Results 1 to 11 of 11
  1. #1
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814

    1999 Explosif, A2C question

    My backup bike (and previously, primary bike,) has been a 1998 Trek 7000ZX, but then this happened.



    So I turned the frame in to see what Trek would do, but I know they don't really have anything I'm interested in/can afford right now, so I went on the search for a replacement frame.

    Ended up picking up a 1999 Explosif frame (853). Got some rust but I'll see how bad it is when it gets here. Photos don't make it look too structural but I've pined over this frame since 1999 so it's a long waited dream come true.

    Now, I know the Explosif in 1999 originally came with the Marzocchi Atom Bomb, which, as far as I can find, had an unsagged A2C of 430 or so. 10% sag would put it at 387. I was running a Surly 1x1 fork on my Trek, which as an A2C of 414. I'm thinking this will be perfectly fine. Anyone have any input?


    Also, any other Explosif anecdotes are welcome. I ride steel road bikes (Kona) but haven't ridden a quality steel MTB... ever. Would be nice to hear some stories about older Kona's and your ownership experience with them.
    Eric

  2. #2
    ish
    ish is offline
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    163
    I would run a triple butted Kona Project 2 fork with an A2C of 410. You can find them in canti only, disc only, or dual canti/disc. Any other rigid fork does not look right on a Kona MTB in my opinion.

    Kona MTBs are some of the best mass produced MTBs from the 90s. Well thought out parts combinations, nice tubing, good geometry.

  3. #3
    Certified Bike Junkie
    Reputation: muddybuddy's Avatar
    Join Date
    Jan 2007
    Posts
    1,740
    I believe that when you calculate sag you do it based on travel not total A-C. Based on 4" of travel, I'm thinking a Project II fork with a 410 A-C would be the one, and shoud be available new from any number of on-line retailers in the $75 range.
    Need: McMahon brake for roller cam mounts, Mountain Goat fork.

  4. #4
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814
    Quote Originally Posted by ish View Post
    I would run a triple butted Kona Project 2 fork with an A2C of 410. You can find them in canti only, disc only, or dual canti/disc. Any other rigid fork does not look right on a Kona MTB in my opinion.

    Kona MTBs are some of the best mass produced MTBs from the 90s. Well thought out parts combinations, nice tubing, good geometry.
    I agree a P2 fork would be ideal, I've just already got the 1x1 so I figured I'd throw it together with that and sell off some of the extra parts this came with to fund a P2 fork. Wanted to be sure the 410 would be ok. The Zocchi Atom Bomb at 2.75" of travel, so about 70mm. 10% of that would be 7mm so it'd drop the A2C to 425 sagged so hopefully that 10mm wont matter too much for the short period I run the 1x1 fork.

    Quote Originally Posted by muddybuddy View Post
    I believe that when you calculate sag you do it based on travel not total A-C. Based on 4" of travel, I'm thinking a Project II fork with a 410 A-C would be the one, and shoud be available new from any number of on-line retailers in the $75 range.
    You're right, not sure what I was thinking. As I said above the Z2 fork was 2.75" of travel or 70mm. With an unsagged A2c of 432, assuming a 10% sag, an A2c of 425 would technically be ideal but the P2's I can find in stock at my usual places are 440 (the 410's seem to be out of stock.) The salsa Cro-Moto fork is 425 A2c and is a straight tapered blade like the P2, so that's an option, but it has disc tabs and ruins the sleek look.

    I have to place an order for a seat post (I've got a bunch of 27.2's but the tube is 27.0) and collar (maybe, not sure what size collar my Trek had, but it was a 27.2 seat post) and a front derailleur anyway so trying to figure out what all I need to budget.

    Thanks both of you for your help and input! I'm pretty excited to test this out on my favorite trails and see how it compares to the Trek. Geometry is similar (Kona is slightly longer) so should be a good comparison of steel v. aluminum.
    Eric

  5. #5
    mtbr member
    Reputation:
    Join Date
    Mar 2014
    Posts
    13
    So what happened? Any updates? Have you ridden it yet?

  6. #6
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814
    This is more or less how it sits right now



    Unfortunately the steerer tube on my 1x1 Fork isn't long enough for the new frame so I'll be getting a new fork. What fork I end up getting will depend on what I can get at the bike shop I've got store credit at - very likely a QBP product and I don't think I'll be able to get a Kona fork from them. So, probably either an Instigator fork (440A2C) or a Salsa Cro-Moto (425 A2C.) Just going by looks this 413 A2c appears very short even compared to other bikes of the same generation. There is a fairly significant BB drop that my Trek didn't have and these don't appear to have when I look at factory photos. Obviously in that photo the seat post is just sort of sitting there, not really pushed down at all. That's a 27.2 seatpost and the tube is 27.0

    The build is kind of turning into neo-retro because I'm getting a bunch of parts given to me on top of the store credit, so I haven't really updated this since it doesn't much fit into the vintage/retro theme. Its a budget build but turning out nicer than my primary bike.

    If anyone else is interested:

    SRAM x7 10 speed medium cage rear der.
    SRAM x7 shifters
    SRAM X7 FD, 2 speed
    Swapped on some VeeRubber Trax tires I had, 26x2.1
    King Headset
    Either an Instigator or CroMoto fork.

    Has XT cranks from the early 2000's, needs a new bottom bracket. Getting some nsbikeco platforms that I am getting for free, and I plan on riding it for a season before I tear it back down, strip it to metal, and repaint or powdercoat it.
    Eric

  7. #7
    artistic...
    Reputation: colker1's Avatar
    Join Date
    Jan 2004
    Posts
    6,477
    that's a lot of seatpost showing..
    want: Ibis ti handlebar. suntour 31.8 front derr. bottom pull

  8. #8
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814
    Quote Originally Posted by colker1 View Post
    that's a lot of seatpost showing..

    Yeah... like I said, its a 27.2 seatpost in a 27.0 seat tube, so I didn't force it down in, just slipped it in as far as it would easily go to get an idea of how it'd look. I've got to order a 27.0 seatpost and a 29.8/30.0 collar for it. The headset isn't fully assembled and the steerer tube isn't long enough for my comfort in this head tube, plus the completely spent bottom bracket and no cables, so it hasn't been ridden yet... but hopefully soon. It was originally going to be built up as a 3x8 but because of some generous folk here on mtbr I wound up with some unexpected parts for the cost of shipping and it'll be 2x10 instead... not exactly a retro build I suppose but it should be fun anyway.
    Eric

  9. #9
    mtbr member
    Reputation:
    Join Date
    Nov 2010
    Posts
    1,867
    For what it's worth I run 100mm travel forks on my 1996 and 2006 Explosifs, A2C on them is 478mm and sag is about 10-15mm. I find the handling is just fine, nice & stable yet still nimble enough to zip through tight singletrack. I briefly had a 75mm travel fork on the 96 and thought it was a bit too twitchy, it was like cheating on tight low speed trails but at higher speeds it felt too unstable. I think the 440mm A2C fork will be the better match.

  10. #10
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814
    Quote Originally Posted by aerius View Post
    For what it's worth I run 100mm travel forks on my 1996 and 2006 Explosifs, A2C on them is 478mm and sag is about 10-15mm. I find the handling is just fine, nice & stable yet still nimble enough to zip through tight singletrack. I briefly had a 75mm travel fork on the 96 and thought it was a bit too twitchy, it was like cheating on tight low speed trails but at higher speeds it felt too unstable. I think the 440mm A2C fork will be the better match.

    Awesome - I was hoping that was the answer because that's what my gut was telling me. I thought about springing for a suspension fork but I like riding rigid every once in a while. Especially when its super cold and the suspension forks I've tried do not like my weight.
    Eric

  11. #11
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    814
    Since there were some people following this, I figured I'd post up the built photos. Haven't had it on trail yet but feels pretty awesome doing some urban riding. Very flickable despite the long fork, easy to lift the front wheel but steady down stairs/etc. I like this geometry. Haven't tried climbing with it but I imagine I'll have an opportunity this weekend to give it a shot.






    X7 front and rear, X7 shifters, 2x10 with and XT 11-34 cassette, and the 9 speed XT crank I got with the bike. Just had to replace the BB. SLX chain rounds it out. Shifts smoothly and beautifully. Cockpit is the 680mm bars and 105mm stem off of my Airborne Seeker, and I'm still running the stock-from-my-Trek Avid V-Brakes with Koolstop pads. NS Bike CO pedals finish it off, along with VeeRubber Track 26x2.1 (more like 1.9-2.0.)

    Oh, and the King headset was a bonus that came with the frame. Picked the frame up as a frame-only and it came with a whooped RS fork that I obviously didn't use, the XT cranks, and the headset in rough condition. My mechanic was able to salvage the headset and it is very smooth. First King I've had.
    Eric

Similar Threads

  1. My Explosif (re)build
    By mr2peak in forum Kona
    Replies: 8
    Last Post: 08-29-2012, 07:07 PM
  2. looking for kona explosif
    By JRR in forum Singlespeed
    Replies: 2
    Last Post: 12-12-2011, 08:14 AM
  3. question about upgrading a kona shred/explosif
    By terminalvertigo in forum Bike and Frame discussion
    Replies: 2
    Last Post: 06-18-2011, 04:00 PM
  4. Kona Explosif
    By micyclebicycle in forum Kona
    Replies: 1
    Last Post: 06-04-2011, 11:16 AM
  5. Powdercoat a Hot or Explosif?
    By mrjustin007 in forum Kona
    Replies: 2
    Last Post: 01-13-2011, 04:44 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •