Forum home Mountain biking forum MTB general

Stupid question about geometry

larkimlarkim Posts: 2,323
edited May 2017 in MTB general
It just occured to me that one feature of front geometry that seems more or less universal is the fact that the stantions are set forward of the steerer column, and the axel is forward of that too.

Presumably moving either of those back or forwards would have an impact on steering response etc? (Or would it, hence the post title?)

Are all forks built to the same spec in this regard, or are there forks which are more / less pronounced in this aspect?
2015 Canyon Nerve AL 6.0 (son #1's)
2011 Specialized Hardrock Sport Disc (son #3s)
2013 Decathlon Triban 3 (red) (mine)
2019 Hoy Bonaly 26" Disc (son #2s)
2018 Voodoo Bizango (mine)
2018 Voodoo Maji (wife's)

Posts

  • Uber_PodUber_Pod Posts: 110
    You could try reading up on caster, mechanical trail and various other related areas until your brain starts to bleed.

    It's a bit like shopping trolley wheels. With the wheel axle set behind, they flap around a lot. You don't really want that on a bike.
    Having the wheel axle set forward makes it much more stable.
  • cooldadcooldad Posts: 32,601
    Pretty much this ^^^, but they are different, a decnt explanation here.

    https://www.pinkbike.com/news/To-the-Po ... ffset.html

    My 29er has G2 (Trek/Gary Fisher) and it seems to work as they say.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • cooldadcooldad Posts: 32,601
    ps not a stupid question at, a very interesting one.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • larkimlarkim Posts: 2,323
    Cheers CD & Uber_Pod. That's a really informative link too.

    Presumably the fork offset options that are referred to in the linked article are only generally available on high end forks which could be used on frames with very different head tube angles, rather than at "my" end of the spectrum (Recon, Reba, XC etc) where variability in frames is presumably a little less pronounced?
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #3s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • cooldadcooldad Posts: 32,601
    Most (RS and Fox) have a different offset for 26, 27.5 and 29er forks, increasing as the wheels get bigger, but yes, apart from the more expensive models, you pretty much take what's offered.

    Mojo and TF Tuned can custom make different offsets, but I think that's more for pros than us normal people.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • larkimlarkim Posts: 2,323
    Just watching the Giro, very little forward trail on those road bikes. Is that a newish development, i'm sure road forks used to sweep forwards a little.
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #3s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • The RookieThe Rookie Posts: 27,748
    It's because instead of being curved the legs are straight but at an angle to the steerer, the dropout is in about the same place relative to the steerer.
  • larkimlarkim Posts: 2,323
    Ah, just a slight of hand in the design to make them look "cooler" then I suppose. Thanks!
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #3s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • cooldadcooldad Posts: 32,601
    Probably cheaper/easier to manufacture as well. And stiffer. Old curved ones were more comfy I think.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
Sign In or Register to comment.