Giant Anthem front tyre rub/clearance issue

cmachine
cmachine Posts: 84
edited July 2015 in MTB workshop & tech
I have a 2012 Giant Anthem X4 which came with Racing Ralphs 2.1 F & R. Great tyres but I felt I was losing grip on the front in some more technical conditions and in fast corners. So I read a few posts from other Anthem owners and have now been using a Nobby Nic 2.25 up front and keep the RR 2.1 in rear for power/speed. It seems to be a pretty decent combo but I've been tackling a lot more gnarly terrain lately and have noticed that when compressed the fork crown is touching the knobblies on the NN. Max tyre clearance for the Anthem is 2.25 I think so I'm at the limit and I'm sure the fork (a Recon) has enough air in it and is not overly sagging. Anyone any views on this or tried something similar? Should I just go back to a thinner tyre to eliminate the crown rub or could it be something wrong with the fork. I like the thicker NN up front but could drop to a 2.1 as these tyres inflate pretty fat anyway. Cheers.
2006 Specialized Hardrock Disc (rebuilt)
2011 BeOne Karma Hardtail (disassembled!)
2012 Giant Anthem X4

Comments

  • Chunkers1980
    Chunkers1980 Posts: 8,035
    How would sag affect tyre rub on the fork? Flex of the fork/wheel combo and tyre roll are all that can do that.
  • The Rookie
    The Rookie Posts: 27,812
    If it's hitting the crown as he says, that means it's compressing far enough to rub, to clarify, by crown you mean the part joking the top of the two stanchions to the steerer tube? Not the arch that is part of the lowers?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cmachine
    cmachine Posts: 84
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19663459#p19663459]The Rookie[/url] wrote:
    If it's hitting the crown as he says, that means it's compressing far enough to rub, to clarify, by crown you mean the part joking the top of the two stanchions to the steerer tube? Not the arch that is part of the lowers?

    Sorry probably using wrong term. It's the arch...The bit of the forks that is part of the lowers, the bit immediately above the tyre.eg if I was fitting a mud fender with zip ties i would attach it to this bit. I'm wondering then if it could be deformation of the tyre. I used to run both tyres at around 35psi but now dropped it to 30-32. Perhaps it's something as simple as tyre pressure causing it to spread out on the rim & run more against the arch?
    2006 Specialized Hardrock Disc (rebuilt)
    2011 BeOne Karma Hardtail (disassembled!)
    2012 Giant Anthem X4
  • cmachine
    cmachine Posts: 84
    I'm thinking now it could be a combo of tyre roll & fork/wheel flex.I don't know as I've never had this before but it would be happening more on gouged rooty sections, fast berms & rock gardens. My other bike doesn't do it but it's a hardtail with more tyre clearance, higher psi & mostly blue/red XC trails. On the Anthem I'm tackling stuff that would be more natural & enduro style.
    2006 Specialized Hardrock Disc (rebuilt)
    2011 BeOne Karma Hardtail (disassembled!)
    2012 Giant Anthem X4
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Nobby Nice is very large for 2.25" and you have a rather flex fork and axle.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • The Rookie
    The Rookie Posts: 27,812
    Tyre too big for the forks!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cmachine
    cmachine Posts: 84
    thanks all. Think I will drop the front NN down to a 2.1 as the 2.25 does inflate big, and keep a 2.1 or 2.25 Racing Ralph on the rear.
    2006 Specialized Hardrock Disc (rebuilt)
    2011 BeOne Karma Hardtail (disassembled!)
    2012 Giant Anthem X4

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