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Change travel, what happens

ed1973ed1973 Posts: 181
edited August 2019 in MTB workshop & tech
So if you were to change the fork on a bike from a 100mm of travel to a new fork with 130mm of travel what’s gonna happen? Apart from having a bit more travel.
Would it completely screw up the bikes geometry?

Posts

  • tom_howardtom_howard Posts: 792
    Depends what the difference in the axle to crown measurement is, it may not be the same as the travel change, but assuming it’s 30mm more than what you have...

    Roughly 1.5 degrees slacker Head angle
    Slightly raised BB and handlebars
    Slightly shorter reach
    Higher risk of snapping head tube/invalidating warranty.

    As for if it will ruin handling, what don’t you like about the way it handles now?
    Santa Cruz 5010C
    Deviate Guide
    Specialized Sequoia Elite
    Pivot Mach 429SL
    Trek Madone 5.2 Di2
    Salsa Mukluk Carbon
    Specialized Turbo Levo Expert 29er
  • ed1973ed1973 Posts: 181
    Tom Howard wrote:
    Depends what the difference in the axle to crown measurement is, it may not be the same as the travel change, but assuming it’s 30mm more than what you have...

    Roughly 1.5 degrees slacker Head angle
    Slightly raised BB and handlebars
    Slightly shorter reach
    Higher risk of snapping head tube/invalidating warranty.

    As for if it will ruin handling, what don’t you like about the way it handles now?

    Thanks for the informative reply.
    It’s a case of wanting to get a frame that I have seen and already having a set of forks.
  • tom_howardtom_howard Posts: 792
    Some frames have a broad range of what fork travel they will accept, what is it?
    Santa Cruz 5010C
    Deviate Guide
    Specialized Sequoia Elite
    Pivot Mach 429SL
    Trek Madone 5.2 Di2
    Salsa Mukluk Carbon
    Specialized Turbo Levo Expert 29er
  • The RookieThe Rookie Posts: 27,748
    And what forks? Plus 20mm is usually OK, plus 30mm can cause issues, most forks can be readily shortened in travel anyway.
  • ed1973ed1973 Posts: 181
    Tom Howard wrote:
    Some frames have a broad range of what fork travel they will accept, what is it?
    BMC Fourstroke
  • The RookieThe Rookie Posts: 27,748
    I wouldn't be putting a 130mm on the front of a 4s, either you want a 4s for what its good at and you'll use a 100 (maybe 110mm) fork or its the wrong bike for your riding!

    What fork (EXACT model), how easy/costly to drop the travel? Or maybe sell and buy an equivalent used one?
  • ed1973ed1973 Posts: 181
    The Rookie wrote:
    I wouldn't be putting a 130mm on the front of a 4s, either you want a 4s for what its good at and you'll use a 100 (maybe 110mm) fork or its the wrong bike for your riding!

    What fork (EXACT model), how easy/costly to drop the travel? Or maybe sell and buy an equivalent used one?
    I have a rockshox revelation that started at 120mm but I got the different spacers to increase the travel so could get it back to 120mm.
    Like I say if it’s going to screw the bike up then I will look at other frame options. This BMC came up cheap so was looking at my options. I could still get the frame and then start to gather the correct parts, I love a project.
  • The RookieThe Rookie Posts: 27,748
    So the EXACT model is probably an older dual air with spacers, you just need more spacers to lower the travel (and it will go to 110 or 100), easy and cheap. If its the later solo air it would mean a new air shaft.
    I like the Rev (have one on my Whyte set to 135mm), it would be a good fit for the 4S, just get it travel adjusted.

    The 4S is a focused XC bike, it will be fine on red trails but not in its element, if that's not the bike you want then however cheap it is it's too expensive!
  • ed1973ed1973 Posts: 181
    The Rookie wrote:
    So the EXACT model is probably an older dual air with spacers, you just need more spacers to lower the travel (and it will go to 110 or 100), easy and cheap. If its the later solo air it would mean a new air shaft.
    I like the Rev (have one on my Whyte set to 135mm), it would be a good fit for the 4S, just get it travel adjusted.

    The 4S is a focused XC bike, it will be fine on red trails but not in its element, if that's not the bike you want then however cheap it is it's too expensive!

    Thanks for the great advice it’s much appreciated.
    I would prefer a bit more travel than 100mm so it’s back to the drawing board.
  • The RookieThe Rookie Posts: 27,748
    Sounds like you're after a trail bike, have a look on ebay the Trek 29er frames go reasonably cheap and Whyte T129 frames pop up as well.
    Mine is a self built T129, Stans wheel, Formula brakes, Rev forks with RCT3 damper and dig valve rebound built using a 29 lower under 26" uppers, Giant dropper, X0 cranks and an RP23 shock. Sub 13.5Kg.
  • ed1973ed1973 Posts: 181
    The Rookie wrote:
    Sounds like you're after a trail bike, have a look on ebay the Trek 29er frames go reasonably cheap and Whyte T129 frames pop up as well.
    Mine is a self built T129, Stans wheel, Formula brakes, Rev forks with RCT3 damper and dig valve rebound built using a 29 lower under 26" uppers, Giant dropper, X0 cranks and an RP23 shock. Sub 13.5Kg.
    Sounds fantastic, I’m pretty sure a trail bike will be fine as I’m only really bombing around Cannock or Sherwood Pines.
  • oxomanoxoman Posts: 8,825
    For cannock and Sherwood red routes I just use my Anthem with no issue's, used to do it with 100mm travel bso. Only bit I don't do on it is stile cop.
    Too many bikes according to Mrs O.
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