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  1. #1
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    question about Specialized M2 frame geometry

    I recently bought a 1995 M2 FS bike with all new components for cheap. The only thing original is the frame itself. I'm curious about the newer fork (a Rock Shox Psylo) and how it fits this frame. I believe this fork has 80-125mm travel, based on how it's set. Either way, it's longer travel than the original Mag21 fork.

    I'm curious about the riding position now. I recently measured the head tube angle and it appears to be about 68.5. I read somewhere on this site that it was 71.5 with the original fork, which is pretty steep, even for that era.

    Modern mtbikes now seem to average about 68, so does this mean that I basically have "modern" geometry now and it's all good? Or are there other factors that would make the fork height more problematic? I know the general rules about pros and cons of slack vs steep angles. I haven't really ridden good bikes enough in technical situations to compare this bike to others.

  2. #2
    Hardtail Steel Forever
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    71 was pretty much standard for XC bikes through 2000 or so.

    These took a 63mm or lower fork. The axle to crown was something in the 390mm range. You can usually get a way with an older 80mm'ish fork with a max axle to crown of around 425mm, newer forks are typically too tall. Anything beyond that, and it really messes up the geometry and the ride quality. The problem with newer 80mm forks is they increased the height so they're routinely 455mm or more. From a Q21 to a current fork, you could be adding 2.5 - 3in in front.

    This is a fairly universal issue with older steep geo bikes from the 90's. If you put a modern fork on them it both raises the bottom bracket and front end quite a bit and overly slackens out the headtube angle. The combination typically ruins the snappy feel that these usually have.

    Separately, I would stay away from Psylo's entirely. They a notably bad fork, they're heavy, flexible, and unreliable.

    This is one of the best options for that frame. It's one of the lightest forks ever made and still have very usable travel and easy to find most parts for: https://www.ebay.com/itm/1998-Rocksh...e/362283430165

    I still have one that is on the original seals and wipers from 1999. Admitedly, I'm afraid to mess with it at this point.
    WTB: Med Bontrager Ti Lite, PM Me...

  3. #3
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    This is super helpful, thanks. That fork seems like it's going to be pretty expensive (more than I paid for the bike!) but I will keep an eye out for one. Are there other fork options you recommend that are newer? I do really like the disc brake that's on there now.

  4. #4
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    any 80mm fork will do. It might be hard to find one with brake posts. If you can find an 80mm sid or a bomber you should be able to maintain it for a bit. The taller forks also slacken the seat tube angle which puts you in a weird pedal position. Newer bikes have slack head tubes but also steep seat tubes for efficient pedaling. https://www.ebay.com/itm/Marzocchi-B...AAAOSw5T9atwGZ this bomber would be pretty sweet. Also 200$ for a good for from this era is about what you will need to pay.
    Looking for a Medium Scott Scale frame, preferably a 2012 in 26.

  5. #5
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    For a more modern and efficient seating position, get a zero setback seatpost.
    https://www.ebay.com/itm/263431342234

  6. #6
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    Do you mean to specify only this specific 1998 80mm SID, or would a different year or length SID suffice? I ask because according to this, the 63mm SID (1998) is already 435mm in height. the 80mm would be in the 450mm range, probably.

    FAQLoad - Mountain bike suspension fork axle to crown measurements

  7. #7
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    That is a good find. I think you would be happy with any 80mm fork. I had a96 stumpjumper with an 80mm judy and it road awesome.
    Looking for a Medium Scott Scale frame, preferably a 2012 in 26.

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