1998 Noleen Cross-Link C fork and K2 Smart Shock info wanted

[RetroKiwiGuy]

Hi all

Thought I would start a new post.  Already asked part of this question.  I want to know what the axle to crown length of the Noleen Cross-Link C fork is and the stroke of the K2 Smart Shock that originally came fitted to the 1998 K2 Proflex 5000 frame?  I am building up such a frame, using aftermarket components and want to compare the original bike setup with what I have got so I can get as close to the original spec.

All I know about the Noleen Cross-Link C fork is it came with 3" of front wheel travel?
And the K2 Smart Shock had an i2i length of 210mm and provided 4" of rear wheel travel?

All info will be greatly appreciated.

[kiwi]

you will need to define"crown for me.I have an x57 crosslink on my 756 so can take some mesurements

[RetroKiwiGuy]

Yes sure.

Length required is from the axle centre, at bottom of fork, to the top of the crown, where the crown race is installed prior to fitting the steerer tube through the headset.  Or in other words at the bottom of the steerer tube where it meets the fork, which is the crown.  I hope that makes sense.

Please view http://www.parktool.com/uploads/images/blog/repair_help/fork20.jpg.  The measurement is to under the race on the fork crown.

[Colin]

see:
http://idriders.com/proflex/smf/index.php?topic=3826.msg28946#msg28946

Col.

[RetroKiwiGuy]

Thanks for the info Colin.

That's the rear shock covered.  I would still like to know what the axle to crown length is of the Noleen Cross-Link C Front fork as I want to compare that length with the length of my 1999 PACE RC37 Double Crown fork, which has a a2c length of 485mm for the 120mm of given travel.  It would be great to compare the two lengths to see how much the front end of the bike is lifted, if at all.

Cheers
Retrokiwiguy

[kiwi]

Thanks for the info Colin.

That's the rear shock covered.  I would still like to know what the axle to crown length is of the Noleen Cross-Link C Front fork as I want to compare that length with the length of my 1999 PACE RC37 Double Crown fork, which has a a2c length of 485mm for the 120mm of given travel.  It would be great to compare the two lengths to see how much the front end of the bike is lifted, if at all.

Cheers
Retrokiwiguy

i will get some measurements tomorrow

[RetroKiwiGuy]

Thanks for the info Colin.

That's the rear shock covered.  I would still like to know what the axle to crown length is of the Noleen Cross-Link C Front fork as I want to compare that length with the length of my 1999 PACE RC37 Double Crown fork, which has a a2c length of 485mm for the 120mm of given travel.  It would be great to compare the two lengths to see how much the front end of the bike is lifted, if at all.

Cheers
Retrokiwiguy

i will get some measurements tomorrow

Hi Kiwi

How did you get on measuring the a2c length of your fork?

Cheers

Retrokiwiguy

[kiwi]

Thanks for the info Colin.

That's the rear shock covered.  I would still like to know what the axle to crown length is of the Noleen Cross-Link C Front fork as I want to compare that length with the length of my 1999 PACE RC37 Double Crown fork, which has a a2c length of 485mm for the 120mm of given travel.  It would be great to compare the two lengths to see how much the front end of the bike is lifted, if at all.

Cheers
Retrokiwiguy

i will get some measurements tomorrow

Hi Kiwi

How did you get on measuring the a2c length of your fork?

Cheers

Retrokiwiguy

sorry mate,i fits fine tomorrow i will drag the old girl out and get some measurements..i have an i dea its actually a girvin crosslink,but its a start eh!

[Colin]

Just measured the Crosslink CS on my 4000se and it's 430mm or 17"

Col

[RetroKiwiGuy]

Thanks for the info Colin

I suspected the a2c length would be lower then my RC37.  It's lower by about 50mm.  So effectively if I go ahead and use the fork I am planning, 120mm, I will slacken the head angle by 2 or 3 degrees, 68 or so degrees instead of the original 71.5 degrees?  I think for every inch in wheel travel, the head angle changes 1 degree approx.  A head angle of 67 or 68 degrees would slacken the bikes geometry to much for xc.  I imagine the bike would be more stable at speed but my main concern is the BB height which will affect stand over clearance.  I need to rethink my plans a wee bit. Fun, fun, fun!

Cheers

[petes97857]

Hi guys
Just to put my tuppence worth in as I have been swapping forks on a few bikes recently and it's not just the length from axle centre line that you should think about to get your figure for tube angle and BB height.

Here are a couple of other things to think about.

How much sag in your forks when in normal sitting position
This is set for my style at 15mm on my Pace RC 38 LT's 100mm travel

Offset from steerer tube line in fork crown /offset in fork travel line to axle mounting

Stack height of lower headset bearings

Wheel/tyre combination OD& tyre pressure

Yes I know all more factors to think about but areas to think about or use for your final set up

And yes I do expect some reaction from forum guru's

Pete

[RetroKiwiGuy]

I don't want to get to technical here but does anyone know if there is a formula for working out the change in BB height.  Obviously increasing the travel of the front fork by say 20mm isn't going to increase the BB by the same amount because the forks are on an angle.  Is it just a percentage in relation to the head angle, so for example, if the head angle was 90 deg any change in fork travel would correlate to 100% change in BB height.  If the Head angle is 71 deg any change in BB height would be 71% (a change of 20mm in fork travel = BB height change of 20 x .71?)  Any input will be greatly appreciated.

[Colin]

I don't want to get to technical here but ..............................

Too late! <GRIN>

Hmmmmm, well it depends upon if Pythagorean trigonometry is too technical............

Let's liken the the front forks on a bike to a right angle triangle, where the the fork leg is the Hypotenuse (c) and the vertical distance from the bottom of the crown to the floor is the Adjacent (a) {the true vertical movement} and the horizontal distance that the fork leads by is the Opposite (b); the head angle of say 71 deg is the plane angle from hoizontal, so the inside angle between (a) and (c) is then 90 deg minus 71 deg = 19deg from the vertical and lets call that Theta.

The ratio of the two sides (a) and (c) defining the angle Theta is a constant, irrespective of their lengths, namely Cosine Theta.

Thus Cosine of 19 deg. is 0.9455........

so, we have our ratio; if the fork leg (c) shortens by 1 then the true vertical (a) will shorten by 0.9455 (units of your choice) for a 71deg head angle

However, this is at the headset and you asked how much the BB height will reduce, well this is then another triangle where Theta is the angle between a hypotenuse line (c) drawn from the crown to the back axle and the horizontal adjacent (a) (fork axle to back axle)).
and this angle theta will reduce as the bike effectively pivots on it back axle (assuming no rear suspension movement) so we can't use that so easily............but an application of geometry will resolve this...........................simplistically, if you have calculated (or measured) the true vertical (a) above, this now becomes the opposite (b) in this triangle and then calculate (or measure) the other true vertical that passes from the BB through the horizontal adjacent line (a) to the Hypotenuse (c) {only measure the vertical length (b)between (a) and (c) as the BB will be below the (c) line}
You will now have two measurments that are say 20 for the fork end vertical and say 5 for the BB vertical, in this example you then have a proportion of 4:1 so if the vertical movement compresses by 4 then the BB vertical will reduce by 1..................simples.............<smile>

however, I am now even boring myself, so I'll leave it at that.

Please feel free to rip my explanation to shreds, there are several simplistic assumptions, not the least of which is ignoring the dreaded "J-Path" of the Crosslink!

I think I should be riding more and thinking less........................

<GRIN>

Col.

[racesrc]

way too much info for me, i am of the "grip it and rip it" group. i put my marzocchi dirt jumper 1 on with a 130mm of travel and gave it a little more sag to be right in the middle of it's travel range. it's super plush and theres plenty of travel both way's. i haven't noticed a difference in feel to my old marzocchi with 85mm travel except how much more plush this one is on the rough stuff.

david

[Spokes]

I was just about to say this but Col beat me to it....... ehem 

Chris