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  1. #1
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    Convert Trail bike to DJ?

    I've realized I really like riding the jumps in my local park and I'm wondering if there are a few modifications I can make to my old hard tail Marin Palisades Trail bike to make it a serviceable DJ bike.

    It's geometry is very different from all DJ bikes I've seen. It has a 20" seat tube and 24" top tube, front shock with 100mm of travel along with a really long stem (around 5") and relatively narrow handlebars.

    Would something like a short stem and wider handle bars make a big enough difference? Or is the stand over height going to kill me and I should just start looking for used DJ bikes on craigslist? My end goal is to avoid trashing my brand new AM bike.

  2. #2
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    I think a 20" seat tube is too tall to jump in any reasonably good way.

    Almost everything about a DJ bike is different from XC/AM, so common wisdom is "don't try to convert," just get a second bike.
    1. DJ fork is tuned to be stiff, not mushy.
    2. Crank arms and spindle are intended for much more stress.
    3. Rims designed for impacts.
    4. Pedals designed for skate-type shoes.
    5. Stems have bmx reach--typically 40mm to 55mm, with most being 50mm.
    etc.



  3. #3
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    DJ and XC bikes are purpose built, however I have used my old Specialized HRXC frame with some select components and now have a pretty "aggressive XC" bike that can rail a pump track or a small set of table tops. Smooth landings and the occasional post ride frame inspections are a must.

    Our local jumps are built into separate loop of an XC based 13 mile trail system, sometimes I will ride the entire trail on my dirt jumper, but those days are growing older as I am too.

    Here is the inspiration for the build.

    Lee Likes Bikes

  4. #4
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    Quote Originally Posted by chain_slap View Post
    DJ and XC bikes are purpose built, however I have used my old Specialized HRXC frame with some select components and now have a pretty "aggressive XC" bike that can rail a pump track or a small set of table tops. Smooth landings and the occasional post ride frame inspections are a must.

    Our local jumps are built into separate loop of an XC based 13 mile trail system, sometimes I will ride the entire trail on my dirt jumper, but those days are growing older as I am too.

    Here is the inspiration for the build.

    Lee Likes Bikes
    That's a good link. A little surprised he didn't say what frame size it is. To me, that's the main limiting factor--people have old xc frames with the seat tube too tall. I think for me, I could still comfortably pump/jump with seat at about 15', maaaybe 16' from the bottom bracket. I have long legs though....

  5. #5
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    Quote Originally Posted by chain_slap View Post
    Thats exactly what I'm going for. I'd really like to be able to ride the 3 miles or single track to the bike park rather than drive. Looks like a project for the spring...

  6. #6
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    My HRXC is a 17" and has the same head tube angle, seat tube angle, and chain stay length. Lees frame is probably a 17" too judging by his height.

  7. #7
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    @terp:

    3 miles? I ride at about 3-4 miles to the bike park on my dirt jump bike... I personally don't see an issue with it... I just stand and pedal most of the time, occasionally stand and coast or lean my knee on the top tube or even sit down on the down hills.... it will take a little getting use to but if you are truly going to use this bike specifically for the bike park, I would highly recommend getting a bike built for a bike park... ie: a dirt jump or slope style bike... you wont regret it.

  8. #8
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    From that leelikebikes link I found a pic where you can see how tall the stand-over is on his bike. It's relatively low. This is the only way what he's talking about will work.

    Some of the mid-2000's dirt jumpers like a Kona Shred, Kona Stuff, DK Xenia had medium height seat tubes.


  9. #9
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    The frame he uses is a specialist stump jumper evo HT, they don't even make it in the US as far as i know.. it is more of an All M HT 26 inch bike slacker and lower slung than the standard Stumpy HT

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    This is what I built up from left over parts, even at 5'9" the stand over height is acceptable with the seat slammed, more for trail and pumping than jumping, sometimes I just want to ride......

  11. #11
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    Just go hit some jumps, even if it's not an ideal set up...if it's fun, keep doing it! I have a 650b hard tail, and I love hitting small dirt jumps with it!

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    Re: Convert Trail bike to DJ?

    Thanks again for setting me strait everyone. The solution was stareing me in the face the whole time: more bikes! Picked up a used gt ruckus dx with a 9 speed cassette to make getting around a little easier. Now I'm off to make new shapes out of my collar bone.

  13. #13
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    nice! have fun!

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