160mm Forks on San Quentin?- Mtbr.com
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  1. #1
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    160mm Forks on San Quentin?

    My third post in three days, this will be the end of it! Basic story is I want to try out an aggressive hardtail but can't hire or afford two quality bikes.
    What are your thoughts of putting my 160mm Pikes on a san quentin? Essentially, buy the SQ 1 and transfer a bunch of parts (dropper, forks, brakes) to beef it up... Or just run the 120mm forks until they crap out.

    Cheers

  2. #2
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    General rule of thumb is 20mm of travel from stock spec, no more than that or the warranty would be voided.


    Sent from my iPhone using Tapatalk

  3. #3
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    Very bad thought. Front wheel will take energy and effort as you try to climb, your higher C.O.G. is not going to benefit you as you head back down. What are you riding now, or what frame did you break?
    The suspension of your bike sucks if it's different than mine. Really. It sucks. Big time.

  4. #4
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    I've never really worried looked into this, and I honestly don't know. What I do know, is if it works, it will change the behavior of the bike pretty dramatically.

    A 160mm fork is over forking that bike by quite a bit. That will slacken the head angle by ~2 degrees, and will raise the bottom bracket by a fair bit (there are calculators out there for doing this that will give you the exact numbers, I'm just feeling a bit lazy tonight). The bottom bracket drop on the San Quentin is 50mm, so even if it raised 20-30mm, that would be enough to change the handling quite a bit.

    Additionally, the seat tube angle would slacken (not sure if its the same 2 degrees as the head angle).

    Presuming that the axle to crown distance isn't a problem (that's the part I don't have a full grasp on, I just know its a "thing" that you should likely measure/check in on) that would leave you with a bike with a ~63 degree head angle, ~73ish degree seat tube angle, and a limited BB drop.

    Alternatively you could throw on an angleset, and the longer fork. I know that would limit the change in angles of the BB and seat tube, and may make for a better behaving bike. But, I don't know all the in's and outs of that method either. I just know it "exists".

    Anyway, maybe I gave you more questions than answers. But perhaps now you have a few things to look into that may eventually lead you to the right answer.

    Good luck .

  5. #5
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    Cheers for the feedback, the San Quentin 3 is 130mm shocks so I thought I may get away with 150mm (change the air shaft) however it's already slack enough at 65 degrees with 130mm shocks. I also like the steep seat tube for climbing so making it slacker with big shocks is a silly idea.
    I'm gonna get my hands on a 130mm debonair air shaft and change that over, then the shocks will be good to go and a pretty good spec for the bike! Hopefully! Open to other ideas though! Cheers for the replies, this forum is an absolute gold mine of knowledge..
    Last edited by anthonylowe; 06-02-2019 at 01:34 AM. Reason: grammer

  6. #6
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    I put a 160mm fork on a frame made for a 120mm. It slackened out the HT angle to 66 degrees and it flies down steeper and rougher terrain and doesn't climb like sh!t. Try it. If if it works for you, and you dig it, keep it that way. Worst case, you can simply go back to less travel.

  7. #7
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    Chucked in a debonair 140mm air shaft in the 160mm forks. Installed them on the SQ and it's awesome. Better than expected - climbed well, and descended awesome! Have no idea what the new geometry is but it feels good. Thanks for the replies

  8. #8
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    Quote Originally Posted by anthonylowe View Post
    Chucked in a debonair 140mm air shaft in the 160mm forks. Installed them on the SQ and it's awesome. Better than expected - climbed well, and descended awesome! Have no idea what the new geometry is but it feels good. Thanks for the replies
    Here's a geo calculator, if you're curious:

    https://bikegeo.muha.cc/

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