Quantcast

What do the different spike tire cuts accomplish

Discussion in 'Downhill & Freeride' started by demo 9, Aug 17, 2012.

  1. demo 9

    demo 9 Turbo Monkey

    Rep/Likes:
    9 / 45
    Joined:
    Jan 31, 2007
    Messages:
    5,924
    Location:
    north jersey
    I always read about people cutting down different spike tires. Anybody care to share what which cuts accomplish. (center only, every other side, ect)

    Specifically I am going to alter a wetscream
     

    Please register to disable this ad.

  2. Raingauge

    Raingauge Monkey

    Rep/Likes:
    0 / 0
    Joined:
    Apr 3, 2008
    Messages:
    693
    Location:
    Canadia
    Uncut Wet Screams feel good when it's only mud and soft dirt for me. They feel squirmy on rocks and roots uncut. If they're cut I can ride them in any conditions without worrying.

    Next mud tire for me is the Dirty Dan. It has a more rounded profile compared to the Wet Screams and they have some sipes from the factory. Or maybe the Hillbilly.
     
  3. Wa-Aw

    Wa-Aw Monkey

    Rep/Likes:
    0 / 0
    Joined:
    Jul 30, 2010
    Messages:
    355
    Location:
    Philippines

    Hillbilly and wet scream experience. Hillbilly is no really a wet tire. It's the perfect loam tire and basic do-everything jack of all trades tire but in the wetscream is just hands down better. In extremely soft mud it feels just as bad as a dry tire.
     
  4. Pslide

    Pslide Turbo Monkey

    Rep/Likes:
    5 / 0
    Joined:
    Jan 14, 2002
    Messages:
    1,381
    Location:
    Feet on the ground, head in the clouds.
    No cut: Soft, wet, deep mud only.
    Center cut only: Good for a mix of soft, wet, mud, but rolls faster and can handle some rock and dry as well. Also incredible on off-cambers.
    Center and shoulder cut: Damp to dry conditions.

    I would not recommend an alternating cut.
     
  5. jnooth

    jnooth Monkey

    Rep/Likes:
    2 / 1
    Joined:
    Sep 19, 2008
    Messages:
    390
    Location:
    Vermont Country
    ^ what he said.

    If its really wet and deep and rolling resistance is still important, only cut the centers. if its starting to dry up but you still need the spikes because they clear well then trim corners as well. I usually dont trim the side nobs as much as the centers if i do cut them all.

    also do not recommend an alternating cut
     
  6. demo 9

    demo 9 Turbo Monkey

    Rep/Likes:
    9 / 45
    Joined:
    Jan 31, 2007
    Messages:
    5,924
    Location:
    north jersey
    Thanks for all the help! Anybody know if a cut would be good for grease? Right now it looks like centers only is the winner, but can anything help it on grease while not killing its potential for mud?
     
  7. - seb

    - seb Turbo Monkey

    Rep/Likes:
    3 / 0
    Joined:
    Apr 10, 2002
    Messages:
    2,929
    Location:
    UK
    Dirty Dans are amazing. I put it all down to the sipes. I used to find wet screams very squirrely on hardpack stuff, even when cut. Dans seem absolutely fine, even un-cut. I feel that they roll quicker too. And much more predictable when they let go.

    You can prise them from my cold, dead hands.
     
  8. HAB

    HAB Chelsea from Seattle

    Rep/Likes:
    81 / 804
    Joined:
    Apr 28, 2007
    Messages:
    10,448
    Location:
    Seattle
    Uncut: spike
    center knobs cut: semi slick
    all the knobs cut: slick
     
  9. S.K.C.

    S.K.C. Turbo Monkey

    Rep/Likes:
    4 / 10
    Joined:
    Feb 28, 2005
    Messages:
    4,105
    Location:
    Pa. / North Jersey
    What rims are you using with your Wet Screams? The rim will dictate tread profile to a certain degree so with a spike, this makes it much more important.

    For greasy conditions (to make sure - we are referring to a thin layer of mud over hardpack or rocks) a traditional cut would be appropriate. Basically, you cut down the center knobs using the bottom of the siping as your cutting guide - Jacy used to do this for Sammy all the time, but it's a major pain in the butt. I know - I've trimmed my share of 'Screams. If you want to get fancy, and go for the "Jedi Tune" you can ramp the leading edge of the center knobs to decrease rolling resistance, but I've never really seen many people do it. By cutting down the center knobs, you decrease rolling resistance, increase stability (this will help eliminate "squirm"), and are able to brake more efficiently on firm terrain.

    By implementing the above cut, you keep the edge knobs intact or "stock" so they are long enough to really penetrate and dig in during cornering. This will help you retain good traction characteristics in mud or grease. The edge knobs on a Wet Scream are reinforced at the base so leaving them full length is OK.

    NOW... if the terrain is primarily rocky and technical with a layer of greasy mud, then I would stick with Minion DHF's or go with the new DHR II's. Spikes on wet or muddy rocks usually means instant death. This is because the tips of the spikes aren't making a large enough contact patch on the rocks to generate traction.

    Hope this helps!
     
    #9 -   Aug 19, 2012
    Last edited: Aug 19, 2012
  10. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

    Rep/Likes:
    93 / 785
    Joined:
    Mar 14, 2005
    Messages:
    4,700
    I was going to post exactly this. The Dans are superior to the Wet Scream in virtually every application in my experience - slightly better performance in the mud (whether deep, greasy, or sloppy) and far superior in any hardpack or dried out areas.

    Personally I'd put the improved performance down to a combination of the rounder profile, better pattern, and those occasional little side knobs that they feature (that the Wet Scream doesn't have at all).

    I didn't feel the need to cut mine either, but it might offer benefits if less of the track is muddy and more is dry.
     
  11. FarkinRyan

    FarkinRyan Monkey

    Rep/Likes:
    2 / 66
    Joined:
    Dec 15, 2003
    Messages:
    515
    Location:
    Squamish, BC
    Huge fan of the Dirty Dan here too. Pretty much unbeatable as a mud tyre but able to hold their own through a range of conditions right through to hardpack. Ran one as a front right through to the end of June here in BC and never regretted it.

    Probably my favourite tyre ever to lean over in the loam or any semi-soft ground condition, they're like a goddamn buzzsaw, you can hear and see them literally tearing chunks out of the ground and spraying them out behind you.
     
  12. Pslide

    Pslide Turbo Monkey

    Rep/Likes:
    5 / 0
    Joined:
    Jan 14, 2002
    Messages:
    1,381
    Location:
    Feet on the ground, head in the clouds.
    So are you guys cutting Dirty Dans or do they work OK uncut in most conditions (except hardpack obviously).
     
  13. boylagz

    boylagz Monkey

    Rep/Likes:
    0 / 2
    Joined:
    Jul 12, 2011
    Messages:
    473
    Location:
    SF bay area
    ^ I have a set of DD's waiting for the fall and winter. Psyched :D
     
  14. - seb

    - seb Turbo Monkey

    Rep/Likes:
    3 / 0
    Joined:
    Apr 10, 2002
    Messages:
    2,929
    Location:
    UK
    I personally find they work fine in even hardpack conditions, uncut. TBH I'd never cut them, as I'm a firm believer that the sipes are what make them work so well. Look at winter tyres on cars - they have lots of sipes that enhance their grip on icy surfaces. People often comment that riding spikes on hardpack is like riding on ice (especially if there's a slick layer on top), and in my opinion the DD sipes fix that issue. Or make it good enough that it doesn't bother you anyway.
     
  15. Pslide

    Pslide Turbo Monkey

    Rep/Likes:
    5 / 0
    Joined:
    Jan 14, 2002
    Messages:
    1,381
    Location:
    Feet on the ground, head in the clouds.
    The main purpose of sipes in a car tire, and slots and grooves for that matter, is to evacuate the water out from under the tread to avoid hydraulic forces lifting the tread blocks and reducing traction (hydroplaning). Sipes are doing this at a more micro level to evacuate water from individual block surfaces. This is especially critical on ice, where a thin film of water forms as soon as the tread comes in contact with the ice. This thin film of water is what makes ice so slippery.

    The downside of sipes is that they reduce your block stiffness, causing the block to lift away from the surface when deformed, reducing grip in some cases. So moar sipes is not moar better...there is a balance.

    If the surface is dry pavement, then you'll get maximum traction with a slick tire, which is why race cars use them. The compound delivers all the grip and there is no need to evacuate water if the surface is dry.

    Now there is a small mechanical force generated by sipes in wet conditions, especially on rougher surfaces, but this is a much smaller component of grip than the tread compound interaction with the surface.

    However, on snow, this relationship is reversed, and the mechanical force generated by sipes (or biting edges) becomes the primary source of traction.

    How does this relate to bike tires? Well, that's not as well known. But you can draw your own conclusions from the above and perhaps also what other dirt sports have found to work. @Seb - your experience is certainly valid, but don't forget the many other differences between the DD and say a wet scream. Block stiffness, block spacing, block height, tread compound (huge), profile, etc.

    Just my 2 cents because I'm bored at work...
     
  16. - seb

    - seb Turbo Monkey

    Rep/Likes:
    3 / 0
    Joined:
    Apr 10, 2002
    Messages:
    2,929
    Location:
    UK
    It probably also helps that I seem to be able to run the Schwalbes at a much lower pressure without puncturing than I could with previously with other tyres. I used to worry about rolling resistance, but these days I'm a firm believer that the correct tyre pressure is "as soft as you can go without pinchflatting".

    Mind you, just last month I drove a 1000 mile round trip, rode for 3 days, and then punctured 50m into my race run. Tits.