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 Post subject: Fork Travel
PostPosted: Wed Nov 07, 2007 10:48 pm 
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IMHO while it looks awful, we at Retro towers oft' forget, (jump bikes accepted), that the reason for a long fork is not to achieve 100 plus (170plus??) of "upwards" travel, but to be able to run a lot of sag so the front end tracks the ground, while the bars remain relatively parallel to the ground.
I ran a 140 mm fork on a bike this Summer and ran it with 50 percent sag, so it gave a really smooth ride both over concave and convex trail contours. It looked lary at rest though.
Static all these forked bikes look too front high, but with a couple of inches or so of sag, with rider aboard look a lot better and have a manageable geometry. So it can be possible to run a 100mm fork and set sag to 50mm thereby putting the geometry back to the correct angles.


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 Post subject:
PostPosted: Wed Nov 07, 2007 11:48 pm 
retrobike rider
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I reckon you're being too nice again Wold. You're just being kind to them, they messed up and used the wrong frame for the 97 pic, but by the following year they got it dead right
http://www.konaretro.com/articles/catal ... Page06.jpg

70 deg static, so equivalent to 71 deg with a rider on board and 20mm sag out of 70, exactly as it should be.

Nice to see that the serious high-end bikes were designed for straight seat posts as well.


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 Post subject:
PostPosted: Thu Nov 08, 2007 1:32 am 
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OldFatTi wrote:
Beautiful!

Andrew - how tall are you?


I'm probably a touch over 6' with longish legs so not that tall.

Even though a 20" may seem on the large size for my height I find it fits prefectly as all of my modern frames have almost identical geometry (24" eff TT etc).


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 Post subject:
PostPosted: Thu Nov 08, 2007 1:50 am 
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andrewl wrote:
OldFatTi wrote:
Beautiful!

Andrew - how tall are you?


I'm probably a touch over 6' with longish legs so not that tall.

Even though a 20" may seem on the large size for my height I find it fits prefectly as all of my modern frames have almost identical geometry (24" eff TT etc).


Yeah Kona's can be like that. That's why I love them. Had a 20" 1992 Kilauea and that seemed to fit pretty nice, if a lttle large.

I'm not trying to steal your identity or owt, I'm just trying to figure out whether I need a 19" or 20" King Kahuna... I'm 6ft 2ish maybe 6ft 3, normal-to-longish legs. Been running round on an 18" Fat with a high stem and long post for the last few years but definately need something bigger and a little less old.


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 Post subject:
PostPosted: Thu Nov 08, 2007 2:58 am 
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Anthony wrote:
It does look fantastic, but on the other hand it reminds me of the horror show in the 1997 catalogue -- same spec, but hopefully not the same frame:
http://www.konaretro.com/articles/catal ... Page06.jpg

This catalogue pic points up very well the perils in putting a long fork like a 90mm Z1 on a frame that wasn’t designed for it. The result is a 68 degree head angle, ok maybe 69 degrees when there’s a rider on board, but still way too slack, because the particular frame in the catalogue was surely designed for a fork a whole two inches shorter than the one on it.

Hopefully Andrew’s frame is more up to date and it was just that they couldn’t get a current frame for the catalogue pic, so they built up an older one.


Anthony, my frame is a 97 frame as in the catalog and other than being a couple of sizes larger than the catalogue bike has the same head angle with the the 100mm Z1. The 97-00 Hei Hei and King Kahuna frame have exactly the same geometry are where not changed to suit the evolving fork travels. (A bit off topic but the geometry was only rejigged to suit the 10omm forks around 2005, so you'll find that side by side a 97 18" frame is identical in all geometry respects to a 2004 frame).

The fork in the 97 catalog photo is a pre production Z1 (steel stanchions not eastern Al) which could also be the cause of some minor differences. The fork in the 98 catalog is the 98 z2 Bam which has 65mm travel.

In 97 you had two basic options from Marzocchi the 100mm Z1 and the 65mm Z2. In my opinion the Z2 makes the head angle too steep and the handling rather sketchy whereas the 100mm gives about a 70 degree head angle and is perfect for the bike.

I was initially concerned that the Z1 may give a choppered effect but in reality I find it better than an 80mm Z2 fork which would fit approximately halfway between the older 65mm forks and this 100mm.

Anyway, if you should find yourself in my part of the world I may let you have a test ride so you can judge for yourself ;)


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 Post subject:
PostPosted: Thu Nov 08, 2007 3:08 am 
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OldFatTi wrote:
I'm just trying to figure out whether I need a 19" or 20" King Kahuna... I'm 6ft 2ish maybe 6ft 3, normal-to-longish legs. Been running round on an 18" Fat with a high stem and long post for the last few years but definately need something bigger and a little less old.


My initial thoughts are that a 20" would be best as a longer TT, shorter stem is preferably for technical riding than the traditional retro long stem short TT, but thats my personal preference.

The only issues I had with the 20" frame is the 6" head tube means you have to find a fork with a long steerer (only an issue if you are using something old) and the when you park it next to a small frame it does look a bit like a Ti gate. The longer forks do look beter on the larger frame though...

Availability of frames may be the thing which influences your decision though :)


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 Post subject:
PostPosted: Thu Nov 08, 2007 3:13 am 
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XR2 wrote:
wow what a fantastic bike, do you happen to know what model of seat you have on it, ive been searching for a wtb saddle in that style and colourscheme for a while now.


Sorry the saddle can with the bits of bike when i got it. If it didn't have yellow on it I would have put an SLR on there instead.


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 Post subject:
PostPosted: Thu Nov 08, 2007 8:41 pm 
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andrewl wrote:
Anthony, my frame is a 97 frame as in the catalog and other than being a couple of sizes larger than the catalogue bike has the same head angle with the the 100mm Z1. The 97-00 Hei Hei and King Kahuna frame have exactly the same geometry are where not changed to suit the evolving fork travels. (A bit off topic but the geometry was only rejigged to suit the 10omm forks around 2005, so you'll find that side by side a 97 18" frame is identical in all geometry respects to a 2004 frame).

The fork in the 97 catalog photo is a pre production Z1 (steel stanchions not eastern Al) which could also be the cause of some minor differences. The fork in the 98 catalog is the 98 z2 Bam which has 65mm travel.

In 97 you had two basic options from Marzocchi the 100mm Z1 and the 65mm Z2. In my opinion the Z2 makes the head angle too steep and the handling rather sketchy whereas the 100mm gives about a 70 degree head angle and is perfect for the bike.

I was initially concerned that the Z1 may give a choppered effect but in reality I find it better than an 80mm Z2 fork which would fit approximately halfway between the older 65mm forks and this 100mm.

Anyway, if you should find yourself in my part of the world I may let you have a test ride so you can judge for yourself ;)


Interesting comments Andrew, but it’s still the case that that was the only Kona catalogue picture ever to show a xc bike with a 68 degree head angle, and I find it hard/impossible to believe that frame was designed with a 100mm fork in mind. Any more than the Explosif was. If you look on Konaretro, the 97 Explosif had a head angle of 70 with a short suspension fork, which is what I think it was designed for, and the Kilauea (which I have) had a 71 angle with P2s. I now run 80mm SIDs, which is kind of ok, but a bit too long so not that snappy. IMHO.

That’s not to say that an extra-long fork is always a disaster – you just lose some of the steering qualities that the designer envisaged, but you gain in terms of the extra travel, and it depends which you prefer. You’re a big guy, you like lots of travel and it works ok on a big frame, so that’s fine for you. But I still say if you went to a custom builder and said you wanted to use a 100mm fork, he wouldn’t design you that frame – he’d design one that had a 70 degree static angle with your chosen fork, or maybe 69.5 if you like it slacker. But not 68, surely?

Thanks for the kind offer, but I think if anything the chances of my ever being in Oz are greater than my chances of clambering onto a size 20, not without a ladder anyway!


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 Post subject:
PostPosted: Fri Nov 09, 2007 3:12 am 
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Anthony wrote:
Interesting comments Andrew, but it’s still the case that that was the only Kona catalogue picture ever to show a xc bike with a 68 degree head angle, and I find it hard/impossible to believe that frame was designed with a 100mm fork in mind. Any more than the Explosif was. If you look on Konaretro, the 97 Explosif had a head angle of 70 with a short suspension fork, which is what I think it was designed for, and the Kilauea (which I have) had a 71 angle with P2s. I now run 80mm SIDs, which is kind of ok, but a bit too long so not that snappy. IMHO.


Anthony I agree that the King Kahuna (and no Kona XC frame before MY2005 for that matter) was designed for a 100mm fork. That said with the 100mm fork the head angle on my bike is not that slack and is certainly not 68degrees. The 97 Z1 manual states that the fork is for DH use only which also makes it an odd choice for a Ti hardtail.

The catalog bike would have been protographed in early 1996 and it is possible that the frame went through some slight changes as the fork on the front definitely did. MY97 Kona bikes started being advertised around June/July 96 from the mags I have which have, which could support this argument too.

Remember the Kona angles quoted in their catalogues are a bit dubious. I can put a 97 frame next to a 98/01/02/04 in the same size and all the measurements and the angles are identical. This means the catalogue info can't be correct for all cases as it covers rigid forks, 65mm forks and 80mm forks which were all standard fitment over the years and are all different axle to crown lengths. Yes they quote a sag corrected figures in some years but even then it doesn't quite add up.

In some respects I'm surprised that you find the 80mm SID makes the steering slow. Rather than the length of the fork, my bet is that it could be more die to the flexy nature of the SID than the length. ;)


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 Post subject: forking
PostPosted: Fri Nov 09, 2007 8:48 am 
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Just to throw a complete spanner in the works, many 65-80mm forks were actually shorter at full extension, axle to crown, than many old rigid forks! I am not on about modern suss corrected, genuine OEM rigids, so a 100mm will possibly only add 25 mm! Try measuring an original P2 or UGLI fork, I was surprised. Take off 30mm of sag and your back at original geometry or steeper!


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