Tight frame-tire fit

Discussion in 'rec.sport.unicycling' started by harper, Jan 2, 2006.

  1. harper

    harper Guest

    My geared 29er, BlueShift, has a Big Apple tire on it right now. I
    started with the Nanoraptor which had quite a bit more clearance than
    the Big Apple. I like the ride of the Big Apple better, especially at
    high pressure.

    Our group went on a ride Saturday and I pumped the tire up to 60psig
    and brought it along. It made a grinding noise like a garbage disposal.
    I could still barely see clearance from the top of the tire to the
    bottom of the crown but the wheel was slightly out of true and it
    rubbed occassionally. Not enough to make the horrible grinding noise I
    was hearing. I thought it was one of the bearings going out.

    Wobbly-John was in town and he surmised that the tire picked up bits of
    grit and ground against the crown. I still thought that was not the
    problem, it was too loud. When I got home I let air out of the tire
    (down to 35psig) and the problem disappeared. In 5psig increments I
    found that I could run the tire at 50psig and still have clearance.

    The tire must have stretched over time because I remember (as well as I
    can still remember) that I had run it at 60psig before. I left the tire
    deflated while stored and put a large label on it reading "50 psig
    MAX."


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
    Tags:


  2. U-Turn

    U-Turn Guest

    forrestunifreak wrote:
    > So what made the grinding noise?



    Musta been the Starbucks he was passing at the time.


    --
    U-Turn

    Weep in the dojo... laugh on the battlefield.
    'LiveWire Unicycles' (http://www.livewireunicycles.com)
    'Strongest Coker Wheel in the World'
    (http://www.unicyclist.com/gallery/albup39)
    '29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)
    'New York Unicycle Club' (http://www.newyorkunicycle.com)
    -- Dave Stockton
    ------------------------------------------------------------------------
    U-Turn's Profile: http://www.unicyclist.com/profile/691
    View this thread: http://www.unicyclist.com/thread/45764
     
  3. harper

    harper Guest

    forrestunifreak wrote:
    > So what made the grinding noise?




    Wobbly-John and U-Turn are correct. Grit from the road and coffee chaf
    from Satrbucks were grinding on the crown.


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  4. Evan Byrne

    Evan Byrne Guest

  5. Klaas Bil

    Klaas Bil Guest

    harper wrote:
    > and put a large label on it reading "50 psig MAX."


    You should add "also for unicyclists!" as you know unicyclists tend to
    ignore max pressure labels on tyres.

    That's interesting that the BA seems to have stretched. I have
    carefully measured my BA size when it was new. Must remember (as well
    as I can remember) to do it again. Although on average I have only 40 -
    50 psi in there. This could be a way to increase your wheel size for
    free, as much as air is for free.


    --
    Klaas Bil
    ------------------------------------------------------------------------
    Klaas Bil's Profile: http://www.unicyclist.com/profile/3442
    View this thread: http://www.unicyclist.com/thread/45764
     
  6. harper

    harper Guest

    Clearance at 60 psig is zero. Clearance at 50 psig is 1mm. The increased
    wheel diameter doesn't buy you much speed if it's dragging on the
    crown.


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  7. harper

    harper Guest

  8. Evan Byrne

    Evan Byrne Guest

  9. Loosemoose

    Loosemoose Guest

    Harper said the Nano had plenty of clearance, its the BA thats giving
    him the clearance problems.

    Don't worry Harper, once you've got a few hundred miles on the beast
    you'll have worn an extra mm from the tyre and will be able to get it
    to 60psi no problem :D. Just get riding!

    Loose.


    --
    Loosemoose

    Dave: "I had a particularly bad UPD & found I'd lost a shoe"
    Officially a  & ~ expert.

    _no1_quote_of_crawley_2005:_
    Leigh: "Where's Trevor"
    Baz: "I think he's upstairs, balancing The Bishop"
    ------------------------------------------------------------------------
    Loosemoose's Profile: http://www.unicyclist.com/profile/6326
    View this thread: http://www.unicyclist.com/thread/45764
     
  10. flyer

    flyer Guest

  11. harper

    harper Guest

    Tire-crown clearance of BlueShift frame with Big Apple tire at 60 psig.


    +-------------------------------------------------------------------+
    |Filename: BlueShift60psig.jpg |
    |Download: http://www.unicyclist.com/attachment/11458 |
    +-------------------------------------------------------------------+

    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  12. harper

    harper Guest

    Tire-crown clearance of BlueShift frame with Big Apple tire at 50 psig.


    +-------------------------------------------------------------------+
    |Filename: BlueShift50psig.jpg |
    |Download: http://www.unicyclist.com/attachment/11459 |
    +-------------------------------------------------------------------+

    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  13. harper

    harper Guest

    Evan Byrne wrote:
    > that looks like plent of clearance.




    Evan-

    The above two photos show the clearance with the Big Apple tire at the
    two different pressures. Sorry I got so much wash out from the flash in
    the second one. You can see through the frame in it at least.


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  14. tholub

    tholub Guest

    I'm running a Big Apple in a Sem XL frame, and it has similar clearance
    issues. But I don't think the irregularities are due to wheel
    imperfections, I think they're due to tire imperfections; I noticed the
    problem the first time I rode the tire after building and truing the
    wheel. With that much air in it, slight differences in the way the
    tire bead is seated can make enough difference to rub the frame.

    Like you, I can reliably run the tire in the narrow frame at 50 psi.


    --
    tholub
    ------------------------------------------------------------------------
    tholub's Profile: http://www.unicyclist.com/profile/804
    View this thread: http://www.unicyclist.com/thread/45764
     
  15. unisk8r

    unisk8r Guest

  16. harper

    harper Guest

    unisk8r wrote:
    > Greg, I have a Dremel with sanding drums, and a nice blue magic
    > marker...




    Why would I want to grind a rubber tire and then try to color it blue?


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
  17. underdog

    underdog Guest

    harper wrote:
    > Why would I want to grind a rubber tire and then try to color it blue?




    LOL :D :D :p :D


    --
    underdog

    'I tell you, we are here on Earth to fart around, and don't let anybody
    tell you different' - Kurt Vonnegut
    ------------------------------------------------------------------------
    underdog's Profile: http://www.unicyclist.com/profile/6197
    View this thread: http://www.unicyclist.com/thread/45764
     
  18. Harper, really, why not just shave a bit off the crown right there? Who
    needs a dremel, that could be done with a file (actually, a half round
    file is preferrable, since it won't clog as readily as a sanding disc).
    Well, I guess I that won't happen...

    I do like the look of that frame... Is it professionaly anodized, or a
    homebrew job? Kudos if you did it yourself.


    --
    gerblefranklin

    http://gallery.unicyclist.com/Trials-Muni

    Nick's main man.

    "I love freedom dearly, ideally, in theory, but in reality we're not
    there yet--Not nearly."--Cold Duck Complex
    ------------------------------------------------------------------------
    gerblefranklin's Profile: http://www.unicyclist.com/profile/4295
    View this thread: http://www.unicyclist.com/thread/45764
     
  19. harper

    harper Guest

    gerblefranklin wrote:
    > Harper, really, why not just shave a bit off the crown right there? Who
    > needs a dremel, that could be done with a file (actually, a half round
    > file is preferrable, since it won't clog as readily as a sanding disc).
    > Well, I guess I that won't happen...
    >
    > I do like the look of that frame... Is it professionaly anodized, or a
    > homebrew job? Kudos if you did it yourself.




    Steve Howard designed and built the frame. He had it professionally
    anodized. You know I'm not about to touch that frame with a file. How
    are your projects coming along? Are you buying accessories for your
    machine tools?


    --
    harper

    -Greg Harper

    B L U E S H I F T

    *jc is the only main man. there can be no other.*

    This is still my nth post....*AWESOME!!!*
    ------------------------------------------------------------------------
    harper's Profile: http://www.unicyclist.com/profile/426
    View this thread: http://www.unicyclist.com/thread/45764
     
Loading...
Loading...