
    Drop your PSI down some as well that is the PSI i ride with but im 195. that should help also.

  6. #6
    LCW
    LCW is offline
    mtbr member
    Reputation: LCW's Avatar
    Join Date
    May 2008
    Posts
    2,916
    What fork you running? Stem? Bar width?
    2011 Yeti 575 - 2015 Fox Float 36 RC2 160 / Fox Float X - 30.6 lbs

  7. #7
    bike rider
    Reputation: Lelandjt's Avatar
    Join Date
    Feb 2008
    Posts
    4,231
    Too fast rear and/or front rebound, not enough fork LSC and/or air pressure.
    Also probably too long a stem and too tall seat.
    Keep the Country country.

  8. #8
    Huffy Rider
    Reputation: motochick's Avatar
    Join Date
    Jun 2010
    Posts
    1,382
    There are a lot of things, many mentioned. Stem too long, seat too high, bars too narrow, tires too small, your tires are way over-inflated for your weight! If you are running tubes, lose them. If you don't have a dropper, get one. It is physically impossible to ride in the proper position on a decent with your seat in the same position it is in for climbing. You need to be low and centered, not hanging your butt off the back. If your butt is off the back you have no control over your front wheel which could make you feel squirrelly. Good luck

  9. #9
    mtbr member
    Reputation:
    Join Date
    May 2010
    Posts
    10
    I know it sounds completely opposite to what you feel at the time, but try to relax. Tense muscles don't flex easily.

    Rob.

  10. #10
    Let the good times roll.
    Reputation: miniwisejosh's Avatar
    Join Date
    Sep 2007
    Posts
    1,158
    Quote Originally Posted by NW-Rider View Post
    I've been riding my 2011 Yeti 575 for about 1 year. As as my skill level gets higher I am riding faster and faster. On some of my recent rides I have felt the bike is unstable or wobbles at high speeds. This usually occurs around 20 MPH and higher. I have tried locking out the front, playing around with more air in the rear shock to no avail. Changing the handles bars from 680mm to 720mm has helped alot with the slower speed stability, but i cannot get past this 20 MPH barrier and feel comfortable. This happens on hard pack, shale, groomed gravel, anything involving what I think is high speed.

    Wrong tires, bike to small, geometry? What could be causing this?

    Small 2011 Yeti 575, I'm 5'5" 150 lbs geared up. Riding on Schwable Nobby Nic's

    Thanks!
    Go to leelikesbikes.com and order the mastering MTB skills book. That's the best advice I can give you. He does an excellent job of teaching bike setup and riding technique.

  11. #11
    Chamois Dropper
    Reputation: natzx7's Avatar
    Join Date
    May 2007
    Posts
    774
    I'm 5'8" 150 lbs and I run 28 lbs, on tubes. What is your stem length?
    2008 GT Force
    Go Veg

  12. #12
    re member
    Reputation: net wurker's Avatar
    Join Date
    Sep 2007
    Posts
    7,696
    Need more downforce. Get a spoiler for your camelbak.
    Rocktoberfest 2014 edit here
    Rocktoberfest 2014 clips here

  13. #13
    mtbr member
    Reputation:
    Join Date
    Apr 2010
    Posts
    54
    Great, thanks for the advice guys. I'm running with my rebound pretty much right in the middle of where it can adjustable for the front and the back. I'll try to play with that and my tire air pressure as well. I'm only 140 geared up, so sounds like I could almost go down to 25psi in the tires.

    I'm riding a 90mm stem, 720 Answer Pro-Carbon bars, and the front fork is a Fox 32 Float150. On the fast descents seat post is down, body positioned behind the saddle.

  14. #14
    mtbr member
    Reputation:
    Join Date
    Jul 2009
    Posts
    1,115
    I'd opt for a 50mm stem if possible, and maybe some wider bars (although thats not necessary) It'll really help with your stability on the bike.

  15. #15
    Huffy Rider
    Reputation: motochick's Avatar
    Join Date
    Jun 2010
    Posts
    1,382
    Shorter stem for sure... If your body is behind the seat you are not centered and have no weight on your front tire which controls your braking and turning. Low and centered not low and back. It might be scary to try riding in the proper position with such a long stem. Don't send your full suspension bike down the hill in front of you. Good luck

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    2,753
    I'll add that you should drop stem length in smaller amounts if you decide to play with that. Shortening the stem will make it easier to get your weight back but it'll also quicken up your steering which is typically used to counter the wide bars. Maybe try a cheap 75 or 70mm stem and decide how it works for you before you plunk down a lot of money.

    Also, I would really like to hear your feedback after dropping your psi into the mid 20's. That will make a big difference.

  17. #17
    mtbr member
    Reputation: mazspeed's Avatar
    Join Date
    Oct 2004
    Posts
    966
    Quote Originally Posted by mnigro View Post
    Also, I would really like to hear your feedback after dropping your psi into the mid 20's. That will make a big difference.
    I would think that would be the other way around.?

    On a side note I have run a 575 on dirt at speed and never felt comfortable on it. Different size and different conditions, but sort of felt the same result. It was a mates bike so I didn't tinker with the rebound, but having a fast rebound can lead to the bouncing effect. I typically have mine set in the middle, not too fast but not to slow either and run about 20 percent sag.

    Also unballanced wheels and tires can have a big effect as well. Are you running stans sauce in the tubes?

  18. #18
    Huffy Rider
    Reputation: motochick's Avatar
    Join Date
    Jun 2010
    Posts
    1,382
    Quote Originally Posted by mazspeed View Post
    I would think that would be the other way around.
    Think of your tires like a basketball. A fully inflated basketball will bounce like crazy..... Now let a bunch of air out of your basketball, not so bouncy. Over inflated tires will bounce on everything out on the trail making it very sketchy.

  19. #19
    mtbr member
    Reputation: MTT77's Avatar
    Join Date
    Aug 2010
    Posts
    302
    I have a 575 and had this same issue -- slight speed wobble at faster speeds on pavement. It never really bothered me, but when I got new wheels (yeah birthday gift!) the wobble went away. That led me to believe it was a less than perfectly true wheel, but I honestly never checked

  20. #20
    I wreck alot
    Reputation: SoWal_MTBer's Avatar
    Join Date
    Jan 2012
    Posts
    242
    Quote Originally Posted by NW-Rider View Post
    I'm riding a 90mm stem, 720 Answer Pro-Carbon bars, and the front fork is a Fox 32 Float150. On the fast descents seat post is down, body positioned behind the saddle.
    I had the exact same experience on my SC Heckler running a Fox 32 Talas. In my personal opinion, the 32mm stanchions at 150mm travel are pretty much at their max. My Heckler felt very unstable on descents with that fork. I've since moved to a Marzocchi 55r that has 35mm stanchions and the bike is completely different when descending. In addition to the larger, heavier fork (it's a coil vs air also), I think the 20mm axle helped stiffen things up quite a bit. Climbs will be tougher, as this fork is a pound heavier, but it really has boosted my confidence and stabilized my bike.

    I'm not an expert and I'm not saying to go buy a new fork.What I am saying is that I think the larger/stiffer stanchions and a stiffer front axle may make you more confident.

    Good luck!

  21. #21
    Perpetual Hack
    Reputation: mykel's Avatar
    Join Date
    Jul 2006
    Posts
    1,823
    Like others have said....

    Drop your tire pressures.
    I'm guessing 25-28lbs..
    (i'm 210+gear and run 27/30 psi F/R)

    Play with your rebound until you get the front and rear balanced.
    Then do runs as suggested and change both front and rear together keeping the balance.
    (My guess is that your rebound is a bit fast giving a sharp skittish feeling.)

    Shorten your stem 90 is too long for trail-riding.
    I would suggest going to 65/70mm first. Changing from long to short is an alien feeling - so go in steps.
    (I used to change from 50mm DH to 70mm XC mode, but now just run 50 for all riding - but it did take a bit of time to adjust as it does affect your entire body position on the bike.)

    As for riding position, if your standing, then get into attack mode.
    Drop your hips - do not just thrust them back.
    This requires a bend in the knee and this can be fatiguing fast if your not used to it.
    Flatten your back, square your shoulders to the bars, drop them a bit and get them back a bit - dont go to extremes, but you will tend to naturally roll them forward so you want to counter that, get your elbows out.
    Light hands, heavy feet - you want to keep your weight over the BB - not braced on / against the bars.
    Hold fast but light - ease up on your grip.
    Let the bike float under you - keep yourself centered and your moves soft, ie in shale going down the bike will dance and can deflect by better than a foot either direction without issue, let it do its job, but keep the reins firm but soft.

    For anything tech, when sitting or doing alot of sitting/standing transitions, drop your seat from the full XC/Climb height an inch. It makes a huge difference in bike control in mixed/rolling/tech terrain.
    (I have a dropper post, and it is the best upgrade to riding I have made with the exception of good suspension since i started riding dirt in 1969 my op of course)

    Im assuming of course that you have no issues with your wheel/tire setup that would induce a wobble at higher speeds - think wheel balance on your car.
    This could be a bent rim, bad tire etc

    As well, if your frame is not straight / out of alignment than this would be more noticeable at speed.

    Does your rig tend to pull one way more than the other?

    Thats about it off the top of me head, more if anything bubble to the surface.

    Good luck

    michael
    A Dirtbag since 1969.
    A Knomer since 2007.

    Knolly Podium V.2
    Knolly Delirium
    Knolly Delirium-T
    RM Slayer . . .

  22. #22
    mtbr member
    Reputation:
    Join Date
    Mar 2010
    Posts
    268
    Convert to 650b wheelset.
    '10 Marin MountVision 650b conversion

  23. #23
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    664
    Quote Originally Posted by NW-Rider View Post
    On some of my recent rides I have felt the bike is unstable or wobbles at high speeds. This usually occurs around 20 MPH and higher. I have tried locking out the front, playing around with more air in the rear shock to no avail. Changing the handles bars from 680mm to 720mm has helped alot with the slower speed stability, but i cannot get past this 20 MPH barrier and feel comfortable. This happens on hard pack, shale, groomed gravel, anything involving what I think is high speed.

    Wrong tires, bike to small, geometry? What could be causing this?

    Small 2011 Yeti 575, I'm 5'5" 150 lbs geared up. Riding on Schwable Nobby Nic's

    Thanks!
    - A WOBBLE is not good, and may be due to a mechanical issue. There could be all kinds of things going on, take it to a shop and have it thoroughly checked out.

    IF it's not mechanical:

    - Adjust your cockpit. As others have stated, a shorter stem can help, although there are other things you can adjust as well. Something to keep in mind - head angle, effective stem length, stack height and bar width are all related and will affect handling.

    - Stay centered and low on the bike when descending, looking as far down the trail as possible

    - Tire pressure is dependent on factors including rider weight, riding style, rim and tire. Don't go off of other peoples recommendations, figure it out on your own. A quick and dirty way to estimate: Start at 35 PSI in the front and 40 PSI in the rear. Go ride your local trail. After the ride, check to see if you have cross marks on the sides of your tires. If no, decrease 2.5 PSI per wheel and repeat. Repeat until you get cross marks, then up the PSI by 2.5. That's the minimum you want to run. After that it all comes down to feel.

    - If you're using clipless pedals, make sure the cleats are centered under the balls of your feet.

  24. #24
    mtbr member
    Reputation: TwoHeadsBrewing's Avatar
    Join Date
    Aug 2009
    Posts
    2,820
    In order of greatest effect on ride stability, I'd change the suspension sag and rebound, then tire pressure, then shorter stem. A lot of instability is just the bike losing contact with the trail and bouncing around, screwing up your line. Running softer suspension and tire pressure can help a lot with this.

    1. Try sag at 30%. You pay for it on the climb, so hopefully you have a lockout or compression knob. On the shock it's not so critical, but you need it soft of the front to keep it from bouncing around. Air the fork up on the low end for your weight, then add a couple PSI after you ride if you're bottoming out more than once a ride.

    2. Slow down the rebound all the way. Go back in two clicks. Ride and add more if it feels too slow or packs down. If you force the fork down quickly standing over the bike, and then lift up, you want the tire to stay on or very close to the ground.

    3. Run tires at 28psi. I'm 175# and run 25 front, 28 rear and have never pinch flatted at this pressure.

    4. Change stem to 60mm.
    "Got everything you need?"

  25. #25
    mtbr member
    Reputation: mazspeed's Avatar
    Join Date
    Oct 2004
    Posts
    966
    Quote Originally Posted by motochick View Post
    Think of your tires like a basketball. A fully inflated basketball will bounce like crazy..... Now let a bunch of air out of your basketball, not so bouncy. Over inflated tires will bounce on everything out on the trail making it very sketchy.
    Don't know about that, but when racing cars or even in any car, or bike, the pressure of the tires are 35psi+. I drop to 20psi in anything I drive, the tires will wobble a bit more.. I am thinking suspension tuning to the tire pressure though. Also like the other gentleman said, something could be amiss. When I rode my friends I am not sure it was tuned perfectly. Maybe the 575 is a tad more sensitive to suspension tuning as opposed to tire pressures.
    Last edited by mazspeed; 10-09-2012 at 05:07 PM.

Page 1 of 2 1 2 LastLast

Posting Permissions

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